CN102053017B - Method and system for testing air flow field of indoor engine test-bed - Google Patents

Abstract

The invention discloses a method for testing an air flow field of an indoor engine test-bed, which is characterized in that in the process of testing an enclosed engine test-bed, aiming at the air inlet impulse, the frontal resistance and the range of an engine vent, a method for modifying following aerodynamic parameters is as follows: F-for Fcl = Delta Fr + Delta Fn + Delta Fp. The invention also discloses a system for testing an air flow field of an indoor engine test-bed, which comprises a data acquisition module (1), a pressure scanning valve (2), a differential pressure sensor (3) and a test pitot tube (4), wherein the pressure scanning valve (2) and the differential pressure sensor (3) are respectively connected with the data acquisition module (1), and the test pitot tube (4) is connected with the data acquisition module (1) respectively by the pressure scanning valve (2) and the differential pressure sensor (3). The method and the system provided by the invention have the advantages that the pneumatic thrust impulse correction data of the indoor engine test-bed can accurately be obtained, and through carrying out comparative analysis on the data, the calibrated thrust correction factor of the test-bed can be given, thereby solving the calibration problem of the engine test-bed, ensuring the test-run demands of the engine test-bed, and bringing huge economic benefits.

Description

A kind of air flow field of indoor engine test-bed method of testing and system

Technical field:

The present invention relates to engine run airflow field method of testing and system, a kind of air flow field of indoor engine test-bed method of testing and system are provided especially

Background technology:

In the prior art, engine is on indoor test bay during test run, because air-flow has the pressure loss during by the test bay gas handling system, and engine there is certain head-on speed, produce the air inlet punching press, the ground quiescent conditions of engine is not met when making test cell run: outflow can cause the measurement thrust loss along static pressure variation and the frictional resistance of engine length, and the nozzle place environment differential static pressure that the test bay exhaust system causes also can cause the measurement thrust loss.Domestic each model engine is because there is no the open-air platform of standard at present, and the stand thrust calibration is just undertaken by intercrossed calibration, then provides stand thrust correction factor.Therefore, interior airflow field situation between the research engine run is analyzed stand thrust loss reason, and then is very important for the test bay Thrust Measuring System provides accurately parameter correction data.

People catch at the better air flow field of indoor engine test-bed method of testing of a kind of technique effect and system.

Summary of the invention:

The purpose of this invention is to provide the better air flow field of indoor engine test-bed method of testing of a kind of technique effect and system.

The invention provides a kind of air flow field of indoor engine test-bed method of testing, it is characterized in that: in enclosed engine testsand process of the test, for input stroke, frontal resistance and engine nozzle scope, set up the modification method of following aerodynamic parameter: modified value=Δ F _r+ Δ F _n+ Δ F _pIn the formula: Δ F _rBe the input stroke modified value, Δ F _nBe the frontal resistance modified value, Δ F _pThe modified value that causes for spout scope negative pressure.

Air flow field of indoor engine test-bed method of testing of the present invention also comprises following content:

Described air flow field of indoor engine test-bed method of testing satisfies following requirement:

One: described input stroke modified value Δ F _rSatisfy following requirement: Δ F _r=F _BYL-F _BY=W _A1* V _BIn the following formula: F _BYL is the thrust without engine intake duct under the input stroke condition, F _BYBe engine input stroke W in closed test bay _A1* V _BThe power (axial force) of admission gear when testing under ≠ 0 condition, wherein: W _A1Be the engine air capacity of flowing through, V _BBe the gas velocity before the engine of test cell;

Its two: described frontal resistance modified value Δ F _nSatisfy following requirement: the frontal resistance of single parts calculates according to following relational expression:

In the formula: C _xBe the frontal resistance coefficient of studied parts, this value depends on down with the wind shape and the Reynolds number of parts

D in the formula _mBe parts cross section, middle part or diameter; μ is pneumatic coefficient of viscosity; A _MiBe the projected area of calculating; ρ is atmospheric density; V _nGas velocity for parts facing the wind records by experiment;

Total modified value Δ F _n=∑ Δ F _Ni, i.e. all and the summation of the frontal resistance of the relevant parts of moving frame;

Its three, the modified value Δ F that described spout scope negative pressure causes _pSatisfy following requirement: adjust Δ F _pMake it satisfy Δ F _pEqual zero; Perhaps calculate modified value by measuring spout and test cell wall differential manometer;

Because the impact of injection air-flow, spout exerts an influence to engine measuring thrust, can eliminate the impact of spout negative pressure by adjusting the method for spout and aiutage distance, namely amasss and the induction tunnel distance L by choosing the nozzle exit _cMethod make Δ F _pEqual zero.If impact can not be eliminated, calculate modified value by measuring spout and test cell wall differential manometer.

The present invention is claimed a kind of air flow field of indoor engine test-bed test macro be used to supporting above-mentioned air flow field of indoor engine test-bed method of testing also, and it is characterized in that: described air flow field of indoor engine test-bed test macro includes following ingredient: data acquisition module 1, pressure scanning valve 2, differential pressure pick-up 3, test pitot tube 4; Wherein: pressure scanning valve 2, differential pressure pick-up 3 are connecting respectively data acquisition module 1, and test is connecting data acquisition module 1 by pressure scanning valve 2, differential pressure pick-up 3 respectively with pitot tube 4.

