CN102798496B - Method for measuring pressure in rotating state - Google Patents

Abstract

The invention discloses a method for measuring pressure in a rotating state. The method comprises: installing a demarcating device on a test piece to form a pressure-tight demarcating chamber, feeding gas into the demarcating chamber, measuring voltage signal values of a sensor and gas pressure values of the corresponding chamber, fitting a curve to obtain a pressure calibration curve in a stationary state; feeding gases with different pressures in the demarcating chamber and rotating the test piece at different rotating speed, measuring the voltage signal values of the sensor corresponding the gas pressure in the present demarcating chamber under each rotating speed, fitting a curve to obtain a pressure calibration curve in the rotating state; obtaining an actual pressure value of the demarcating chamber through temperature of the demarcating chamber under each rotating speed, and modifying the pressure calibration curve in the rotating state; and combining the modified calibration curve and the signal values under each rotating speed measured by the pressure sensor in a test condition to obtain an actual pressure value of the pressure sensor. The method for measuring pressure in the rotating state makes test results capable of being reference, and ensures measuring precision of the test at the same time.

Description

Pressure measurement method under a kind of rotation status

Technical field

The present invention relates to pressure survey field, specifically, strain pressure transducer is rotated to demarcation under state to obtain different rotating speeds lower sensor output signal and the actual calibration curve of experiencing force value corresponding relation, utilize this calibration curve can accurately record the pressure under rotation status, be particularly useful for the pressure survey of the rotary parts such as aero-engine turbine disk.

Background technology

Along with the progress of technology, improve the front fuel gas temperature of turbine and become the important channel of improving modern aeroengine performance, but also can cause the negative effect of the excessive grade of turbine disk thermal load simultaneously.In order to guarantee the safe and reliable work of turbine, except improving on turbine material, cooling also quite important to the turbine disk.In order to improve cooling structure design, to reduce the demand to cooling tolerance, and then improve the performance of engine, need to understand mobile fundamental characteristics in different turbine disk cavity configurations in depth.

Near carrying out aeromotor rotary part, during the flowing experiment of fluid, its surperficial pressure can be used as the important references of calculating the suffered axial force of these parts, research rotary part Flow Structure Nearby etc. conventionally.Because rotary part exists the problem of sound conversion when the pressure survey, therefore there is larger difficulty.For the pressure survey under rotation status, have now two kinds can supply the thinking of using for reference:

One, because rotational pressure is difficult to measure, static pressure is technical comparatively ripe in measuring method and measuring accuracy etc., therefore the pressure of rotation status can be converted into static pressure, measures.Specifically, in certain radial position place, pressure port is set exactly, rotational pressure is caused to certain static cavity, and then press force measurement in static cavity.There is certain defect in the method: first, need to accomplish strict sealing in real time coordinating between static cavity and revolving part, this difficulty in actual operation is large and all will reach seal request when each experiment, comparatively loaded down with trivial details; Secondly, under high speed conditions, the bearing heating amount of sound parts junction is larger, and this can cause larger inhomogeneous temperature rise in pressure pipe inside, thereby causes gaging pressure higher than actual pressure and be difficult to quantize.

Its two, the gas at measuring point place is caused in the enclosed cavity in rotation pressure dish, utilize the pressure transducer being placed in cavity measure cavity pressure and the pressure signal recording is exported by slip ring electrical feedthrough.The pressure transducer using in the method is strain pressure transducer.Strain pressure transducer contains diaphragm structure, its principle of work for can deform when diaphragm is experienced certain pressure, this distortion will cause membrane resistance to change and then change the output signal of sensor, and has corresponding relation between diaphragm deformation and sensor output signal.When using sensors measure pressure, the output signal that can cause according to distortion changes to judge force value.But, under rotation status, sensor, also will be because rotary centrifugal force produces additional deformation except the effect of being under pressure produces distortion, and its size is because the relation of diaphragm and rotary centrifugal force and pressure is difficult to judge.In addition, the sealing problem in pressure pipe and pressure dish inner sealing cavity is also comparatively loaded down with trivial details, and the centrifugal supercharging that need to produce the gas column in pressure pipe under rotation status is revised.

Above two kinds of methods all need to be carried out impermeability work when each data acquisition, prevent that the pressure acquisition result that Leakage Gas causes from being forbidden; For the error evaluation correction aspect of experiment, two kinds of methods all fail to provide good analysis result simultaneously.

