Noise characteristic measurement system and method for liquid rocket engine test bench

Abstract

The present invention provides a liquid rocket engine test bench noise characteristic measurement system and method, relating to the field of aerospace technology. The noise characteristic measurement system comprises: a support body, multiple microphones disposed on the support body, and a test system disposed within a cavity corresponding to the support body. The support body comprises a first support and a second support, each of which is provided with multiple microphones to form a first microphone array and a second microphone array. The first microphone array and the second microphone array surround the test system to collect noise data from the test system while the test system is operating. The noise characteristic measurement system and method for a liquid rocket engine test bench provided by the present invention can effectively simulate the conditions during actual liquid rocket engine testing and launch, ensuring that noise data more closely resembles the actual launch environment of a liquid rocket engine, thereby helping to improve the safety and reliability of aerospace launches.

Description

Technical Field

[0001] The present invention relates to the field of aerospace technology, and in particular to a noise characteristic measurement system and a measurement method for a liquid rocket engine test bench. Background Art

[0002] Typically, the noise generated by the supersonic jet ejected from a liquid rocket engine can reach 170dB, potentially causing irreversible damage to onboard payloads, components, and ground equipment, resulting in harm and loss to the environment and personnel, and seriously threatening the safety and reliability of space launches. Therefore, experimental research on liquid rocket engine jet noise is of great significance.

[0003] At present, there are few experimental studies on the jet noise of liquid rocket engines. In the relevant studies that have been made public, most of them have built systems for the noise generated by free jets, and arranged acoustic sensors or microphones at key locations of the supply system and the engine. For example, the flow state of the free jet downstream of the nozzle is close to an axisymmetric mode centered on the nozzle axis. Therefore, the acoustic sensor will be arranged on the axial cross-section of the nozzle. The data collected at different positions are then processed by software to obtain the frequency domain information and sound pressure level of the noise field, and then the influence of factors such as propellant mixture ratio, nozzle outlet Mach number, chamber pressure, and the presence or absence of guide grooves at the nozzle outlet on the noise characteristics of the nozzle free jet can be explored.

[0004] However, during actual liquid rocket engine testing and launches, the nozzle is often pointed vertically downward. The jet ejected from the nozzle will impact the guide surface and be deflected. The generated noise is more complexly distributed than that of a free jet due to reflection and diffraction from the guide groove wall. Therefore, the existing method of arranging acoustic sensors makes it difficult to accurately obtain the noise distribution of the nozzle jet with a guide groove, which restricts the development of space launch noise reduction technology. Summary of the Invention

[0005] In view of this, an object of the present invention is to provide a noise characteristic measurement system and measurement method for a liquid rocket engine test bench to alleviate the above technical problems.

[0006] In a first aspect, an embodiment of the present invention provides a noise characteristic measurement system for a liquid rocket engine test bench, the noise characteristic measurement system comprising: a bracket body, a plurality of microphones arranged on the bracket body, and a test system arranged inside a cavity corresponding to the bracket body; wherein the bracket body comprises a first bracket and a second bracket, wherein the volume of the cavity corresponding to the first bracket is greater than the volume of the cavity corresponding to the second bracket, and the cavity corresponding to the second bracket is arranged inside the cavity corresponding to the first bracket; the test system is arranged inside the cavity corresponding to the second bracket; the first bracket and the second bracket are respectively provided with a plurality of microphones; wherein the microphones on the first bracket form a first microphone array, and the microphones on the second bracket form a second microphone array; the first microphone array and the second microphone array surround the test system to collect noise data of the test system when the test system is running.

[0007] In combination with the first aspect, an embodiment of the present invention provides a first possible implementation scheme of the first aspect, wherein each of the above-mentioned second brackets is provided with at least one microphone at a different height; the microphones at the same height arranged on multiple second brackets constitute a horizontal array, and the second microphone array is a cylindrical array composed of the horizontal arrays of different heights.

[0008] In combination with the first possible implementation of the first aspect, an embodiment of the present invention provides a second possible implementation of the first aspect, wherein the above-mentioned second bracket is a movable bracket; and the projection distance of each second bracket on the bottom surface of the cavity corresponding to the first bracket is consistent with the center distance of the bottom surface, so that the horizontal array constitutes the columnar array.

