Aircraft engine noise measurement system and method

Abstract

The invention discloses an aero-engine noise measurement system, comprising: a module support, a test bench, an engine test stand, an engine, and a three-degree-of-freedom mobile measurement device; the engine is connected to the engine test stand; the three-degree-of-freedom mobile measurement device comprises a horizontal module, a radial module, and a circumferential module; the horizontal module is arranged parallel to the axial direction of the engine, the circumferential module is slidably arranged on the horizontal module, and the circumferential module is arranged on the outer periphery of the engine in an arc shape; the radial module is arranged on the circumferential module, and a noise collection probe is arranged at the end; the noise measurement system also comprises an acceleration sensor, a signal collector, a computer system, a noise signal collection and analysis system, and a three-axis module controller; the acceleration sensor is used to measure the rotation frequency signal of the engine; the noise signal collection and analysis system is connected to the computer system and the noise collection probe; the three-axis module controller is connected to the computer system and is used to control the movement of the three-degree-of-freedom mobile measurement device.

Description

Technical Field

[0001] The present invention relates to the technical field of aero-engines, and in particular to a system and method for measuring noise of an aero-engine. Background Art

[0002] The noise of aviation turbofan engines is mainly generated by the following four structures: fan, compressor, turbine and combustion chamber, and jet noise. For high bypass ratio turbofan engines, most of the noise transmitted forward in the engine inlet channel is generated by the fan components, of course, there is also a small part of the compressor. The part transmitted backward through the external exhaust system is mainly the aerodynamic noise of the fan components accompanied by a large amount of external jet noise; and the noise transmitted backward through the internal exhaust system is composed of two parts, first the internal high-speed jet, and then the noise of some core mechanisms. For low bypass ratio turbofan engines, jet noise is dominant, and for low bypass ratio turbofan engines with afterburner, the jet noise value is even greater.

[0003] Because the noise of aircraft engines is caused by the vibration of irregular airflow inside them, it will also have a certain vibration effect on the internal structure of the engine itself, resulting in an increase in the loss rate of some internal components and affecting the life of the engine. At the same time, these unstable airflows will also affect the theoretically designed gas flow distribution inside the engine, thereby reducing the utilization efficiency of some fluids inside the engine and causing excessive fuel consumption. Therefore, accurate measurement of the experimental noise of the entire aircraft engine and accurate positioning of the noise source, so as to achieve accurate analysis of the noise data generated by the components, will be beneficial to the aerodynamic design of aircraft engine components and the improvement of the overall performance of the aircraft, and is one of the methods to improve the performance of aircraft engines.

[0004] At present, ground test of aircraft engines is generally carried out on the test bench, which is specially used to carry out ground test of different types of aircraft engines. The ground test takes into account the noise measurement experiment of aircraft engines. However, the noise measurement in the whole aircraft engine test has always been a difficult point. There are two methods: one is to lead out the noise generated by the internal components of the aircraft engine through a certain method for measurement. For the noise generated by the internal components, the method of opening holes in the engine casing and installing the noise-leading components destroys the inherent structure of the original engine casing. In addition, the installed lead-out components also have an impact on the work of the aircraft engine itself, and the measurement results cannot guarantee the original state. The noise measurement of the whole aircraft engine test component is made in the casing, but only at a certain position in the circumference. Therefore, due to the dynamic working process of the aircraft engine, the noise point is not necessarily the noise source or the best point, so the purpose of accurate measurement cannot be achieved. Another method is to use a mobile measurement frame to carry out mobile measurement on the outside of the aircraft engine. The noise of the whole aircraft engine test component is measured from the outside. Compared with the casing opening, the casing of the aircraft engine is not damaged, and the measurement data is traceable. However, the external parts of the aircraft engine casing are too complicated, including fuel system pipelines, oil system pipelines, and accessory casings, etc., and there are also a large number of test circuits and measurement pipelines. Therefore, it is more difficult to measure the noise of components outside the aircraft engine, and it is difficult for the probe to reach the part to be measured or close to the measurement part. It is also difficult to find the noise source, the measurement data is messy, and the noise source is unknown.

[0005] In view of this, this application is hereby filed. Summary of the invention

[0006] The present invention provides an aircraft engine noise measurement system and method to solve the above-mentioned technical problems.

