CN102053017A - 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

Test bay airflow field method of testing and system in a kind of engine room

Technical field:

The present invention relates to engine run airflow field method of testing and system, test bay airflow field method of testing and system in a kind of engine room are provided especially

Background technology:

In the prior art, engine is on indoor test bay during test run, because air communication has the pressure loss when crossing 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 the 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 not because of still there being the open-air platform of standard at present, and the stand thrust calibration is just undertaken by intercrossed calibration, provides stand thrust correction factor then.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 the data of parameter correction accurately.

People catch at test bay airflow field method of testing and system in the better engine room of a kind of technique effect.

Summary of the invention:

The purpose of this invention is to provide test bay airflow field method of testing and system in the better engine room of a kind of technique effect.

The invention provides test bay airflow field method of testing in a kind of engine room, it is characterized in that: in enclosed engine testsand process of the test, at input stroke, frontal resistance and engine nozzle scope, set up the modification method of following aerodynamic parameter: F-F _Cl=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.

Test bay airflow field method of testing also comprises following content in the engine room of the present invention:

Test bay airflow field method of testing satisfies following requirement in the described engine room:

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 of engine intake duct under the no 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: $\mathrm{\&Delta;}{F}_{\mathrm{ni}}=C_x{A}_{\mathrm{mi}}\&times;\frac{\mathrm{\&rho;}{\mathrm{<figure-callout\; id="2"\; label="V\; n"\; filenames="DEST\_PATH\_HSB00000079485200023.png,H2009102197121E00061.png"\; state="\{\{state\}\}">V</figure-callout>}}_n^{}}{2};$ In the formula: C _xFor being studied the frontal resistance coefficient of parts, this value depends on the shape and the Reynolds number of parts down with the wind $R_c=\frac{\mathrm{\&rho;}{V}_n{d}_m}{\mathrm{\&mu;}},$ 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 an atmospheric density; V _nGas velocity for parts facing the wind records by experiment;

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

The also claimed interior test bay airflow field test macro of a kind of engine room that is used to support test bay airflow field method of testing in the above-mentioned engine room of the present invention, it is characterized in that: test bay airflow field test macro includes following ingredient in the described engine room: 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 data acquisition module 1 respectively, and test is connecting data acquisition module 1 by pressure scanning valve 2, differential pressure pick-up 3 respectively with pitot tube 4.

Test bay airflow field test macro also comprises following preferred content in the engine room of the present invention:

Also include controller 5, router 6 in the test bay airflow field test macro in the described engine room; Router 6 is connecting controller 5, data acquisition module 1, pressure scanning valve 2 respectively.

Also include air velocity transducer 7 in the test bay airflow field test macro in the described engine room, it is connected with data acquisition module 1;

Employed data acquisition module 1 is specially the PXI acquisition system in the interior test bay airflow field test macro of described engine room; Controller 5 specifically is a computing machine; 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 accurately obtaining of the pneumatic momentum thrust of indoor test run stand 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 test run stands, 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.

The data of engine in the correction of the pneumatic momentum thrust of indoor test run stand can be accurately obtained in this test, by the data comparative 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 synoptic diagram;

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

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

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

Fig. 5 is the velocity test transducer arrangements figure 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 synoptic diagram of layouting;

Figure 11 is that No. 12 test bay measurement points distribute;

Figure 12 is that No. 15 test bay measurement points distribute;

Figure 13 is that No. 8 test bay measurement points distribute;

Figure 14 is the differential pressure measurement synoptic diagram;

Figure 15 measures the cloth point diagram for 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

Test bay airflow field method of testing in a kind of engine room in enclosed engine testsand process of the test, at input stroke, frontal resistance and engine nozzle scope, is set up the modification method of following aerodynamic parameter: F-F _Cl=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.

