A test and analysis method for hammer shock waves in aero-engines based on dynamic pressure

Abstract

This invention discloses a dynamic pressure-based method for testing and analyzing hammer shock waves in aero-engines, belonging to the field of aero-engine testing and structural strength design. The method first uses a surge-induced pressure method to generate hammer shock waves at the engine inlet. Based on the flow field characteristics of the air intake outlet section (AIP section) during surge, dynamic total pressure and static pressure measuring points are arranged in a combination of circumferential and radial directions. Pressure signals are synchronously recorded using a high-speed data acquisition system, and four characteristic parameters—surge overpressure, overpressure ratio, loading time, and pressure rise rate—are defined to quantitatively analyze the intensity, spatial distribution, and dynamic process of the hammer shock waves. This invention achieves rapid, accurate, and comprehensive characterization of the aerodynamic load of hammer shock waves, providing reliable input loads directly for the strength design of complex structures such as S-curve air intakes, thereby improving aircraft safety.

Description

Technical Field

[0001] This application belongs to the field of aero-engine testing and structural strength design, and specifically relates to a hammer shock wave test and analysis method for aero-engines based on dynamic pressure. Background Technology

[0002] When an aircraft engine experiences surge or even in-flight shutdown, the sudden decrease in airflow, accompanied by the release of high-pressure energy from the compressor, causes an instantaneous (millisecond-level) pressure surge at the engine inlet, building upon the steady-state flow pressure. The magnitude of this pressure surge results in shock waves of varying strengths, which rapidly propagate upstream of the inlet, known as hammer shock waves. The load they exert on the inlet is called the hammer shock wave load.

[0003] Selecting the accurate hammer shock wave aerodynamic load strength for the structural strength design of the S-curve air intake is one of the important issues facing the development of new aircraft. Summary of the Invention

[0004] To address the aforementioned problems, this application provides a method for testing and analyzing hammer shock waves in aero-engines based on dynamic pressure, comprising:

[0005] S1. Multiple dynamic pressure measuring points are arranged at the engine intake duct outlet section (AIP section). The measuring point arrangement scheme is as follows: 6 wall static pressure measuring points are evenly distributed around the AIP section, 6 total pressure measuring points are evenly distributed on the circumference with a relative radius of 0.9, and 1 total pressure measuring point is arranged on the circumference with a relative radius of 0.8, in the high-pressure zone and the low-pressure zone formed by the pressure plate; the dynamic pressure sensor is installed at each measuring point and connected to the signal conditioner and the parallel data acquisition system to complete the test system debugging;

[0006] S2. Start the engine and warm it up. Use the insert plate method to force the engine into a surge state. During the entire surge process, continuously collect the dynamic pressure signals of each measuring point of the AIP section, and simultaneously collect the pulsating pressure signal of the compressor outlet wall as a reference.

[0007] S3. Based on the data collected in step S2, select the data segments for the hammerless shock wave condition, the loading process, and the unloading process, and calculate the following characteristic parameters for each dynamic pressure measuring point:

[0008] Surge overpressure: The maximum pressure jump at the measuring point during loading after surge occurs;

[0009] Surge overpressure ratio: The ratio of the surge overpressure to the average pressure at the measuring point under hammerless shock wave conditions;

[0010] Surge overpressure loading time: the time it takes for the pre-surge pressure to rise to the peak surge overpressure;

[0011] Surge overpressure rise rate: the ratio of the surge overpressure to the surge overpressure loading time;

[0012] S4. Based on the calculation results of step S3, analyze the circumferential and radial distribution characteristics of the hammer shock wave load of the AIP section, obtain the maximum hammer shock wave load and its location, so as to characterize the hammer shock wave intensity and support the structural strength design of the air intake.

[0013] Preferably, the measuring point arrangement scheme is designed to distribute the high and low pressure zones formed in the AIP cross section when the insert plate is inserted from bottom to top to induce breathing.

[0014] Preferably, the bandwidth of the signal conditioner is not less than 1000Hz, and the sampling rate of the parallel data acquisition system is set to 20K / s.

[0015] Preferably, the calculation method for the "time-averaged pressure at the measuring point under hammerless shock wave conditions" is as follows: before surge occurs, select a pressure data period of 0.1 to 0.2 seconds and calculate its arithmetic mean.

[0016] Preferably, the analysis includes plotting the surge overpressure ratio distribution curve of the static pressure on the circumferential wall of the AIP section, and the total pressure surge overpressure ratio distribution curve at a relative radius of 0.9.

[0017] Preferably, the method includes: inserting a plate on the cross-section of the engine intake manifold, using a stepper motor to control the insertion depth of the plate, and using the stepper motor to control the insertion depth of the plate until engine surge occurs.

[0018] A system for implementing the aforementioned test and analysis method comprises multiple dynamic pressure sensors arranged in the AIP section of an engine for sensing pressure and converting it into electrical signals;

[0019] A signal conditioner, connected to each of the aforementioned dynamic pressure sensors, is used to amplify and condition the electrical signals;

[0020] A parallel data acquisition system, connected to the signal conditioner, is used to acquire and record dynamic pressure data from all channels at high speed and synchronously.

