Solid rocket engine underwater test data processing method

Abstract

The invention provides a solid rocket engine underwater test data processing method. The method comprises the following steps of S1, test original signal data acquisition, S2, test original signal data preprocessing, S3, test data time domain analysis after preprocessing in S2, S4, test data frequency domain analysis after preprocessing in S2, and S5, test data time frequency analysis after preprocessing in S2. According to the underwater test data processing method provided by the invention, the test data are processed through Fourier transform, short-time Fourier transform and wavelet transform, and the test data are excavated comprehensively and deeply from the aspects of time domain, frequency domain and the like by adopting various signal processing methods; the method can master the frequency spectrum characteristics of the underwater test data of the solid rocket engine and the time-varying rule, facilitates the deep research of the working characteristics of the underwater solid rocket engine, and provides an important basis for the performance evaluation and fault detection and diagnosis of the underwater solid rocket engine.

Description

Technical Field

[0001] The invention belongs to the technical field of solid rocket engines, and in particular relates to a method for processing underwater test data of solid rocket engines. Background Art

[0002] The research, development and testing of underwater solid rocket engines are crucial to the development of underwater launch technology. Underwater testing of solid rocket engines is different from ground testing. In addition to being affected by environmental factors such as the high density and high pressure of the water medium, the gas-liquid two-phase flow between the high-temperature and high-pressure combustion gas generated by the underwater ignition of the solid rocket engine and the low-temperature water medium causes the engine underwater thrust signal and other test data to have drastic parameter changes, serious signal mixing and difficulty in distinguishing. As a key performance indicator, the change law of test data such as thrust provides a key basis for engine performance verification, design optimization and safety assessment. Therefore, it is necessary to use digital signal processing technology to conduct time and frequency domain analysis on the test data to reveal the spectral characteristics and time-varying characteristics of the underwater solid rocket engine test signal data.

[0003] Time domain analysis is based on the time scale to grasp the change of the amplitude of the test signal data over time, and frequency domain analysis understands the amplitude-frequency characteristics of the test signal data as it changes with frequency on the frequency scale, but both cannot provide information on the change of the signal frequency over time, while time-frequency analysis such as short-time Fourier transform and wavelet transform can analyze the frequency characteristics of the test signal data as it changes over time, which can better extract signal features, and the local analysis accuracy of wavelet transform is higher. The above methods can improve the level of test signal data processing and analysis, which has important practical significance for the working status monitoring, performance judgment, fault detection and diagnosis of underwater solid rocket engines.

[0004] At present, there is no relevant standard for the underwater test data processing method of solid rocket engines. The use of general solid rocket engine ground / air test data processing methods cannot remove the interference factors in the underwater test data, making it difficult to further analyze the underwater working characteristics of the engine. This will lead to insufficient analysis of the time-varying characteristics and time-varying information of the underwater test signal data, and the research on the working characteristics of underwater solid rocket engines is not comprehensive and accurate enough. Summary of the invention

[0005] The technical problem solved by the present invention is: to overcome the limitations of the existing solid rocket engine underwater test data processing method, and to provide a solid rocket engine underwater test data processing method, for different underwater working stages of the solid rocket engine, to understand the instantaneous distribution law of the engine test data based on time domain analysis; to grasp the amplitude-frequency characteristics of the engine test data as the signal frequency changes based on frequency domain analysis; to comprehensively grasp the time-varying characteristics and spectrum information of the engine test data based on time-frequency analysis, so as to meet the research needs of the underwater working characteristics of the solid rocket engine.

[0006] The present invention provides a method for processing underwater test data of a solid rocket engine, comprising the following steps:

[0007] S1: Experimental raw signal data acquisition

[0008] According to the underwater ignition test of solid rocket engine, the test data measurement and acquisition system automatically collects the original signal data;

[0009] The original signal data includes thrust signal data and pressure signal data;

[0010] The test data measurement and acquisition system includes an underwater high-speed camera, a thrust sensor, a pressure sensor, a data acquisition instrument, and a computer;

[0011] S2: Preprocessing of raw signal data

[0012] Preprocess the raw signal data of the test, including the division of solid rocket motor working stages and filtering processing;

[0013] The solid rocket engine working phases are divided into ascending phase, balancing phase and descending phase according to thrust;

[0014] The filtering process uses a filter to filter out the influence of the natural frequency of the thrust bench structure test equipment, and at the same time removes the coupling effect of other factors when the solid rocket engine works underwater;

[0015] The other factors include the high-temperature and high-speed jet of gas and the high back-pressure water environment when the solid rocket engine works underwater;

[0016] S3: Time domain analysis of experimental data after S2 preprocessing

[0017] Perform time domain analysis on the test data after S2 preprocessing, and obtain the digital characteristics of the test signal data according to different working stages of the engine;

[0018] S4: Frequency domain analysis of test data after S2 preprocessing

[0019] Perform Fourier transform spectrum analysis on the test signal data after S2 preprocessing to obtain the frequency and amplitude changes of the test signal data;