Test bay airflow field method of testing also comprises following content in the described engine room of present embodiment:

Test bay airflow field method of testing satisfies following requirement in the described engine room:

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 (open-air platform) of engine intake duct under the no 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: $\mathrm{\&Delta;}{F}_{\mathrm{ni}}=C_x{A}_{\mathrm{mi}}\&times;\frac{\mathrm{\&rho;}{\mathrm{<figure-callout\; id="2"\; label="V\; n"\; filenames="DEST\_PATH\_HSB00000079485200023.png,H2009102197121E00061.png"\; state="\{\{state\}\}">V</figure-callout>}}_n^{}}{2};$ In the formula: C _xFor being studied the frontal resistance coefficient of parts, this value depends on the shape and the Reynolds number of parts down with the wind $R_c=\frac{\mathrm{\&rho;}{V}_n{d}_m}{\mathrm{\&mu;}},$ 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 an atmospheric density; V _nGas velocity for parts facing the wind records by experiment;

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

Present embodiment also includes the interior test bay airflow field test macro of a kind of engine room that is used to support test bay airflow field method of testing in the above-mentioned engine room.Test bay airflow field test macro includes following ingredient in the described engine room: 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 data acquisition module 1 respectively, and test is connecting data acquisition module 1 by pressure scanning valve 2, differential pressure pick-up 3 respectively with pitot tube 4.

Test bay airflow field test macro also comprises following content in the described engine room:

Also include controller 5, router 6 in the test bay airflow field test macro in the described engine room; Router 6 is connecting controller 5, data acquisition module 1, pressure scanning valve 2 respectively.

Also include air velocity transducer 7 in the test bay airflow field test macro in the described engine room, it is connected with data acquisition module 1;

Employed data acquisition module 1 is specially the PXI acquisition system in the interior test bay airflow field test macro of described engine room; Controller 5 specifically is a computing machine; 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 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) " comprehensive conclusion report is prepared in the experiment that SARI A-109 ground test stand is demarcated ".

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.Whether the differential static pressure of checking 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 complete afterburning state.In the test run test,, engine begins to carry out data acquisition after 3 minutes when arriving set condition.

2) test falls in the test cell admission pressure:

(see the A-A cross section of Fig. 1) 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, and the pressure of obtaining each point falls, thus the pressure that calculates the test cell falls.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 intends adopting movable supporting frame, and 3 meters in distance engine intake the place ahead, 6 meters and 9 meters are measured the test cell admission pressure respectively and fallen.

3) test cell inlet flow field distribution tests:

(see the A-A cross section of Fig. 1) in distance engine intake the place ahead, arranged 25 flow sensors.The flow sensor arrangenent diagram is seen Fig. 2.By the output of multi-channel data acquisition device acquisition stream speed sensors, 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 for use 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 intends adopting movable supporting frame, and 3 meters in distance engine intake the place ahead, 6 meters and 9 meters are measured the test cell airflow field respectively and distributed.

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 elementary errors pressure pressure sensor, P ₁₁And P ₂₁Be one group, P ₁₁Insert the differential pressure pick-up high-pressure side, P ₂₁Insert the differential pressure pick-up low pressure end.P ₁₂And P ₂₂Be one group, P ₁₂Insert the differential pressure pick-up high-pressure side, P ₂₂Insert the 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,, need to increase check point in order better to analyze engine flow field on every side.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, promptly 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, promptly measure P42 and P22 point differential static pressure.

Because the influence 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, a steel wire (see figure 3) being installed between exhausr port and the exhaust injection tube, on steel wire, fasten cloth, in experiment, observe the airflow reflux situation with video camera with the side.

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.Transducer arrangements 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 the gas flow temperature at engine intake place more accurately, 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 processing

1) calculating falls in test cell pressure:

The mean pressure of each measurement point is: ${\stackrel{\&OverBar;}{P}}_i=\frac{1}{6}\underset{n=1}{\overset{6}{\mathrm{\&Sigma;}}}{P}_{\mathrm{in}};$ In the formula: P _iBe 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: P _Di=P _At-P _iIn the formula: P _DiFor the pressure of representing i to order falls, P _AtFor representing the on-site atmospheric pressure value in test cell.

