Method for correcting influence parameters of derived acoustic sensing system in high-temperature environment

Abstract

The invention provides a method for correcting influence parameters of an export type acoustic sensing system in a high-temperature environment, and relates to the technical field of detection sensing. The method comprises the following steps: firstly, acquiring a target original sound signal at a high-temperature jet device through an export type acoustic sensing system, and acquiring a reference sound signal under the same working condition by using a high-precision probe; performing fast Fourier transform on the target original sound signal and the reference sound signal to obtain a corresponding frequency domain signal; a standard signal emitted by a standard acoustic emitter is collected by using the same export type acoustic sensing system on a correction system, a test signal and the standard signal are compared by adopting a direct comparison method to obtain a frequency domain compensation signal, and the frequency domain compensation signal is synthesized with a frequency domain signal of a target original acoustic signal to obtain a correction acoustic signal of a tested target. Compared with a signal obtained by high-precision equipment, the corrected sound signal obtained by the method has the advantages that the precision loss is small, the cost is greatly reduced, and the method has wider temperature and size application scenes and has a good effect when being applied to noise measurement of an aero-engine in a high-temperature environment.

Description

Technical Field

[0001] The present invention relates to the field of detection and sensing technologies, and particularly to a method for correcting influence parameters of an exportable acoustic sensing system in a high-temperature environment. Background Art

[0002] With the continuous development of the civil aviation industry, the impact of aircraft noise on humans has become increasingly prominent. Aircraft noise is characterized by high sound pressure level and wide influence range. On the one hand, it can cause varying degrees of damage to people's hearing and health, interfering with the normal life of residents in communities around airports. On the other hand, in severe cases, it may damage aircraft components, posing a threat to the stability and integrity of the aircraft structure. To accurately measure various parameters of noise, the aviation engine noise test technology urgently needs to be developed.

[0003] Regarding the noise measurement in the internal flow channels of components such as the compressor, combustion chamber, turbine, afterburner, and tail nozzle of an aviation engine under complex environmental conditions such as high temperature, high pressure, and high flow velocity, several technical solutions have been proposed abroad since the 1970s. One is to apply a cooling sheath outside a capacitive microphone or a piezoelectric microphone. Due to factors such as the formation of local cold regions caused by the cooling sheath under high-temperature and high-pressure conditions, which in turn leads to large thermal gradients, the size and configuration of the sensor device can cause distortion of sound, and it cannot be installed under certain on-site conditions, thus limiting its use. The second is a fiber-optic type sensor, which has good frequency response characteristics below 550 °C. However, beyond this temperature, vibration and thermal gradients will significantly degrade the performance of the optical fiber, limiting the use of this sensor. The third is a sound wave duct system, which has the characteristics of adapting to higher temperatures and a wide dynamic range, and has been applied to a certain extent in tasks such as the NASA high-temperature traveling wave tube tester and the noise test of gas turbine engines in the United States.

[0004] The advantages of the noise measurement technology based on sound wave ducts are mainly reflected in the following aspects: First, the temperature range of the working environment, the measured sound pressure and frequency range, and the single high-temperature working time that can be adapted; second, the feasibility, technical maturity, reliability, and cost of the established test sensor system.

[0005] It should be noted that compared with traditional technologies, although the sound wave duct technology has the advantage of adapting to higher temperatures, it also has problems such as signal attenuation and the inability to correctly reflect time-domain and frequency-domain signals. This is because when transmitting sound through a pipeline, the wave duct limits the signal frequency band bandwidth and may introduce resonance peaks in an unpredictable manner, and the pressure time-domain waveform may not be fully transmitted through the sound wave duct; in addition, since the sound wave duct system requires the use of a cooling water jacket, its cooling section must be long enough, resulting in signal attenuation. Therefore, for the high-temperature noise test technology and test system based on sound wave ducts, detailed static and dynamic characteristic calibrations are required during the research and development and use processes, and on this basis, frequency-domain compensation and correction technologies need to be studied. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for correcting influence parameters of an exportable acoustic sensing system in a high-temperature environment in view of the deficiencies of the above-mentioned prior art. The method uses a correction system to calibrate the signals of the exportable acoustic sensing system, measures its frequency-domain attenuation, and then compensates the frequency-domain attenuation to the frequency-domain signal of the measured signal, so that the signal can completely reflect the time-domain characteristics of the acoustic signal of the object to be measured.