Air flow field of indoor engine test-bed test macro of the present invention also comprises following preferred content:

Also include controller 5, router 6 in the described air flow field of indoor engine test-bed test macro; Router 6 is connecting respectively controller 5, data acquisition module 1, pressure scanning valve 2.

Also include air velocity transducer 7 in the described air flow field of indoor engine test-bed test macro, it is connected with data acquisition module 1;

Employed data acquisition module 1 is specially the PXI acquisition system in the described air flow field of indoor engine test-bed test macro; Controller 5 is computing machine specifically; Pressure scanning valve 2 specifically has in parallel two, is arranged in router 6 and test with between the pitot tube 4.

In terms of existing technologies, the present invention

Economic benefit: this test provides force data for engine at the Obtaining Accurate of the pneumatic momentum thrust of indoor its Test Rig correction, in a way can the alternative measurements engine.Calculate according to a calibration engine, but create beneficial result reaches 3,000 ten thousand yuan.

Social benefit: this test macro can detect newly-built stand or transformation stand airflow field situation, and thrust magnitude provides foundation for engine obtains accurately in indoor test run.Be applicable to all its Test Rigs, set up this test macro, the raising that raising engine run technical merit is built scientific research level to follow-up stand has great facilitation.

This test energy Obtaining Accurate engine is in the data of the pneumatic momentum thrust of indoor its Test Rig correction, by the Data Comparison analysis, provide bench alignment thrust correction factor, solve the engine pedestal calibration problem, guarantee the bench test drive demand, its economic benefit of bringing is huge.

Description of drawings:

Fig. 1 is the test cell schematic diagram;

Fig. 2 is total pressure probe and wind gage arrangenent diagram;

Fig. 3 is intake and exhaust pressure reduction measuring point distribution plan;

Fig. 4 is engine negative pressure test point arrangenent diagram;

Fig. 5 is the velocity test sensor arrangenent diagram that facings the wind;

Fig. 6 is the acquisition system block diagram;

Fig. 7 is the PXI system;

Fig. 8 is the connection of pressure scanning valve reference edge;

Fig. 9 is the wind gage calibration data;

Figure 10 is for testing the shelf schematic diagram of layouting;

Figure 11 is No. 12 test bay measurement point distributions;

Figure 12 is No. 15 test bay measurement point distributions;

Figure 13 is No. 8 test bay measurement point distributions;

Figure 14 is the differential pressure measurement schematic diagram;

Figure 15 is that the cloth point diagram is measured in the aerodynamic parameter correction;

Figure 16 is No. 12 complete afterburning situation velocity field cloud atlas of platform;

Figure 17 is No. 15 complete afterburning situation velocity field cloud atlas of platform;

Figure 18 is No. 8 complete afterburning situation velocity field cloud atlas of platform.

Embodiment:

Embodiment 1

A kind of air flow field of indoor engine test-bed method of testing in enclosed engine testsand process of the test, for input stroke, frontal resistance and engine nozzle scope, is set up the modification method of following aerodynamic parameter: modified value=Δ F _r+ Δ F _n+ Δ F _pIn the formula: Δ F _rBe the input stroke modified value, Δ F _nBe the frontal resistance modified value, Δ F _pThe modified value that causes for spout scope negative pressure.

The described air flow field of indoor engine test-bed method of testing of the present embodiment also comprises following content:

Described air flow field of indoor engine test-bed method of testing satisfies following requirement:

One: described input stroke modified value Δ F _rSatisfy following requirement: Δ F _r=F _BYL-F _BY=W _A1* V _B

In the following formula: F _BYLBe the thrust (open-air platform) without engine intake duct under the input stroke condition, F _BYBe engine input stroke W in closed test bay _A1* V _BThe power (axial force) of admission gear when testing under ≠ 0 condition, wherein: W _A1Be the engine air capacity of flowing through, V _BBe the gas velocity before the engine of test cell;

Its two: described frontal resistance modified value Δ F _nSatisfy following requirement: the frontal resistance of single parts calculates according to following relational expression:

In the formula: C _xBe the frontal resistance coefficient of studied parts, this value depends on down with the wind shape and the Reynolds number of parts

D in the formula _mBe parts cross section, middle part or diameter; μ is pneumatic coefficient of viscosity; A _MiBe the projected area of calculating; ρ is atmospheric density; V _nGas velocity for parts facing the wind records by experiment;

Total modified value Δ F _n=∑ Δ F _Ni, i.e. all and the summation of the frontal resistance of the relevant parts of moving frame;

Its three, the modified value Δ F that described spout scope negative pressure causes _pSatisfy following requirement: adjust Δ F _pMake it satisfy Δ F _pEqual zero; Perhaps calculate modified value by measuring spout and test cell wall differential manometer;

Because the impact of injection air-flow, spout exerts an influence to engine measuring thrust, can eliminate the impact of spout negative pressure by adjusting the method for spout and aiutage distance, namely amasss and the induction tunnel distance L by choosing the nozzle exit _cMethod make Δ F _pEqual zero.If impact can not be eliminated, calculate modified value by measuring spout and test cell wall differential manometer.