Test cell average pressure drop P is: $\stackrel{\&OverBar;}{P}=\frac{1}{17}\underset{n=1}{\overset{17}{\mathrm{\&Sigma;}}}{P}_{\mathrm{Dn}}.$

2) airflow field calculates before the engine of test cell:

The mean flow rate of each measurement point is: $\stackrel{\&OverBar;}{V_{\mathrm{Bi}}}=\frac{1}{6}\underset{n=1}{\overset{6}{\mathrm{\&Sigma;}}}{V}_{\mathrm{Bin}};$ In the formula: V _BiMean 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 V in flow field _BFor: $\stackrel{\&OverBar;}{V_B}=\frac{1}{25}\underset{i=1}{\overset{25}{\mathrm{\&Sigma;}}}\stackrel{\&OverBar;}{V_{\mathrm{Bi}}}.$

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

The mean flow rate of each measurement point is: ${\stackrel{\&OverBar;}{V}}_i=\frac{1}{6}\underset{n=1}{\overset{6}{\mathrm{\&Sigma;}}}{V}_{\mathrm{in}};$ In the formula: V _iMean 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 V in flow field is: $\stackrel{\&OverBar;}{V}=\frac{1}{3}\underset{i=1}{\overset{3}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{V}}_i.$

4) exhaust injection tube mixer gas-flow Flow Field Calculation:

The 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:

$P_{\mathrm{total}}-P=\frac{1}{2}\mathrm{\&rho;}{\mathrm{<figure-callout\; id="2"\; label="V"\; filenames="DEST\_PATH\_HSB00000079485200023.png,H2009102197121E00061.png"\; state="\{\{state\}\}">V</figure-callout>}}^2;$

Can get through deriving: $V=\sqrt{\frac{2(P_{\mathrm{total}}-P)}{\mathrm{\&rho;}}};$ In the formula: P _TotalFor inlet air flow stagnation pressure P is the charge air flow static pressure; V is a charge air flow speed; ρ is an atmospheric density;

I point flow velocity is: $\stackrel{\&OverBar;}{V_{\mathrm{yi}}}=\frac{1}{6}\underset{n=1}{\overset{6}{\mathrm{\&Sigma;}}}\sqrt{\frac{2(P_{\mathrm{totalin}}-P_{\mathrm{in}})}{\mathrm{\&rho;}}};$ In the formula: V _YiBe the mean flow rate of representing i to order; 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) the gas flow temperature field distribution is calculated:

The medial temperature that i is ordered is: $\stackrel{\&OverBar;}{T_{\mathrm{yi}}}=\frac{1}{6}\underset{n=1}{\overset{6}{\mathrm{\&Sigma;}}}{T}_{\mathrm{yin}};$ In the formula: T _YiFor representing an injection tube temperature i point medial temperature; T _YinFor representing an injection tube 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 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 bigger.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 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 bigger.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 for use, 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 for use, 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 a calibration point, and ordinate is by the difference between school wind gage and the standard).

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

Table 1 testing apparatus summary sheet

Sequence number

The testing apparatus title

Purposes

Measurement range and class of accuracy

Quantity

Remarks

1

Wind gage

Be used for the test of flow field, test cell and frontal resistance

0 ~ 40m/s ± (0.2m/s+1% measured value)

28

2

Stagnation pressure tube

Be used for the test cell pressure fall-off test

17

3

Hyperchannel scanning valve

Be used for pressure survey

0.1％FS

3

4

The multi-channel data acquisition device

Be used for output of wind gage signal and thermocouple signal acquisition

0.01％

40 the tunnel

5

Micro-pressure sensor

Being used for intake and exhaust cross section differential static pressure measures

