CN204514392U - The digital indication flow meter of a kind of experimental teaching band piezometric tube display - Google Patents
The digital indication flow meter of a kind of experimental teaching band piezometric tube display Download PDFInfo
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- CN204514392U CN204514392U CN201520219340.3U CN201520219340U CN204514392U CN 204514392 U CN204514392 U CN 204514392U CN 201520219340 U CN201520219340 U CN 201520219340U CN 204514392 U CN204514392 U CN 204514392U
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Abstract
The utility model discloses the digital indication flow meter of a kind of experimental teaching band piezometric tube display, comprising: for generation of the differential flow signal generator of pressure difference signal; Two groups of manometric module, often organize manometric module and comprise pressure measurement cylinder, are communicated with positioning pipe and piezometric tube; For detecting the pressure transducer of two pressure measurement cylinder compressed air pressure differences; Pressure signal for being detected by pressure transducer converts the micro computer digital display meter head of flow to; For pacifying the fixed support of piezometric tube; For demarcating the graduated scale of liquid level in piezometric tube.The utility model device, comprehensive, novelty make use of the difficult problem that fluid mechanics principle solves experiment measuring display, and combine traditional piezometric tube and modern measurement technology, there is high precision, high display property, can be widely used in hydrodynamic calculations instruments used for education, can be motivated students' interest in learning, inspire the creativity consciousness of student, useful to cultivation innovation ability, possesses good teaching efficiency.
Description
Technical field
The utility model relates to experimental measurement field, is specifically related to the digital indication flow meter of a kind of experimental teaching band piezometric tube display.
Background technology
Hydraulics and fluid mechanics are main specialized core courses of the many specialties of engineering and polytechnic universities.Modern hydraulics is based upon experiment, theory, calculates on three large pillars, and therefore, experiment is content indispensable in teaching link.
Wherein, experimental teaching low discharge, small pressure difference, the high-precision digital-display flow measurement device of small pipeline current, be in space state at present.For small desk fluid mechanics hydraulics instruments used for education, because its caliber is usually below 30 millimeters, flow 5-300ml/s, flow is often very little, is traditionally main with weight chronometry or volume chronometry hand dipping.If when being equipped with modern measuring instrument conventional on the market, in experimental teaching application, but there is a lot of problem, for typical differential flow instrument:
Differential signal generator (the routine venturi of differential flow instrument, orifice plate etc.) the flow signal pressure reduction great majority that produce are only 0.1-80 centimeter water column, and existing flow instrument is directly connected with the pressure tap of pressure difference signal generator by sensor by cross current pipe, the pressure of sensor is transmitted by water body, sensor side is sealing, inside there is air barrier, pressure water post in communicating pipe can not act directly on the pressure chip of sensor, again because the pressure communication channel in sensor is very tiny, thus on liquid gas interface, very large surface tension is produced, its value can reach 1-5 centimeter water column, even larger, the pressure error of flow signal is made to reach more than 10%, low and middle-end flow error can be caused to reach 10%-30%, thus this type of flow instrument cannot for there being the experiment device for teaching of high-precision requirement.
Now commercially also there are the non-differential flow instruments such as the turbo flow meter of supply pipe with small pipe diameter, but the flow measurement range of the above precision of this type flowmeter 1%-2% at present, the 70%-100% of its full scale, all inapplicable below 30%, and common small sized desk-top fluid mechanics hydraulics instruments used for education empirical flow scope is just in time in less than 30%, so be also to select.Thus for a long time the high precision flow of small desk Hydrodynamics in Teaching instrument is in the space state in market.
Meanwhile, as the piezometric tube of one of pressure measuring instrument the most conventional in hydraulics and hydrodynamic calculations process, it is measurement mechanism indispensable in such experiment teaching instrument.In this field experimental apparatus configuration, according to often kind of experiment demand, in order to measure the pressure signal at multiple position in experimental channel or water tank simultaneously, multiple piezometric tube can be fixed on rack of measuring pressure side by side by same level height, form one group of row's formula many piezometric tube measuring cell, this traditional pressure tester can pass through pressure transfer mode, with piezometric tube water colunm height very vivid demonstrate each pressure tap pressure size, possess good teaching efficiency.Certainly, how the row's of application ducted multiple pressure head of formula many piezometric tube experiments of measuring is also the basic pressure testing method that student needs to be grasped.As the differential flow instrument of education experiment application, if can by differential flow signal generator 2 end pressure signal high precision be converted to flow gauge outfit display while, pressure values is gone out again by piezometric tube water column simultaneous display, that just can integrate with traditional pressure measuring tool, possesses better teaching efficiency.
But tradition to be arranged formula piezometric tube and high precision as above-mentioned to be applicable to the differential pressure flowmeter that low discharge measures and to combine, and a whole set of site measuring and control type innovative experiment device can be integrated into, a lot of problem is also had to need to solve, such as the automatic vent problem of real-time zeroing problem, many piezometric tube.
Real-time zeroing problem: as this kind of electric measuring instrument, usually needs real-time check for zero, after electronic scale weighing, removes weight and just can verify its zero point, and the quite stable at zero point of this instrument.But for pipe stream, owing to being subject to the impact of temperature and Fluid Pressure Field in experimentation, thus zero point is not very stable.Traditional flowmeter, when needs zeroing or check for zero, often needs to carry out barrier gate when pipeline is full of current, makes in-pipe flow transfixion.This can stop experimental implementation halfway for education experiment, under the state coming back to experiment beginning, re-starts experiment, very inconvenient.Therefore, it is possible in experimentation, do not need shutdown when, in real time zeroing or check for zero extremely important.
The automatic vent problem of many piezometric tube: when applying piezometric tube water column and measuring pressure tap pressure, often there are bubble or gas column are detained communicating pipe bottom piezometric tube and between pressure tap, the measuring error of piezometric tube can be caused, must drain to the delay bubble of communicating pipe for this reason, subject claim this be piezometric tube exhaust.Its method utilizes ear washing bulb (blowing up a balloon) to inflate draining to every root piezometric tube, then the water pressure gravity flow of measuring point is utilized to flow in piezometric tube, its bubble be communicated with in tubule is taken away, until be full of continuous print liquid below liquid level in communicating pipe and piezometric tube with current.This bleeding can manage it to single tube, but the measuring cell to multitube, the especially piezometric tube of tens of, experimenter often feels to be difficult to bear.In order to realize electrical autocontrol exhaust, handled easily, be that whole experimental provision can realize the function of the telnet experiment towards MOOC in the future simultaneously, the present inventor once trial air pump carries out the method for electricity exhaust, solve this difficult problem, but need to arrange a little air pump to each root piezometric tube, the synchronous degassing function of many piezometric tube could be realized.This is because every root piezometric tube measuring point pressure is different, some piezometric tube measuring point pressure is very low, even close to atmospheric pressure, in the case, if adopt the mode of multitube one pump to be vented, as long as so there is the pressure measurement port of wherein one or a few piezometric tube to discharge air-flow, gas circuit short circuit will be caused, the main channel upward pressure of gas circuit is die-offed, and causes other piezometric tube all not arrange water, does not thus reach synchronous exhaust effect.So want to use the mode of multitube one pump to be vented, also will design special structure, ingenious utilization fluid mechanics principle could solve.