[0021] The data processing unit is used to perform steps S3 and S4 in claim 1, calculate the characteristic parameters of the hammer shock wave, and perform analysis.

[0022] Compared with existing CFD (Computational Fluid Dynamics) software numerical simulation analysis, this application realizes rapid and accurate engineering measurement of hammer shock wave intensity, can comprehensively characterize hammer shock wave characteristics, and meet the structural strength design requirements of S-curve (other) air intakes. Attached Figure Description

[0023] Figure 1 This is a diagram showing the installation of the engine insert plate;

[0024] Figure 2 This is a schematic diagram showing the distribution of the high and low zones of the AIP cross-section when the insert plate is inserted from bottom to top;

[0025] Figure 3 This is a schematic diagram of the measurement point layout on the AIP section;

[0026] Figure 4 This is a typical schematic diagram of the inlet hammer impact wave test waveform during engine surge;

[0027] Figure 5 This is a schematic diagram of a hammer shock wave dynamic pressure testing system.

[0028] Figure 6 This is a schematic diagram of the circumferential distribution of the hammer shock wave intensity. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are only some, not all, of the embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0030] This invention provides a method for testing and analyzing hammer shock waves in aero-engines based on dynamic pressure. This method excites hammer shock waves through a specific experimental procedure, and utilizes precise measurement point arrangement and parametric analysis to comprehensively characterize the characteristics of the hammer shock waves, thereby supporting the structural strength design of the air intake. Details are as follows:

[0031] 1. Engine testing breathing method

[0032] To obtain the hammer shock wave load for structural design, the surge overpressure characteristics and cross-sectional distribution at the engine inlet need to be measured. Engineering practice and research show that surge induced by inlet total pressure distortion has a higher overpressure ratio than other surge-inducing methods, providing a conservative upper limit load for structural design. Therefore, this method uses a plate distortion generator to induce total pressure distortion to force the engine into surge. The specific implementation steps are as follows: the insertion depth of the plate is controlled by a stepper motor until the engine surges; after triggering surge, the engine is immediately de-surged through the anti-surge system to ensure safety. Figure 1 This is a schematic diagram of the engine insert installation.

[0033] 2. Measurement point layout scheme

[0034] The insertion of the inlet plate creates distinct high-pressure and low-pressure zones at the engine intake outlet section (AIP section), and their distribution is related to the insertion direction of the inlet plate (e.g., the flow field distribution when the inlet plate is inserted from bottom to top is as follows). Figure 2 (As shown). To comprehensively characterize the circumferential uniformity and radial (total pressure) distribution characteristics of the hammer shock wave aerodynamic load at the AIP section, measurement points need to be arranged in the high-pressure zone, low-pressure zone, and at different radial and circumferential positions. Taking the insertion of the insert plate from bottom to top as an example, the specific arrangement of the measurement points is as follows. Figure 3 As shown, it includes:

[0035] Six static pressure pulsation measurement points are evenly distributed around the AIP section.

[0036] Six total pressure pulsation measurement points are evenly distributed on a circle with a relative radius of 0.9.

[0037] One total pressure measurement point is arranged in both the high-pressure area and the low-pressure area on a circle with a relative radius of 0.8.

[0038] 3. Definition of Hammer Shock Wave Characteristic Parameters

[0039] To quantitatively characterize hammer shock waves, four key dynamic characteristic parameters are defined, whose physical meaning is based on Figure 4 The typical pressure waveform shown (including loading and unloading processes) is as follows:

[0040] Surge overpressure: The maximum pressure jump at the intake outlet measuring point during the loading process after surge occurs, denoted by O. s ;

[0041] Surge overpressure ratio: The ratio of surge overpressure to the average pressure at a measuring point under hammerless shock wave conditions is called the overpressure ratio, denoted by R. op It visually demonstrates the multiple by which the local pressure increases due to the impact of the hammer wave.

[0042] Its calculation formula is as follows (1):

[0043]

[0044] In the formula:

[0045] The maximum jump pressure at the AIP section measuring point during the loading process after p-surge occurs;

[0046] p locates - indicates the average pressure value at the measuring point location under conditions where there is no hammer impact wave in the air intake. The time length is usually taken as 0.1~0.2 seconds, and its calculation formula is as shown in formula (2).

[0047]

[0048] Surge overpressure loading time: The time it takes for the pre-surge pressure to rise to the peak surge overpressure, denoted by T. l .

[0049] Surge overpressure rise rate: The ratio of surge overpressure to surge overpressure loading time, denoted by R. p .

[0050] 4. Test Analysis Process

[0051] Based on the above method, the test analysis is performed according to the following steps:

[0052] System Installation and Debugging: Based on the determined measurement point plan, install test probes on the engine's AIP (Air-In-Place) section. The test system (principle as follows) Figure 5 The dynamic pressure sensor signal is amplified by a signal conditioner with a bandwidth of not less than 1000Hz and compared with the pulsating pressure P3m on the compressor outlet wall.