The present embodiment also includes be used to a kind of air flow field of indoor engine test-bed test macro of supporting above-mentioned air flow field of indoor engine test-bed method of testing.Described air flow field of indoor engine test-bed test macro includes following ingredient: data acquisition module 1, pressure scanning valve 2, differential pressure pick-up 3, test pitot tube 4; Wherein: pressure scanning valve 2, differential pressure pick-up 3 are connecting respectively data acquisition module 1, and test is connecting data acquisition module 1 by pressure scanning valve 2, differential pressure pick-up 3 respectively with pitot tube 4.

Described air flow field of indoor engine test-bed test macro also comprises following content:

Also include controller 5, router 6 in the described air flow field of indoor engine test-bed test macro; Router 6 is connecting respectively controller 5, data acquisition module 1, pressure scanning valve 2.

Also include air velocity transducer 7 in the described air flow field of indoor engine test-bed test macro, it is connected with data acquisition module 1;

Employed data acquisition module 1 is specially the PXI acquisition system in the described air flow field of indoor engine test-bed test macro; Controller 5 is computing machine specifically; Pressure scanning valve 2 specifically has in parallel two, is arranged in router 6 and test with between the pitot tube 4.

Other relevant issues explanations of the present embodiment:

1, according to technological document:

1) HBJ11-98, the aircraft engine test stand design discipline;

2) GJB 721-89, whirlpool spray fanjet test bay calibrating standard;

3) " the comprehensive conclusion of Preparatory work of experiment that SARI A-109 ground test stand is demarcated is reported ".

2, test event and index

1) test falls in the test cell admission pressure.Check the test cell admission pressure falls whether to be not more than 500Pa;

2) test cell inlet flow field distribution tests.Whether the air mean flow rate in the inspection test cell is greater than 10m/s;

3) differential static pressure between engine charge cross section and exhaust cross section is measured.Check that whether the differential static pressure in intrinsic motivation air inlet cross section, test cell and engine exhaust cross section is greater than 100Pa;

4) test cell fuel gas return-flow test.Check whether exhaust system has backflow between engine run;

5) the parts gas velocity test of facining the wind;

6) engine exhaust cross-section radial flow-field test;

7) engine intake stagnation temperature test.

3, method of testing

1) test mode:

To the test event in the third-largest item, need in the following one of four states of engine, carry out: idling rating, high pressure conversion rotating speed 90% state, maximum rating and full Afterburning condition.In the test run test, when arriving set condition, engine begins to carry out data acquisition after 3 minutes.

2) test falls in the test cell admission pressure:

(see the A of Fig. 1-A cross section) in distance engine intake the place ahead, arrange 17 stagnation pressure tubes, the stagnation pressure tube arrangenent diagram is seen Fig. 2.Measure stagnation pressure tube stagnation pressure P by multi-path pressure scanning valve _t, residing atmospheric pressure P subtracts each other with the test cell, obtains the Pressure Drop of each point, thereby calculates the Pressure Drop of test cell.During test, the data of every stagnation pressure tube record are no less than 6 times, are spaced apart 2 seconds at every turn.The admission pressure of diverse location falls before the engine in order to test out, and scheme is intended adopting movable supporting frame, in 3 meters in distance engine intake the place ahead, 6 meters and 9 meters measure respectively the test cell admission pressure and fall.

3) test cell inlet flow field distribution tests:

(see the A of Fig. 1-A cross section) in distance engine intake the place ahead, arranged 25 flow velocity sensors.The flow sensor arrangenent diagram is seen Fig. 2.Gather the output of flow sensor by Multichannel data acquisition device, obtain the flow velocity of each point, obtain the test cell velocity flow profile.During test, the data of every wind gage record are no less than 6 times, are spaced apart 2 seconds at every turn.The flow velocity maximum of considering the test cell is no more than 15m/s, therefore selects the hot diaphragm type wind gage to carry out fluid-velocity survey.For the airflow field that can better test out diverse location before the engine distributes, scheme is intended adopting movable supporting frame, in 3 meters in distance engine intake the place ahead, 6 meters and 9 meters measure respectively the test cell airflow field and distribute.

4) differential static pressure between engine charge cross section and exhaust cross section is measured:

According to bar regulation A.4.2 among the navigation mark GBJ11-98, in the centre position that is positioned at engine breathing cross section and side walls, the static pressure measurement point is installed on highly identical with the engine center absolute altitude height, measure the differential static pressure in engine breathing cross section, static pressure measurement adopts pressure guiding pipe and little differential pressure sensor.Engine differential static pressure measuring point arrangenent diagram is seen Fig. 3.Measure and adopt differential pressure pressure transducer, P ₁₁And P ₂₁Be one group, P ₁₁Access differential pressure pick-up high-pressure side, P ₂₁Access differential pressure pick-up low pressure end.P ₁₂And P ₂₂Be one group, P ₁₂Access differential pressure pick-up high-pressure side, P ₂₂Access differential pressure pick-up low pressure end.During test, the data of every differential pressure pickup record are no less than 6 times, are spaced apart 2 seconds at every turn.

Because the test cell room unit has closing in, as shown in Figure 3, in order better to analyze engine flow field on every side, need to increase check point.The corner position of engine and side walls is installed the static pressure measurement point on highly identical with the engine center absolute altitude height, measure the differential static pressure in this point and exhaust cross section, namely measures P32 and P22 point differential static pressure; The static pressure measurement point is installed in centre position in flex point and engine exhaust cross section on highly identical with the engine center absolute altitude height, namely measure P42 and P22 point differential static pressure.