Summary of the invention

The problem existing in order to solve prior art, the present invention proposes the pressure measurement method under rotation status that a kind of easy and simple to handle, precision easily guarantees, overcome the Leakage Gas problem of the equipment such as the sound interface that exists or pressure pipe, pressure dish in measuring process, strain pressure transducer is rotated to demarcation under state to obtain different rotating speeds lower sensor output signal and the actual calibration curve of experiencing force value corresponding relation, utilizes calibration curve to obtain the pressure under rotation status accurately.

Pressure measurement method under a kind of rotation status of the present invention, completes by following step:

Step 1: the installation of pressure transducer;

Pressure transducer is arranged in the installation of sensors hole of running through two sides having on experimental piece, is used for the pressure distribution situation of experiments of measuring part tested surface; Described pressure transducer adopts strain pressure transducer.

Step 2: caliberating device is installed;

Fixing caliberating device on experimental piece tested surface, forms airtight demarcation chamber, and the measurement point of pressure transducer is positioned at and demarcates chamber.

Step 3: the pressure calibration of stationary state lower pressure sensor;

To demarcating in chamber, pass into gas, by temperature measuring device, record the temperature of demarcating in chamber, and measurement in real time passes into the force value of gas, pressure transducer records in real time and demarcates voltage signal values corresponding to intracavity gas pressure simultaneously, matching draw the curve map between voltage signal gaseous tension corresponding to it thus, as the pressure calibration curve of stationary state lower pressure sensor.

Step 4: the pressure calibration of rotation status lower pressure sensor;

To demarcating in chamber, pass into quantitative gas, in the current demarcation chamber of surveying by pressure transducer, pass into the voltage signal values that gaseous tension is corresponding,, according to the pressure calibration curve of stationary state pressure transducer in step 3, obtain passing into the gas pressure value that gas is corresponding in current demarcation chamber; Subsequently respectively with n ₁, n ₂, n ₃..., n _jrotating speed rotation test part, choosing of each rotating speed is consistent with experiment condition medium speed setting value; By pressure transducer, record in current demarcation chamber and pass under gaseous tension, experimental piece when every speed, the voltage signal that pressure transducer records; Change to demarcate subsequently the pressure that passes into gas in chamber, carry out said process, finally obtain demarcating in chamber and respectively pass under gaseous tension, experimental piece when every speed, the voltage signal values that pressure transducer records; Matching drawing under each tachometer value thus, the curve map between voltage signal gaseous tension corresponding to it, as the pressure calibration curve of rotation status lower pressure sensor; In said process, by temperature measuring device, recorded in demarcation chamber and respectively passed under gaseous tension, experimental piece, when every speed, is demarcated the temperature value in chamber.

Step 5: the pressure calibration curve to rotation status lower pressure sensor is revised matching;

Each passes under gaseous tension, experimental piece when every speed, actual gas pressure value P in demarcation chamber corresponding to voltage signal values that pressure transducer records _jfor:

$P_j={\mathrm{<figure-callout\; id="0"\; label="P"\; filenames="HDA00001932834100031.png"\; state="\{\{state\}\}">P</figure-callout>}}_0\&CenterDot;\frac{T_j}{T_0}---\left(1\right)$

Wherein, P ₀for demarcating under stationary state, in chamber, pass into gas pressure value; T ₀for demarcating the temperature value in chamber under stationary state; T _jfor demarcating cavity temperature value under each rotating speed under rotation status.

By P _jas experimental piece, when the every speed, pressure transducer records demarcation intracavity gas force value corresponding to voltage signal values, the correction of the pressure calibration curve of rotation status lower pressure sensor in performing step 4 thus.

Step 6: caliberating device is taken off and can carry out the measurement of rotational pressure under experiment condition, by obtaining experiment condition lower pressure sensor, under every speed, record pressure sensor calibrating curve after the correction obtaining in signal value integrating step 5, obtain the actual force value of experiencing of pressure transducer.

The invention has the advantages that:

1, the pressure measurement method under rotation status of the present invention, omit the gas circuit design to pressure measurement chambers by the gas bleed of measuring point place, in simplified measurement structure, avoided the centrifugal supercharging of gas column existing in Leakage Gas situation that pressure equipment exists and bleed process, the experimental error that temperature deviation causes;

2, the pressure measurement method under rotation status of the present invention, focuses on calibration phase by impermeability work and can effectively monitor impermeability situation, has guaranteed that the flow process of experimental phase is smooth and easy accurately credible with data simultaneously;

3, the pressure measurement method under rotation status of the present invention, has carried out error analysis correction to nominal data, and this calibration result is applied to experiment measuring process and makes experimental result have referential, has also guaranteed the precision in experiment measuring process simultaneously.