[0053] (As a reference signal) and other data are sent to the PXI high-speed parallel acquisition system (sampling rate set to 20K / s) for synchronous acquisition and real-time display. System integration testing must be completed before the test to ensure the reliability of each channel.

[0054] Data Acquisition: After the engine warms up, a pressure plate was used to induce surge, and all dynamic pressure signals were continuously recorded throughout the process. The engine was marked when it entered surge for subsequent offline analysis.

[0055] Parameter calculation: The test data was analyzed using playback software. Referring to the waveform characteristics of P3m, data segments of the hammerless shock wave condition, loading process, and unloading process were manually selected, and the four characteristic parameters Ps, Rop, T1, and Rp of all 14 measuring points of the AIP section (6 wall static pressures, 6 total pressures at a relative radius of 0.9, and 2 total pressures at a relative radius of 0.8) were calculated respectively.

[0056] Characteristic analysis: Based on the calculation results, plot the circumferential distribution curves of the wall static pressure and the overpressure ratio Rop at a relative radius of 0.9 (see example). Figure 6 The maximum hammer shock wave overpressure ratio and its location at the AIP section are given, and the loading and unloading times at each measuring point are analyzed, thereby comprehensively characterizing the hammer shock wave intensity and distribution characteristics.

[0057] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for testing and analyzing hammer shock waves in aero-engines based on dynamic pressure, characterized in that, include: S1. Multiple dynamic pressure measuring points are arranged on the engine AIP section. The measuring point arrangement scheme is as follows: 6 wall static pressure measuring points are evenly distributed around the AIP section, 6 total pressure measuring points are evenly distributed on the circumference of a circle with a relative radius of 0.9, and 1 total pressure measuring point is arranged on the circumference of a circle with a relative radius of 0.8, in the high-pressure zone and the low-pressure zone formed by the pressure plate; the dynamic pressure sensor is installed at each measuring point and connected to the signal conditioner and the parallel data acquisition system to complete the test system debugging; S2. Start the engine and warm it up. Use the insert plate method to force the engine into a surge state. During the entire surge process, continuously collect the dynamic pressure signals of each measuring point of the AIP section, and simultaneously collect the pulsating pressure signal of the compressor outlet wall as a reference. S3. Based on the data collected in step S2, select the data segments for the hammerless shock wave condition, the loading process, and the unloading process, and calculate the following characteristic parameters for each dynamic pressure measuring point: Surge overpressure: The maximum pressure jump at the measuring point during loading after surge occurs; Surge overpressure ratio: The ratio of the surge overpressure to the average pressure at the measuring point under hammerless shock wave conditions; Surge overpressure loading time: the time it takes for the pre-surge pressure to rise to the peak surge overpressure; Surge overpressure rise rate: the ratio of the surge overpressure to the surge overpressure loading time; S4. Based on the calculation results of step S3, analyze the circumferential and radial distribution characteristics of the hammer shock wave load of the AIP section, obtain the maximum hammer shock wave load and its location, so as to characterize the hammer shock wave intensity and support the structural strength design of the air intake.

2. The method for testing and analyzing hammer shock waves in aero-engines based on dynamic pressure according to claim 1, characterized in that, In step S1, the measuring point arrangement scheme is set up to distribute the high and low pressure zones formed in the AIP section when the insert plate is inserted from bottom to top into the gas pressure.

3. The method for testing and analyzing hammer shock waves in aero-engines based on dynamic pressure according to claim 1, characterized in that, In step S1, the bandwidth of the signal conditioner is not less than 1000Hz, and the sampling rate of the parallel data acquisition system is set to 20K / s.

4. The method for testing and analyzing hammer shock waves in aero-engines based on dynamic pressure according to claim 1, characterized in that, In step S3, the method for calculating the time-averaged pressure at the measuring point under the hammerless shock wave condition is as follows: before surge occurs, select a pressure data period of 0.1 to 0.2 seconds and calculate its arithmetic mean.

5. The method for testing and analyzing hammer shock waves in aero-engines based on dynamic pressure according to claim 1, characterized in that, In step S4, the analysis includes plotting the surge overpressure ratio distribution curve of the static pressure on the circumferential wall of the AIP section, and the total pressure surge overpressure ratio distribution curve at a relative radius of 0.

9.

6. The method for testing and analyzing hammer shock waves in aero-engines based on dynamic pressure according to claim 1, characterized in that, include: An insert plate is placed on the cross-section of the engine intake manifold, and a stepper motor controls the insertion depth of the insert plate until engine surge occurs.

7. A system for implementing the test and analysis method as described in any one of claims 1-6, characterized in that, Multiple dynamic pressure sensors are arranged in the AIP section of the engine to sense pressure and convert it into electrical signals; A signal conditioner, connected to each of the aforementioned dynamic pressure sensors, is used to amplify and condition the electrical signals; A parallel data acquisition system, connected to the signal conditioner, is used to acquire and record dynamic pressure data from all channels at high speed and synchronously. The data processing unit is used to perform steps S3 and S4 in claim 1, calculate the characteristic parameters of the hammer shock wave, and perform analysis.

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