[0009] In combination with the first aspect, an embodiment of the present invention provides a third possible implementation scheme of the first aspect, wherein the cavity corresponding to the above-mentioned second bracket and the cavity corresponding to the first bracket overlap relative to the center projection of the bottom surface; the microphones arranged on the first bracket are horizontally distributed on the top surface of the first bracket to form the first microphone array, and the shape corresponding to the first microphone array is a circle with at least one preset radius with the center of the top surface as the center.

[0010] In combination with the first possible implementation of the first aspect, an embodiment of the present invention provides a fourth possible implementation of the first aspect, wherein the above-mentioned test system includes a test engine, a test guide trough matching the test engine, an adjustment unit connected to the engine, and a supply unit connected to the adjustment unit; wherein the test engine and the test guide trough are obtained by scaling the actual size of the liquid rocket engine; the center of the bottom surface of the external reference body corresponding to the test system overlaps with the center of the bottom surface of the cavity corresponding to the first bracket.

[0011] In combination with the fourth possible implementation of the first aspect, an embodiment of the present invention provides a fifth possible implementation of the first aspect, wherein the dimensions of the cylindrical array and the external reference body corresponding to the test system satisfy the following relationship: ;

[0012] Wherein, R represents the radius of the cylindrical array, h represents the height of the cylindrical array, l 1. l 2 and l 3 respectively represent the length, width and height of the circumscribed reference body, d1 and d2 respectively represent the distances from the center of the bottom surface to the sides of the circumscribed reference body on the bottom surface, and d3 represents the distance from the center of the bottom surface to the top surface of the circumscribed reference body.

[0013] In combination with the first possible implementation of the first aspect, an embodiment of the present invention provides a sixth possible implementation of the first aspect, wherein the center of the projection of the horizontal array formed by the microphones at the same height overlaps with the center of the bottom surface; and the projections of the microphones included in the horizontal array on the bottom surface are arranged at equal intervals relative to the center of the bottom surface.

[0014] In combination with the fourth possible implementation of the first aspect, the embodiment of the present invention provides a seventh possible implementation of the first aspect, wherein the above-mentioned testing system further includes a microphone provided in the supply unit.

[0015] In a second aspect, an embodiment of the present invention further provides a method for measuring the noise characteristics of a liquid rocket engine test bench, which is applied to the noise characteristics measurement system described in the first aspect, the noise characteristics measurement system comprising: a bracket body, a plurality of microphones arranged on the bracket body, and a test system arranged inside a cavity corresponding to the bracket body, the test system comprising a test engine, a test guide groove matching the test engine, an adjustment unit connected to the test engine, and a supply unit connected to the adjustment unit; the method comprises: configuring operating parameters of the test system; starting the test system, and making the test engine operate according to the operating parameters through the adjustment unit; collecting sound pressure signals of the plurality of microphones included in the first microphone array and the second microphone array; analyzing the noise of the test engine included in the test system based on the sound pressure signals to obtain the noise characteristics of the test engine, so as to infer the noise characteristics of the real liquid rocket engine test bench based on the noise characteristics of the test engine.

[0016] In combination with the second aspect, an embodiment of the present invention provides a first possible implementation method of the second aspect, wherein the above method also includes: starting the microphone before starting the test system, recording the initial value of the microphone; calibrating the microphone based on the initial value to obtain a calibration file of the microphone.

[0017] The embodiments of the present invention bring the following beneficial effects:

[0018] Embodiments of the present invention provide a liquid rocket engine test bench noise characteristic measurement system and method. The noise characteristic measurement system includes a support body, microphones disposed on the support body, and a test system disposed within a cavity corresponding to the support body. Furthermore, the support body further includes a first support and a second support. The volume of the cavity corresponding to the first support is larger than the volume of the cavity corresponding to the second support, allowing the cavity corresponding to the second support to be disposed within the cavity corresponding to the first support. The test system is disposed within the cavity corresponding to the second support, and multiple microphones are disposed on each of the first and second supports. The microphones on the first support form a first microphone array, and the microphones on the second support form a second microphone array. The first and second microphone arrays surround the test system to collect noise data from the test system while the test system is operating. Because the microphone arrays surround the test system, the test system can effectively simulate conditions during actual liquid rocket engine testing and launches, thereby making the resulting noise data more similar to the actual launch environment of the liquid rocket engine. This improves the accuracy and authenticity of engine noise characteristic tests and contributes to improving the safety and reliability of space launches.