Accompanying drawing explanation

Fig. 1 is the pressure measurement method process flow diagram under rotation status of the present invention;

Fig. 2 demarcates apparatus structure schematic diagram in the present invention;

Fig. 3 is that while being static in the present invention, charged pressure is the cavity pressure change curve after 9.90KPa;

Fig. 4 demarcates the perspective view of chamber on Plane of rotation in the present invention.

In figure:

1-experimental piece 2-pressure transducer 3-shell 4-valve cock

5-valve inside 6-thermopair 7-demarcates chamber 8-spring

Embodiment

Below in conjunction with accompanying drawing, the present invention is described in further detail.

Pressure measurement method under a kind of rotation status of the present invention, as shown in Figure 1, completes by following step:

Step 1: the installation of pressure transducer 2;

Pressure transducer 2 is arranged in the installation of sensors hole of running through two sides having on experimental piece 1, is used for the pressure distribution situation of experiments of measuring part 1 tested surface.Described pressure transducer 2 adopts little, the highly sensitive strain pressure transducer 2 of inertia, and its principle of work is that pressure-sensitive diaphragm deforms while being subject to certain pressure, and this distortion causes output signal to change.Because pressure transducer 2 in rotation status downforce experiments of measuring actual condition is with 1 rotation of rotation test part, the distortion of pressure-sensitive diaphragm is by the common result that is experimental piece 1 measured point pressure and centrifugal force, therefore before being rotated pressure survey, need to be rotated the pressure calibration of experimental piece 1 measurement point under state, to remove the impact of the suffered centrifugal force of pressure-sensitive diaphragm.

Step 2: caliberating device is installed;

Caliberating device comprises demarcates housing 3, valve inside 5, thermopair 6, as shown in Figure 2, the integrative-structure of described demarcation shell 3 for being formed by housing and valve cock 4, wherein, housing is tubular shell, one end sealing, on blind end, have tubular valve cock 4, valve cock 4 is communicated with enclosure interior, and the other end is opening, openend is bolted on experimental piece 1 tested surface, guarantees that the projection of cross section, installation of sensors hole on perpendicular is positioned at the projection of demarcation shell 3 cross sections on perpendicular inner.For the ease of demarcating the connection of housing, demarcate shell nozzle end and be circumferentially designed with flange; And in order to make obturation effect better, at above-mentioned demarcation shell nozzle end 6 and 1 of experimental piece, be provided with rubber pad.Described valve inside 5 is positioned at valve cock 4 inside, valve inside 5 inside are provided with the spring 8 of retractable, therefore can be used for being filled with gas and preventing gas leakage to demarcating 7 inside, chamber, by valve inside 5 is installed, make to demarcate the inner closed structure that forms of shell 3, as demarcating chamber 7.Described thermopair 6 is arranged in the thermocouple mounting hole that runs through two sides having on experimental piece 1, makes the temperature detection end of thermopair 6 be positioned at demarcation chamber 7, is used for measuring the temperature of demarcating in chamber 7; It is air tight that thermopair 6 guarantees that thermopair 6 and 1 of experimental piece fit tightly after installing, thus the impermeability that guarantees to demarcate chamber 7.As shown in Figure 3, charged pressure is the cavity pressure change curve after 9.90KPa when static, can see that pressure fluctuates among a small circle, can reach requirement of experiment.

When demarcating, chamber 7 volumes are enough little, demarcate chamber 7 internal pressures and equal original pressure value everywhere.But in actual conditions, demarcate chamber 7 and have certain volume, therefore can produce certain influence to the calibration result of rotation status lower pressure sensor.Therefore the radial position that in the present invention, pressure transducer 2 measurement points is placed in to 7 kernel of section points belows, demarcation chamber can effectively reduce the calibrated error causing because demarcating chamber 7 volumes;