Utility model content
The digital indication flow meter providing the display of a kind of experimental teaching band piezometric tube of the present utility model, apply principles of fluid mechanics cleverly, devise the differential digital indication flow meter of high precision being applicable to experiment low discharge and measuring, combine with traditional row's formula piezometric tube, well traditional measurement means and modern measurement technology are unified, be integrated into a whole set of site measuring and control type innovative experiment measurement mechanism, have splendid teaching efficiency concurrently.
A digital indication flow meter for experimental teaching band piezometric tube display, comprising:
For generation of the differential flow signal generator of pressure difference signal; With two pressure taps on described differential flow signal generator;
Two groups of manometric module, often organize manometric module and comprise a pressure measurement cylinder, each pressure measurement cylinder bottom is provided with water inlet, top is provided with connection positioning pipe, the piezometric tube be connected with described connection positioning pipe; Two groups of manometric module are connected respectively by two pressure taps of respective pressure measurement cylinder lower water inlet with described differential flow signal generator; Two pressure taps of described differential flow signal generator are two pressure taps exporting pressure reduction, and one is that pressure is high-end, and one is pressure low side;
Be connected with two pressure measurement cylinders in two groups of manometric module, for detecting the pressure transducer of described two pressure measurement cylinder compressed air pressure differences;
Be connected with described pressure transducer, the pressure signal for being detected by described pressure transducer converts the micro computer digital display meter head of flow to;
For installing the fixed support of two piezometric tube in two groups of manometric module;
For unified graduated scale, the zero graduation of described graduated scale and the same level face, bottom surface being communicated with positioning pipe in described two pressure measurement cylinders of demarcating liquid level in described two piezometric tube.
Following as preferred structure of the present utility model:
The digital indication flow meter of described experimental teaching band piezometric tube display, also comprise: two automatically controlled breather valves, each automatically controlled breather valve at least comprises three tunnels, one tunnel of each automatically controlled breather valve is communicated with a pressure measurement cylinder compressed air, another road of each automatically controlled breather valve is connected with described pressure transducer, and each automatically controlled breather valve also has a road and air conducting.
The digital indication flow meter of described experimental teaching band piezometric tube display, also comprises: the air pump be communicated with the open top of described piezometric tube.
Described air pump is communicated with by the open top of shunt with two piezometric tube, is connected with damping element between described shunt and piezometric tube, described shunt is sealedly connected with the automatically controlled breather valve of exhaust; Described damping element is seal, and the seal is provided with the air hole of ventilating for described shunt and described piezometric tube.
Exhaust nozzle and the described shunt of described air pump are tightly connected.
Described pressure transducer is relative pressure sensor, specifically can adopt pressure difference sensor.
Described fixed support is provided with horizontal survey chute, and this horizontal survey chute is provided with slide block, and described graduated scale is be arranged on the ruler on described slide block.
Described ruler is provided with elongated hole, and this ruler to be coordinated with this elongated hole by screw and is fixed on described slide block.
The water inlet of described pressure measurement cylinder is positioned at the sidewall bottom of described pressure measurement cylinder.
The digital indication flow meter of the utility model experimental teaching band piezometric tube display has 2 straight pipe type piezometric tube be vertically arranged on side by side on fixed support, air is led in the open top of piezometric tube, there is water inlet bottom surface, piezometric tube can vertically be placed on the desktop of the level of mixing up under fixed support supports, a horizontal survey chute is had on fixed support top, horizontal survey chute is hung with one piece of slide block, ruler (transparent) top has the elongated hole of vertical direction, be screwed on slide block, slide block can move horizontally, transparent ruler just can be used with same zero elevation reference field, measure water colunm height in each piezometric tube.Simultaneously in order to keep ruler zero point, elevation surface level inserted with pressure measurement cylinder top is communicated with same level face, positioning pipe bottom surface, by slide block bottom for being connected and fixed the vertical elongated hole of ruler, finely tune the fixed position up and down of ruler.
Fixed support is placed on one and mixes up on the experiment desktop of level, and table top limit is provided with two that connect, that be with zero-bit elevation location pressure measurement cylinders corresponding to piezometric tube, and can make of clear perspex material, inner retaining is clearly visible, facilitates Germicidal efficacy.Further, two pressure measurement cylinder external and internal compositionses, size are identical, are fixedly bonded on same level connecting bottom board.Pressure measurement cylinder height is higher than surface level about about the 1 ~ 3cm at ruler zero point.Pressure measurement cylinder can be a hollow cylinder or polygon hollow column structure, and as row's formula pressure measurement cylinder, each barrel can directly vertically seal bonding with same connecting bottom board, using connecting bottom board as each pressure measurement cylinder seal base.Each pressure measurement cylinder end face has an aperture, vertical insert sealing and is bonded with one and is communicated with positioning pipe with the water inlet pipe of water inlet bottom piezometric tube with external diameter.The general internal diameter of water inlet pipe being communicated with positioning pipe and water inlet has about 4mm more greatly.Connection positioning pipe exceeds end face and is about 1cm, is convenient to seal external PVC water service hose, and is communicated with inlet seal bottom corresponding piezometric tube, forms the sealing ventilating water pipe of piezometric tube water column.Be communicated with positioning pipe and insert the pressure measurement cylinder degree of depth about 1 ~ 3cm, bottom surface level, and keep the surface level isoplanar with ruler elevation at zero point.Two pressure measurement cylinder lower sidewall have a pressure measurement water inlet close to bottom surface, and salable external water service hose is connected on two pressure taps (i.e. pressure measurement mouth) of differential flow signal generator.Differential flow signal generator is last point of experimental channel, and pipeline is connected with the head piece that goes out of Experimental Water Tank by experiment.
