A method for extracting the rotating speed of a rocket engine turbine pump based on parameter spectrum analysis

Abstract

The application discloses a rocket engine turbine pump rotating speed extraction method based on parameter spectrum analysis, and solves the technical problems of high calculation complexity, long operation time and poor real-time performance of a calculation method for obtaining the phase information of the first-order signal of the vibration signal by carrying out Hilbert demodulation on the first-order signal of the vibration signal, deriving the phase information of the first-order signal of the vibration signal with respect to time, and finally calculating the instantaneous rotating speed of the turbine pump according to the derivation result, and comprises the following steps: collecting a fuel pump acceleration response signal, selecting a sliding window for the collected data to obtain a to-be-processed signal, carrying out band-pass filter processing on the to-be-processed signal, carrying out power spectrum calculation on the processed data in an autoregressive process to obtain a single-sideband power spectrum, and calculating the rotating speed of the turbine pump based on the peak frequency of the single-sideband power spectrum.

Description

Technical Field

[0001] This invention relates to a method for extracting the rotational speed of a rocket engine turbopump, specifically a method for extracting the rotational speed of a rocket engine turbopump based on parameter spectrum analysis. Background Technology

[0002] The combustion process of a rocket engine includes several cycle modes, such as the gas generator cycle, the staged combustion cycle, and the expansion cycle. Each cycle mode requires a turbopump. Therefore, the turbopump is a core component of the rocket engine, and its operating status directly determines the overall performance and reliability of the rocket engine.

[0003] The turbopump rotational speed is a core and critical parameter of a rocket engine. By measuring and analyzing the turbopump rotational speed, the performance parameters of the rocket engine can be obtained.

[0004] In existing technologies, turbopump speed measurement typically employs a "frequency acquisition + frequency-voltage conversion" method. This involves installing a sensor inside the turbopump to acquire frequency signals, utilizing the correlation between the voltage generated by the cutting coil and the speed, and then converting the acquired frequency signal into a voltage signal using a frequency-voltage conversion acquisition card, thereby calculating the turbopump speed. This process requires two conversions: "speed - frequency signal - voltage signal - speed," which is complex and results in low conversion accuracy. Furthermore, sensor installation requires handling the turbopump; however, due to the turbopump's complex structure, improper handling can not only affect test accuracy but also lead to poor turbopump sealing.

[0005] Chinese invention patent CN119267263A discloses a method and related apparatus for determining the rotational speed of a liquid rocket engine turbopump. The method includes: acquiring the vibration signal and rotational speed signal of the turbopump, wherein the rotational speed signal is calculated from the original key phase signal of the turbopump; processing the vibration signal using a Volk-Kalman filter based on the rotational speed signal to obtain a first-order vibration signal; performing Hilbert demodulation on the first-order vibration signal to obtain its phase information; and differentiating the phase information of the first-order vibration signal with respect to time, calculating the instantaneous rotational speed of the turbopump based on the derivative result. This turbopump rotational speed calculation method has high computational complexity, long processing time, and poor real-time performance. Summary of the Invention

[0006] The purpose of this invention is to solve the technical problems of high computational complexity, long operation time, and poor real-time performance in the existing technology, which uses Hilbert demodulation of the first-order vibration signal to obtain the phase information of the first-order vibration signal, then differentiates the phase information of the first-order vibration signal with respect to time, and finally calculates the instantaneous speed of the turbopump based on the differentiation result. This invention provides a method for extracting the speed of a rocket engine turbopump based on parametric spectrum analysis.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for extracting the turbopump rotational speed of a rocket engine based on parametric spectrum analysis is disclosed. The method is used to extract the turbopump rotational speed of a rocket engine, which includes a fuel pump coaxially arranged with the turbopump, and the rotational speed of the fuel pump is the same as that of the turbopump. The method is characterized by the following steps:

[0009] Step 1: Install an acceleration sensor on the housing of the fuel pump, with the measurement direction of the acceleration sensor aligned with the axial direction of the fuel pump. Start the rocket engine under test and collect the axial acceleration of the fuel pump to obtain the acceleration response signal x(i), i = 1, …, N, where N represents the data length. T represents the total sampling time. Sampling rate;

[0010] Step 2: Set a sliding window of length M, and select the acceleration response signal x(i) along the time axis to obtain P sets of datasets to be processed. p = 1, 2, ..., P Where S represents the sliding window step size, , , And A is a positive integer;

[0011] Step 3: Apply bandpass filters to the P groups of datasets to be processed. Calculations were performed to obtain the P groups of narrowband response signals. ;

[0012] Step 4: Response signal of group P narrowband Power spectrum calculations were performed based on the autoregressive process to obtain P groups of narrowband response signals. Their respective single-sideband power spectra ;

[0013] Step 5: Analyze the single-sideband power spectrum of group P. Using the maximum value index, the single-sideband power spectrum of the p-th group is obtained. peak frequency ;

[0014] Step 6: Based on the acquired peak frequency Calculate the p-th set of datasets to be processed. fuel pump speed at the time of data collection The calculation formula is as follows:

[0015] ;

[0016] Obtain the fuel pump speed values ​​at P sampling times. Since the turbine pump speed is the same as the fuel pump speed, the turbine pump speed values ​​at P acquisition times are obtained, thus completing the extraction of the rocket engine turbine pump speed.

[0017] Furthermore, in step 2, the data length M of the sliding window is a power of 2, and the step size of the sliding window is... .

[0018] Furthermore, step 4 specifically involves:

[0019] Step 4.1: Process the P groups of datasets to be processed. Establish a K-order autoregressive model, and calculate the formula as follows:

[0020] ;

[0021] in, These are the autoregressive coefficients, k = 1, 2, ..., K;

[0022] The variance is A white noise sequence with a mean of 0;

[0023] Step 4.2: Perform a Z-transform on the calculation formula obtained in Step 4.1 to obtain the following calculation formula:

[0024] ;

[0025] Step 4.3, Substituting the values ​​into the calculation formula obtained in step 4.2, and converting the Z-domain to the frequency domain, we obtain the single-sideband power spectrum. The calculation formula is as follows:

[0026] ;

[0027] in, Let V be the variance of the white noise.

[0028] Furthermore, the specific calculation process in step 3 is as follows:

[0029] ;

[0030] Where h(i) are the bandpass filter coefficients.

[0031] Furthermore, the specific calculation formula for step 5 is as follows:

[0032] ;

[0033] The beneficial effects of this invention are:

[0034] 1. This invention discloses a method for extracting the rotational speed of a rocket engine turbopump based on parametric spectrum analysis. It utilizes a sliding window to perform acceleration signal spectrum analysis, extracting the peak frequency of the acceleration signal within the sliding window, and acquiring the turbopump rotational speed signal throughout the entire test phase. Due to the influence of the generator and thrust chamber combustion process, as well as the nozzle flow field, the acceleration response signal is a broadband randomly excited structural response signal. This structural response signal contains a large amount of random noise interference, making it difficult to obtain a high-quality response signal spectrum through simple spectrum analysis. Furthermore, the difficulty of subsequent feature extraction for the rotational frequency will increase accordingly. Therefore, a bandpass filter is used to filter and extract the narrowband response signal from the dataset to be processed, removing interference signals. Then, a power spectrum calculation based on an autoregressive process is performed on the narrowband response signal to obtain a single-sideband power spectrum. Finally, calculate the peak frequency. This allows for the extraction of the turbopump rotational speed. Parametric spectral analysis based on the acceleration response signal enables the extraction of rotational frequency based on vibration response, resulting in high accuracy and good real-time performance for turbopump rotational speed extraction.

[0035] 2. This invention provides a method for extracting the turbopump rotational speed of a rocket engine based on parametric spectrum analysis. This method involves setting the data length M of the window to a power of 2 and the step size of the sliding window. This can improve the time resolution of subsequent speed signals.