[0007] The above technical objectives of the present invention are achieved through the following technical solutions:

[0008] In one aspect of the present disclosure, an aircraft engine noise measurement system is disclosed, comprising:

[0009] Module bracket, test bench, engine test stand, engine, three-degree-of-freedom mobile measurement device;

[0010] The engine test stand is arranged at the lower part of the test bench, and the engine is connected to the engine test stand;

[0011] The three-degree-of-freedom mobile measuring device includes a horizontal module, a radial module, and a circumferential module;

[0012] The horizontal module is arranged parallel to the axial direction of the engine, the circumferential module is slidably arranged on the horizontal module, and the circumferential module is arranged in an arc shape on the outer periphery of the engine;

[0013] The radial module is arranged on the circumferential module, and a noise collection probe is arranged at the end thereof;

[0014] The noise measurement system also includes an acceleration sensor, a signal collector, a computer system, a noise signal acquisition and analysis system, and a three-axis module controller;

[0015] The acceleration sensor is used to measure the rotation frequency signal of the engine and is connected to the computer system through the signal collector;

[0016] The noise signal acquisition and analysis system is connected to the computer system and the noise acquisition probe;

[0017] The three-axis module controller is connected to the computer system and is used to control the movement of the horizontal module, radial module and circumferential module.

[0018] Optionally, the circumferential module is an arc of 1 / 4 of a circle.

[0019] In another aspect of the present disclosure, a method for measuring aircraft engine noise is disclosed, comprising the following steps:

[0020] Step 1: Build the measurement system and compile the system software: including three-degree-of-freedom control, frequency monitoring, noise source identification and analysis, and perform logic fusion.

[0021] Step 2: Test run and debugging.

[0022] Step 3. Start the axial noise measurement test of the whole aircraft engine test. Formulate the test outline. According to the aircraft engine test requirements, the aircraft engine test conditions are divided into low-speed state, cruising state, and high-speed state; according to the aircraft engine working conditions, the aircraft engine speed is taken at the three states for experiment, that is, 0.25n max 、0.5n max 、0.75n max ; where n max The maximum permissible speed of the turbojet engine; the pulsation value of the aircraft engine rotation frequency is monitored in real time by an acceleration sensor and is synchronized with the noise measurement, which serves as the basis for noise evaluation and analysis;

[0023] Step 4: First, perform a rough positioning scan test and set the aircraft engine speed to 0.25n max, keep the aircraft engine speed unchanged, and start to quickly scan the positions of the aircraft engine axial noise-generating parts in this state, in the following order: compressor, combustion chamber, turbine, tail nozzle outlet, and then scan and define the coordinates;

[0024] Step 5, repeat step 4, scan and measure the aircraft engine speed at 0.5n max 、0.75n max Noise of different components under speed conditions.

[0025] Step 6, analyze the data measured in steps 4 and 5, find the precise location of the specific noise sources of the compressor, combustion chamber, turbine, and tail nozzle outlet of the aero-engine that generate noise at different speeds from the test data, and organize the coordinate position table.

[0026] Step 7: Eliminate other interference noises and further obtain accurate radial coordinates.

[0027] Step 8: Start the precise point measurement test of the aircraft engine axial noise, and set the aircraft engine speed to 0.25n max , starting from the noise-generating parts of the aircraft engine, i.e., the compressor, combustion chamber, turbine, and tail nozzle outlet, according to the three-dimensional coordinate table obtained in step 7, the precise point data of the noise generated by the four parts are measured in sequence, each measuring point is measured for t seconds, the noise data is collected and recorded and stored; the rotation frequency of the aircraft engine is measured synchronously;

[0028] Step 9, repeat step 8 to complete the measurement of the aircraft engine speed of 0.5n max 、0.75n max Accurate point noise under speed conditions;

[0029] Step 10, analyzing the test data of steps 8 and 9, and providing the rules and reasons for the noise generated by the components at the same rotation frequency, as a reference for the design and optimization of aircraft engine components.

[0030] Furthermore, in step 2: in order to test whether the system has any influence on the operation of the aircraft engine, the aircraft engine is tested and debugged, and the thrust platform data is recorded, and the data before and after the installation of the three-degree-of-freedom mobile measuring device are compared to analyze whether it has any influence on the aircraft engine test run; in addition, during the test run, the entire noise test system is operated and debugged, and whether the operation of the aircraft engine has any interference and influence on the test system is analyzed.

[0031] Furthermore, in step 4, scanning and defining coordinates include: the horizontal module moves at an interval of S meters, the circumferential module moves quickly on the 1 / 4 outer circle of the aircraft engine at a moving speed of V, and the radial module remains stationary and is located at the outermost edge to prevent the noise collection probe from accidentally touching the external pipes of the aircraft engine; the noise probe collects noise signals at different circumferential positions of the aircraft engine at an interval of n degrees and records them; after scanning 1 / 4 of the circumference, the horizontal module moves S meters along the axial direction of the aircraft engine, and the circumferential module continues to scan the 1 / 4 cross-sectional noise of the aircraft engine at this position; repeat this operation until the compressor, combustion chamber, turbine, and tail nozzle outlet are scanned; and the rotation frequency of the aircraft engine is synchronously measured.