0~2kPa，0.1％FS

4

6

Barometric pressure sensor

Be used for the test cell atmospheric pressure measurement

0.02％

1

7

Pitot tube

Be used for exhaust cross section flow-field test

7

8

Total temperature sensor

Gas flow temperature is tested before being used for airscoop shroud

4

9

Notebook computer

Be used for data acquisition and processing

2

10

Video camera

Being used to monitor the test cell air refluxes

1

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: test this time, worked out capture program specially.This capture program uses Labview to write, and has taked the structure of Server-Client.Wherein operation Server program in the PXI system in the test cell is mainly finished the collection and the transmission of data.In between control, use notebook computer operation Client end program, mainly finish the tasks such as acceptance, demonstration and storage of data.Adopt 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 outdoor relatively 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 HBJ11-98 " aircraft engine test stand design discipline " and GJB721-89 relevant regulations such as " whirlpool spray fanjet test bay calibrating standards ".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 that by flow-field test two stands of the flow field uniformity of No. 8 platforms and other are compared poor, 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:, the frontal resistance modified value is carried out estimation bigger than normal by formula (6) here: referring to table 5 owing to do not record the frontal resistance coefficient of each parts of stand by research technique:

Table 5

	Parts frontal resistance coefficient C xMaximal value	Parts projection estimated area A m(m) 2	Parts wind stream speed v n(m/s)	Frontal resistance correction estimated value Δ F n(N)
					No. 12 platforms	1	4	5.7	79
No. 15 platforms	1	4	5.3	68
					No. 8 platforms	1	4	5.8	81.3

From frontal resistance estimated value bigger than normal as can be seen, 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 preceding square section far away static pressure, Pa; A is the test cell sectional area, m ²

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

1. total MAF G of test cell ₀

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

Wherein: A is the test cell sectional area, is known parameters; ρ is an atmospheric density, kg/m ³,, can adopt the density of normal atmosphere for general calculating; 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 compare uniform.Therefore in this test,, selected four representative measuring points, and do not measured in space, whole cross section at 9m place, engine the place ahead.

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 in the too much measuring point of engine arranged around and averages.

In this test, this parameter obtains by Calculation Method:

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 the sectional area of A ', just can calculate v for runner around the engine _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 from (1) formula, accurately measure differential static pressure (p _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, accurately measuring this differential pressure is to calculate a key issue of input stroke correction.

Accurately measure 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, has only 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 preceding once test, just because of not recognizing more above-mentioned factors, thus instrument select and method of testing on have some problems, 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) accurate measurement:

At first, on measuring point is arranged, take the method for multi-point average, on the cross section, front and back, respectively arranged 4 pitot tubes respectively, 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 littler, the differential pressure pick-up that accuracy is higher.The differential pressure pick-up range that test is this time used is 200Pa, and accuracy reaches 0.1%.

At last, on-the-spot little 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:

Measurement to some keys is illustrated above, and each 2 test parameter is gathered as following table 1:

Table 6 test parameter gathers

Sequence number	Calculate parameters needed	Test or computing method
			1	The test cell area A	Known
2	Density	Get normal atmosphere density: 1.209kg/m 3
			3	Engine the place ahead far away mean flow rate v m	At 9m place, engine the place ahead, four representative measuring points have been selected
4	Engine intake airflow G1	Known
			5	Runner mean wind speed v around the engine m′	Calculate with (3) formula

6

Differential static pressure (p s′-p 0s)

Multipoint-parallel is measured; Select 200Pa for use, 0.1% differential pressure pick-up

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

6) test result:, No. 12 platforms and No. 15 platforms are tested according to above-mentioned testing program.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