Because the impact of injection air-flow, spout exerts an influence to engine measuring thrust.In order better to monitor the flow field situation at engine nozzle place, between engine nozzle and ground, test cell, arrange two total-pressure probes, Fig. 4 is seen in the position of layouting.Among the figure, measure 1 and 2 between differential static pressure, judge whether spout has negative pressure.

5) fuel gas return-flow test: above the cross section, test cell, with the side steel wire (see figure 3) being installed between exhausr port and the exhaust injection cylinder, fasten cloth at steel wire, in experiment, observe the airflow reflux situation with video camera.

6) the parts gas velocity test of facining the wind: in order to assess the frontal resistance of push system and engine mount, in the E-E of Fig. 1 Cross section Design the velocity surveys of facining the wind of 3 hotting mask flow sensors.Sensor is arranged and is seen Fig. 5, V ₁, V ₂, V ₃Point is the flow sensor layout points.During test, the data of every speed pickup record are no less than 6 times, are spaced apart 2 seconds at every turn.

7) engine exhaust cross-section radial flow-field test: in order to analyze engine nozzle place flow field situation, consider the feasibility of test, during test, arrange 4 pitot tube flow sensors at engine nozzle and between the walls, by measuring stagnation pressure and static pressure, the flow field in analysis to measure cross section.Simultaneously, also can judge the spout negative pressure.

8) engine intake stagnation temperature test: in order to measure more accurately the gas flow temperature at engine intake place, on original four temperature sensors of engine charge cover next door, arrange that 4 braces have total temperature sensor of shielding and diffusion function to measure the gas flow temperature of air inlet.

4, data are processed

1) the test cell Pressure Drop calculates:

The mean pressure of each measurement point is:

In the formula: Be 6 tonometric mean values of i measurement point, P _InBe n collection value of i measurement point;

The pressure of each measurement point is reduced to: In the formula: P _DiThe Pressure Drop of ordering for representing i, P _AtFor representing the on-site atmospheric pressure value in test cell.

The test cell average pressure drop

For:

2) the computation of the gas flow field before the engine of test cell:

The mean flow rate of each measurement point is:

In the formula:

Mean flow rate for i fluid-velocity survey point before the expression engine; V _BinFor representing the n time measured value of i fluid-velocity survey point before the engine; The mean flow rate in flow field

For:

3) the parts gas velocity of facining the wind is calculated:

The mean flow rate of each measurement point is:

In the formula:

Mean flow rate for i fluid-velocity survey point before the expression engine; V _InFor representing the n time measured value of i fluid-velocity survey point before the engine; The mean flow rate in flow field

For:

4) exhaust injection cylinder mixing section gas-flow Flow Field Calculation:

Total differential static pressure in the gas velocity measurement and the conversion of gas velocity: according to the aerodynamics principle, the pass between total differential static pressure and the charge air flow speed is:

$P_{\mathrm{total}}-P=\frac{1}{2}\mathrm{\&rho;}{\mathrm{<figure-callout\; id="2"\; label="V"\; filenames="DEST\_PATH\_HSB00000079485200023.png"\; state="\{\{state\}\}">V</figure-callout>}}^2;$

Can get through deriving:

In the formula: P _TotalBe the inlet air flow stagnation pressure; P is the charge air flow static pressure; V is charge air flow speed; ρ is atmospheric density;

I point flow velocity is:

In the formula:

The mean flow rate of ordering for representing i; P _TotalinMeasure measured stagnation pressure value the n time for representing i measurement point; P _InMeasure measured static pressure the n time for representing i measurement point; I is 1～5 for value.

5) gas flow temperature linear accelerator:

The medial temperature that i is ordered is:

In the formula:

For representing an injection cylinder temperature i point medial temperature; T _YinFor representing an injection cylinder temperature temperature value that the i point records for the n time; Wherein temperature sensor will be through coefficient of restitution calibration and erection rate error.

5, test macro: the test macro that the present embodiment needs is a Multi parameters Test Macro, and the parameter kind is many, comprises pressure signal, wind velocity signal and temperature signal etc.Measuring point is also many simultaneously, and requires picking rate very fast, and data volume is also larger.According to above-mentioned requirements, adopted the PXI acquisition system, the acquisition system block diagram is as shown in Figure 6.

The test macro that the present embodiment needs is a Multi parameters Test Macro, and the parameter kind is many, comprises pressure signal, wind velocity signal and temperature signal etc.Measuring point is also many simultaneously, and requires picking rate very fast, and data volume is also larger.According to above-mentioned requirements, adopted the PXI acquisition system, the acquisition system block diagram is as shown in Figure 6.The testing tool equipment introduction is as follows:

1) PXI system: according to the test needs, adopt PXI system as shown in Figure 7, the frequency acquisition of whole system is 5Hz.

2) pressure scanning valve: the pressure scanning valve has been selected DSA3217, and range is 1psi, its accuracy be full scale ± 0.12%.Method has as shown in Figure 8 been taked in the connection of reference edge, to guarantee the stable of reference edge.

3) pitot tube: test is to make pitot tube by oneself with pitot tube, and the making of pitot tube is fully according to the relevant regulations of NPL.Pitot tube has passed through calibration before use, and its coefficient is all between 0.997～1.003.