[0032] Furthermore, step 7 includes: when the aircraft engine is stopped, finding the corresponding point on the aircraft engine according to the coordinate table of step 6, and observing the external auxiliary pipeline of the casing at the point; using a mobile measuring device to move the probe so that the probe is close to the aircraft engine casing, and ensuring that the probe is not in contact with the external pipeline of the aircraft engine, so that the measured noise data is more accurate, the picked-up noise component is more single, which is conducive to eliminating other interfering noises, thereby facilitating the analysis of the noise generation mechanism; recording the radial coordinate position of each point, and forming an accurate measurement point table of the axial noise of the three-dimensional aircraft engine whole machine test with the coordinate table of step 6; with the help of program design, the pipelines and auxiliary facilities around the outside of the aircraft engine can be bypassed, and the axial noise of the aircraft engine can be accurately measured.

[0033] Furthermore, in step 3, the rotation speeds in aviation low speed state, cruising state, and high speed state are: 4500 rpm, 9000 rpm, and 13500 rpm.

[0034] Furthermore, in step 5, the horizontal module movement interval is 100 mm. The circumferential module uses the vertical bottom of the aircraft engine as the origin to perform noise scanning measurement on 1 / 4 of the circumference of the aircraft engine, with a movement speed of 1° / s and a data recording interval angle of 10 degrees; the radial coordinate uses the arc track of the circumferential module as the origin.

[0035] The beneficial effects of the present invention include:

[0036] 1. The present invention can accurately locate the axial noise source of the aircraft engine whole machine test, locate the noise-generating component or even a certain part, study the noise generation mechanism, and optimize the design of the noise-generating component, saving a lot of research costs and time.

[0037] 2. The present invention accurately locates the axial noise source of the aircraft engine, so the measured noise signal is more accurate, the collected noise signal is more simple, and it is easy to remove noise and interference sound, which is conducive to correct analysis of the signal.

[0038] 3. The aircraft engine external noise scanning method of the present invention can easily avoid the aircraft engine external pipelines and accessory casings and other components, and cooperate with the fixed-point control of the software so that the measuring probe can be inserted into any gap and get infinitely close to the casing, providing the necessary conditions for obtaining accurate signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic diagram of the structure of the aircraft engine noise measurement system;

[0040] Figure 2 This is a schematic diagram of the structure of the aircraft engine noise measurement system from another angle.

[0041] In the figure: 1. module bracket; 2. horizontal module; 3. jet airflow; 4. test bench; 5. engine test stand; 6. engine; 7. acceleration sensor; 8. signal collector; 9. computer system; 10. noise signal acquisition and analysis system; 11. three-axis module controller; 12. radial module; 13. circumferential module; 14. noise collection probe. DETAILED DESCRIPTION

[0042] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0043] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. 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.

[0045] like Figure 1-2As shown, the engine 6 is installed on the test bench 4, and the thrust performance of the engine 6 under different working conditions is measured by the engine test stand 5. The three-degree-of-freedom mobile measuring device includes: a horizontal module 2, a circumferential module 13, and a radial module 12. The three-degree-of-freedom mobile measuring device is installed on the module bracket 1. The installation method is: the horizontal module 2 is along the axis direction of the aircraft engine 6 and is parallel to the axis of the engine 6. The circumferential module 13 is installed on the slider of the horizontal module 2 and can move at a fixed point along the axis direction of the engine 6. The radial module 12 is installed on the circumferential module 13, and the radial module 12 can move at a fixed point along the circumferential module 13. The noise collection probe 14 is installed on the radial module 12, and the position between the noise collection probe 14 and the engine 6 can be adjusted. The function and working process of the entire system components are as follows: the acceleration sensor 7 monitors the rotation frequency signal of the aircraft engine, which is input into the computer system 9 through the signal collector 8 to be synchronized with the noise measurement signal as one of the basic conditions for evaluating the generation of noise. The movement of the three-degree-of-freedom mobile measuring device is completed by the three-axis module controller 11, which receives the control instructions of the computer system 9, thereby realizing the precise movement of the noise collection probe 14. The noise collection probe 14 senses the noise signal and transmits it to the noise signal collection and analysis system 10 in the form of an electrical signal. The noise signal collection and analysis system 10 transmits the original noise signal to the computer system 9 after analysis, and the computer system 9 finally makes an analysis and judgment, and performs real-time signal collection and control.

