A test method for studying the impact of shock waves on engine operation

Abstract

The invention discloses an experimental method for studying the influence of shock waves on engine operation, belonging to the field of aircraft test technology. The invention utilizes an inlet model, a real engine and shock wave simulation technology, and in view of the characteristics of shock wave overpressure, combines the use of dynamic sensors, simulates the overpressure pressure generated by the shock wave in the flow field outside the inlet flow path entrance, and the dynamic changes of the load and distortion of the flow field inside the inlet flow path and the engine, and realizes the measurement of parameters such as aerodynamic load and distortion of the model inlet flow path and the inner surface of the engine under the influence of the explosion shock wave, and whether the engine can work stably. By studying the changes in important parameters and the working state of the engine, the influence of shock waves on the stable operation of the engine is analyzed.

Description

Technical Field

[0001] The invention relates to a test method for studying the influence of shock waves on engine operation, belonging to the technical field of aircraft testing. Background Art

[0002] The engine is one of the most important components in an aircraft power plant, and the stable operation of the engine is an important indicator for evaluating the design of an aircraft. The air intake method used in early aircraft was simple, and the shock wave had little effect on the air intake and engine aerodynamic characteristics. The survivability and vulnerability of the aircraft mainly considered the structural strength of the aircraft. However, modern military fighters and high-stealth unmanned combat aircraft now mostly use complex large S-bend serpentine air intakes, which have prominent internal stability and dynamic aerodynamic load problems. When the engine is working stably, the aerodynamic characteristic parameters such as air intake distortion are required to be high.

[0003] The impact of shock waves on the aerodynamic characteristics of the engine is mainly that when the external structure of the aircraft is not damaged, the shock wave overpressure changes the flow field at the inlet flow path and the engine inlet. The changes in the flow field will have a direct impact on the load and distortion of the engine wall, blades and other components: first, it will cause changes in the flow field at the entrance of the aircraft inlet, causing uneven distribution of airflow parameters in each section of the inlet, changing the dynamic distortion of the inlet, and then affecting the performance of the engine and its components, which may affect the stable operation of the engine. This is also an aircraft application issue that aircraft development units are concerned about. Second, it changes the load changes inside and outside the inlet duct and the engine, which may cause structural deformation and damage, and will seriously affect the safety and use of the aircraft.

[0004] Therefore, it is urgent to propose an experimental method to study the impact of shock waves on engine operation in order to solve the above technical problems. Summary of the invention

[0005] The purpose of the research and development of the present invention is to solve the problem of studying the impact of shock waves on the air intake duct and the working state of the engine, and to provide technical support for evaluating the impact of shock waves on the stability and safety design of the air intake system of an aircraft through experimental technology. A brief overview of the present invention is given below to provide a basic understanding of certain aspects of the present invention. It should be understood that this overview is not an exhaustive overview of the present invention. It is not intended to determine the key or important parts of the present invention, nor is it intended to limit the scope of the present invention.

[0006] The technical solution of the present invention:

[0007] A test method for studying the influence of shock waves on engine operation, comprising:

[0008] Step 1: an air intake model is set up at the test site, and a shock wave generating device is installed in front of the air intake model through a mounting bracket;

[0009] Step 2, the air inlet model is provided with an air inlet flow path, an engine is arranged behind the air inlet flow path, and the engine has engine blades;

[0010] Step 3, installing an intake duct outlet dynamic and static pressure measurement rake at the outlet behind the intake duct flow path, and installing dynamic sensors at the inlet of the intake duct model, along the intake duct flow path, and on the engine;

[0011] Step 4: Debug the engine to ensure that it operates normally during the test;

[0012] Step 5, debugging the shock wave generating device so that the shock wave generated by the shock wave generating device can generate the required overpressure value at the inlet position of the air inlet model;

[0013] Step 6: During the test, the engine is operated so that the engine blades reach the speed required for the test and a fixed flow rate is formed in the inlet flow path;

[0014] Step 7, the dynamic sensor starts dynamic data collection;

[0015] Step 8, after the entire flow field from the inlet of the air intake model to the engine outlet is stable, the shock wave generating device generates a shock wave, completes dynamic data collection, ends the test, and obtains dynamic pressure data of the shock wave on the air intake model and the engine;

[0016] Step 9: if there are multiple engine operating states and different shock wave overpressure states, repeat the above steps 4-8 accordingly to obtain dynamic pressure data of the shock wave on the inlet duct model and the engine under different engine operating states and different shock wave overpressure states;

[0017] Step 10, by analyzing the wall load test data, engine operation data and engine working status obtained by the dynamic sensor on the engine, the impact of the shock wave on the inlet flow path load and the engine operation is studied.