Demarcate that chamber 7 is more little to be more conducive to make to demarcate chamber 7 internal pressures and to approach original pressure value everywhere, and the factors such as the acceptable size of demarcating chamber 7 and rotating speed, radius of turn are associated larger, by choosing the radius a that demarcates chamber, by following method, obtain demarcating the maximal value error △ P between each two-dimentional infinitesimal and original pressure in chamber _max, until the maximal value error △ P obtaining by the demarcation chamber radius a choosing _maxmeet and to realize demand, concrete grammar is as follows: irrelevant because of the centrifugal force in rotary course and axial distance, therefore can make and demarcate chamber 7 axial lengths is h=1, and the two-dimensional problems that three-dimensional scaling chamber 7 are converted into demarcation 7 bottom surfaces, chamber are analyzed.As shown in Figure 4, be the projection of caliberating device under experimental piece 1 Plane of rotation, wherein demarcating chamber 7 radiuses is a, demarcation chamber 7 bottom center's points are R apart from the distance of turning axle; The turning axle axle center O of take sets up polar coordinate system as the line of limit, demarcation chamber bottom center and axis of rotation as pole axis, can determine thus r direction and the θ direction of this coordinate system; In polar coordinates r direction, to demarcating the interior gas in chamber 7, carry out infinitesimal, getting r is that polar coordinates initial point O is to the distance of infinitesimal; Make the interior gaseous tension P of infinitesimal even; And the upper and lower surface of infinitesimal is under pressure and is respectively P _r+drand P _r, the difference of two pressure will provide the rotation centripetal force of gas in infinitesimal.Because the pressure of gas in infinitesimal is P, by the equation of gas state, calculates and obtain gaseous mass in infinitesimal

r _ggas law constant for air; T is for demarcating the interior temperature in chamber 7, and making it is constant;

, to infinitesimal upper and lower surface pressure differential, have:

$P_{r+\mathrm{dr}}-P_r={\mathrm{\&omega;}}^{2}r\&CenterDot;\frac{P}{R_{g}T}\mathrm{dr}---\left(1\right)$

In formula, ω is angular velocity of rotation, exists and is related to ω=2 π n with rotation speed n; R is the distance of infinitesimal and true origin, and dr is the differential apart from r.

Simplified style (1):

$\frac{\mathrm{dP}}{\mathrm{dr}}=\frac{{\mathrm{\&omega;}}^2}{R_{g}T}r\&CenterDot;P---\left(2\right)$

$\frac{\mathrm{dP}}{P}=\frac{{\mathrm{\&omega;}}^2}{R_{g}T}r\&CenterDot;\mathrm{dr}---\left(3\right)$

By equation both sides respectively integration can obtain:

$P=\exp (\frac{{\mathrm{\&omega;}}^2}{2R_{g}T}\&CenterDot;r^2+C_1)---\left(4\right)$

Order

above formula (4) can be changed into

$P=C\&CenterDot;\exp (\frac{{\mathrm{\&omega;}}^2}{2R_{g}T}\&CenterDot;r^2)---\left(5\right)$

In formula, C ₁and C is the constant relevant with the position of demarcating chamber, dimensional parameters and the factors such as physical parameter in chamber of demarcating.Under static state, demarcate the interior gaseous mass m in chamber 7 _chambercan be obtained by the equation of gas state:

Wherein, P ₀for demarcating the interior original pressure in chamber 7;

Because experimental piece 1 is under rotation status, demarcate chamber 7 internal pressures and distribute and change, can obtain by the gaseous mass integration in infinitesimal demarcating under rotation status the interior gaseous mass m in chamber 7 _chamber':

Wherein, dV is two-dimentional element of volume, and ρ is the gas density in infinitesimal, α be infinitesimal the maximum subtended angle of θ direction half; From the cosine law:

$\mathrm{\&alpha;}=\arccos \frac{R^2+r^2-a^2}{2\mathrm{Rr}}---\left(8\right)$

Owing to demarcating the interior mass conservation in chamber 7 before and after rotation, have:

$\frac{P_0}{R_{g}T}\&CenterDot;\mathrm{\&pi;}{a}^2=\frac{C}{R_{g}T}{\&Integral;}_{R-a}^{R+a}\exp \left(\frac{{\mathrm{\&omega;}}^2}{{2R}_{g}T}{r}^2\right)\&CenterDot;2r\&CenterDot;\mathrm{\&alpha;dr}---\left(9\right)$

By (8), (9), can be obtained:

$C=\frac{2}{{\mathrm{<figure-callout\; id="0"\; label="P"\; filenames="HDA00001932834100031.png"\; state="\{\{state\}\}">P</figure-callout>}}_0\&CenterDot;\mathrm{\&pi;}{a}^2}{\&Integral;}_{R-a}^{R+a}\exp (\frac{{\mathrm{\&omega;}}^2}{2R_{g}T}\&CenterDot;r^2)\&CenterDot;r\&CenterDot;\arccos \frac{R^2+r^2-a^2}{2\mathrm{Rr}}\&CenterDot;\mathrm{dr}---\left(10\right)$

Chamber 7 internal pressure distribution P will can be demarcated in C substitution (5).