[0020] S5: Time-frequency analysis of experimental data after S2 preprocessing

[0021] Perform short-time Fourier transform and wavelet transform time-frequency analysis on the test signal data after S2 preprocessing, and obtain the time-varying characteristics and spectrum information of the test signal data by analyzing the results of short-time Fourier transform and wavelet transform;

[0022] Preferably, the thrust signal test data is subjected to time-frequency analysis in combination with short-time Fourier transform, wherein a suitable window function and its length are selected according to the signal acquisition data length and computational efficiency. The parameters should ensure that the signal within the time window is locally stable, and the time-frequency spectrum of the thrust signal is obtained to observe the energy distribution of the thrust signal at different times and frequencies, and to extract the time-varying information of the signal to gain an in-depth understanding of the characteristics of the signal, including the time of occurrence of the thrust peak and the change characteristics of the thrust oscillation frequency.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The method for processing underwater test data of a solid rocket engine provided by the present invention reasonably divides the working stages of the underwater test of the engine in combination with the standard, grasps the working characteristics of the underwater solid rocket engine, and provides a key basis for performance verification and design optimization of the underwater solid rocket engine; for the test data of different working stages of the underwater test of the solid rocket engine, the underwater test data is processed in sections according to the ascending section, the balancing section and the descending section, the dynamic characteristics of the engine during underwater operation are effectively processed, and a variety of signal processing methods are used to deeply mine the test data from all aspects in the time domain, frequency domain, etc., and the time-varying characteristics and spectrum information of the engine test data are fully displayed, the analysis angle is more comprehensive, and the test data is processed accurately and effectively, which can effectively support the precise control of the weapon system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 A schematic diagram of a flow chart of a method for processing underwater test data of a solid rocket engine provided by the present invention;

[0027] Figure 2 Thrust-time test curve of solid rocket motor underwater test;

[0028] Figure 3 Fourier transform amplitude-frequency diagram of the thrust signal of the ascent phase of the solid rocket motor underwater test;

[0029] Figure 4 Fourier transform amplitude-frequency diagram of thrust signal of balance section of underwater test of solid rocket motor;

[0030] Figure 5 Fourier transform amplitude-frequency diagram of thrust signal of descent phase of solid rocket motor underwater test;

[0031] Figure 6 The short-time Fourier transform time-frequency spectrum of the thrust signal of the ascent phase of the solid rocket motor underwater test;

[0032] Figure 7 Short-time Fourier transform time-frequency spectrum of the thrust signal of the balance section of the solid rocket motor underwater test;

[0033] Figure 8 Short-time Fourier transform time-frequency spectrum of the thrust signal of the solid rocket motor during the descent phase of the underwater test.

[0034] Specific implementation methods

[0035] In conjunction with the accompanying drawings, the solid rocket engine underwater test data processing method of the present invention is described in detail by taking the thrust test data analysis of a solid rocket engine at an underwater working depth of 150m as an example. The flowchart of the processing method is shown in FIG. Figure 1 As shown, the details are as follows:

[0036] S1. Experimental raw signal data acquisition

[0037] An underwater ignition test was conducted on a solid rocket engine. The data measurement and acquisition system mainly includes an underwater high-speed camera, a pressure sensor, a thrust sensor, a data acquisition instrument, and a computer. The data measurement and acquisition system is used to automatically collect the underwater working test data of the solid rocket engine, including thrust signal data and pressure signal data.

[0038] In the thrust-time curve of the solid rocket engine ground test, the engine thrust slowly climbs to the steady-state thrust, while the engine thrust working in the deep water environment suddenly rises and then tends to a stable oscillation state. In the engine thrust decrease stage, the ground test thrust slowly and smoothly decreases to 0. After the underwater solid rocket engine is turned off, the pressure difference between the inside and outside of the engine causes water to flow back, forming a small oscillation, and there is a negative thrust phenomenon, such as Figure 2 As shown;

[0039] S2: Preprocessing of thrust raw signal test data

[0040] Firstly, considering the influence of the natural frequency of the test equipment, the thrust signal is filtered with an appropriate cutoff frequency. Then, according to the "QJ1047A-2018 Solid Rocket Engine Pressure-Time, Thrust-Time Data Processing Method", the engine thrust working stages are divided into ascending stage, balance stage and descending stage, and the thrust / time curve results are analyzed.