During experiment, experimental channel is full of full packages current, two pressure taps (i.e. pressure measurement mouth) of differential flow signal generator can produce pressure reduction, after connecting pressure measurement cylinder, it is inner that water can enter pressure measurement cylinder from sidewall water inlet bottom pressure measurement cylinder, after water level arrives the bottom surface surface level of top connection positioning pipe, water level no longer rises, water can enter connection positioning pipe, then piezometric tube is entered, form piezometric tube water column, after each piezometric tube water colunm height is stable, horizontal slip ruler, measure the head pressure that two piezometric tube water colunm height numerical value are two pressure tap relative ruler elevation at zero point reference level surfaces of corresponding differential flow signal generator respectively.One section of air column then can be sealed to its top at the connection positioning pipe bottom surface surface level of pressure measurement cylinder, owing to being communicated with the surface level isoplanar of positioning pipe bottom surface surface level and ruler zero point, so this section of seal compression air column pressure is piezometric head pressure and atmospheric pressure sum.
In order to measure this section of seal compression air column pressure, an aperture is had on pressure measurement cylinder top, the snorkel sealing bonding insertion one thinner (can insert from top, also can insert from upper portion side wall), the highest water surface in bucket is not encountered in snorkel bottom surface, and the salable external hollow vent pressure measurement flexible pipe of pressure measurement cylinder outside about about 1cm stayed by snorkel.In order to pressure and the pressure reduction of the touring electrical measurement of energy two pressure measurement cylinder compressed airs, two pressure measurement cylinders respectively by a-road-through gas pressure measurement flexible pipe, then are connected with the two ends pressure measurement interface of pressure transducer through an automatically controlled breather valve (i.e. automatically controlled threeway) respectively.Two electric control valves have 3 road valves, and the first via is communicated with pressure measurement cylinder snorkel with by pressure measurement flexible pipe, and the second tunnel leads to air, the 3rd tunnel respectively with two pressure measurement orifice of pressure transducer.Two automatically controlled three-way air valves when no power, the first via and the 3rd tunnel conducting, the second tunnel is not communicated with other two tunnels; During energising, the second tunnel is communicated with the 3rd tunnel, and the first via is not communicated with other two tunnels.
Final pressure sensor signal is sent by traditional circuit change and is input to micro computer digital display meter head, by the switching control combination of two electric control valves (i.e. automatically controlled three-way air valve), can two pressure taps of touring display differential flow signal generator are corresponding on micro computer digital display meter head piezometric tube water colunm height digital display value, the pressure reduction that recorded by pressure transducer to convert the experimental channel flow value obtained.
Meanwhile, the textural association that two electric control valves (i.e. automatically controlled three-way air valve) are communicated with the pressure measurement cylinder of positioning pipe with band also has a very important real-time zeroing function.Pressure sensor signal by traditional circuit become send be input to micro computer digital display meter head time; usually traditional sensor zeroing compensating circuit can be provided with; prior art can be adopted; can realize pressure transducer input pressure difference signal is zero; and output voltage non-vanishing time, compensating approach be no-voltage export function.Traditional sensor zeroing compensating circuit cardinal principle is the magnitude of voltage utilizing potentiometer change sensor to export to micro computer gauge outfit, the signal negative terminal voltage that micro computer digital display meter head is received can regulate, thus make the displayed value of micro computer digital display meter head, be adjustable as zero.In this measurement mechanism, liquid gas interface due to two pressure measurement cylinders keeps contour, therefore, in the mode of any moment all by making two electric control valves (i.e. automatically controlled three-way air valve) be energized simultaneously of experimentation, two of pressure transducer pressure tap are communicated with air simultaneously, then regulate by the potentiometer of zeroing compensating circuit operation of returning to zero in real time.
But, if select two pressure measurement cylinders are not communicated with positioning pipe structure, liquid gas interface can not be allowed to keep contour, then under the constant voltage head of Experimental Water Tank, close experimental channel go out to flow valve, when keeping experimental channel full-section pipe-flow flow to be zero, two lie in the pressure measurement cylinder on the good desktop of leveling because liquid level is not contour in cylinder, certainly non-vanishing to the input pressure difference signal of pressure transducer by pressurized air conduction pressure, now output voltage is also non-vanishing, operate according to zeroing, when experimental channel flow is zero, we should regulate the potentiometer compensating approach in zeroing compensating circuit to be that no-voltage exports to micro computer digital display meter head, to show flow null value, but the operation that this zeroing compensates can only be initial in experiment, carry out during experimental channel full-section pipe-flow zero flow, cannot can to return to zero in real time at any time in experimentation as the aforementioned operation.
In the experimental provision of above-mentioned utility model, be air pressure when in pressure measurement cylinder, the air column of connection positioning pipe bottom surface closed upper part is initial, the pressure of being come by differential flow signal generator two end pressure tap (i.e. pressure measurement mouth) conduction in pressure measurement cylinder (or piezometric tube synchronously import water column pressure) understands air column in compression cylinder, liquid gas interface in cylinder is made to be increased beyond the surface level at ruler zero point, although this error relative error not high (<0.2%), but when piezometric tube water column is higher, such as during 80cm, when in pressure measurement cylinder, initial occluded air post height is 3cm, error has 0.22cm.This measures zeroing in real time and actual flow or can produce some measuring error, in order to improve precision, eliminate this error, consider the automatic vent of piezometric tube simultaneously, the gas bubbles left easily brought during to eliminate initial water inlet in piezometric tube, this experimental provision devises the aerator of a pump multitube, and structure is as follows: add on two piezometric tube tops the shunt be connected with piezometric tube, connects the damping element of two piezometric tube and shunt; The air pump (in this experimental provision, can micro air pump be adopted) be connected with shunt, the exhaust electric control valve be connected with shunt (i.e. automatically controlled two breather valves).
When reality is implemented, a set of fluid mechanics hydraulic experiment device is except pipeline flow needs measurement, also to measure the pressure of multiple point, piezometric tube number for pressure measurement has 2 ~ 20 usually, therefore shunt is generally the gas circuit linker of more than triple channel, namely on fixed support, 2 ~ 20 piezometric tube are installed, but when implementing according to the technical solution of the utility model, namely only need access 2 piezometric tube from 2 ~ 20 piezometric tube can realize the utility model object.In the utility model embodiment, piezometric tube is two, and shunt can adopt gas circuit threeway, and a road seals with the exhaust nozzle of air pump and is communicated with, and also has two-way to be sealed with the open top of two piezometric tube by damping element and is communicated with.
Damping element is seal, the seal is provided with the air hole of ventilating for shunt and piezometric tube, this air hole is damping hole, and be the micropore that the damping element of the complete trapping of energy in connecting pipe is offered, its pore size can reach the exhaust outlet effect of choked flow supercharging.
