CN206410842U - The force balance of tiny area windage resistance in a kind of measurement Boundary Layer on Flat Plate - Google Patents
The force balance of tiny area windage resistance in a kind of measurement Boundary Layer on Flat Plate Download PDFInfo
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- CN206410842U CN206410842U CN201620961138.2U CN201620961138U CN206410842U CN 206410842 U CN206410842 U CN 206410842U CN 201620961138 U CN201620961138 U CN 201620961138U CN 206410842 U CN206410842 U CN 206410842U
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- force balance
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- control plane
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Abstract
The utility model provides a kind of force balance for measuring tiny area windage resistance in Boundary Layer on Flat Plate, includes balancing pole, support bar, blade type fulcrum, floating control plane and force snesor etc..In experimental study and engineer applied, we are frequently necessary to measure the windage resistance in turbulent boundary layer, and its size is only 10‑4Number N level is even lower.However, domestic and international market being capable of direct measurement so small windage resistance exactly without ready-made instrument.Force balance in the utility model is applied to the accurate measurement of windage resistance in Boundary Layer on Flat Plate, and resolution ratio is up to 5 × 10‑5N。
Description
Technical field
The utility model belongs to hydrodynamics air drag field of measuring technique, more particularly to a kind of measurement Boundary Layer on Flat Plate
The force balance of interior tiny area windage resistance and its demarcation, suitable fluid mechanics laboratory and relevant speciality school,
Research institute uses.
Background technology
In experimental study and engineer applied, we are frequently necessary to measure the tiny air frictional resistance in turbulent boundary layer
(10-4Number N level is even lower), however, domestic and international market being capable of the such small sky of direct measurement exactly without ready-made instrument
Gas frictional resistance.Although having the means of a variety of indirectly measurements, such as optics, electromagnetism, thermal conduction study, specific coatings at present
Deng, but these measurement means can not all reach good effect or because the difficult accuracy of its demarcation is relatively low.The utility model is
One hypersensitivity is supported on the force balance on blade, and the windage resistance that floating control plane is subject to passes through force balance
Amplification is delivered to force snesor, then the output signal of force snesor is acquired by computer.The air being subject to due to flat board
Frictional resistance is minimum, it is impossible to which the method that force snesor is demarcated using traditional counterweight, the utility model successfully solves the problem,
Local windage resistance is calculated to VELOCITY DISTRIBUTION using hot-wire anemometer Measured Boundary laminar flow, and dynamometry day is demarcated with this
It is flat.Measurement result is verified compared with the result integrated by the local friction of hot-wire measurement.
The utility model uses method measured directly, and the air being subject to by force sensor measuring floating control plane rubs
Resistance is wiped, and proposes a kind of new scaling method to complete current tasks of science.Rubbed with direct method measurement surface air
Wiping resistance helps to reduce extraneous, the interference of factor in the middle of such as light, magnetic field, so that with very high precision.Its is simple
Dynamometry scaling method is adapted to large-scale promotion, has broad application prospects.Meanwhile, can be flat as other using the utility model
The standard of edges of boards interlayer windage resistance measurement method or reference.
Utility model content
In view of the prior art is defective, the utility model is mainly used in windage resistance in measurement Boundary Layer on Flat Plate
Power.In order to solve the problem of superficial air frictional resistance in boundary layer experiment is difficult to accurate measurement, the utility model is provided
The force balance of tiny area windage resistance in a kind of measurement Boundary Layer on Flat Plate based on lever principle.The force balance
Measurement accuracy be 5%, in theory, minimum can differentiate 5 × 10-5The frictional force of N sizes.
The utility model is achieved through the following technical solutions, tiny area windage in one kind measurement Boundary Layer on Flat Plate
The force balance of resistance, including, flat board 1, support bar 3, balancing pole 4, counterweight 5, fulcrum 6, force snesor 7, floating control plane
9, wherein, flat board and floating control plane are in same plane and there is minim gap, and floating control plane is connected with support bar
And be placed on fulcrum, fulcrum and sensor are arranged on balancing pole, and two counterweights are respectively arranged at the two ends of balancing pole.
Wherein, preferably described gap length scope is 0.4 between 0.6mm.
The force balance is demarcated using hot-wire anemometer.The boundary layer under different wind speed is measured using hot-wire anemometer
Rate curve, and skin friction resistance is calculated according to rate curve, rower is entered to force balance according to the resistance calculated
It is fixed.
Fluid flows through flat board, and the windage resistance that floating control plane is subject to is transmitted by support bar, fulcrum, balancing pole
After act on a sensor.