[0019] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or understood by practicing the present invention. The purposes and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings.

[0020] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 A schematic diagram of a noise characteristic measurement system for a liquid rocket engine test bench provided by an embodiment of the present invention;

[0023] Figure 2 A schematic structural diagram of a test system provided by an embodiment of the present invention;

[0024] Figure 3 A schematic diagram of another noise characteristic measurement system for a liquid rocket engine test bench provided by an embodiment of the present invention;

[0025] Figure 4 A top view of a noise characteristic measurement system for a liquid rocket engine test bench provided by an embodiment of the present invention;

[0026] Figure 5 A flow chart of a method for measuring noise characteristics of a liquid rocket engine test bench provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work shall fall within the scope of protection of the present invention.

[0028] Currently, the microphones used in existing liquid rocket engine jet noise tests cannot accurately capture the jet noise distribution of a nozzle with a guide groove. Furthermore, the sound pressure data currently obtained, used as an indicator for evaluating noise level and directivity, requires further processing. Furthermore, to conduct noise characteristic tests that more closely resemble the actual launch environment of a liquid rocket engine, both the test measurement system layout and subsequent data processing methods need to be improved.

[0029] Based on this, the embodiments of the present invention provide a liquid rocket engine test bench noise characteristic measurement system and measurement method, which can effectively improve the above-mentioned problems, so as to more comprehensively evaluate the noise level close to the actual liquid rocket engine launch state, and can measure the noise characteristics generated during the launch of the actual liquid rocket engine.

[0030] To facilitate understanding of this embodiment, a noise characteristic measurement system for a liquid rocket engine test bench disclosed in an embodiment of the present invention is first introduced in detail.

[0031] In one possible implementation, an embodiment of the present invention provides a noise characteristic measurement system for a liquid rocket engine test bench (hereinafter referred to as the noise characteristic measurement system). The noise characteristic measurement system includes: a support body, a plurality of microphones disposed on the support body, and a test system disposed within a cavity corresponding to the support body. For ease of understanding, Figure 1 The figure shows a schematic diagram of a noise characteristic measurement system for a liquid rocket engine test bench. Specifically, Figure 1 , shown is a front view of a noise characteristic measurement system.

[0032] like Figure 1 As shown, the bracket body includes a first bracket 10 and a second bracket 20, wherein the volume of the cavity corresponding to the first bracket 10 is larger than the volume of the cavity corresponding to the second bracket, and the cavity corresponding to the second bracket is arranged inside the cavity corresponding to the first bracket; the test system 30 is arranged inside the cavity corresponding to the second bracket.

[0033] The first bracket and the second bracket are respectively provided with multiple microphones 40; wherein, the microphones 40 on the first bracket 10 form a first microphone array, and the microphones 40 on the second bracket form a second microphone array; the first microphone array and the second microphone array surround the test system 30 to collect noise data of the test system when the test system 30 is running.

[0034] In specific implementation, the test system in an embodiment of the present invention includes a test engine, a test guide trough matching the test engine, an adjustment unit connected to the engine, and a supply unit connected to the adjustment unit; wherein the test engine and the test guide trough are obtained by scaling the actual size of the liquid rocket engine, and the test system also includes a microphone arranged in the supply unit.

[0035] That is, the noise characteristic measurement system in the embodiment of the present invention is mainly aimed at analyzing the noise characteristics of the liquid rocket engine with a guide groove in the launch state. Therefore, the above-mentioned test system in the embodiment of the present invention is actually a scaled-down liquid rocket engine system, and the scaled-down liquid rocket engine system has a guide groove. Therefore, Figure 1 , a schematic diagram of the structure of the test engine 301 and the test guide trough 302 is also shown. Figure 2 Also shown is a structural schematic diagram of a test system, including a test engine 301 and a test diversion trough 302, as well as an adjustment unit 303, a supply unit 304, a microphone 40 provided in the supply unit 304, and a microphone 40 provided in the test engine 301 and the test diversion trough 302.