4) differential pressure pick-up: differential pressure pick-up has adopted Druck LPX5000 series, and transducer range is ± 500Pa that accuracy reaches the output of 0.1%, 4～20mA electric current.Sensor has also passed through calibration.

5) air velocity transducer: air velocity transducer has been selected E+E 65 type film wind gages, its accuracy is ± (measured value of 0.2m/s+2%), test has all been passed through calibration with sensor, the index that meets above-mentioned accuracy, see Fig. 9 (horizontal ordinate is calibration point, and ordinate is by the difference between school wind gage and the standard).

Testing apparatus gathers: equipment is used in this time test, is summarized in table 1.

Table 1 testing apparatus summary sheet

Sensor and testing apparatus that accuracy requirement is arranged all will be through examining and determine or calibrating, and data accurately reaches reliably when guaranteeing test.

6, data acquisition program: this time test, worked out specially capture program.This capture program uses Labview to write, and has taked the structure of Server-Client.Wherein the operation of the PXI system in test cell Server program is mainly finished data acquisition and transmission.In between control, use notebook computer operation Client end program, mainly finish the tasks such as acceptance, demonstration and storage of data.Adoption Network transmission between notebook computer and PXI system.

7, measuring point is arranged: referring to accompanying drawing 10,11,12,13.

8, test result

1) conventionally test result:

No. 12 test baies: it is the drop-out value that the relatively outdoor referenmce atomsphere of the average stagnation pressure of measured section is pressed that mean pressure falls; The stand mean flow rate is the mean wind speed of mean engine outside outer flow passage.Referring to table 2.

Table 2

No. 15 test baies, referring to table 3:

Table 3

No. 8 test baies, referring to table 4:

Table 4

According to relevant regulations such as HBJ11-98 " aircraft engine test stand design discipline " and GJB721-89 " whirlpool spray fanjet test bay calibrating standard ".Following aerodynamic conditions should be satisfied in the flow field, test cell:

Test falls in the test cell admission pressure.The test cell admission pressure falls and should be not more than 500Pa;

Test cell inlet flow field distribution tests.The big-block engine test bay, the air mean flow rate in the test cell should be not more than 15m/s.

Differential static pressure between engine charge cross section and exhaust cross section is measured.The differential static pressure in intrinsic motivation air inlet cross section, test cell and engine exhaust cross section should be not more than 100Pa.

Test cell fuel gas return-flow test.Exhaust system should guarantee not produce backflow between engine run.

Data in the table of comparisons can be seen, three stands of test all satisfy above-mentioned requirements.But can see by flow-field test, two stands of the flow field uniformity of No. 8 platforms and other are compared poor, and this structure with its gas handling system is relevant, and detailed flow field analysis is referring to flow field cloud analysis Figure 10,11,12.

2) frontal resistance estimation: owing to not recording the frontal resistance coefficient of each parts of stand by research technique, the frontal resistance modified value is carried out estimation bigger than normal by formula (6) here: referring to table 5:

Table 5

Can find out from the estimated value that frontal resistance is bigger than normal, compare with the input stroke modified value, the frontal resistance correction can be ignored.

3) input stroke correction

The calculating of input stroke modified value can be carried out according to following formula.

ΔF _r=G ₀v _m-(G ₀-G ₁)v _m′-(p _s′-p _0s)A （1）

In the formula: G ₀Be total MAF of test cell, kg/s; v _mBe engine the place ahead far away mean flow rate; G ₁Be engine intake airflow, kg/s; v _m' be runner mean wind speed around the engine, m/s; p _s' be air intake duct stagnation region static pressure, Pa; p _0sBe engine front square section far away static pressure, Pa; A is the test cell sectional area, m ²

4) testing scheme: according to (1) formula, need clearly test or disposal route just like next tittle.

1. total MAF G of test cell ₀

G ₀Calculated by following formula: G ₀=ρ v _mA (2)

Wherein: A is the test cell sectional area, is known parameters; ρ is atmospheric density, kg/m ³, for general calculating, can adopt the density of normal atmosphere; v _mBe engine the place ahead far away mean flow rate.

In previous test, we are 4m before the engine intake cross section, and 6m and 9m place with 25 air velocity transducers, are arranged to the measuring point matrix of 5x5, have recorded the wind speed profile in three cross sections.By analyzing data, we find No. 12 and No. 15 test cells in wind speed still more uniform.Therefore in this test, at 9m place, engine the place ahead, selected four representative measuring points, and do not measured at whole Section Space.

2. engine intake airflow G ₁: this parameter is that test run must be surveyed parameter, can directly be calculated by test bay to provide.

3. runner mean wind speed v around the engine _m': actual measurement obtains that the runner mean wind speed possesses certain difficulty around the engine, and what its reason need here to be is mean wind speed, is difficult to represent by certain any wind speed, simultaneously, also is difficult to average at the too much measuring point of engine arranged around.

In this test, this parameter is to obtain by the method for calculating:

Recording G ₀After, (G in fact ₀-G ₁) be exactly a known quantity, and its physical significance is passed through the engine flow quality flow of runner on every side just.Suppose that A ' for the sectional area of runner around the engine, just can calculate v _m'.