[0018] Preferably: dynamic sensors installed at the inlet of the inlet duct model and along the inlet duct flow path measure the inlet duct flow path inlet overpressure and the inlet duct flow path wall load, an inlet duct outlet dynamic and static pressure measurement rake is installed at the outlet behind the inlet duct flow path to measure the dynamic distortion of the inlet duct flow path outlet, and the dynamic sensor installed on the engine measures the load changes on the engine wall caused by the shock wave.

[0019] Preferably, the step of studying the influence of the shock wave on the inlet flow path load and the engine operation in step 10 includes:

[0020] Step 10.1, observe whether the engine is stalled or malfunctioning;

[0021] Step 10.2, determining whether the engine is in an unstable state;

[0022] Step 10.3, Compressor Flow Coefficient :

[0023] ;

[0024] In the formula, is the axial velocity of the engine's inlet airflow; U is the tangential velocity at the average radius of the engine's rotor, according to the compressor's flow coefficient Determine the instability state, that is, if the inlet flow coefficient of a compressor or fan at a certain stage of the engine of this model is The flow coefficient range is less than the critical instability point of this type of engine It is an unstable state;

[0025] Step 10.4, determine whether the following dynamic parameters exceed the standard according to the operation requirements of each engine:

[0026] Calculates the average value of the dynamic pressure measured by the dynamic sensor over time ,as follows:

[0027] ;

[0028] Where T is the effective sample time length; N is the number of each dynamic sensor, is the total pressure collected by the Nth dynamic sensor over time;

[0029] Get the dynamic pulsation pressure variance ,as follows:

[0030] ;

[0031] Obtain the standard RMS value of pulsating pressure ,as follows:

[0032] ;

[0033] Calculate single turbulence ,as follows:

[0034] ;

[0035] In the formula, is the average pressure at the inlet outlet;

[0036] Get the average turbulence ,as follows:

[0037] ;

[0038] Where K is the number of dynamic sensors;

[0039] The average turbulence obtained by The influence of the shock wave 4 on the load of the intake passage 7 and the operation of the engine 9 is determined.

[0040] The present invention has the following beneficial effects:

[0041] 1. The present invention can simulate the impact of shock waves on the air intake and the real engine under different working conditions, and evaluate the impact of shock waves on the stability and safety of the aircraft power system through experiments. It is simple to implement, easy to achieve, and has no restrictions on the test site and wide applicability.

[0042] 2. The present invention can study the impact of shock waves on the air intake duct and the working state of the engine, and provide technical support for evaluating the impact of shock waves on the stability and safety design of the air intake system of aircraft through experimental technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a test state diagram of a test method for studying the impact of shock waves on engine operation.

[0044] In the figure: 1-test site, 2-mounting bracket, 3-shock wave generating device, 4-shock wave, 5-intake duct model, 6-dynamic sensor, 7-intake duct flow path, 8-intake duct outlet dynamic and static pressure measuring rake, 9-engine, 10-engine blade. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is described below by the specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0046] The connection mentioned in the present invention is divided into fixed connection and detachable connection. The fixed connection is a non-detachable connection including but not limited to conventional fixed connection methods such as folding connection, rivet connection, bonding connection and welding connection. The detachable connection includes but not limited to conventional detachable methods such as threaded connection, snap connection, pin connection and hinge connection. When the specific connection method is not clearly defined, it is assumed that at least one connection method can always be found in the existing connection methods to achieve the function. Those skilled in the art can choose according to their needs. For example: a fixed connection is selected as a welding connection, and a detachable connection is selected as a hinge connection.

[0047] Specific implementation method 1: Combination Figure 1The present embodiment is described. A test method for studying the impact of shock waves on engine operation in the present embodiment includes:

[0048] Step 1: an air intake model 5 is provided in a test site 1, and a shock wave generating device 3 is installed in front of the air intake model 5 through a mounting bracket 2;

[0049] Step 2, the air inlet model 5 is provided with an air inlet flow path 7, an engine 9 is arranged behind the air inlet flow path 7, and the engine 9 is provided with an engine blade 10;

[0050] Step 3, installing an intake duct outlet dynamic and static pressure measuring rake 8 at the outlet behind the intake duct flow path 7, and installing dynamic sensors 6 at the inlet of the intake duct model 5, along the intake duct flow path 7 and on the engine 9;

[0051] Step 4, debugging the engine 9 to ensure that the engine 9 operates normally as a whole during the test and can reach the corresponding speed and flow rate according to the test requirements;