[0036] In specific implementation, the noise output by the microphone 40 may be further processed, such as performing spectrum feature analysis or sound pressure level distribution feature analysis.

[0037] in, Figure 2 In the test, the supply system is used to deliver the working fluid for the test, and the regulating unit includes switching components such as valves to control the pressure or flow rate of the liquid in the test engine 301, etc., so that the noise data of the corresponding test system can be obtained under each operating parameter.

[0038] further, Figure 1 In the test system, the relative positions of the test engine 301 and the test guide groove 302 are consistent with the state of a real liquid rocket engine during launch. Therefore, based on the noise characteristic measurement system provided in the embodiment of the present invention, the analysis of the directivity of the jet noise of the scaled liquid rocket engine nozzle with a guide groove on different horizontal planes and the distribution characteristics in different frequency domains can more comprehensively evaluate the noise level close to the launch state of a real liquid rocket engine.

[0039] Therefore, an embodiment of the present invention provides a noise characteristic measurement system, which includes a support body, microphones disposed on the support body, and a test system disposed within a cavity corresponding to the support body. Furthermore, the support body further includes a first support and a second support, wherein the volume of the cavity corresponding to the first support is larger than the volume of the cavity corresponding to the second support, so that the cavity corresponding to the second support can be disposed within the cavity corresponding to the first support, and the test system is disposed within the cavity corresponding to the second support. A plurality of microphones are disposed on each of the first support and the second support. The microphones on the first support form a first microphone array, and the microphones on the second support form a second microphone array. The first microphone array and the second microphone array surround the test system to collect noise data from the test system while the test system is operating. Since the test system is surrounded by microphone arrays, the conditions during actual liquid rocket engine testing and launch can be effectively simulated, thereby making the obtained noise data closer to the actual launch environment of the liquid rocket engine, thereby improving the accuracy and authenticity of noise characteristic tests and contributing to improving the safety and reliability of space launches.

[0040] In actual use, the microphone in the embodiment of the present invention is also called an acoustic sensor, capable of converting sound signals into electrical signals for measurement. Furthermore, the test system in the embodiment of the present invention is actually a scaled-down liquid rocket engine system. To accurately measure the jet noise characteristics of a scaled-down liquid rocket engine nozzle with a guide groove in the scaled-down liquid rocket engine system, each second bracket in the embodiment of the present invention is equipped with at least one microphone at different heights. Multiple microphones at the same height installed on the second brackets form a horizontal array, and the second microphone array is a cylindrical array composed of horizontal arrays at different heights.

[0041] Specifically, the above-mentioned second bracket is a movable bracket, such as a movable bracket in a vertical state such as a tripod, and the projection distance of each second bracket on the bottom surface of the cavity corresponding to the first bracket is consistent with the center distance of the bottom surface, so that the horizontal array constitutes a cylindrical array.

[0042] For ease of understanding, Figure 3 A schematic diagram of another noise characteristic measurement system is shown, wherein: Figure 3 The figure shows a schematic diagram of the three-dimensional structure of the noise characteristic measurement system, wherein the second support 20 is in the form of a tripod, and four microphones are set on each tripod at different heights. At the same time, the tripod is arranged with a cylindrical measurement surface, so that the microphones form a cylindrical array, that is, Figure 3 In the figure, the cylindrical shadow represents the cylindrical array of microphones.

[0043] in, Figure 3In the figure, the first bracket is a rectangular frame bracket as an example, and the cavity enclosed by the rectangular frame bracket is larger than the cavity enclosed by the tripod, so that the cylindrical array formed by the microphone is arranged inside the cavity enclosed by the rectangular frame bracket, and the cavity corresponding to the second bracket and the cavity corresponding to the first bracket overlap relative to the center projection of the bottom surface.

[0044] That is, the center of the bottom surface of the rectangular frame bracket overlaps with the center of the bottom surface of the columnar array.

[0045] Furthermore, the microphones provided on the first bracket are horizontally distributed on the top surface of the first bracket to form a first microphone array, and the shape corresponding to the first microphone array is a circle with at least one preset radius and the center of the top surface as the center. Figure 3 On the basis of Figure 4 A top view of a noise characteristic measurement system is shown. Figure 4 It can be seen that the projection of the tripod on the bottom surface forms an approximately circular shape.