Each damping element is positioned in the connecting pipe between the outlet of shunt and the open top of piezometric tube respectively, makes air-flow can only flow into each piezometric tube from damping hole.
In normal measurement situation, piezometric tube open top must lead to air, on shunt, be provided with the automatically controlled breather valve of the exhaust be communicated with it (automatically controlled two breather valves of concrete available open type) for this reason, connected by conventional control circuit, it is energized when air pump works closedown simultaneously, and when air pump stops, power-off is simultaneously opened automatically.
By upper, during energising, air pump is left, be vented automatically controlled breather valve (automatically controlled two breather valves of open type) and close, 2 pipes that can carry out piezometric tube are vented and reset operation simultaneously.Due to the current limliting pressurization of damping element, utilize a micro air pump, just can synchronously be vented 2 and even many piezometric tube simultaneously, even if under some pressure measurement end of piezometric tube all leads to atmospheric condition, also drainage exhaust can be carried out to the piezometric tube remaining press liquid in a single pipe wherein.In this experimental provision, electric control exhaust also has reset function be detained bubble in elimination piezometric tube while, namely during actual exhaust air operation, need to wait each pipe water column in piezometric tube all to enter in each pressure measurement cylinder, and liquid gas interface in each cylinder is forced down by the pressurized air that air pump is blown into, connection positioning pipe bottom surface surface level in each cylinder of firm disengaging, after reaching reset effect, then makes air pump, breather valve power-off.Now, each pressure measurement cylinder internal upper part is no longer the air column of initial atmosphere pressure, and be through the pressurized air post of air pump air blowing press-in, air pump stops, after breather valve is opened, reopen the gas circuit that pressure measurement cylinder top communicates with ambient atmosphere, but equally due to the current limliting pressurization of damping element, while in pressure measurement cylinder, liquid level gos up to be extruded away by the damping hole of the damping element of piezometric tube by cylinder internal upper part pressurized air, pressure equilibrium can be obtained by pressurized air that is automatic and cylinder internal upper part, when in pressure measurement cylinder, liquid level goes back up to the bottom surface surface level being communicated with positioning pipe in cylinder, two measurement points that namely the closed compression air column pressure of each pressure measurement cylinder internal upper part equal differential flow signal generator in corresponding experimental channel conduct the head pressure+atmospheric pressure of coming.Thereafter, in corresponding piezometric tube, water column goes back up to onesize water column pressure height, and two pressure measurement cylinder internal upper part pressurized air because compressed and achieved gas-liquid pressure balance before closing, make liquid gas interface increase so can not recompress, produce the error with ruler elevation at zero point surface level.Resetted by exhaust cleverly like this and design and operation, initial atmosphere pressure air column in pressure measurement cylinder can be eliminated accurately and compress the systematic error brought, improve experimental precision.
In the above-described embodiments, during embody rule, damping hole (i.e. air hole) size of damping element needs to be applied in which fluid mechanics hydraulic experiment device according to this measurement mechanism, and according to the number of row's formula piezometric tube, main snorkel piezometric head decides.Such as, Integrated predict model has in the experimental provision of 6 piezometric tube at one, the utility model only need access and use 2 piezometric tube can realize the utility model object from 6 piezometric tube, the piezometric head of its piezometric tube 1 ~ 6 is generally within 1 meter, if wherein 5 piezometric tube lead directly to air, all the other piezometric tube give the pressure water head of 1 meter water column, so to get rid of the pressure water in this root piezometric tube, then its air pressure provided must more than 1 meter, and the atmospheric pressure that is air pump is defeated by main snorkel should be greater than 1 meter water column.Experimentally, determine damping hole (i.e. air hole) size of damping element, make the pressure on main channel reach this requirement by the damping hole current limliting supercharging of each pipe, the degassing function of a pump multitube could be realized.
A kind of experimental measurement method, the digital indication flow meter of band piezometric tube display of the experimental teaching described in employing, and comprise the following steps:
(1) liquid full packages flowing in differential flow signal generator, liquid enters into pressure measurement cylinder and piezometric tube from two pressure taps of differential flow signal, and stop liquid flowing makes the flow of liquid full-section pipe-flow in differential flow signal generator be zero;
(2) booster air pump and the automatically controlled breather valve of closedown exhaust, reset operation is vented to two piezometric tube simultaneously, liquid gas interface in two pressure measurement cylinders is made all to depart from the bottom surface of the connection positioning pipe in cylinder, close air pump and open the gas circuit being vented automatically controlled breather valve, rising of groundwater level in piezometric tube is stablized, to observe in two piezometric tube water column whether co-altitude, whether observe in piezometric tube and in the flexible pipe be communicated with pressure measurement cylinder also has bubble to adhere to, if highly inconsistent or/and there is bubble to adhere to, then repeat step (2), if highly consistent and do not have bubble to adhere to, then enter step (3),
(3) by compensating circuit, pressure transducer is initially returned to zero, by two of pressure transducer measurement interfaces logical air simultaneously, realize returning to zero in real time;
(4) after having returned to zero, start experiment, make liquid flow in differential flow signal generator, experimentally need adjust flux, after each flow regulation is stable, repeat the exhaust reset operation of step (2), eliminate after pressure measurement cylinder internal upper part air compressing changes the error brought, can while strong by two side pressures of two differential flow signal generators of piezometric tube synchro measure, and data on flows strong by two side pressures of the differential flow signal generator of micro computer gauge outfit tour inspection again.
Described experimental measurement method, also comprises step (5): control two automatically controlled breather valves all obstructed air time, micro computer gauge outfit will display pressure transducer export pressure difference signal conversion flow number; When controlling one of them another obstructed air of logical air of two automatically controlled breather valves, the pressure values that micro computer gauge outfit will show with that one end be connected of obstructed air in two automatically controlled breather valves on differential flow signal generator.
Compared with prior art, the utility model tool has the following advantages:
The digital indication flow meter of the utility model experimental teaching band piezometric tube display is provided with two and can controls the contour liquid cyclostrophic of liquid level and to remodel pressure measurement cylinder (be called for short pressure measurement cylinder), by differential flow signal generator with between pressure transducer by the mode of the direct transmission of pressure of the liquid be communicated with in positioning pipe, by the bitubular of liquid gas shift, change the medium of gas into, send pressure to pressure transducer, avoid the pressure error of almost 10% rank that the surface tension of liquid that causes owing to there are very difficult emptying minute bubbles when liquid directly contacts with the airtight connecting pipe of pressure transducer brings, make the precision of Small flowrate measurement can bring up to more than 1% by 10%, and the high-precision digital-display flow instrument having filled up desk-type small fluid mechanics hydraulic experiment instrument is blank.Also avoid the corrosion to pressure transducer that liquid and pressure transducer Long contact time are easily brought simultaneously, improve pressure transducer serviceable life and the long-time precision used.