No. 12 platforms	State	Thrust (kN)	Atmospheric density (kg/m^3)	Cross section average velocity (m/s)	Area of section (m^2)	Engine air capacity (kg/s)	Outer flow passage speed (m/s)	Differential static pressure (Pa)	Input stroke correction (N)	Relative correction %
											008-9-24?15:20	Maximum	?75.2	1.209	5.605	100	112.591	4.737	9.301	2051.9	2.73
2008-9-24 15:14	Complete afterburning	122.5	1.209	6.638	100	112.156	5.788	10.083	2340.3	1.91
											2008-9-24 18:49	Maximum	75.3	1.209	5.574	100	112.463	4.705	9.352	2049.2	2.72
2008-9-24 18:52	Complete afterburning	122.7	1.209	6.677	100	112.745	5.821	9.977	2344.5	1.91
											No. 15 platforms	State	Thrust (kN)	Atmospheric density (kg/m^3)	Cross section average velocity (m/s)	Area of section (m^2)	Engine air capacity (kg/s)	Outer flow passage speed (m/s)	Differential static pressure (Pa)	Input stroke correction (N)	Relative correction %
2008-9-22 21:18	Maximum	67.6	1.209	5.326	100	121.080	4.383	12.434	2381.5	3.52
											2008-9-22 21:20	Complete afterburning	114.5	1.209	5.581	100	122.723	4.627	16.259	2837.3	2.48
2008-9-25 15:37	Maximum	67.4	1.209	5.163	100	123.557	4.197	12.528	2374.5	3.52
											2008-9-25 15:38	Complete afterburning	114.7	1.209	5.485	100	123.525	4.524	14.749	2671.5	2.33
No. 8 platforms	State	Thrust (kN)	Atmospheric density (kg/m^3)	Cross section average velocity (m/s)	Area of section (m^2)	Engine air capacity (kg/s)	Outer flow passage speed (m/s)	Differential static pressure (Pa)	Input stroke correction (N)	Relative correction %
											2008-12-10 17:38	Maximum	75.2	1.209	8.439	64	110.983	7.153	2.421	1875.7	2.49
2008-12-10 17:45	Complete afterburning	122.5	1.209	7.724	64	110.997	6.423	6.708	2161.5	1.76

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 computing formula of input stroke correction, as follows:

${u_c}^2\left(\mathrm{\&Delta;}{F}_r\right)={\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="DEST\_PATH\_HSB00000079485200023.png"\; state="\{\{state\}\}">C</figure-callout>}}_1^2{u}^2\left(\mathrm{\&rho;}\right)+{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="DEST\_PATH\_HSB00000079485200023.png,H2009102197121E00061.png"\; state="\{\{state\}\}">C</figure-callout>}}_2^2{u}^2\left(v_m\right)+{\mathrm{<figure-callout\; id="3"\; label="C"\; filenames="DEST\_PATH\_HSB00000079485200023.png"\; state="\{\{state\}\}">C</figure-callout>}}_3^2{u}^2\left(A\right)+{\mathrm{<figure-callout\; id="4"\; label="C"\; filenames="DEST\_PATH\_HSB00000079485200023.png,H2009102197121E00071.png"\; state="\{\{state\}\}">C</figure-callout>}}_4^2{u}^2\left(A^{\&prime;}\right)+{\mathrm{<figure-callout\; id="5"\; label="C"\; filenames="DEST\_PATH\_HSB00000079485200023.png,H2009102197121E00062.png"\; state="\{\{state\}\}">C</figure-callout>}}_5^2{u}^2\left(G_1\right)+{\mathrm{<figure-callout\; id="6"\; label="C"\; filenames="DEST\_PATH\_HSB00000079485200023.png,H2009102197121E00061.png"\; state="\{\{state\}\}">C</figure-callout>}}_6^2{u}^2\left(\mathrm{\&Delta;p}\right)---\left(4\right)$

In the formula: ${\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="DEST\_PATH\_HSB00000079485200023.png"\; state="\{\{state\}\}">C</figure-callout>}}_1={v_m}^{2}A-\frac{{v_m}^2{A}^2}{A^{\&prime;}}+\frac{{\mathrm{<figure-callout\; id="1"\; label="G"\; filenames="DEST\_PATH\_HSB00000079485200023.png"\; state="\{\{state\}\}">G</figure-callout>}}_1^2}{A^{\&prime;}{\mathrm{\&rho;}}^2};$