[0046] Figure 4 In FIG, the microphones 40 enclosed by the dotted circle are the microphones horizontally distributed on the top surface of the first bracket, that is, the microphones 40 enclosed by the dotted circle constitute the first microphone array. Figure 4 The first microphone array shown includes two circles of circularly distributed microphones, that is, the shape of the first microphone array is two concentric circles with different radii, with the center of the top surface as the origin.

[0047] Furthermore, the center of the projection of the horizontal array formed by the microphones at the same height on the bottom surface overlaps with the center of the bottom surface; that is, Figure 3 The center of the projection of the central microphone cylindrical array on the bottom surface overlaps with the center of the bottom surface. At the same time, the projections of the microphones included in the horizontal array on the bottom surface are arranged at equal angles relative to the center of the bottom surface. At the same time, the projections of the microphones horizontally distributed on the top surface of the first bracket on the bottom surface, the projections of the microphones included in the horizontal array on the bottom surface, and the line connecting the center of the bottom surface are generally straight lines, that is, the projections of the first microphone array on the bottom surface are also arranged at equal angles relative to the center of the bottom surface. Figure 4 In the figure, the 45° equal-spaced angle setting is shown. In other embodiments, it can also be set to other equal-spaced angles such as 30°. The specific setting can be made according to actual usage, and the embodiment of the present invention does not limit this.

[0048] based on Figure 3 and Figure 4The microphones are distributed in a manner such that the center of the bottom surface of the circumscribed reference body corresponding to the test system overlaps with the center of the bottom surface of the cavity corresponding to the first bracket. The circumscribed reference body corresponding to the test system can be considered as a circumscribed rectangular parallelepiped frame for the test system. This circumscribed rectangular parallelepiped frame is actually a virtual shape, and the center of its bottom surface overlaps with the center of the bottom surface of the cavity corresponding to the first bracket. That is, the test system is centered at the bottom center of the cavity corresponding to the first bracket, so that the first microphone array and the second microphone array surround the test system to collect noise data of the test system while the test system is operating. The noise data at this time corresponds to the nozzle jet noise data of a scaled-down liquid rocket engine with a guide groove.

[0049] In actual use, the construction process of the noise characteristic measurement system provided in the embodiment of the present invention includes the following steps:

[0050] Step 110, designing a scaled-down engine and a scaled-down guide trough according to the actual size of the liquid rocket engine, that is, obtaining the test engine and test guide trough in the embodiment of the present invention, and at the same time, configuring the adjustment unit and supply system of the test engine.

[0051] Step 120: Assemble and fix the test engine and the test guide trough.

[0052] Step 130, according to the above Figure 3 and Figure 4 The microphones are arranged in a manner as follows, wherein the specific process of arranging the microphones is as follows:

[0053] (1) In order to more accurately measure the nozzle jet noise characteristics of a scaled-down liquid rocket engine with a guide groove, according to the relevant standards for noise measurement, a complete cylindrical measurement surface arrangement, that is, a cylindrical array, is adopted to arrange the first bracket and the second bracket, as well as the microphones on the first bracket and the second bracket.

[0054] (2) Based on the actual dimensions of the test engine and the test duct, the dimensions of the external reference body corresponding to the test system are obtained. In the embodiment of the present invention, the external reference body adopts the smallest external rectangular parallelepiped of the test system. Therefore, the dimensions of the external reference body include length, width and height.

[0055] (3) According to the pre-configured noise measurement standard, the distances from the center of the bottom surface of the first bracket and the second bracket to the sides of the external reference body on the bottom surface, as well as the distances from the center of the bottom surface to the top surface of the external reference body are set, and the sizes of the first bracket and the second bracket are determined based on the relationship between the sizes of the cylindrical array and the external reference body corresponding to the test system.

[0056] Specifically, in the embodiment of the present invention, the dimensions of the external reference body corresponding to the columnar array and the test system satisfy the following relationship:

[0057]

[0058] Where R represents the radius of the cylindrical array, h represents the height of the cylindrical array, l 1. l 2 and l 3 respectively represent the length, width and height of the circumscribed reference body, d1 and d2 respectively represent the distances from the center of the bottom surface to the sides of the circumscribed reference body on the bottom surface, and d3 is the distance from the center of the bottom surface to the top surface of the circumscribed reference body. Since the test system is directly placed on the bottom surface, d3 = l 3.