Innovation and application fluid mechanics principle, devise the UNICOM's positioning pipe in pressure measurement cylinder, both can by pressure tap pressure by having sealed gas circuit pressure transmission to pressure transducer, direct electrical measurement is facilitated to obtain the relative atmospheric pressure pressure of Relative Zero elevation, again by sealing waterway pressure transmission in traditional piezometric tube, form piezometric tube water column, while micro computer digital display meter head display flow, use two piezometric tube water column simultaneous display differential flow signal generator two ends pressure measurement mouths that can also be vivid conduct the pressure of coming, with venturi, orifice plates etc. the in the last hundred years long-term traditional differential pressure flowmeter application writing book of teaching match, this experimental teaching is applicable to experimental teaching with the digital indication flow meter of band piezometric tube display and uses very much.
By making UNICOM's positioning pipe bottom surface and the piezometric tube zero point of scale same level face at pressure measurement cylinder top, automatically can determine that pressure reduction zero point of the relative atmospheric pressure that pressure transducer is measured and piezometric tube scale unsettled elevation zero (piezometric head benchmark zero-bit elevation) such as to protect at the zero-bit, be difficult to the difficult problem at unification benchmark zero point when solving traditional piezometric tube configuration digital display pressure gauge, also solve the problem how two pressure measurement cylinders accurately keep liquid level contour simultaneously.Also lay the first stone for system can return to zero and be vented reset raising measuring accuracy at any time in real time.
After use liquid gas shift pressure measurement cylinder, apply automatically controlled miniature Standard Valve Design gas path on-off switched system cleverly, by touring switching, the tour inspection of 2 groups of each pipe heads of piezometric tube and flow pressure-difference can be realized with a pressure transducer, match with a pump multitube aerator simultaneously, achieve the function that in experimentation, system can return to zero in real time, and by the special Examination on experimental operation that exhaust resets, thoroughly can eliminate the liquid level that pressure measurement cylinder internal upper part air compressing brings and raise the pressure measurement error caused.
The principle of then damping hole current limliting supercharging in innovative usage fluid mechanics in a pump multitube aerator, save the troublesome operation every root piezometric tube being exhausted respectively to draining with ear washing bulb, and air pump consumption is few, structure is simple, easy to operate, good exhaust effect, also facilitates the operation that electric control exhaust resets, not only be applicable to this flow measurement device, be also specially adapted to the manometric automatic control exhaust of row's formula of more multitube.
The utility model is as hydrodynamic calculations teaching flowmeter, the multiple principle of fluid mechanics that make use of that is comprehensive, novelty solves an experiment measuring difficult problem, can be motivated students' interest in learning, inspire the creativity consciousness of student, useful to cultivation innovation ability, possesses good teaching efficiency.
Accompanying drawing explanation
Fig. 1 is the structural representation of the digital indication flow meter of a kind of experimental teaching band of the utility model piezometric tube display.
Embodiment
As shown in Figure 1, be the digital indication flow meter of a kind of experimental teaching band of the utility model piezometric tube display, comprise: for generation of the differential flow signal generator 29 of pressure difference signal, with two pressure taps on differential flow signal generator 29; Two groups of manometric module, often group manometric module comprises a pressure measurement cylinder 11, and each pressure measurement cylinder 11 bottom is provided with water inlet 12, top is provided with and is communicated with positioning pipe 10, the piezometric tube 2 be connected with connection positioning pipe 10; Two groups of manometric module are connected with two pressure taps of differential flow signal generator 29 respectively by respective pressure measurement cylinder 11 lower water inlet 12; Be connected with two pressure measurement cylinders 11 in two groups of manometric module, for detecting the pressure transducer 19 of two pressure measurement cylinder 11 compressed air pressure differences, pressure transducer 19 specifically can adopt differential pressure pickup; Be connected with pressure transducer 19, the pressure signal for being detected by pressure transducer 19 converts the micro computer digital display meter head 23 of flow to; For installing the fixed support 1 of two piezometric tube 2 in two groups of manometric module; For graduated scale, the zero graduation of graduated scale and the same level face, bottom surface being communicated with positioning pipe 10 in two pressure measurement cylinders 11 of liquid level in unified demarcation two piezometric tube 2.The water inlet of pressure measurement cylinder 11 is positioned at the sidewall bottom of pressure measurement cylinder 11.
The experimental teaching digital indication flow meter of band piezometric tube display, also comprise: two automatically controlled breather valves, i.e. automatically controlled three-way air valve 17 and an automatically controlled three-way air valve 18, each automatically controlled breather valve at least comprises three tunnels, one tunnel of each automatically controlled breather valve is communicated with pressure measurement cylinder 11 compressed air, another road of each automatically controlled breather valve is connected with pressure transducer 19, and each automatically controlled breather valve also has a road and air conducting.
The experimental teaching digital indication flow meter of band piezometric tube display, also comprises: the air pump 43 be communicated with the open top of piezometric tube 2.Air pump 43 is communicated with the open top of two piezometric tube 2 by shunt 41, is connected with damping element 42, shunt 41 is sealedly connected with automatically controlled two breather valves 44 (being namely vented automatically controlled breather valve) between shunt 41 and piezometric tube 2; Damping element 42 is seal, and the seal is provided with the air hole of ventilating for shunt 41 and piezometric tube 2.Exhaust nozzle and the shunt 41 of air pump 43 are tightly connected.
Fixed support 1 is provided with horizontal survey chute 8, and this horizontal survey chute 8 is provided with slide block 5, and graduated scale is the ruler 3 be arranged on slide block 5.Ruler 3 is provided with elongated hole 7, and this ruler 3 to be coordinated with this elongated hole 7 by screw 6 and is fixed on slide block 5.
The digital indication flow meter of the utility model experimental teaching band piezometric tube display has the piezometric tube 2 that 2 are vertically arranged on the straight pipe type on fixed support 1 side by side, air is led in piezometric tube 2 open top, there is water inlet 4 bottom surface, piezometric tube 2 can vertically be placed on the desktop 25 of the level of mixing up under fixed support 1 supports, a horizontal survey chute 8 is had on fixed support 1 top, horizontal survey chute 8 is hung with one piece of slide block 5, ruler 3 (transparent) top has the elongated hole 7 of vertical direction, be fixed on slide block 5 by screw 6, moving horizontally slide block 5 just can use transparent ruler 3 with same zero elevation reference field, measure water colunm height in each piezometric tube 2.Simultaneously being communicated with same level face, positioning pipe 10 bottom surface in order to what keep the elevation surface level 26 at zero point of ruler to insert with pressure measurement cylinder 11 top, by slide block 5 bottom for being connected and fixed the vertical elongated hole 7 of ruler 3, finely tuning the fixed position up and down of ruler 3.