[0052] Step 5, debugging the shock wave generating device 3 so that the shock wave 4 emitted by the shock wave generating device 3 can generate the required overpressure value at the inlet position of the air inlet model 5;

[0053] Step 6, during the test, ignite and operate the engine 9, so that the engine blades 10 reach the speed required for the test, and form a fixed flow rate in the inlet flow path 7;

[0054] Step 7, the dynamic sensor 6 starts dynamic data collection;

[0055] Step 8, after the entire flow field from the inlet of the air intake model 5 to the outlet of the engine 9 is stable, the shock wave generating device 3 generates a shock wave 4, completes the dynamic data acquisition, ends the test, and obtains the dynamic pressure data of the shock wave 4 on the air intake model 5 and the engine 9;

[0056] Step 9, if there are multiple engine 9 working states and different shock wave 4 overpressure states, such as engine 9 slow speed, 80%, 90%, 95%, 100% speed, etc., repeat the above steps 4-8 accordingly to obtain dynamic pressure data of the shock wave 4 on the inlet duct model 5 and the engine 9 under different engine 9 working states and different shock wave 4 overpressure states;

[0057] Step 10, by analyzing the wall load test data obtained by the dynamic sensor 6 on the engine 9, the engine 9 operation data and the engine 9 working state, the impact of the shock wave 4 on the inlet flow path 7 load and the engine 9 operation is studied.

[0058] The dynamic sensors 6 installed at the inlet of the intake duct model 5 and along the intake duct flow path 7 measure the inlet overpressure of the intake duct flow path 7 and the wall load of the intake duct flow path 7; the intake duct outlet dynamic and static pressure measuring rake 8 is installed at the outlet behind the intake duct flow path 7 to measure the dynamic distortion of the intake duct flow path 7 outlet; the dynamic sensor 6 installed on the engine 9 measures the load changes caused by the shock wave 4 on the wall of the engine 9.

[0059] This embodiment utilizes the inlet model 5, the real engine 9 and the shock wave 4 simulation technology, and in view of the characteristics of the overpressure of the shock wave 4, combines the use of the dynamic sensor 6, simulates the overpressure pressure generated by the shock wave 4 in the flow field outside the inlet flow path 7 and the dynamic changes of the flow field load and distortion in the inlet flow path 7 and the engine 9, and realizes the measurement of the parameters such as the aerodynamic load and distortion on the inner surface of the model inlet flow path 7 and the engine 9 under the influence of the explosion shock wave 4, and whether the engine 9 can work stably. By studying the changes in important parameters and the working state of the engine 9, the impact of the shock wave 4 on the stable operation of the engine 9 is analyzed.

[0060] The shock wave generating device 3 can generate the shock wave 4 in the form of shock tube pressure explosion, or in the form of ignition explosion. The form is not limited, and the main thing is to simulate the overpressure of the shock wave 4 at the inlet entrance required for the test.

[0061] The shock wave generating device 3 is position-adjustable, not only in the front, but also in multiple positions on the side.

[0062] The dynamic sensor 6 can withstand the high temperature and high pressure caused by the operation of the engine 9.

[0063] The test site 1 may be equipped with test equipment on the ground or in a wind tunnel, and the test location is not limited.

[0064] The step 10 of studying the influence of the shock wave 4 on the load of the inlet flow path 7 and the operation of the engine 9 includes:

[0065] Step 10.1, observe whether the engine 9 is flameout or malfunctioning;

[0066] Step 10.2, judging whether the engine 9 is in an unstable state; that is, judging whether the engine 9 is close to an unstable state by the fact that the flow coefficient of the compressor or fan of the engine 9 is less than the flow coefficient of its critical instability point, as follows:

[0067] Step 10.3, Compressor Flow Coefficient :

[0068] ;

[0069] In the formula, is the axial velocity of the inlet airflow of the engine 9; U is the tangential velocity at the average radius of the rotor of the engine 9. If the inlet flow coefficient of a compressor or fan of a certain stage of the engine 9 is The range is less than the flow coefficient of the critical instability point of this model engine 9 It is an unstable state;

[0070] Step 10.4, check whether the wall surface of the inlet flow path 7, the engine blades 10 and other components are physically damaged, and determine whether the following dynamic parameters exceed the standard according to the operating requirements of each engine 9:

[0071] Calculate the average value of the dynamic pressure measured by the dynamic sensor 6 over time ,as follows:

[0072] ;

[0073] Where, T is the effective sample time length; N is the number of each dynamic sensor 6, is the total pressure collected over time by the Nth dynamic sensor 6;

[0074] Get the dynamic pulsation pressure variance ,as follows:

[0075] ;

[0076] Obtain the standard RMS value of pulsating pressure ,as follows:

[0077] ;

[0078] Calculate single turbulence ,as follows:

[0079] ;

[0080] In the formula, is the average pressure at the inlet outlet;

[0081] Get the average turbulence ,as follows:

[0082] ;

[0083] Wherein, K is the number of dynamic sensors 6;

[0084] The average turbulence obtained by The influence of the shock wave 4 on the load of the intake passage 7 and the operation of the engine 9 is determined.