[0059] In actual use, the above-mentioned d1 and d2 can also be set arbitrarily according to the size of the test system to be tested and other factors. Usually, in order to facilitate calculation and measurement, d1 and d2 are usually set to the same value, such as 1m, but usually not less than 0.5m. Furthermore, the difference between any two of the above-mentioned d1, d2 and d3 should not be greater than a certain threshold, such as not greater than 1.5 times of any one, so as to make the size of the noise characteristic measurement system more reasonable.

[0060] The dimensions of the specific noise characteristic measurement system can be set according to actual measurement needs on the premise of meeting the above requirements, and the embodiment of the present invention does not limit this.

[0061] (4) Determine the number of microphones to be arranged on the first bracket and the second bracket.

[0062] After the first bracket and the second bracket are set according to the dimensions in (3) above, the number of microphones needs to be further determined. Usually, the second microphone array corresponds to a cylindrical array, that is, the total number of microphones set on the second bracket is n. s The number of microphones forming the first microphone array on the first bracket is represented by n T Indicates that, usually, n s and n T The following relationship is satisfied:

[0063] ;

[0064] Wherein, h represents the height of the columnar array determined above.

[0065] (5) Since noise generation is a non-steady-state process, considering the deflection of the jet noise with the guide groove, according to the various dimensional parameters of the cylindrical array determined above, the second bracket and the microphones on the top surface of the first bracket are further arranged at equal intervals relative to the center of the bottom surface according to the projection of the microphones included in the horizontal array on the bottom surface, such as Figure 4 The 45° equal spacing angle is set in the middle, thereby forming a first microphone array and a second microphone array, wherein the effect diagram can refer to the above Figure 3 and Figure 4 .

[0066] Based on the above-determined dimensions of the first bracket and the second bracket, and the number of microphones arranged on the first bracket and the second bracket, the noise characteristic measurement system in the embodiment of the present invention can be obtained after assembly.

[0067] Specifically, when assembling the bracket body, the following components are usually included: a profile bracket for supporting the top surface of the first bracket. In the embodiment of the present invention, an aluminum profile is used; and a tripod for mounting the microphone of the second microphone array.

[0068] The aluminum profiles can be standard 40×40 sections, with most connections secured by angle brackets. A connecting plate can be installed in the center of the top surface. Furthermore, an L-shaped connecting plate can be installed in the area where the microphone is mounted, secured with screws. Extension clips can be installed at the corresponding height of the tripod to facilitate microphone installation.

[0069] Furthermore, after the microphone is installed, it is necessary to further calibrate the microphone, that is, record the ambient noise in the current environment as the initial value of the microphone, and save it as a calibration file for use.

[0070] (6) Install the test system

[0071] The test system installation process includes the installation of the test engine and the test guide trough, as well as the connection of the main pipeline and pressure measurement pipeline in the test engine and the adjustment unit, and the corresponding valves.

[0072] Based on the noise characteristic measurement system installed above, an embodiment of the present invention further provides a noise characteristic measurement method for a liquid rocket engine test bench, which is applied to the noise characteristic measurement system. Specifically, the noise characteristic measurement system includes: a bracket body, a plurality of microphones arranged on the bracket body, and a test system arranged inside a cavity corresponding to the bracket body. The test system includes a test engine, a test guide groove matched with the test engine, an adjustment unit connected to the test engine, and a supply unit connected to the adjustment unit, such as Figure 5 The flowchart of a method for measuring noise characteristics of a liquid rocket engine test bench shown in FIG. 1 includes the following steps:

[0073] Step S502, configuring the operating parameters of the test system;

[0074] Usually, when measuring noise characteristics, it is necessary to measure the noise characteristics of the side and top layer of the test system under different working conditions. The working condition parameters can be adjusted through the solenoid valve of the above-mentioned adjustment unit. At the same time, the above-mentioned test engine can also be pre-designed with multiple replacement test pieces to facilitate testing the corresponding noise characteristics of different test engines under the same working condition parameters.