Fixed support 1 is placed on one and mixes up on the experiment desktop 25 of level, table top limit is provided with two and correspondingly with piezometric tube 2 connects, and the pressure measurement cylinder 11 of band zero-bit elevation location, can make of clear perspex material, inner retaining is clearly visible, facilitates Germicidal efficacy.Further, two pressure measurement cylinder 11 external and internal compositionses, size are identical, are fixedly bonded on same level connecting bottom board 14.Pressure measurement cylinder 11 height is higher than surface level about about the 1 ~ 3cm at ruler 3 zero point.Pressure measurement cylinder 11 can be a hollow cylinder or polygon hollow column structure, and as row's formula pressure measurement cylinder, each barrel can directly vertically seal bonding with same connecting bottom board 14, using connecting bottom board 14 as each pressure measurement cylinder 11 seal base.Each pressure measurement cylinder 11 end face has an aperture, vertical insert sealing and is bonded with one and is communicated with positioning pipe 10 with the water inlet pipe of water inlet 4 bottom piezometric tube 2 with external diameter.The general internal diameter of water inlet pipe being communicated with positioning pipe 10 and water inlet 4 has about 4mm more greatly.Be communicated with positioning pipe 10 to exceed end face and be about 1cm, be convenient to seal external PVC water service hose 9, and seal with water inlet 4 bottom corresponding piezometric tube 2 and be communicated with, the sealing ventilating water pipe of formation piezometric tube 2 water column.Be communicated with positioning pipe 10 and insert pressure measurement cylinder 11 degree of depth about 1 ~ 3cm, bottom surface level, and keep surface level 26 isoplanar with ruler 3 elevation at zero point.Two pressure measurement cylinder 11 lower sidewall have a pressure measurement water inlet 12 close to bottom surface, and salable external water service hose 28 is connected on two pressure taps of differential flow signal generator 29.Differential flow signal generator 29 is the flow measurement pipeline section that can produce pressure difference signal, the conventional flow such as concrete employing venturi, orifice plate or ozzle measure compacting and test pipeline section, also be the part on experimental channel 30, and pipeline 30 is connected with the head piece that goes out of Experimental Water Tank 33 by experiment.Two pressure taps on differential flow signal generator 29 are separately positioned on high pressure spot and the low pressure point of traditional differential pressure measurement experiment pipeline section, open below these 2 tube walls 2 apertures insert 2 stainless steel hollow tubulars can as pressure tap draw connector, overflow plate 34 is provided with in Experimental Water Tank 33, Experimental Water Tank 33 is divided into into water workspace and overflow area by overflow plate 34, the bottom of water inlet workspace is provided with water inlet, the bottom of overflow area is provided with water delivering orifice, the water inlet water inlet of water tank 33 by experiment, form overflow liquid level 35, the constant pressure water supply of experimental channel 30 is provided.
During experiment, experimental channel 30 is full of full packages current, two pressure taps of differential flow signal generator 29 can produce pressure reduction, after connecting pressure measurement cylinder 11, it is inner that water can enter pressure measurement cylinder 11 from sidewall water inlet 12 bottom pressure measurement cylinder 11, after water level arrives the bottom surface surface level 26 of top connection positioning pipe 10, water level no longer rises, water can enter and be communicated with positioning pipe 10, then piezometric tube 2 is entered, form piezometric tube water column 27, after each piezometric tube water colunm height is stable, horizontal slip ruler 3, measure the head pressure that 2 pipe water colunm height numerical value are two pressure measurement mouth relative ruler 3 elevation at zero point reference level surfaces 26 of corresponding differential flow signal generator 29 respectively.One section of air column then can be sealed to its top at the connection positioning pipe 10 bottom surface surface level 26 of pressure measurement cylinder 11, due to connection positioning pipe 10 bottom surface surface level 26 and surface level 26 isoplanar at ruler zero point, so this section of seal compression air column pressure is piezometric head pressure and atmospheric pressure sum.
In order to measure this section of seal compression air column pressure, an aperture is had on pressure measurement cylinder 11 top, the stainless steel snorkel 13 sealing a bonding insertion internal diameter 2mm (can insert from top, also can insert from upper portion side wall), the highest water surface in bucket is not encountered in snorkel 13 bottom surface, and the salable external hollow vent pressure measurement flexible pipe 15 of pressure measurement cylinder 11 outside about about 1cm stayed by snorkel 13.In order to pressure and the pressure reduction of the touring electrical measurement of energy two pressure measurement cylinder compressed airs, two pressure measurement cylinders 11 respectively by a-road-through gas pressure measurement flexible pipe 15, then are connected with pressure transducer 19 with an automatically controlled three-way air valve 18 through an automatically controlled three-way air valve 17 respectively.Automatically controlled three-way air valve 17 and automatically controlled three-way air valve 18 have 3 road valves, and the first via is communicated with pressure measurement flexible pipe 15, and the second tunnel leads to air, and the 3rd tunnel is communicated with pressure measurement interface 21 with the pressure measurement interface 20 of pressure transducer 19 respectively.Automatically controlled three-way air valve 17 and automatically controlled three-way air valve 18 when no power, the first via and the 3rd tunnel conducting, the second tunnel is not communicated with other two tunnels; During energising, the second tunnel is communicated with the 3rd tunnel, and the first via is not communicated with other two tunnels.
Final pressure sensor 19 signal is sent by traditional circuit change and is input to micro computer digital display meter head 23, by the switching control combination of automatically controlled three-way air valve 17, can two pressure measurement mouths of touring display differential flow signal generator 29 are corresponding on micro computer digital display meter head 23 piezometric tube water colunm height digital display value, the pressure reduction that recorded by pressure transducer 19 to convert the experimental channel flow value obtained.
Meanwhile, the textural association that automatically controlled three-way air valve 17,18 and band are communicated with the pressure measurement cylinder 11 of positioning pipe 10 also has a very important real-time zeroing function.Pressure transducer 19 signal by traditional circuit become send be input to micro computer digital display meter head 23 time; usually traditional sensor zeroing compensating circuit can be provided with; prior art can be adopted; realizing pressure transducer 19, to input pressure difference signal be zero; and output voltage non-vanishing time, compensating approach be no-voltage export function.Traditional sensor zeroing compensating circuit cardinal principle is the magnitude of voltage utilizing potentiometer change sensor to export to micro computer digital display meter head 23, the signal negative terminal voltage that micro computer digital display meter head 23 is received can regulate, thus make the displayed value of micro computer digital display meter head 23, be adjustable as zero.In this measurement mechanism, liquid gas interface due to two pressure measurement cylinders 11 keeps contour, therefore, in any moment of experimentation all by making automatically controlled three-way air valve 17,18 circuit ON obtain mode simultaneously, two of pressure transducer 19 pressure tap are communicated with air simultaneously, then regulate by the potentiometer of zeroing compensating circuit operation of returning to zero in real time.