${\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="DEST\_PATH\_HSB00000079485200023.png,H2009102197121E00061.png"\; state="\{\{state\}\}">C</figure-callout>}}_2=2\mathrm{\&rho;}{v}_{m}A-\frac{{2\mathrm{<figure-callout\; id="2"\; label="A"\; filenames="DEST\_PATH\_HSB00000079485200023.png,H2009102197121E00061.png"\; state="\{\{state\}\}">A</figure-callout>}}^2\mathrm{\&rho;}{v}_m}{A^{\&prime;}}+\frac{2G_{1}A}{A^{\&prime;}};$

${\mathrm{<figure-callout\; id="3"\; label="C"\; filenames="DEST\_PATH\_HSB00000079485200023.png"\; state="\{\{state\}\}">C</figure-callout>}}_3=\mathrm{\&rho;}{v}_m^2-\frac{2{{\mathrm{<figure-callout\; id="2"\; label="v\; m"\; filenames="DEST\_PATH\_HSB00000079485200023.png,H2009102197121E00061.png"\; state="\{\{state\}\}">v</figure-callout>}}_m}^2\mathrm{\&rho;A}}{A^{\&prime;}}+\frac{{2v}_m{G}_1}{A^{\&prime;}}-\mathrm{\&Delta;p};$

${\mathrm{<figure-callout\; id="4"\; label="C"\; filenames="DEST\_PATH\_HSB00000079485200023.png,H2009102197121E00071.png"\; state="\{\{state\}\}">C</figure-callout>}}_4=\frac{1}{A^{\&prime;2}}(\mathrm{\&rho;}{v_m}^2{A}^2-2{\mathrm{<figure-callout\; id="1"\; label="v\; m\; AG"\; filenames="DEST\_PATH\_HSB00000079485200023.png"\; state="\{\{state\}\}">v</figure-callout>}}_m{\mathrm{AG}}_{}{}_1+\frac{{{\mathrm{<figure-callout\; id="1"\; label="G"\; filenames="DEST\_PATH\_HSB00000079485200023.png"\; state="\{\{state\}\}">G</figure-callout>}}_1}^2}{\mathrm{\&rho;}});$

${\mathrm{<figure-callout\; id="5"\; label="C"\; filenames="DEST\_PATH\_HSB00000079485200023.png,H2009102197121E00062.png"\; state="\{\{state\}\}">C</figure-callout>}}_5=\frac{{2v}_{m}A}{A^{\&prime;}}-\frac{{2\mathrm{<figure-callout\; id="1"\; label="G"\; filenames="DEST\_PATH\_HSB00000079485200023.png"\; state="\{\{state\}\}">G</figure-callout>}}_1}{\mathrm{\&rho;}{A}^{\&prime;}};$

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 or the like 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 input stroke correction uncertainty evaluation table as shown in table 8 thus in order.

Can see that 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%, and the result still is 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 as Figure 16, Figure 17 and shown in Figure 180, the Z negative sense among the figure is the engine charge direction.

Can see that by the velocity field cloud atlas 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 than 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 carried out check and analysis, all satisfy military standard of China, simultaneously by test, computational analysis stand thrust loss reason, influence accounts for the about 2-3% of engine gross thrust to pneumatic momentum to thrust, and it is basic identical with the correction factor that calculates with the calibration engine to have verified that analytical calculation draws the average correction factor of each thrust.

The pneumatic gauging calibration is one of indoor test run stand thrust dynamic calibration method of normal employing in the world, by the aerodynamic parameter flow-field test, carry out correlation analysis and calculate, draw the modified value to motor power such as pneumatic momentum, can realize each test run stand thrust calibration of A л-31 φ engine.