$v_m^{\&prime;}=\frac{(G_0-G_1)}{\mathrm{\&rho;}{A}^{\&prime;}}---\left(3\right)$

4. differential static pressure (p _s'-p _0s):

Can see Measurement accuracy differential static pressure (p from (1) formula _s'-p _0s) be very crucial, the measuring error of several handkerchiefs will cause the very large deviation of input stroke correction net result after multiply by whole test cell sectional area.Therefore, this differential pressure of Measurement accuracy is to calculate a key issue of input stroke correction.

Measurement accuracy differential static pressure (p _s'-p _0s) be very difficult, its reason mainly contains two: one, the magnitude of this differential static pressure is very little, only has about 10Pa; Its two, the rugged surroundings between engine run (vibration, various interference etc.).Differential pressure about engine run on-the-spot test 10Pa, its difficulty is well imagined.In fact, in front once test, just because of not recognizing more above-mentioned factors, thereby select and there are some problems in method of testing at instrument, finally cause the measuring error of this parameter excessive, can't carry out the calculating of input stroke.

In this test, we have taked measure from several links, guarantee differential static pressure (p _s'-p _0s) Measurement accuracy:

At first, be set up the method for taking multi-point average at measuring point cloth, on the cross section, front and back, respectively arranged respectively 4 pitot tubes, after again 4 hydrostatic measuring points on each cross section being accumulated, reach differential pressure pick-up.What in fact, differential pressure pick-up recorded is the poor of cross section, front and back static pressure mean value.

Secondly, selected range less, the differential pressure pick-up that accuracy is higher.The differential pressure pick-up range that this time test is used is 200Pa, and accuracy reaches 0.1%.

At last, on-the-spot differential pressure gauge also in parallel, whether the measurement that is used for the field-checking differential pressure pick-up is normal.As shown in figure 14:

The above is illustrated the measurement of some keys, and each 2 test parameter is gathered such as following table 1:

Table 6 test parameter gathers

5) measuring point is arranged explanation: the layout of measuring point as shown in figure 15.

6) test result: according to above-mentioned testing program, No. 12 platforms and No. 15 platforms are tested.According to above-mentioned computing method, test figure to be put in order and calculated, result of calculation is summarized in the following table.

Table 7 input stroke correction result summary sheet

Can see from table 7 result, for different stands, the modified value of input stroke there are differences, this may be because the difference of stand aerodynamic arrangement causes, also may be because used different engines (in test by the end of September, what No. 12 platforms and No. 15 platforms used is different engines) cause, also might because the intake air temperature difference cause.

7) test analysis on Uncertainty: according to (1) formula and (2) formula, can list the uncertainty calculation formula of input stroke correction, as follows:

${u_c}^2\left(\mathrm{\&Delta;}{F}_r\right)={\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="DEST\_PATH\_HSB00000079485200021.png,DEST\_PATH\_HSB00000079485200022.png"\; state="\{\{state\}\}">C</figure-callout>}}_1^2{u}^2\left(\mathrm{\&rho;}\right)+{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="DEST\_PATH\_HSB00000079485200023.png"\; state="\{\{state\}\}">C</figure-callout>}}_2^2{u}^2\left(v_m\right)+{\mathrm{<figure-callout\; id="3"\; label="C"\; filenames="DEST\_PATH\_HSB00000079485200023.png"\; state="\{\{state\}\}">C</figure-callout>}}_3^2{u}^2\left(A\right)+{\mathrm{<figure-callout\; id="4"\; label="C"\; filenames="DEST\_PATH\_HSB00000079485200023.png"\; state="\{\{state\}\}">C</figure-callout>}}_4^2{u}^2\left(A^{\&prime;}\right)+{\mathrm{<figure-callout\; id="5"\; label="C"\; filenames="DEST\_PATH\_HSB00000079485200023.png"\; state="\{\{state\}\}">C</figure-callout>}}_5^2{u}^2\left(G_1\right)+{\mathrm{<figure-callout\; id="6"\; label="C"\; filenames="H2009102197121E00061.png,H2009102197121E00071.png"\; state="\{\{state\}\}">C</figure-callout>}}_6^2{u}^2\left(\mathrm{\&Delta;p}\right)---\left(4\right)$

In the formula: ${\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="DEST\_PATH\_HSB00000079485200021.png,DEST\_PATH\_HSB00000079485200022.png"\; state="\{\{state\}\}">C</figure-callout>}}_1={v_m}^{2}A-\frac{{v_m}^2{A}^2}{A^{\&prime;}}+\frac{{\mathrm{<figure-callout\; id="1"\; label="G"\; filenames="DEST\_PATH\_HSB00000079485200021.png,DEST\_PATH\_HSB00000079485200022.png"\; state="\{\{state\}\}">G</figure-callout>}}_1^2}{A^{\&prime;}{\mathrm{\&rho;}}^2};$

${\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="DEST\_PATH\_HSB00000079485200023.png"\; state="\{\{state\}\}">C</figure-callout>}}_2=2\mathrm{\&rho;}{v}_{m}A-\frac{2{\mathrm{<figure-callout\; id="2"\; label="A"\; filenames="DEST\_PATH\_HSB00000079485200023.png"\; state="\{\{state\}\}">A</figure-callout>}}^2\mathrm{\&rho;}{v}_m}{A^{\&prime;}}+\frac{2G_{1}A}{A^{\&prime;}};$