But, if select two pressure measurement cylinders 11 are not communicated with positioning pipe 10 structure, liquid gas interface can not be allowed to keep contour, then under the constant voltage head of Experimental Water Tank 33, close experimental channel 30 go out to flow valve, when keeping experimental channel 30 full-section pipe-flow flow to be zero, two lie in the pressure measurement cylinder 11 on the good desktop 25 of leveling because liquid level is not contour in cylinder, certainly non-vanishing to the input pressure difference signal of pressure transducer 19 by pressurized air conduction pressure, now output voltage is also non-vanishing, operate according to zeroing, when experimental channel flow is zero, we should regulate the potentiometer compensating approach in zeroing compensating circuit to be that no-voltage exports to micro computer digital display meter head 23, to show flow null value, but the operation that this zeroing compensates can only be initial in experiment, carry out during experimental channel 30 full-section pipe-flow zero flow, cannot can to return to zero in real time at any time in experimentation as the aforementioned operation.
In the experimental provision of above-mentioned enforcement, be air pressure when in pressure measurement cylinder 11, the air column of connection positioning pipe 10 bottom surface closed upper part is initial, air column in pressure (or water column pressure of piezometric tube 2 synchronously importing) the meeting compression cylinder of coming is conducted by differential flow signal generator 29 2 end pressure measurement mouth in pressure measurement cylinder 11, liquid gas interface in cylinder is made to be increased beyond the surface level 26 at ruler zero point, although this error relative error not high (<0.2%), but when piezometric tube 2 water column is higher, such as during 80cm, when in pressure measurement cylinder 11, initial occluded air post height is 3cm, error has 0.22cm.This measures zeroing in real time and actual flow or can produce some measuring error, in order to improve precision, eliminate this error, consider the automatic vent of piezometric tube 2 simultaneously, the gas bubbles left easily brought during to eliminate initial water inlet in piezometric tube 2, add the aerator of a pump multitube when this experimental provision is specifically implemented, structure is as follows: add on two piezometric tube 2 tops the shunt 41 be connected with piezometric tube, connects the damping element 42 of two piezometric tube 2 and shunt 41; The air pump 43 (in this experimental provision, can micro air pump be adopted) be connected with shunt 41, automatically controlled two breather valves 44 be connected with shunt 41.
When reality is implemented, a set of fluid mechanics hydraulic experiment device is except pipeline flow needs measurement, and also will measure the pressure of multiple point, the piezometric tube number for pressure measurement has 2 ~ 20 usually, and therefore shunt 41 is generally the gas circuit linker of more than triple channel.In this example, piezometric tube 2 is two, and shunt 41 can adopt gas circuit threeway, and a road seals with the exhaust nozzle of air pump 43 and is communicated with, and also has two-way to be sealed with the open top of two piezometric tube 2 by damping element 42 and is communicated with.
Damping element 42 is seal, the seal is provided with the air hole of ventilating for shunt 41 and piezometric tube 2, this air hole is damping hole, and be the micropore that the damping element 42 of the complete trapping of energy in connecting pipe is offered, its pore size can reach the exhaust outlet effect of choked flow supercharging.
Each damping element 42 is positioned in the connecting pipe between the outlet of shunt 41 and the open top of piezometric tube 2 respectively, makes air-flow can only flow into each piezometric tube 2 from damping hole.
In normal measurement situation, piezometric tube 2 open top must lead to air, is provided with automatically controlled two breather valves 44 be communicated with it for this reason, is connected by conventional control circuit on shunt 41, it is energized when air pump 43 works closedown simultaneously, and when air pump 43 stops, power-off is simultaneously opened automatically.
By upper, during energising, air pump 43 is left, automatically controlled two breather valves 44 close, and 2 pipes that can carry out piezometric tube 2 are vented and reset operation simultaneously.Due to the current limliting pressurization of damping element 42, utilize a micro air pump 43, just can synchronously be vented 2 and even many piezometric tube 2 simultaneously, even if under some pressure measurement end of piezometric tube 2 all leads to atmospheric condition, also drainage exhaust can be carried out to the piezometric tube remaining press liquid in a single pipe wherein.In this experimental provision, electric control exhaust also has reset function be detained bubble in elimination piezometric tube while, namely during actual exhaust air operation, need to wait each pipe water column in piezometric tube 2 all to enter in each pressure measurement cylinder 11, and liquid gas interface in each cylinder is forced down by the pressurized air that air pump 43 is blown into, connection positioning pipe bottom surface surface level in each cylinder of firm disengaging, after reaching reset effect, then makes air pump 43, automatically controlled two breather valve 44 power-off.Now, each pressure measurement cylinder 11 internal upper part is no longer the air column of initial atmosphere pressure, and be through the pressurized air post of air pump air blowing press-in, air pump 43 stops, after automatically controlled two breather valves 44 are opened, reopen the gas circuit that pressure measurement cylinder 11 top communicates with ambient atmosphere, but equally due to the current limliting pressurization of damping element 42, while in pressure measurement cylinder 11, liquid level gos up to be extruded away by the damping hole of the damping element 42 of piezometric tube 2 by cylinder internal upper part pressurized air, pressure equilibrium can be obtained by pressurized air that is automatic and cylinder internal upper part, when in pressure measurement cylinder 11, liquid level goes back up to the bottom surface surface level 26 being communicated with positioning pipe 10 in cylinder, namely the closed compression air column pressure of each pressure measurement cylinder 11 internal upper part equal each pressure tap of differential flow signal generator 29 in corresponding experimental channel and conduct the head pressure+atmospheric pressure of coming.Thereafter, in corresponding piezometric tube 2, water column goes back up to onesize water column pressure height, and two pressure measurement cylinder 11 internal upper part pressurized air because compressed and achieved gas-liquid pressure balance before closing, make liquid gas interface increase so can not recompress, produce the error with ruler elevation at zero point surface level.Resetted by exhaust cleverly like this and design and operation, initial atmosphere pressure air column in pressure measurement cylinder can be eliminated accurately and compress the systematic error brought, improve experimental precision.