Containment vessel 2 is set on the outside of force balance, force balance is in the state of closing, outside air flowing pair is reduced
Force balance is disturbed.
Wherein, balancing pole is helicitic texture, and two counterweights can adjust balance position, dynamometry on balancing pole by rotating
Each part of balance is in tight connection, makes force snesor in its ormal weight with the horizontal level for focusing on balancing pole by adjusting
Worked in journey.
Further, the material that preferably described support bar is used is density is small and rigidity is big polyoxymethylene (match
Steel), and be preferred to use hollow design to reduce quality.The quality of support bar has very high shadow to force balance temporal resolution
Ring, quality, which crosses conference, reduces the response speed of force balance, influence the sensitivity of force balance；Support bar rigidity not enough then can
Support bar in measurement process is caused to deform upon, so as to influence the accuracy of measurement.Therefore, support bar is used in this force balance
Density is small and the match Steel material of rigidity greatly.
The force balance of described measurement Boundary Layer on Flat Plate windage resistance, support bar 3 is placed on fulcrum 6, preferably
For the fulcrum of blade type, the tiny area windage resistance acted in floating control plane 9 passes through support bar 3 and balancing pole
4 pass to force snesor 7, its multiplication factor by force snesor 7 to blade type fulcrum 6 distance and floating control plane 9 to
The distance of blade type fulcrum is determined.
Wherein, sensor is fixed on balancing pole by connecting bolt 8, the preferred high sensitivity force snesor of sensor.Pass
Sensor can change the horizontal level of force snesor 7 by connecting bolt 8, so as to adjust the multiplication factor of force balance.This
The multiplication factor of force balance is 45 times, in order to actual combination, can design various sizes of force balance reach it is different
Multiplication factor.
The windage resistance acted in floating control plane, by balance amplify after be delivered to force snesor output voltage
Signal, in order to determine the relation between windage resistance and force snesor output voltage that floating control plane is subject to, it is necessary to
Force balance is demarcated.For rough surface, force balance can be demarcated using counterweight.Weight calibrating device one
As be made up of parts such as counterweight, fine rule, fixed pulley and supports, the air that the frictional force between each part and hydraulically smooth surface are subject to
Frictional resistance is in same magnitude.Therefore, for smooth surface, the method for counterweight demarcation is no longer applicable.The utility model proposes
A kind of brand-new scaling method, in full-blown turbulent boundary layer, the sky that is subject to using smooth surface under known wind speed
Gas frictional resistance is demarcated to force balance, and it is as follows that it implements process：
Under zero-pressure gradient, the power that force snesor is subject to all is from the windage resistance that floating control plane is subject to,
For full-blown turbulent boundary layer, the windage resistance that smooth surface is subject to is expired with the wall shear rate in boundary layer
Sufficient formula：
In formula, τwThe windage resistance being subject to for smooth surface, uτSheared for full-blown turbulent boundary layer internal face
Speed, ρ is atmospheric density, and area can be expressed as the frictional resistance F that A smooth surface is subject to：
F=τwA=ρ uτ 2A (2)
Measured using hot-wire anemometer (HWA) and flow to VELOCITY DISTRIBUTION in Boundary Layer on Flat Plate under different wind speed, further according to
Clauser rules, formula is met in full-blown turbulent boundary layer logarithmic region：
Wherein
y+=yuτ/ν (5)
In formula, ν is air movement viscosity,It is respectively average flow direction speed and away from wall distance, subscript in boundary layer with y
"+" represents the variable after nondimensionalization.Draw full-blown turbulent boundary layer logarithmic region average speed, shear rate and away from wall
The relation of face height：
So as to calculate the shear rate u of turbulent boundary layer under different wind speedτ, due to u in floating control planeτChange is very
Small, front and rear edge difference is less than 1%, thus can use the wall shear rate of floating control planar central position as in plane
Average wall shear rate, then the windage resistance that floating control plane is subject to is obtained by formula (2) calculating.
The utility model includes relative to the beneficial effect of prior art：
In boundary layer experiment, the windage resistance that floating control plane is subject to is amplified by force balance to be transmitted
To force snesor, it is then converted to voltage signal and is acquired by computer.The floating control plane of this force balance can be with
For rough surface or smooth surface, balancing pole and counterweight are that power is passed in balance and regulation force balance in order to ensure force balance
Sensor is preloaded.Force balance using highly sensitive force snesor to ensure that data are reliable, and by changing its level side
To the multiplication factor of position adjustment force balance so that the features such as whole force balance has high accuracy, high-resolution.Meanwhile,
The utility model additionally provides a kind of convenience and the high scaling method of accuracy for being used to fully develop turbulent boundary layer.