[0085] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be arranged and combined, and those skilled in the art can exhaust all possibilities based on the mathematical knowledge of arrangement and combination. Therefore, the present invention will no longer describe the technical solutions after arrangement and combination one by one, but it should be understood that the technical solutions after arrangement and combination have been disclosed by the present invention.

[0086] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A test method for studying the influence of shock waves on engine operation, characterized in that: include: Step 1: An air intake duct model (5) is provided at a test site (1), and a shock wave generating device (3) is installed in front of the air intake duct model (5) via a mounting bracket (2); Step 2: an air intake duct model (5) is provided with an air intake duct flow path (7), an engine (9) is arranged behind the air intake duct flow path (7), and an engine blade (10) is provided on the engine (9); Step 3, installing an intake duct outlet dynamic and static pressure measuring rake (8) at the outlet behind the intake duct flow path (7), and installing dynamic sensors (6) at the inlet of the intake duct model (5), along the intake duct flow path (7) and on the engine (9); Step 4, debugging the engine (9) to ensure that it operates normally during the test; Step 5, debugging the shock wave generating device (3) so that the shock wave (4) emitted by the shock wave generating device (3) can generate a desired overpressure value at the inlet position of the air inlet duct model (5); Step 6, during the test, the engine (9) is operated to make the engine blades (10) reach the speed required for the test, and a fixed flow rate is formed in the inlet flow path (7); Step 7, the dynamic sensor (6) starts dynamic data collection; Step 8, after the entire flow field from the inlet of the air intake model (5) to the outlet of the engine (9) is stabilized, the shock wave generating device (3) generates a shock wave (4), completes dynamic data acquisition, ends the test, and obtains dynamic pressure data of the shock wave (4) on the air intake model (5) and the engine (9); Step 9, if there are multiple engine (9) operating states and different shock wave (4) overpressure states, repeat the above steps 4-8 accordingly to obtain dynamic pressure data of the shock wave (4) on the inlet duct model (5) and the engine (9) under different engine (9) operating states and different shock wave (4) overpressure states; Step 10, by analyzing the wall load test data obtained by the dynamic sensor (6) on the engine (9), the engine (9) operation data and the engine (9) working state, the impact of the shock wave (4) on the inlet flow path (7) load and the engine (9) operation is studied; Dynamic sensors (6) installed at the inlet of the inlet model (5) and along the inlet flow path (7) measure the inlet overpressure and the wall load of the inlet flow path (7) at the inlet flow path (7), an inlet outlet dynamic and static pressure measuring rake (8) is installed at the outlet behind the inlet flow path (7) to measure the dynamic distortion of the outlet of the inlet flow path (7), and a dynamic sensor (6) installed on the engine (9) measures the load change caused by the shock wave (4) on the wall of the engine (9); The step of studying the influence of the shock wave (4) on the load of the inlet flow path (7) and the operation of the engine (9) in step 10 comprises: Step 10.1, observe whether the engine (9) is stalled or malfunctions; Step 10.2, determining whether the engine (9) is in an unstable state; Step 10.3, Compressor Flow Coefficient In the formula, C x is the axial velocity of the inlet airflow of the engine (9); U is the tangential velocity at the average radius of the rotor of the engine (9), according to the flow coefficient of the compressor Determine the instability state; Step 10.4, judging whether the following dynamic parameters exceed the standard according to the operation requirements of each engine (9): Calculate the average value μ of the dynamic pressure measured by the dynamic sensor (6) over time PN ,as follows: Where T is the effective sample time length; N is the number of each dynamic sensor (6), P N (t) is the total pressure collected by the Nth dynamic sensor (6) over time; Get the dynamic pulsating pressure variance as follows: Obtain the standard RMS value of the pulsating pressure (ΔP RMS ) N ,as follows: Calculate single turbulence T uN ,as follows: In the formula, is the average pressure at the inlet duct outlet; Get the average turbulence as follows: Where K is the number of dynamic sensors (6); The average turbulence obtained by The influence of the shock wave (4) on the load of the intake passage (7) and the operation of the engine (9) is determined.

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