In sum, the experimental measurement method of the digital indication flow meter of a kind of experimental teaching of the utility model band piezometric tube display is as follows:
(1) when in Experimental Water Tank 33, liquid level is in overflow liquid level 35 elevation, there is constant pressure experimentation head, experimental channel 30 full packages is kept to flow out stream, in experimental channel 30, water can enter pressure measurement cylinder 11 and piezometric tube 2 respectively by two end pressure taps of the differential flow signal generator 29 on pipeline, now, that closes experimental channel 30 goes out head piece valve, keeps full-section pipe-flow flow in experimental channel 30 to be zero.
(2) be energized air pump 43 and automatically controlled two breather valves 44, reset operation is vented to two piezometric tube 2 simultaneously, liquid gas interface in two pressure measurement cylinders 11 is made all to depart from the bottom surface of the connection positioning pipe 10 in cylinder, i.e. power-off air pump 43 and automatically controlled two breather valves 44, open the gas circuit of automatically controlled two breather valves 44, rising of groundwater level in piezometric tube 2 is stablized, to observe in two piezometric tube 2 water column whether co-altitude, bubble whether is also had to adhere in piezometric tube 2 and in the flexible pipe be communicated with pressure measurement cylinder 11, if have, repeat (2) step exhaust reset operation, it is general that can to get rid of bubble 1 ~ 2 time clean, complete the effect that the pressurized air inflation in pressure measurement cylinder 11 resets simultaneously.Until, water column co-altitude in two piezometric tube 2, and do not have bubble to adhere in piezometric tube 2 and in the flexible pipe be communicated with pressure measurement cylinder 11, step (3) can be entered;
(3) now, micro computer digital display meter head 23 display should be zero, time non-vanishing, can initially to return to zero operation by regulating the compensating circuit of pressure transducer 19.Meanwhile, control automatically controlled three-way air valve 17 and 18 and be energized simultaneously, two pressure tap of pressure transducer 19 all lead to air simultaneously, pressure reduction is zero, and namely Operation system setting is to the state that returns to zero in real time, if through operation of initially returning to zero, then can verify, micro computer digital display meter head 23 should be shown as zero equally.
(4) that opens experimental channel 30 goes out head piece valve, experimentally need to regulate the flow in experimental channel, after each flow regulation is stable, come again the exhaust reset operation of (2) step, eliminate after pressure measurement cylinder 11 internal upper part air compressing changes the error brought, can while strong by two side pressures of two differential flow signal generators 29 of piezometric tube 2 synchro measure, again by micro computer gauge outfit tour inspection data.
(5) control automatically controlled three-way air valve 17 and 18 all no power time, micro computer digital display meter head 23 by display pressure transducer 19 export pressure difference signal conversion flow number; Control automatically controlled three-way air valve 17 to be energized, during automatically controlled three-way air valve 18 no power, micro computer gauge outfit 23 is by one end pressure values of the differential flow signal generator 29 of display; Control automatically controlled three-way air valve 17 no power, when automatically controlled three-way air valve 18 is energized, micro computer gauge outfit 23 is by the other end pressure values of the differential flow signal generator 29 of display.
Claims (8)
1. an experimental teaching digital indication flow meter for band piezometric tube display, is characterized in that, comprising:
For generation of the differential flow signal generator of pressure difference signal, with two pressure taps on described differential flow signal generator;
Two groups of manometric module, often organize manometric module and comprise a pressure measurement cylinder, each pressure measurement cylinder bottom is provided with water inlet, top is provided with connection positioning pipe, the piezometric tube be connected with described connection positioning pipe; Two groups of manometric module are connected respectively by two pressure taps of respective pressure measurement cylinder lower water inlet with described differential flow signal generator;
Be connected with two pressure measurement cylinders in two groups of manometric module, for detecting the pressure transducer of described two pressure measurement cylinder compressed air pressure differences;
Be connected with described pressure transducer, the pressure signal for being detected by described pressure transducer converts the micro computer digital display meter head of flow to;
For installing the fixed support of two piezometric tube in two groups of manometric module;
For unified graduated scale, the zero graduation of described graduated scale and the same level face, bottom surface being communicated with positioning pipe in described two pressure measurement cylinders of demarcating liquid level in described two piezometric tube.
2. the digital indication flow meter of experimental teaching band piezometric tube according to claim 1 display, it is characterized in that, also comprise: two automatically controlled breather valves, each automatically controlled breather valve at least comprises three tunnels, one tunnel of each automatically controlled breather valve is communicated with a pressure measurement cylinder compressed air, another road of each automatically controlled breather valve is connected with described pressure transducer, and each automatically controlled breather valve also has a road and air conducting.
3. the digital indication flow meter of experimental teaching band piezometric tube according to claim 2 display, is characterized in that, also comprise: the air pump be communicated with the open top of described piezometric tube.
4. the digital indication flow meter of experimental teaching band piezometric tube according to claim 3 display, it is characterized in that, described air pump is communicated with by the open top of shunt with two piezometric tube, be connected with damping element between described shunt and piezometric tube, described shunt be sealedly connected with the automatically controlled breather valve of exhaust;
Described damping element is seal, and the seal is provided with the air hole of ventilating for described shunt and described piezometric tube.
5. the digital indication flow meter of experimental teaching band piezometric tube according to claim 4 display, it is characterized in that, exhaust nozzle and the described shunt of described air pump are tightly connected.
6. the digital indication flow meter of experimental teaching band piezometric tube according to claim 1 display, it is characterized in that, described fixed support is provided with horizontal survey chute, and this horizontal survey chute is provided with slide block, and described graduated scale is be arranged on the ruler on described slide block.
7. the digital indication flow meter of experimental teaching according to claim 6 band piezometric tube display, it is characterized in that, described ruler is provided with elongated hole, and this ruler to be coordinated with this elongated hole by screw and is fixed on described slide block.
8. the digital indication flow meter of experimental teaching band piezometric tube according to claim 1 display, it is characterized in that, the water inlet of described pressure measurement cylinder is positioned at the sidewall bottom of described pressure measurement cylinder.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104807508A (en) * | 2015-04-13 | 2015-07-29 | 浙江大学 | Digital display flow meter for experiment teaching based on piezometer tube display and measuring method thereof |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104807508A (en) * | 2015-04-13 | 2015-07-29 | 浙江大学 | Digital display flow meter for experiment teaching based on piezometer tube display and measuring method thereof |
| CN104807508B (en) * | 2015-04-13 | 2018-01-05 | 浙江大学 | A kind of experimental teaching is with the digital indication flow meter and measuring method shown with pressure-measuring pipe |
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