[0075] Step S504, starting the test system and operating the test engine according to the operating parameters through the regulating unit;

[0076] Before starting the test system, the microphone needs to be activated and its initial values ​​recorded. The microphone is then calibrated based on these initial values ​​to create a calibration file. Specifically, the initial values ​​are the ambient noise recorded in the current environment. During subsequent analysis, the ambient noise data collected by the microphone is subtracted from the ambient noise in the calibration file to eliminate the effects of ambient noise.

[0077] Step S506, collecting sound pressure signals of the plurality of microphones included in the first microphone array and the second microphone array;

[0078] Step S508 , analyzing the noise of the test engine included in the test system based on the sound pressure signal to obtain the noise characteristics of the test engine, so as to infer the noise characteristics of the actual liquid rocket engine test bench based on the noise characteristics of the test engine.

[0079] In actual use, the microphone in the embodiment of the present invention collects noise data, which is actually a sound pressure-time signal. Therefore, the sound pressure signal obtained in the above step S506 is actually a relationship between voltage and time.

[0080] Furthermore, by analyzing the noise data of each microphone included in the first microphone array and the second microphone array, the sound pressure-time signals at different measurement positions can be obtained. Then, by further referring to the sound pressure and sound pressure level conversion formula and considering the weighting network, the pressure level distribution of noise at different heights under the same working conditions can be obtained. For example, the A weighting network can be used to obtain the A sound pressure level distribution, etc. In addition, the B weighting network or the C weighting network can also be used, which is subject to actual usage and is not limited in this regard in the embodiment of the present invention.

[0081] Furthermore, the sound pressure level distribution results obtained above can be further combined with octave formula conversion, such as 1 / 3 octave formula conversion, etc., to obtain the energy distribution of noise in different frequency bands under the same working conditions and the same location.

[0082] The specific weighting network and the further processing of the sound pressure level distribution result can be set according to actual usage, and the embodiment of the present invention does not limit this.

[0083] In summary, the noise characteristic measurement system and method for a liquid rocket engine test bench provided in the embodiments of the present invention fully consider the jet noise distribution characteristics of a scaled-down liquid rocket engine nozzle with a guide trough. Based on the dimensions of the test engine and test guide trough obtained by scaling, a cylindrical array of microphones is arranged to collect sound pressure signals. During the data processing phase, the test data is directly processed into a common indicator for evaluating noise levels. While ensuring that the test engine and the real engine are scaled down to a certain scale, a 1 / 3 octave frequency spectrum of the real liquid rocket engine noise can be obtained. This forms a noise characteristic measurement system that is more suitable for evaluating the directivity and frequency distribution characteristics of noise generated during the launch of a real liquid rocket engine at different altitudes. This contributes to the development of liquid rocket engine launch noise reduction technology and has strong engineering application significance.

[0084] The noise characteristic measurement method of the liquid rocket engine test bench provided in the embodiment of the present invention has the same technical features as the noise characteristic measurement system provided in the above embodiment, so it can also solve the same technical problems and achieve the same technical effects.

[0085] Those skilled in the art will clearly understand that, for the sake of convenience and brevity of description, the specific working process of the noise characteristic measurement method of the liquid rocket engine test bench described above can refer to the corresponding process in the aforementioned embodiment and will not be repeated here.

[0086] In addition, in the description of the embodiments of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0087] If the functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the portion that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage media include various media capable of storing program code, such as USB flash drives, mobile hard drives, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical disks.