[0046] The present invention is specifically implemented on an aviation turbojet engine test bench, and only the experimental process under one working condition is introduced.

[0047] The inlet diameter of a certain aircraft engine is D=680mm, the length is 5800mm, the maximum outer diameter of the external pipeline and accessory casing is 1020mm, and the maximum speed is 18000rpm. Therefore, considering the measurement of high-temperature gas jet noise and avoiding external pipeline components, the horizontal module of the three-degree-of-freedom measurement device is 8800mm, the circumferential module is a 1 / 4 arc module with a diameter of 1600mm, and the radial module is a 500mm linear module.

[0048] Verify the influence of the three-degree-of-freedom displacement measurement device on the thrust performance of the aircraft engine. The aircraft engine speed is 0.25nmax. The recorded data are shown in Table 1:

[0049]

[0050] Table 1

[0051] Formulate an experimental outline: The maximum design speed of an aircraft engine is 18,000 rpm, so the speeds in the aviation low-speed state, cruising state, and high-speed state are 4,500 rpm, 9,000 rpm, and 13,500 rpm respectively.

[0052] When the aircraft engine speed is 0.25n max =4500rpm, start scanning the noise-generating parts of the aircraft engine, starting with the compressor. The compressor inlet is taken as the origin of the horizontal module coordinates, the tail nozzle outlet is the end point, and the horizontal module movement interval is 100mm. The circumferential module uses the vertical bottom of the aircraft engine as the origin to perform noise scanning and measurement on 1 / 4 of the circumference of the aircraft engine. The movement speed is 1° / s, and the data recording interval angle is 10 degrees. The radial coordinate uses the arc track of the circumferential module as the origin. The data tables are shown in Tables 2 and 3 (only the first two sets of data for the compressor are taken as examples), Table 2 is for the compressor (0mm); Table 3 is for the compressor (100mm):

[0053]

[0054] Table 2

[0055]

[0056] Table 3

[0057] After analyzing the scanning data of all components, the coordinate points of the components generating the maximum noise are obtained as shown in Table 4:

[0058]

[0059] Table 4

[0060] Based on the coordinate points in Table 4, observe the specific external conditions of the above coordinate points when the aircraft engine is stopped, move the radial module as close to the aircraft engine casing as possible, visually move the probe, record the radial coordinates and combine them with the coordinates in Table 4 to form Table 5:

[0061]

[0062] Table 5

[0063] The noise points are measured according to the coordinate points in the above table. The measurement time for each point is 60 seconds and the data will not be repeated.

[0064] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims

1. A method for measuring aircraft engine noise, characterized in that: An aircraft engine noise measurement system is included, wherein the aircraft engine noise measurement system includes: Module bracket, test bench, engine test stand, engine, three-degree-of-freedom mobile measurement device; The engine test stand is arranged at the lower part of the test bench, and the engine is connected to the engine test stand; The three-degree-of-freedom mobile measuring device includes a horizontal module, a radial module, and a circumferential module; The horizontal module is arranged parallel to the axial direction of the engine, the circumferential module is slidably arranged on the horizontal module, and the circumferential module is arranged in an arc shape on the outer periphery of the engine; The radial module is arranged on the circumferential module, and a noise collection probe is arranged at the end thereof; The noise measurement system also includes an acceleration sensor, a signal collector, a computer system, a noise signal acquisition and analysis system, and a three-axis module controller; The acceleration sensor is used to measure the rotation frequency signal of the engine and is connected to the computer system through the signal collector; The noise signal acquisition and analysis system is connected to the computer system and the noise acquisition probe; The three-axis module controller is connected to the computer system and is used to control the movement of the horizontal module, radial module, and circumferential module; The circumferential module is an arc of 1 / 4 of a circle; The following steps are also included: Step 1: Build the measurement system and compile the system software: including three-degree-of-freedom control, frequency monitoring, noise source identification and analysis, and perform logic fusion; Step 2: test run and debugging; Step 3. Start the axial noise measurement test of the whole aircraft engine test. Formulate the test outline. According to the aircraft engine test requirements, the aircraft engine test conditions are divided into low-speed state, cruising state, and high-speed state; according to the aircraft engine working conditions, the aircraft engine speed is taken at the three states for experiment, that is, 0.25n max 、0.5n max 、0.75n max ; where n max The maximum permissible speed of the turbojet engine; the pulsation value of the aircraft engine rotation frequency is monitored in real time by an acceleration sensor and is synchronized with the noise measurement, which serves as the basis for noise evaluation and analysis; Step 4: First, perform a rough positioning scan test and set the aircraft engine speed to 0.25n max , keep the aircraft engine speed unchanged, and start to quickly scan the positions of the aircraft engine axial noise-generating parts in this state, in the following order: compressor, combustion chamber, turbine, tail nozzle outlet, and then scan and define the coordinates; Step 5, repeat step 4, scan and measure the aircraft engine speed at 0.5n max 、0.75n max Noise of different components under speed conditions; Step 6, analyzing the data measured in steps 4 and 5, finding the precise location of the specific noise source of the compressor, combustion chamber, turbine, and tail nozzle outlet of the aero-engine at different speeds of the noise-generating components from the test data, and compiling a coordinate position table; Step 7, eliminate other interference noises and further obtain accurate radial coordinates; Step 8: Start the precise point measurement test of the aircraft engine axial noise, and set the aircraft engine speed to 0.25n max , starting from the noise-generating parts of the aircraft engine, i.e., the compressor, combustion chamber, turbine, and tail nozzle outlet, according to the three-dimensional coordinate table obtained in step 7, the precise point data of the noise generated by the four parts are measured in sequence, each measuring point is measured for t seconds, the noise data is collected and recorded and stored; the rotation frequency of the aircraft engine is measured synchronously; Step 9, repeat step 8 to complete the measurement of the aircraft engine speed of 0.5n max 、0.75n max Accurate point noise under speed conditions; Step 10, analyzing the test data of steps 8 and 9, and providing the rules and reasons for the noise generated by the components at the same rotation frequency, as a reference for the design and optimization of aircraft engine components.