[0036] 3. This invention provides a method for extracting the turbopump rotational speed of a rocket engine based on parametric spectrum analysis, by analyzing P sets of datasets to be processed. By establishing a K-order autoregressive model and performing Z-variance and Z-domain to frequency domain conversion, a method for calculating turbopump speed is obtained, which can improve the dataset... The frequency resolution during spectral analysis is improved to obtain a more stable rotational speed signal. Attached Figure Description

[0037] Figure 1 This is a time history diagram of the acceleration response signal acquired in step 1 of an embodiment of the method for extracting the speed of a rocket engine turbopump based on parametric spectrum analysis of the present invention.

[0038] Figure 2This is a time history diagram of the p-th group of acceleration signals (after narrowband filtering) in step 3 of an embodiment of the rocket engine turbopump speed extraction method based on parametric spectrum analysis of the present invention.

[0039] Figure 3 This is a schematic diagram of the single-sideband power spectrum of the p-th acceleration signal in step 4 of an embodiment of the rocket engine turbopump speed extraction method based on parametric spectrum analysis of the present invention.

[0040] Figure 4 This is a schematic diagram of the rotational speed value and time extracted by the rotational frequency of the power spectrum of each acceleration signal in an embodiment of the method for extracting the rotational speed of a rocket engine turbopump based on parametric spectrum analysis according to the present invention. The waveform represents the rotational speed signal extracted based on the acceleration signal.

[0041] Figure 5 This is a comparative example of an embodiment of a rocket engine turbopump speed extraction method based on parameter spectrum analysis, showing an engine speed signal measured by a speed sensor. Detailed Implementation

[0042] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] A method for extracting the turbopump rotational speed of a rocket engine based on parametric spectrum analysis is disclosed. The method is used to extract the turbopump rotational speed of a rocket engine, which includes a fuel pump coaxially arranged with the turbopump, and the rotational speed of the fuel pump is the same as that of the turbopump. The method includes the following steps:

[0044] Step 1: Install an acceleration sensor on the housing of the fuel pump, with the measurement direction of the acceleration sensor aligned with the axial direction of the fuel pump. Start the rocket engine under test. Figure 1 As shown, the axial acceleration of the fuel pump is acquired to obtain the acceleration response signal x(i), i = 1, …, N, where N represents the data length. T represents the total sampling time, which is usually based on the test run time. Based on the engine test conditions, the sampling rate in this embodiment is selected as 25600Hz.

[0045] Step 2: Set a sliding window of length M, and select the acceleration response signal x(i) along the time axis to obtain P sets of datasets to be processed. p = 1, 2, ..., P Where S represents the sliding window step size. , , And A is a positive integer; the sliding window step size in this embodiment This means that the overlap is 50% and the sliding window data length M is a power of 2, such as M=512, 1024, etc.

[0046] Step 3, as follows Figure 2 As shown, bandpass filters are used to process P groups of datasets. Calculations were performed to obtain the P groups of narrowband response signals. The calculation process is as follows:

[0047] ;

[0048] Where h(i) are the bandpass filter coefficients.

[0049] Step 4, as follows Figure 4 As shown, the narrowband response signal of group P. Power spectrum calculations were performed based on the autoregressive process to obtain P groups of narrowband response signals. Their respective single-sideband power spectra Specifically:

[0050] Step 4.1: Process the P groups of datasets to be processed. Establish a K-order autoregressive model, and calculate the formula as follows:

[0051] ;

[0052] in, The autoregressive coefficients are k = 1, 2, ..., K;

[0053] The variance is A white noise sequence with a mean of 0;

[0054] Step 4.2: Perform a Z-transform on the calculation formula obtained in Step 4.1. The result is as follows:

[0055] ;

[0056] Squaring and combining the two sides above, the result is as follows:

[0057] ;

[0058] Step 4.3, Substituting the values ​​into the calculation formula obtained in step 4.2, and converting the Z-domain to the frequency domain, we obtain the single-sideband power spectrum. The calculation formula is as follows:

[0059] ;

[0060] in, Let V be the variance of the white noise.