If △ is P=P-P ₀, calculate its maximal value △ P _maxcan be used as the maximum error in calibration process, in order to characterize stated accuracy.

Illustrate the choosing method of demarcating chamber 7 radiuses below: the maximum (top) speed in supposition experiment condition is 3000rpm; Dimensional parameters in calibration process is respectively R=340mm, 2a=30mm, h=14mm; The interior original pressure in chamber 7 is P to the maximum ₀=5KPa, temperature constant is T=293K; By accuracy computation formula, can obtain △ P _max=1.06KPa, this time error is larger, therefore should further reduce to demarcate chamber 7 sizes to reduce measuring error △ P _maxvalue; All the other parameter constants, when 2a=10mm, △ P _max=0.354KPa, error can meet the requirement of experiment, can be used as the size of demarcating chamber 7, and the size that is less than these demarcation chamber 7 radiuses all can be applied.

Step 3: stationary state lower pressure sensor 2(: pressure calibration experimental piece 1 measured point);

When experimental piece 1 remains static lower time, the valve inside in caliberating device 5 is taken out in valve cock 4, the snorkel of pressure calibration instrument is connected with valve cock 4, and junction gluing is strictly sealed.By pressure calibration instrument, to demarcating in chamber 7, pass into gas (air) subsequently, and measure in real time and show the force value that passes into gas, send to data processing unit (computing machine); Pressure transducer 2 records Demarcate Gas chamber 7 interior gaseous tension corresponding voltage signal value in real time, by data acquisition unit, gathers and send to data processing unit.Thermopair 6 is measured the temperature of demarcating in chamber 7 in real time, by data acquisition unit collection, sends to data processing unit; The variation of now demarcating chamber 7 interior temperature is faint, can be considered definite value.Thus, by data processing unit by the voltage signal values receiving with demarcate the interior gas pressure value in chamber 7 and carry out matching and draw the curve map (mV-KPa curve) between voltage signal and its corresponding gaseous tension, as the pressure calibration curve of stationary state lower pressure sensor 2 (being the pressure calibration curve of experimental piece 1 rotating speed pressure transducer 2 while being zero), the benchmark that diaphragm deformation and pressure change when static is simultaneously in order to judge that whether follow-up rotation is to diaphragm deformation generation considerable influence.

Step 4: the pressure calibration of rotation status lower pressure sensor 2;

Valve inside 5 is screwed in valve cock 4, makes to demarcate chamber 7 and form air-tight state, by gas injection device (inflator), by valve inside 5, to demarcating in chamber 7, pass into gas, by block, valve cock 4 is sealed, and will block a shot and 4 gluings sealings of valve cock; By pressure transducer 2, can survey in current demarcation chamber 7 and pass into the voltage signal values that gas is corresponding, according to the pressure calibration curve of stationary state pressure transducer 2 in step 3, just can obtain passing into the gaseous tension that gas is corresponding in current demarcation chamber 7.Until impermeability in chamber after good and pressure stability, respectively with n ₁, n ₂, n ₃..., n _jrotating speed rotation test part 1, choosing of each rotating speed is consistent with experiment condition medium speed setting value.After each stabilization of speed, by pressure transducer 2, just can record in current demarcation chamber 7 and pass under gaseous tension, experimental piece 1 when every speed, the voltage signal that pressure transducer 2 records.

Change subsequently and demarcate the pressure that passes into gas in chamber 7, carry out said process, finally obtaining demarcating in chamber 7 respectively passes under gaseous tension, experimental piece 1 is when every speed, the voltage signal values that pressure transducer 2 records, by data acquisition module, gather, and send to data processing module, by data processing unit, each receiving demarcated in chamber 7 and passed into gaseous tension, the voltage signal that each tachometer value and pressure transducer 2 record carries out matching and draws under each tachometer value, the voltage signal curve map that pass between gaseous tension corresponding to it, pressure calibration curve as rotation status lower pressure sensor 2.In said process, data acquisition module also gathers to demarcate in chamber 7 and respectively passes under gaseous tension, and experimental piece 1, when every speed, is demarcated the temperature value in chamber 7, sends to data processing module, for subsequent calls.And to demarcating in chamber 7, passing into before gas at every turn, all need to carry out step 3, the pressure calibration that stationary state lower pressure sensor 2 is carried out, to guarantee that diaphragm deformation deviation is in tolerance interval, prevent that pressure transducer 2 diaphragms from occurring to be obviously out of shape and to be difficult to recovery, affect experimental result.