[0041] S3: Time domain analysis of experimental data after S2 preprocessing

[0042] Perform time domain analysis on the thrust signal test data after S2 preprocessing, draw time domain curves of thrust signals in three different working stages: ascending stage, balancing stage and descending stage, and perform mean, variance and root mean square value analysis on the thrust signal test data within the time domain;

[0043] S4: Frequency domain analysis of test data after S2 preprocessing

[0044] The thrust signal test data after S2 preprocessing is analyzed in the frequency domain. The thrust signal amplitude-frequency diagram is obtained by combining Fourier transform. The frequency characteristics of the thrust signal are analyzed. There are sudden frequencies of different amplitudes in the three different working stages of the solid rocket engine underwater, namely the ascent stage, the balance stage and the descent stage, and there is a multi-order frequency attenuation phenomenon, such as Figure 3 , Figure 4 , Figure 5 As shown;

[0045] S5: Time-frequency analysis of experimental data after S2 preprocessing

[0046] Perform short-time Fourier transform and wavelet transform time-frequency analysis on the test signal data after S2 preprocessing, and obtain the time-varying characteristics and spectrum information of the test signal data by analyzing the results of short-time Fourier transform and wavelet transform;

[0047] Preferably, the thrust signal test data is subjected to time-frequency analysis in combination with short-time Fourier transform, wherein a suitable window function and its length are selected according to the signal acquisition data length and computational efficiency, and the parameters should ensure that the signal within the time window is locally stable, obtain the thrust signal time-frequency diagram, observe the energy distribution of the thrust signal at different times and frequencies, extract the signal time-varying information, and deeply understand the characteristics of the signal, including the thrust peak occurrence time and the thrust oscillation frequency change characteristics;

[0048] Because the short-time Fourier transform uses the same resolution to analyze the entire thrust signal, the local analysis accuracy is not high, so the thrust signal test data is analyzed in time-frequency mode in combination with wavelet transform. The appropriate wavelet basis function is selected according to the time-frequency resolution or computational efficiency requirements, and the wavelet face spectrum is used to present the time-frequency analysis results, such as Figure 6 , Figure 7 , Figure 8 As shown in the figure, in addition to observing the energy distribution of test signal data such as thrust at different times and frequencies, it is also compared and verified with the short-time Fourier transform time-frequency analysis results, and the time-frequency characteristics of test signal data such as thrust at different engine working stages are analyzed.

[0049] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention using the above disclosed contents without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the contents of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for processing underwater test data of a solid rocket engine, characterized in that: The method aims at different underwater working stages of solid rocket engines. The instantaneous distribution law of engine test data is understood based on time domain analysis. The amplitude-frequency characteristics of engine test data as signal frequency changes are mastered based on frequency domain analysis. The time-varying characteristics and spectrum information of engine test data are fully mastered based on time-frequency analysis. A variety of signal processing methods are used to effectively process the dynamic characteristics of the engine during underwater working, which is used for underwater working characteristics research of solid rocket engines.

2. A method for processing underwater test data of a solid rocket engine according to claim 1, characterized in that: The method specifically comprises the following steps: S1: Experimental raw signal data acquisition According to the underwater ignition test of the solid rocket engine, the test data measurement and acquisition system is used to automatically collect the test raw signal data; S2: Preprocessing of raw signal data Preprocess the raw signal data of the test, including the division of solid rocket engine working stages and filter value processing; S3: Time domain analysis of experimental data after S2 preprocessing Perform time domain analysis on the test signal data after S2 preprocessing, and obtain the digital characteristics of the test signal data according to different working stages of the engine; S4: Frequency domain analysis of test data after S2 preprocessing Perform Fourier transform spectrum analysis on the test signal data after S2 preprocessing to obtain the frequency and amplitude changes of the test signal data; S5: Time-frequency analysis of experimental data after S2 preprocessing The test data after S2 preprocessing is subjected to short-time Fourier transform and wavelet transform time-frequency analysis. By analyzing the results of short-time Fourier transform and wavelet transform, the time-varying characteristics and spectrum information of the test signal data are obtained.

3. A method for processing underwater test data of a solid rocket engine according to claim 2, characterized in that: The test original signal data includes thrust signal data and pressure signal data.

4. A method for processing underwater test data of a solid rocket engine according to claim 2, characterized in that: The test data measurement and acquisition system comprises an underwater high-speed camera, a thrust sensor, a pressure sensor, a data acquisition instrument and a computer.

5. The method for processing underwater test data of a solid rocket engine according to claim 2, characterized in that: The engine operation phases described in S2 are divided into ascending phase, balancing phase and descending phase according to thrust.

6. A method for processing underwater test data of a solid rocket engine according to claim 2, characterized in that: The filtering process of the thrust signal preprocessing described in S2 utilizes a filter to filter out the influence of the natural frequency of the thrust bench structure test equipment.

7. A method for processing underwater test data of a solid rocket engine according to claim 2, characterized in that: The digital features of the signal in the time domain analysis of the thrust signal described in S3 include mean, variance, and root mean square value.

8. A method for processing underwater test data of a solid rocket engine according to claim 2, characterized in that: The window function in the short-time Fourier transform described in S5 determines the analysis accuracy according to the signal acquisition data length and calculation efficiency, ensuring that the signal within the time window is locally stable.

9. A method for processing underwater test data of a solid rocket engine according to claim 2, characterized in that: The wavelet transform time-frequency analysis described in S5 selects a wavelet basis function according to the time-frequency resolution or computational efficiency requirements, and uses a wavelet spectrum diagram to present the time-frequency analysis results.

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