2. The method for measuring aircraft engine noise according to claim 1, characterized in that: In step 2: In order to test whether the system has any impact on the operation of the aircraft engine, the aircraft engine is tested and debugged, and the thrust platform data is recorded. The data before and after the installation of the three-degree-of-freedom mobile measuring device are compared to analyze whether it has any impact on the aircraft engine test. In addition, during the test, the entire noise test system is operated and debugged to analyze whether the operation of the aircraft engine has any interference and impact on the test system.

3. The method for measuring aircraft engine noise according to claim 1, characterized in that: In step 4, scanning and defining coordinates include: the horizontal module moves at an interval of S meters, the circumferential module moves quickly on the 1 / 4 outer circle of the aircraft engine at a moving speed of V, and the radial module remains stationary and is located at the outermost edge to prevent the noise collection probe from accidentally touching the external pipes of the aircraft engine; the noise probe collects noise signals at different circumferential positions of the aircraft engine at an interval of n degrees and records them; after scanning 1 / 4 of the circumference, the horizontal module moves S meters along the axial direction of the aircraft engine, and the circumferential module continues to scan the 1 / 4 cross-sectional noise of the aircraft engine at this position; repeat this operation until the compressor, combustion chamber, turbine, and tail nozzle outlet are scanned; and the rotation frequency of the aircraft engine is measured synchronously.

4. The method for measuring aircraft engine noise according to claim 1, characterized in that: Step 7 includes: when the aircraft engine is stopped, find the corresponding point on the aircraft engine according to the coordinate table of step 6, and observe the external auxiliary pipeline of the casing at the point; use the mobile measuring device to move the probe so that the probe is close to the aircraft engine casing, and ensure that the probe is not in contact with the external pipeline of the aircraft engine, so that the measured noise data is more accurate, the picked-up noise component is more single, which is conducive to eliminating other interfering noises, thereby facilitating the analysis of the noise generation mechanism; record the radial coordinate position of each point, and form an accurate measurement point table of the axial noise of the three-dimensional aircraft engine whole machine test with the coordinate table of step 6; with the program design, the pipelines and auxiliary facilities around the aircraft engine can be bypassed to accurately measure the axial noise of the aircraft engine.

5. The method for measuring aircraft engine noise according to claim 1, characterized in that: In step 3, the speeds in aviation low speed state, cruising state, and high speed state are: 4500rpm, 9000rpm, and 13500rpm.

6. The method for measuring aircraft engine noise according to claim 3, characterized in that: In step 5, the horizontal module moves at an interval of 100 mm, and the circumferential module uses the vertical bottom of the aircraft engine as the origin to perform noise scanning measurement on 1 / 4 of the circumference of the aircraft engine. The movement speed is 1° / s, and the data recording interval angle is 10 degrees; the radial coordinate uses the arc track of the circumferential module as the origin.

Images