Step 5: the pressure calibration curve to rotation status lower pressure sensor 2 is revised matching;

In calibration process, temperature factor and demarcation chamber 7 bulk factors can impact calibration result, and in actual calibration process, temperature can inevitably change with factors such as rotational times, by the equation of gas state

P·V _m＝R·T （1）

Known, demarcating chamber 7 internal pressures also can variation with temperature and change.When processing experimental data, need to the pressure causing because of temperature variation be changed and be revised.Further analyze and show, when temperature rises 1 ℃ time, cavity pressure rising 0.371KPa, this can produce certain impact for demarcating.Therefore, in step 5, respectively pass under gaseous tension, experimental piece 1 is when every speed, the voltage signal values that pressure transducer 2 records should be corresponding with the interior gas pressure value in demarcation chamber 7 (actual gas pressure value) after temperature impact, and not correspondence respectively passes into gas pressure value, by the known P/T of formula (1), be definite value thus, by data processing module, obtaining each passes under gaseous tension, experimental piece 1 when every speed, demarcation chamber 7 interior actual gas pressure value P corresponding to voltage signal values that pressure transducer 2 records _jfor:

$P_j={\mathrm{<figure-callout\; id="0"\; label="P"\; filenames="HDA00001932834100031.png"\; state="\{\{state\}\}">P</figure-callout>}}_0\&CenterDot;\frac{T_j}{T_0}---\left(2\right)$

Wherein, P ₀for demarcating under stationary state, in chamber 7, pass into gas pressure value (demarcating original pressure in chamber); T ₀for demarcating the temperature value in chamber 7 under stationary state; T _jfor demarcating the interior temperature value in chamber 7 under each rotating speed under rotation status; Above-mentioned pressure and temperature are respectively absolute pressure and Kelvin temperature.

By P _jas experimental piece 1 when the every speed, the interior gas pressure value in demarcation chamber 7 corresponding to voltage signal values that pressure transducer 2 records, the correction of the pressure calibration curve of rotation status lower pressure sensor 2 in performing step four thus, has got rid of the impact of temperature factor on calibration result.

Step 6: caliberating device is taken off and can carry out the measurement of rotational pressure under experiment condition, experiment condition lower pressure sensor 2 is recorded under every speed after the correction that signal value obtains in step 5 to corresponding force value in pressure transducer 2 calibration curves, can get rid of thus the impact of centrifugal force on pressure transducer 2 interior diaphragm distortion under rotation status, obtain the actual force value of experiencing of pressure transducer 2.Its measuring error is the △ P that uses calculation of parameter such as demarcating chamber radius a to obtain in step 2 _max.

By the pressure measurement method under rotation status of the present invention, by nominal data has been carried out to error analysis correction, this calibration result is applied to experiment measuring process and makes experimental result have referential, has also guaranteed the precision in experiment measuring process simultaneously.

Claims (9)

1. the pressure measurement method under rotation status, is characterized in that: by following step, complete:

Step 1: the installation of pressure transducer;

Pressure transducer is arranged in the installation of sensors hole of running through two sides having on experimental piece, is used for the pressure distribution situation of experiments of measuring part tested surface; Described pressure transducer adopts strain pressure transducer;

Step 2: caliberating device is installed;

Fixing caliberating device on experimental piece tested surface, forms airtight demarcation chamber, and the measurement point of pressure transducer is positioned at and demarcates chamber; The radius choosing method in described demarcation chamber is:

It is a that chamber radius is demarcated in order, and demarcation chamber bottom center's point is R apart from the distance of turning axle; The turning axle axle center O of take is limit, and the line of demarcating chamber bottom center and axis of rotation is that pole axis is set up polar coordinate system, determines thus r direction and the θ direction of this coordinate system; In r direction, to demarcating intracavity gas, carry out infinitesimal, getting r is that polar coordinates initial point O is to the distance of infinitesimal; Make the interior gaseous tension P of each infinitesimal even; And the upper and lower surface of infinitesimal is under pressure and is respectively P _r+drand P _r, the difference of two pressure will provide the rotation centripetal force of gas in infinitesimal; Because the pressure of gas in infinitesimal is P, by the equation of gas state, calculates and obtain gaseous mass in infinitesimal

r _ggas law constant for air; T is for demarcating cavity temperature, and making it is constant;