In experimental study and engineer applied, we are frequently necessary to measure the windage resistance in turbulent boundary layer, its
Size is only 10-4Number N level is even lower.However, domestic and international market without ready-made instrument can exactly direct measurement it is such
Small windage resistance.Force balance in the utility model is applied to the accurate survey of windage resistance in Boundary Layer on Flat Plate
Amount, resolution ratio is up to 5 × 10-5N。
Brief description of the drawings
A kind of Fig. 1 knots for measuring the force balance of tiny area windage resistance in Boundary Layer on Flat Plate of the present utility model
Structure schematic diagram；
Fig. 2 uses the curve synoptic diagram that force balance of the present utility model is demarcated.
Wherein, flat board 1, containment vessel 2, support bar 3, balancing pole 4, counterweight 5, fulcrum 6, sensor 7, connecting bolt 8 floats
Control plane 9.
Embodiment
The specific embodiment party of sensor manufacturing process of the present utility model and method of work is discussed in detail below in conjunction with the accompanying drawings
Formula, but the utility model is not limited to this：
Embodiment 1
As shown in figure 1, a kind of force balance for measuring tiny area windage resistance in Boundary Layer on Flat Plate, including, put down
Plate 1, support bar 3, balancing pole 4, counterweight 5, fulcrum 6, force snesor 7, floating control plane 9, wherein, flat board and floating control are flat
Face is in same plane and there is minim gap, and floating control plane is connected and is placed on fulcrum with support bar, fulcrum and biography
Sensor is arranged on balancing pole, and two counterweights are respectively arranged at the two ends of balancing pole.
Wherein, gap length scope is 0.4 between 0.6mm.
Fluid flows through flat board, and the windage resistance that floating control plane is subject to is transmitted by support bar, fulcrum, balancing pole
After act on a sensor.
It is preferred that, increase containment vessel 2 on the outside of force balance, force balance is in the state of closing, reduce outside air
Flowing is disturbed force balance.
Wherein, preferably balancing pole is helicitic texture, and two counterweights by rotating can adjust balance position on balancing pole,
Each part of force balance is in tight connection.
Further, the material that preferably described support bar is used is density is small and rigidity is big polyoxymethylene (match
Steel), and it is preferred to use hollow design.
The multiplication factor of the dynamometry is by the distance and floating control plane 9 of force snesor 7 to blade type fulcrum 6 to knife
The distance of piece type fulcrum 6 is determined.It is preferred that the multiplication factor of this force balance is 45 times.
The scaling method of embodiment 2
Using the force balance described in embodiment 1, by known 7 different wind speed (0m/s, 2.4m/s, 3.08m/s,
3.57m/s, 4.25m/s, 4.78m/s, 4.96m/s) under the windage resistance that is subject to of floating control plane and force snesor it is defeated
The relation pair force balance gone out between voltage is demarcated, and obtains calibration curve as shown in Figure 2, as seen from the figure, force balance
The windage resistance that is subject to of output voltage and floating control plane the characteristics of there is highly linear, global error is less than 5%.
In actual applications, appropriate wind speed can be chosen as needed to be demarcated.
For the utility model person of an ordinary skill in the technical field, the utility model design is not being departed from
Under the premise of, some simple deduction or replace can also be made, protection domain of the present utility model should be all considered as belonging to.
Claims (10)
1. a kind of force balance for measuring tiny area windage resistance in Boundary Layer on Flat Plate, it is characterised in that including：Flat board
(1), support bar (3), balancing pole (4), counterweight (5), blade type fulcrum (6), force snesor (7), floating control plane (9), its
In, flat board and floating control plane are in same plane and there is minim gap, and floating control plane is connected and put with support bar
Put on fulcrum, fulcrum and sensor are arranged on balancing pole, two counterweights are respectively arranged at the two ends of balancing pole.
2. force balance according to claim 1, it is characterised in that：The gap length scope is 0.4 to 0.6mm.
3. force balance according to claim 1, it is characterised in that：Containment vessel (2) is set on the outside of force balance.
4. force balance according to claim 1, it is characterised in that：The balancing pole is helicitic texture, and counterweight can be flat
On weighing apparatus bar balance position is adjusted by rotating.