[0088] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0089] Finally, it should be noted that the above embodiments are only specific implementation methods of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that any person skilled in the art can modify or easily conceive of changes to the technical solutions described in the above embodiments within the technical scope disclosed by the present invention, or replace some of the technical features therein with equivalents. Such modifications, changes or replacements do not deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A noise characteristic measurement system for a liquid rocket engine test bench, characterized in that: The noise characteristic measurement system comprises: A support body, a plurality of microphones disposed on the support body, and a test system disposed inside a cavity corresponding to the support body; The bracket body includes a first bracket and a second bracket, wherein the volume of the cavity corresponding to the first bracket is greater than the volume of the cavity corresponding to the second bracket, and the cavity corresponding to the second bracket is arranged inside the cavity corresponding to the first bracket; The testing system is arranged inside the cavity corresponding to the second bracket; The first bracket and the second bracket are respectively provided with a plurality of microphones; wherein the microphones on the first bracket form a first microphone array, and the microphones on the second bracket form a second microphone array; The first microphone array and the second microphone array surround the test system to collect noise data of the test system when the test system is running; At least one microphone is provided on each of the second brackets at different heights; The microphones at the same height arranged on the plurality of second brackets form a horizontal array, and the second microphone array is a cylindrical array formed by the horizontal arrays at different heights; The cavity corresponding to the second bracket and the cavity corresponding to the first bracket overlap with each other in their central projection relative to the bottom surface; The microphones arranged on the first bracket are horizontally distributed on the top surface of the first bracket to form the first microphone array, and the shape corresponding to the first microphone array is a circle with at least one preset radius with the center of the top surface as the center.

2. The noise characteristic measurement system according to claim 1, wherein: The second bracket is a movable bracket; Moreover, the projection of each second bracket on the bottom surface of the cavity corresponding to the first bracket is at the same distance from the center of the bottom surface, so that the horizontal array constitutes the columnar array.

3. The noise characteristic measurement system according to claim 1, wherein: The test system includes a test engine, a test guide trough matched with the test engine, a regulating unit connected to the test engine, and a supply unit connected to the regulating unit; The test engine and the test guide trough are obtained by scaling the actual size of the liquid rocket engine; The center of the bottom surface of the circumscribed reference body corresponding to the test system overlaps with the center of the bottom surface of the cavity corresponding to the first bracket.

4. The noise characteristic measurement system according to claim 3, wherein: The dimensions of the cylindrical array and the external reference body corresponding to the test system satisfy the following relationship: Wherein, R represents the radius of the cylindrical array, h represents the height of the cylindrical array, l 1. l 2 and l 3 respectively represent the length, width and height of the circumscribed reference body, d1 and d2 respectively represent the distances from the center of the bottom surface to the sides of the circumscribed reference body on the bottom surface, and d3 represents the distance from the center of the bottom surface to the top surface of the circumscribed reference body.

5. The noise characteristic measurement system according to claim 3, wherein: The center of the projection of the horizontal array formed by the microphones at the same height on the bottom surface overlaps with the center of the bottom surface; Furthermore, projections of the microphones included in the horizontal array on the bottom surface are arranged at equal intervals relative to the center of the bottom surface.

6. The noise characteristic measurement system according to claim 3, wherein: The testing system further includes a microphone disposed on the supply unit.

7. A method for measuring the noise characteristics of a liquid rocket engine test bench, characterized in that: A noise characteristic measurement system for a liquid rocket engine test bench according to any one of claims 1 to 6, the noise characteristic measurement system comprising: a support body, a plurality of microphones disposed on the support body, and a test system disposed within a cavity corresponding to the support body, the test system comprising a test engine, a test flow guide matched with the test engine, an adjustment unit connected to the test engine, and a supply unit connected to the adjustment unit; The bracket body includes a first bracket and a second bracket; At least one microphone is provided on each of the second brackets at different heights; The microphones at the same height arranged on the plurality of second brackets form a horizontal array, and the second microphone array is a cylindrical array formed by the horizontal arrays at different heights; The cavity corresponding to the second bracket and the cavity corresponding to the first bracket overlap with each other in their central projection relative to the bottom surface; The microphones provided on the first bracket are horizontally distributed on the top surface of the first bracket to form the first microphone array, and the shape corresponding to the first microphone array is a circle with at least one preset radius and a center of the top surface as the center of the circle; The method comprises: Configuring the operating parameters of the test system; Starting the test system and operating the test engine according to the operating parameters through the regulating unit; collecting sound pressure signals of the plurality of microphones included in the first microphone array and the second microphone array; The noise of the test engine included in the test system is analyzed based on the sound pressure signal to obtain the noise characteristics of the test engine, so as to infer the noise characteristics of the real liquid rocket engine test bench based on the noise characteristics of the test engine.

8. The method according to claim 7, characterized in that The method further comprises: starting the microphone before starting the test system and recording the initial value of the microphone; The microphone is calibrated based on the initial value to obtain a calibration file of the microphone.

Images