, to infinitesimal upper and lower surface pressure differential, have:

$P_{r+\mathrm{dr}}-P_r={\mathrm{\&omega;}}^{2}r\&CenterDot;\frac{P}{R_{g}T}\mathrm{dr}---\left(2\right)$

In formula, ω is angular velocity of rotation, exists and is related to ω=2 π n with rotation speed n; R is the distance of infinitesimal and true origin, and dr is the differential apart from r;

Simplified style (2):

$\frac{\mathrm{dP}}{\mathrm{dr}}=\frac{{\mathrm{\&omega;}}^2}{R_{g}T}r\&CenterDot;P---\left(3\right)$

$\frac{\mathrm{dP}}{P}=\frac{{\mathrm{\&omega;}}^2}{R_{g}T}r\&CenterDot;\mathrm{dr}---\left(4\right)$

By equation both sides respectively integration can obtain:

$P=\exp (\frac{{\mathrm{\&omega;}}^2}{{2R}_{g}T}\&CenterDot;r^2+C_1)---\left(5\right)$ Order

above formula (5) can be changed into:

$P=C\&CenterDot;\exp (\frac{{\mathrm{\&omega;}}^2}{{2R}_{g}T}\&CenterDot;r^2)---\left(6\right)$

In formula, C ₁and C is the constant relevant with the position of demarcating chamber, dimensional parameters and the factors such as Physical Constants in chamber of demarcating;

Under static state, intracavity gas quality m _chambercan be obtained by the equation of gas state:

Wherein, P ₀for demarcating original pressure in chamber;

Because experimental piece is under rotation status, cavity pressure distributes and to change, and can obtain by the gaseous mass integration in infinitesimal demarcating under rotation status intracavity gas quality m _chamber':

Wherein, dV is two-dimentional element of volume, and ρ is the gas density in infinitesimal, α be infinitesimal the maximum subtended angle of θ direction half; From the cosine law:

$\mathrm{\&alpha;}=\arccos \frac{R^2+r^2-a^2}{2\mathrm{Rr}}---\left(9\right)$

Owing to demarcating the mass conservation in chamber before and after rotation, have:

$\frac{P_0}{R_{g}T}\&CenterDot;{\mathrm{\&pi;a}}^2=\frac{C}{R_{g}T}{\&Integral;}_{R-a}^{R+a}\exp \left(\frac{{\mathrm{\&omega;}}^2}{{2R}_{g}T}{r}^2\right)\&CenterDot;2r\&CenterDot;\mathrm{\&alpha;dr}---\left(10\right)$

By (9), (10), can be obtained:

$C=\frac{2}{P_0\&CenterDot;{\mathrm{\&pi;a}}^2}{\&Integral;}_{R-a}^{R+a}\exp (\frac{{\mathrm{\&omega;}}^2}{{2R}_{g}T}\&CenterDot;r^2)\&CenterDot;r\&CenterDot;\arccos \frac{R^2+r^2-a^2}{2\mathrm{Rr}}\&CenterDot;\mathrm{dr}---\left(11\right)$

To in C substitution (6), can demarcate cavity pressure distribution P;

If Δ P=P-P ₀, calculate its maximal value Δ P _maxcan be used as the maximum error in calibration process, in order to characterize stated accuracy;

The radius a that demarcates chamber by choosing determines the pressure of each point under rotation status and the maximal value error delta P between original pressure in demarcation chamber _max, until the maximal value error delta P obtaining by the demarcation chamber radius a choosing _maxmeet requirement of experiment;

Step 3: the pressure calibration of stationary state lower pressure sensor;

To demarcating in chamber, pass into gas, by temperature measuring device, record the temperature of demarcating in chamber, and measurement in real time passes into the force value of gas, pressure transducer records in real time and demarcates voltage signal values corresponding to intracavity gas pressure simultaneously, matching draw the curve map between voltage signal gaseous tension corresponding to it thus, as the pressure calibration curve of stationary state lower pressure sensor;

Step 4: the pressure calibration of rotation status lower pressure sensor;