5. force balance according to claim 1, it is characterised in that：Sensor is fixed on balancing pole by connecting bolt 8
On, sensor can change the horizontal level of force snesor (7) by connecting bolt (8).
6. force balance according to claim 1, it is characterised in that：The material of the support bar is polyoxymethylene.
7. force balance according to claim 1, it is characterised in that：The material of the support bar is hollow design.
8. force balance according to claim 1, it is characterised in that：The fulcrum is the fulcrum of blade type.
9. force balance according to claim 1, it is characterised in that：The multiplication factor of the dynamometry by force snesor 7 to
The distance and floating control plane (9) of blade type fulcrum (6) are determined to the distance of blade type fulcrum.
10. force balance according to claim 9, it is characterised in that：The multiplication factor is 45 times.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201620961138.2U CN206410842U (en) | 2016-08-26 | 2016-08-26 | The force balance of tiny area windage resistance in a kind of measurement Boundary Layer on Flat Plate |
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| CN201620961138.2U CN206410842U (en) | 2016-08-26 | 2016-08-26 | The force balance of tiny area windage resistance in a kind of measurement Boundary Layer on Flat Plate |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108692912A (en) * | 2018-04-28 | 2018-10-23 | 中国空气动力研究与发展中心超高速空气动力研究所 | A kind of double frictional resistance balance measurement methods of swimming cloths |
| CN110132526A (en) * | 2019-05-29 | 2019-08-16 | 中国科学院力学研究所 | A kind of low disturbing pulse type shock tunnel strain type face frictional resistance balance |
| CN111141479A (en) * | 2020-02-13 | 2020-05-12 | 北京航空航天大学 | Test device for improving measurement precision of plate friction resistance |
| CN111175016A (en) * | 2020-03-13 | 2020-05-19 | 中国空气动力研究与发展中心高速空气动力研究所 | Surface friction resistance wind tunnel measuring method based on box type friction resistance balance |
| CN111189611A (en) * | 2020-03-13 | 2020-05-22 | 中国空气动力研究与发展中心高速空气动力研究所 | Wind tunnel test method based on strain type two-component surface friction resistance measuring balance |
| CN112161775A (en) * | 2020-08-17 | 2021-01-01 | 东华大学 | Method and device for testing wind resistance performance of grid fabric |
| CN113670567A (en) * | 2021-08-24 | 2021-11-19 | 哈尔滨工业大学（深圳） | High dynamic response force measuring balance for measuring wall surface friction resistance and calibration method thereof |
-
2016
- 2016-08-26 CN CN201620961138.2U patent/CN206410842U/en not_active Expired - Fee Related
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108692912A (en) * | 2018-04-28 | 2018-10-23 | 中国空气动力研究与发展中心超高速空气动力研究所 | A kind of double frictional resistance balance measurement methods of swimming cloths |
| CN110132526A (en) * | 2019-05-29 | 2019-08-16 | 中国科学院力学研究所 | A kind of low disturbing pulse type shock tunnel strain type face frictional resistance balance |
| CN111141479A (en) * | 2020-02-13 | 2020-05-12 | 北京航空航天大学 | Test device for improving measurement precision of plate friction resistance |
| CN111175016A (en) * | 2020-03-13 | 2020-05-19 | 中国空气动力研究与发展中心高速空气动力研究所 | Surface friction resistance wind tunnel measuring method based on box type friction resistance balance |
| CN111189611A (en) * | 2020-03-13 | 2020-05-22 | 中国空气动力研究与发展中心高速空气动力研究所 | Wind tunnel test method based on strain type two-component surface friction resistance measuring balance |
| CN111175016B (en) * | 2020-03-13 | 2020-12-15 | 中国空气动力研究与发展中心高速空气动力研究所 | Surface friction resistance wind tunnel measuring method based on box type friction resistance balance |
| CN111189611B (en) * | 2020-03-13 | 2021-05-25 | 中国空气动力研究与发展中心高速空气动力研究所 | Wind tunnel test method based on strain type two-component surface friction resistance measuring balance |
| CN112161775A (en) * | 2020-08-17 | 2021-01-01 | 东华大学 | Method and device for testing wind resistance performance of grid fabric |
| CN113670567A (en) * | 2021-08-24 | 2021-11-19 | 哈尔滨工业大学（深圳） | High dynamic response force measuring balance for measuring wall surface friction resistance and calibration method thereof |
| CN113670567B (en) * | 2021-08-24 | 2024-04-09 | 哈尔滨工业大学（深圳） | High dynamic response force measuring balance for measuring wall friction resistance and calibration method thereof |
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