${\mathrm{<figure-callout\; id="3"\; label="C"\; filenames="DEST\_PATH\_HSB00000079485200023.png"\; state="\{\{state\}\}">C</figure-callout>}}_3=\mathrm{\&rho;}{v}_m^2-\frac{2{{\mathrm{<figure-callout\; id="2"\; label="v\; m"\; filenames="DEST\_PATH\_HSB00000079485200023.png"\; state="\{\{state\}\}">v</figure-callout>}}_m}^2\mathrm{\&rho;A}}{A^{\&prime;}}+\frac{2v_m{G}_1}{A^{\&prime;}}-\mathrm{\&Delta;p};$

${\mathrm{<figure-callout\; id="4"\; label="C"\; filenames="DEST\_PATH\_HSB00000079485200023.png"\; state="\{\{state\}\}">C</figure-callout>}}_4=\frac{1}{{A^{\&prime;}}^2}(\mathrm{\&rho;}{v_m}^2{A}^2-2v_{\mathrm{<figure-callout\; id="1"\; label="m\; A\; G"\; filenames="DEST\_PATH\_HSB00000079485200021.png,DEST\_PATH\_HSB00000079485200022.png"\; state="\{\{state\}\}">m</figure-callout>}}A{G}_{}{}_1+\frac{{{\mathrm{<figure-callout\; id="1"\; label="G"\; filenames="DEST\_PATH\_HSB00000079485200021.png,DEST\_PATH\_HSB00000079485200022.png"\; state="\{\{state\}\}">G</figure-callout>}}_1}^2}{\mathrm{\&rho;}});$

${\mathrm{<figure-callout\; id="5"\; label="C"\; filenames="DEST\_PATH\_HSB00000079485200023.png"\; state="\{\{state\}\}">C</figure-callout>}}_5=\frac{2v_{m}A}{A^{\&prime;}}-\frac{2{\mathrm{<figure-callout\; id="1"\; label="G"\; filenames="DEST\_PATH\_HSB00000079485200021.png,DEST\_PATH\_HSB00000079485200022.png"\; state="\{\{state\}\}">G</figure-callout>}}_1}{\mathrm{\&rho;}{A}^{\&prime;}};$

C ₆＝-A。

According to the technical indicator of the instrument of selecting, in conjunction with the in-site measurement situation, conservative estimation:

The error of density value is in 2%; The measuring error of wind speed is in 2%; The evaluated error of area is in 0.8%; The evaluated error of circulation area is in 1.2%; The measuring error of engine intake airflow is in 1%;

The measuring error of differential pressure is in 8%, and the error of differential pressure measurement has the factor of the following aspects: one, the error of differential pressure pick-up itself, according to the technical indicator of sensor in 0.1%; Its two, point position is chosen improper, although chosen the method for multipoint-parallel in the test, each measuring point mean pressure is the average static pressure in this cross section, conservative estimation, its error is in 2.5%; Its three, the error of whole measuring system, whole pressure measuring system has wherein comprised all too many levels as shown in Figure 1, therefore vibration during such as long Distance Transmission, engine run etc. guarantees to estimate that this error is in 5%.Comprehensive more above-mentioned factors, the total differential pressure measurement error of conservative estimation is in 8%.

The repeatability of momentum correction is in 1.5N.

Can put out thus input stroke correction uncertainty evaluation table as shown in table 8 in order.

Can see from above-mentioned uncertainty evaluation, the maximum uncertainty of input stroke correction test derives from the measurement of differential pressure.In this test, taked multiple test to guarantee that the measurement of differential pressure, front have been chatted and.From the result, expanded uncertainty is controlled in 10%, result or gratifying.

Table 8 input stroke correction uncertainty evaluation table

9, flow field nephanalysis

In order to strengthen the analysis of Velocity Field between different test baies and same test bay different cross section, the spy has drawn the velocity field cloud atlas of each test bay and same test bay different cross section, and such as Figure 16, Figure 17 and shown in Figure 180, the Z negative sense among the figure is the engine charge direction.

Negotiation speed field cloud atlas can see, the flow field of No. 12 platforms and No. 15 platforms is more even, and the flow field of No. 8 platforms is very inhomogeneous.The center section flow velocity of ground proximity is very high, has reached the magnitude of 15m/s, and in addition, the center flow velocity is also higher.This gas handling system with this stand is relevant, and its air inlet barrier hinders for some reason in the bottom and can't close.From the flow field, air-flow is directly pounded earthward, and the gas velocity of ground proximity one deck is very high, and at the position, corner, two base angles especially, because wall and other barriers, air-flow velocity is very low.

10, conclusion:

Measure by the stand aerodynamic parameter, 3 stand aerodynamic parameters are detected analysis, all satisfy military standard of China, simultaneously by test, computational analysis stand thrust loss reason, impact accounts for approximately 2-3% of engine gross thrust to pneumatic momentum on thrust, has verified that analytical calculation draws the average correction factor of each thrust basic identical with the correction factor that calculates with the calibration engine.

The pneumatic gauging calibration is one of indoor its Test Rig thrust dynamic calibration method of in the world normal employing, by the aerodynamic parameter flow-field test, carry out correlation analysis and calculate, draw pneumatic momentum etc. to the modified value of motor power, can realize each its Test Rig thrust calibration of А л-31 ф engine.