To demarcating in chamber, pass into quantitative gas, by pressure transducer, record in current demarcation chamber and pass into the voltage signal values that gaseous tension is corresponding,, according to the pressure calibration curve of stationary state pressure transducer in step 3, obtain passing into the gas pressure value that gas is corresponding in current demarcation chamber; Subsequently respectively with n ₁, n ₂, n ₃..., n _jrotating speed rotation test part, choosing of each rotating speed is consistent with experiment condition medium speed setting value; By pressure transducer, record in current demarcation chamber and pass under gaseous tension, experimental piece when every speed, the voltage signal that pressure transducer records; Change to demarcate subsequently the pressure that passes into gas in chamber, carry out said process, finally obtain demarcating in chamber and respectively pass under gaseous tension, experimental piece when every speed, the voltage signal values that pressure transducer records; Matching drawing under each tachometer value thus, the voltage signal curve map that pass between gaseous tension corresponding to it, as the pressure calibration curve of rotation status lower pressure sensor; In said process, by temperature measuring device, recorded in demarcation chamber and respectively passed under gaseous tension, experimental piece, when every speed, is demarcated the temperature value in chamber;

Step 5: the pressure calibration curve to rotation status lower pressure sensor is revised matching;

Each passes under gaseous tension, experimental piece when every speed, actual gas pressure value P in demarcation chamber corresponding to voltage signal values that pressure transducer records _jfor:

$P_j=P_0\&CenterDot;\frac{T_j}{T_0}---\left(1\right)$

Wherein, P ₀for demarcating under stationary state, in chamber, pass into gas pressure value; T ₀for demarcating the temperature value in chamber under stationary state; T _jfor demarcating cavity temperature value under each rotating speed under rotation status;

By P _jas experimental piece, when the every speed, pressure transducer records demarcation intracavity gas force value corresponding to voltage signal values, the correction of the pressure calibration curve of rotation status lower pressure sensor in performing step 4 thus;

Step 6: caliberating device is taken off and can carry out the measurement of rotational pressure under experiment condition, by obtaining experiment condition lower pressure sensor, under every speed, record pressure sensor calibrating curve after the correction obtaining in signal value integrating step 5, obtain the actual force value of experiencing of pressure transducer.

2. the pressure measurement method under a kind of rotation status as claimed in claim 1, is characterized in that: in described step 4, pass into before gas to demarcating in chamber at every turn, all need carry out step 3, stationary state lower pressure sensor is carried out to pressure calibration.

3. the pressure measurement method under a kind of rotation status as claimed in claim 1, is characterized in that: in described step 3 and step 4, demarcating needs to guarantee to demarcate chamber in the chamber in and seal after gas injection.

4. the pressure measurement method under a kind of rotation status as claimed in claim 1, is characterized in that: described caliberating device comprises demarcates housing, valve inside, thermopair; Wherein, demarcate the integrative-structure of shell for being formed by housing and valve cock, wherein, housing is tubular shell, and one end sealing, has tubular valve cock on blind end, valve cock is communicated with enclosure interior, and the other end is opening, and openend is fixing on experimental piece tested surface by bolt; Described valve inside is positioned at valve cock inside, makes to demarcate enclosure and forms closed structure, as demarcating chamber; Described thermopair is arranged in the thermocouple mounting hole that runs through two sides having on experimental piece as temperature measuring device, makes the temperature detection end of thermopair be positioned at demarcation chamber; After the installation of TC, guarantee to fit tightly between thermopair and experimental piece.

5. the pressure measurement method under a kind of rotation status as claimed in claim 4, is characterized in that: described demarcation shell nozzle end is circumferentially designed with flange.

6. the pressure measurement method under a kind of rotation status as claimed in claim 4, is characterized in that: between described demarcation shell nozzle end and experimental piece, be provided with rubber pad.

7. the pressure measurement method under a kind of rotation status as claimed in claim 4, is characterized in that: described valve inside inside is provided with coil tension spring.

8. the pressure measurement method under a kind of rotation status as claimed in claim 4, it is characterized in that: described valve inside is taken out in valve cock, snorkel by pressure calibration instrument is connected with valve cock, realize and under stationary state, demarcate gas injection in chamber, and measure in real time and show the force value that passes into gas.

9. the pressure measurement method under a kind of rotation status as claimed in claim 4, is characterized in that: will by valve inside, to demarcating in chamber, pass into gas by inflator.

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