Embodiment 2

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

1) test bay airflow field method of testing satisfies one of following requirement or the wherein combination of the two arbitrarily in the described engine room:

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 (open-air platform) of engine intake duct under the no 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: $\mathrm{\&Delta;}{F}_{\mathrm{ni}}=C_x{A}_{\mathrm{mi}}\&times;\frac{\mathrm{\&rho;}{\mathrm{<figure-callout\; id="2"\; label="V\; n"\; filenames="DEST\_PATH\_HSB00000079485200023.png,H2009102197121E00061.png"\; state="\{\{state\}\}">V</figure-callout>}}_n^{}}{2};$ In the formula: C _xFor being studied the frontal resistance coefficient of parts, this value depends on the shape and the Reynolds number of parts down with the wind $R_c=\frac{\mathrm{\&rho;}{V}_n{d}_m}{\mathrm{\&mu;}},$ 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 an atmospheric density; V _nGas velocity for parts facing the wind records by experiment;

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

2) present embodiment also includes the interior test bay airflow field test macro of a kind of engine room that is used to support test bay airflow field method of testing in the above-mentioned engine room.Test bay airflow field test macro includes following ingredient in the described engine room: 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 data acquisition module 1 respectively, and test is connecting data acquisition module 1 by pressure scanning valve 2, differential pressure pick-up 3 respectively with pitot tube 4.

Claims (6)

1. the interior test bay airflow field method of testing of engine room is characterized in that: in enclosed engine testsand process of the test, at input stroke, frontal resistance and engine nozzle scope, set up the modification method of following aerodynamic parameter: F-F _Cl=Δ F _r+ Δ F _n+ Δ F _p

In 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.

2. according to test bay airflow field method of testing in the described engine room of claim 1, it is characterized in that: test bay airflow field method of testing satisfies one of following requirement or its combination in the described engine room:

One: described input stroke modified value Δ F _rSatisfy following requirement: Δ F _r=F _BYL-F _BY=V _A1* V _BIn the following formula: F _BYLBe the thrust of engine intake duct under the no 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: $\mathrm{\&Delta;}{F}_{\mathrm{ni}}=C_x{A}_{\mathrm{mi}}\&times;\frac{\mathrm{\&rho;}{V}_n^2}{2};$ In the formula: C _xFor being studied the frontal resistance coefficient of parts, this value depends on the shape and the Reynolds number of parts down with the wind $R_c=\frac{\mathrm{\&rho;}{V}_n{d}_m}{\mathrm{\&mu;}},$ 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 an atmospheric density; V _nGas velocity for parts facing the wind records by experiment;

Total modified value Δ F _n=∑ Δ F _Mi, 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.

3. test bay airflow field test macro in the engine room, it is characterized in that: test bay airflow field test macro includes following ingredient in the described engine room: 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 data acquisition module (1) respectively, and test is connecting data acquisition module (1) by pressure scanning valve (2), differential pressure pick-up (3) respectively with pitot tube (4).

4. according to test bay airflow field test macro in the described engine room of claim 3, it is characterized in that: also include controller (5), router (6) in the test bay airflow field test macro in the described engine room; Router (6) is connecting controller (5), data acquisition module (1), pressure scanning valve (2) respectively.

5. according to test bay airflow field test macro in the described engine room of claim 4, it is characterized in that: also include controller (5), router (6) in the test bay airflow field test macro in the described engine room; Router (6) is connecting controller (5), data acquisition module (1), pressure scanning valve (2) respectively.

6. according to test bay airflow field test macro in the described engine room of claim 5, it is characterized in that: also include air velocity transducer (7) in the test bay airflow field test macro in the described engine room, it is connected with data acquisition module (1);

Employed data acquisition module (1) is specially the PXI acquisition system in the interior test bay airflow field test macro of described engine room; Controller (5) specifically is a computing machine; 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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