[0061] Step 5: Analyze the single-sideband power spectrum of group P. Using the maximum value index, the single-sideband power spectrum of the p-th group is obtained. peak frequency The calculation formula is as follows:

[0062] ;

[0063] Step 6: Based on the acquired peak frequency Calculate the p-th set of datasets to be processed. fuel pump speed at the time of data collection The calculation formula is as follows:

[0064] ;

[0065] Obtain the fuel pump speed values ​​at P sampling times. Since the turbine pump speed is the same as the fuel pump speed, the turbine pump speed values ​​at P acquisition times are obtained, thus completing the extraction of the rocket engine turbine pump speed.

[0066] like Figure 5 The figure shows the test results of the speed sensor installed on the turbopump. The test results of the original speed sensor are compared and verified with the test results of this embodiment, which proves that the embodiment of the present invention has good adaptability to the engine speed adjustment under different operating conditions, and the engine fuel pump acceleration signal can be used to extract the turbopump speed.

[0067] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present invention should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for extracting the rotational speed of a turbine pump of a rocket engine based on parametric spectral analysis, for extracting the rotational speed of a turbine pump of a rocket engine, the rocket engine comprising a fuel pump coaxially arranged with the turbine pump, and the rotational speed of the fuel pump being the same as the rotational speed of the turbine pump; characterized in that, The method comprises the following steps: Step 1, install an acceleration sensor on the housing of the fuel pump, the measurement direction of the acceleration sensor is the same as the axial direction of the fuel pump, start the rocket engine to be tested, collect the axial acceleration of the fuel pump to obtain an acceleration response signal x(i), i = 1, …, N, wherein N represents the data length, , T represents the total sampling time, is the sampling rate; Step 2, set the sliding window with data length M, and select the acceleration response signal x(i) along the time axis to obtain P groups of data sets to be processed ; p = 1, 2,..., P, , wherein S represents the sliding window step, , , , and A is a positive integer; Step 3, respectively using band-pass filter to P group of data sets to be processed Carrying out calculation, obtaining P group of narrow-band response signals ; Step 4, P set narrowband response signals , respectively, based on the power spectrum calculation of the autoregressive process, P set narrowband response signals Each single sideband power spectrum ; Step 5, obtaining the peak frequency of the p-th group of single sideband power spectrum respectively using the maximum index, corresponding to obtain the peak frequency of the p-th group of single sideband power spectrum ;​ Step 6, calculating the peak frequency based on the acquired peak frequency , calculating the pth set of data to be processed the fuel pump rotation speed value at the acquisition time , the calculation formula is as follows: ； P values of fuel pump rotating speed at P collection instants are obtained Since the turbine pump rotating speed is the same as the fuel pump rotating speed, P values of turbine pump rotating speed at P collection instants are obtained, and the extraction of the turbine pump rotating speed of the rocket engine is completed.

2. The method of claim 1, wherein: In step 2, the data length M of the sliding window is a power of 2, and the step size of the sliding window is .

3. The method of claim 1, wherein, Step 4 is specifically as follows: Step 4.1, processing the data set of group P An autoregressive model of order K is established, and the calculation formula is as follows: ； wherein are autoregressive coefficients, k = 1, 2,..., K; is a white noise sequence with variance and mean 0. Step 4.2, the calculation formula obtained in step 4.1 is subjected to Z transformation to obtain the following calculation formula: ； Step 4.3, Substituting the values ​​into the calculation formula obtained in step 4.2, and converting the Z-domain to the frequency domain, we obtain the single-sideband power spectrum. The calculation formula is as follows: ； wherein is the variance of the white noise.

4. The method of claim 1, wherein, The specific calculation process in step 3 is as follows: ； Wherein, h(i) is a band-pass filter coefficient.

5. The parameter spectrum analysis based turbo pump speed extraction method of claim 1, wherein, The specific calculation formula in step 5 is as follows: 。

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