Embodiment 2

The present embodiment and embodiment 1 content are basic identical, and its difference is:

1) described air flow field of indoor engine test-bed method of testing satisfies one of following requirement or the wherein arbitrarily combination of the two:

One: described input stroke modified value Δ F _rSatisfy following requirement: Δ F _r=F _BYL-F _BY=W _A1* W _BIn the following formula: F _BYLBe the thrust (open-air platform) without engine intake duct under the input stroke condition, F _BYBe engine input stroke W in closed test bay _A1* V _BThe power (axial force) of admission gear when testing under ≠ 0 condition, wherein: W _A1Be the engine air capacity of flowing through, V _BBe the gas velocity before the engine of test cell;

Its two: described frontal resistance modified value Δ F _nSatisfy following requirement: the frontal resistance of single parts calculates according to following relational expression: In the formula: C _xBe the frontal resistance coefficient of studied parts, this value depends on down with the wind shape and the Reynolds number of parts

D in the formula _mBe parts cross section, middle part or diameter; μ is pneumatic coefficient of viscosity; A _MiBe the projected area of calculating; ρ is atmospheric density; V _nGas velocity for parts facing the wind records by experiment;

Total modified value Δ F _n=∑ Δ F _Ni, i.e. all and the summation of the frontal resistance of the relevant parts of moving frame;

Its three, the modified value Δ F that described spout scope negative pressure causes _pSatisfy following requirement: adjust Δ F _pMake it satisfy Δ F _pEqual zero; Perhaps calculate modified value by measuring spout and test cell wall differential manometer;

Because the impact of injection air-flow, spout exerts an influence to engine measuring thrust, can eliminate the impact of spout negative pressure by adjusting the method for spout and aiutage distance, namely amasss and the induction tunnel distance L by choosing the nozzle exit _cMethod make Δ F _pEqual zero.If impact can not be eliminated, calculate modified value by measuring spout and test cell wall differential manometer.

2) the present embodiment also includes be used to a kind of air flow field of indoor engine test-bed test macro of supporting above-mentioned air flow field of indoor engine test-bed method of testing.Described air flow field of indoor engine test-bed test macro includes following ingredient: data acquisition module 1, pressure scanning valve 2, differential pressure pick-up 3, test pitot tube 4; Wherein: pressure scanning valve 2, differential pressure pick-up 3 are connecting respectively data acquisition module 1, and test is connecting data acquisition module 1 by pressure scanning valve 2, differential pressure pick-up 3 respectively with pitot tube 4.

Claims (3)

1. an air flow field of indoor engine test-bed method of testing in enclosed engine testsand process of the test, for input stroke, frontal resistance and engine nozzle scope, is set up the modification method of following aerodynamic parameter: modified value=Δ F _r+ Δ F _n+ Δ F _pIn the formula: Δ F _rBe the input stroke modified value, Δ F _nBe the frontal resistance modified value, Δ F _pThe modified value that causes for spout scope negative pressure; It is characterized in that: described air flow field of indoor engine test-bed method of testing satisfies following requirement one or a combination set of:

One: described input stroke modified value Δ F _rSatisfy following requirement: Δ F _r=F _BYL-F _BY=W _A1* V _BIn the following formula: F _BYLBe the thrust without engine intake duct under the input stroke condition, F _BYBe engine input stroke W in closed test bay _A1* V _BThe power of admission gear when testing under ≠ 0 condition, wherein: W _A1Be the engine air capacity of flowing through, V _BBe the gas velocity before the engine of test cell;

Its two: described frontal resistance modified value Δ F _nSatisfy following requirement: the frontal resistance of single parts calculates according to following relational expression:

In the formula: C _xBe the frontal resistance coefficient of studied parts, this value depends on down with the wind shape and the Reynolds number of parts

D in the formula _mBe parts cross section, middle part or diameter; μ is pneumatic coefficient of viscosity; A _MiBe the projected area of calculating; ρ is atmospheric density; V _nGas velocity for parts facing the wind records by experiment;

Total modified value Δ F _n=∑ Δ F _Ni, i.e. all and the summation of the frontal resistance of the relevant parts of moving frame;

Its three, the modified value Δ F that described spout scope negative pressure causes _pSatisfy following requirement: adjust Δ F _pMake it satisfy Δ F _pEqual zero; Perhaps calculate modified value by measuring spout and test cell wall differential manometer.

2. air flow field of indoor engine test-bed test macro, it is characterized in that: described air flow field of indoor engine test-bed test macro includes following ingredient: data acquisition module (1), pressure scanning valve (2), differential pressure pick-up (3), test are with pitot tube (4); Wherein: pressure scanning valve (2), differential pressure pick-up (3) are connecting respectively data acquisition module (1), and test is connecting data acquisition module (1) by pressure scanning valve (2), differential pressure pick-up (3) respectively with pitot tube (4);

Also include controller (5), router (6), air velocity transducer (7) in the described air flow field of indoor engine test-bed test macro; Router (6) is connecting respectively controller (5), data acquisition module (1), pressure scanning valve (2); Air velocity transducer (7) is connected with data acquisition module (1).

3. according to the described air flow field of indoor engine test-bed test macro of claim 2, it is characterized in that: employed data acquisition module (1) is specially the PXI acquisition system in the described air flow field of indoor engine test-bed test macro; Controller (5) is computing machine specifically; Pressure scanning valve (2) specifically has in parallel two, is arranged in router (6) and test with between the pitot tube (4).

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