[0007] To solve the above technical problem, the technical solution adopted by the present invention is:

[0008] A method for correcting influence parameters of an exportable acoustic sensing system in a high-temperature environment, which is used to correct the frequency-domain signal of the acoustic signal measured by the exportable acoustic sensing system. This method is assisted by a high-temperature jet correction system including a signal generator, a signal amplifier, a standard sound generator, a pipeline structure, and a temperature control module; the signal generator generates electrical signals corresponding to sine waves at each frequency according to the set frequency and frequency interval; the signal generator and the signal amplifier are connected by a data line, and the signal amplifier amplifies the electrical signals generated by the signal generator and provides them to the standard sound generator; the signal amplifier and the standard sound generator are connected by a data line, and the standard sound generator converts the electrical signals into corresponding sine wave acoustic signals and then sends them into the pipeline structure; the temperature control module heats the pipeline structure to keep a certain temperature in the pipeline structure;

[0009] The correction method specifically includes the following steps:

[0010] Step 1: Collect the target original acoustic signal at the high-temperature jet device through the exportable acoustic sensing system, and at the same time collect the reference acoustic signal under the same working conditions with a high-precision probe device;

[0011] Step 2: Perform a fast Fourier transform on the collected target original acoustic signal and reference acoustic signal to obtain the frequency-domain signals of the target original acoustic signal and reference acoustic signal;

[0012] Step 3: Use the same set of exportable acoustic sensing systems on the high-temperature jet correction system to collect the standard signals emitted by the standard sound emitter to obtain test signals; adopt the direct comparison method to compare the measured test signals with the standard signals emitted by the standard sound generator, that is, obtain the frequency-domain compensation signal of this set of exportable acoustic sensing systems;

[0013] Step 4: Synthesize the frequency-domain signal of the target original acoustic signal collected by the exportable acoustic sensing system with the obtained frequency-domain compensation signal to obtain the corrected acoustic signal of the target to be measured.

[0014] Further, the specific method of step 2 is:

[0015] Step 2.1: Input two discrete time-domain signals, namely the target original acoustic signal and the reference acoustic signal measured in Step 1, and the input sequence length is n;

[0016] Step 2.2: Based on the Cooley-Tukey algorithm, divide the input sequence into two groups according to the parity of the time index, and recursively decompose it into smaller subsequences until the time-domain signal is decomposed into several sequences of length 2;

[0017] After the n-point time-domain signal is decomposed into sequences of length 2, directly calculate the frequency-domain signal; when the time-domain signal is extended to N points and decomposed into sequences of length 2, it is transformed into the following formula:

[0018]

[0019]

[0020] In the formula, x(n) is the time-domain signal, and X(r) is the frequency-domain signal; is the rotation factor;

[0021] Arrange the calculation results in bit-reversed order, that is, convert its position serial number into binary, reverse it, and reorder it after reversal. After arrangement, the frequency-domain signal is obtained.

[0022] The beneficial effects of adopting the above technical solutions are as follows: The method for correcting the influence parameters of the derived acoustic sensing system under high-temperature environment provided by the present invention can be effectively applied to the noise measurement occasions under high-temperature environment; it effectively reduces the cost required for noise measurement experiments, can conduct more repeated experiments, obtain more analyzable data, and improve the experimental efficiency. Description of the Drawings

[0023] Figure 1 It is the overall architecture diagram of the method for correcting the influence parameters of the derived acoustic sensing system under high-temperature environment provided by the embodiment of the present invention;

[0024] Figure 2 It is the frequency-domain narrowband spectrogram of the reference signal provided by the embodiment of the present invention;

[0025] Figure 3 It is the frequency-domain narrowband spectrogram of the corrected signal provided by the embodiment of the present invention. Detailed Embodiments

[0026] The following combines the drawings and embodiments to further describe in detail the specific embodiments of the present invention. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0027] This embodiment proposes a method for correcting the influencing parameters of a derived acoustic sensing system in a high-temperature environment to perform frequency-domain signal correction on the acoustic signals measured by the derived acoustic sensing system.

[0028] This embodiment mainly includes a correction system and a correction method. The high-temperature jet device, the derived acoustic sensing system, and the high-precision probe are all preconditions or auxiliary equipment in the process, and they are all existing technologies. The description of them is to illustrate the overall method process.

[0029] As Figure 1 shown, the method of this embodiment is as follows.

[0030] The high-temperature jet device includes a gas source, a pressure control system, an electric air loudspeaker, a pipeline structure main body, a control microphone, a closed-loop sound control software, a heating device, and a thermocouple. The gas source supplies pressurized air to the electric air loudspeaker. The electric air loudspeaker generates a specified sound field inside the pipeline structure main body, and the internal sound intensity is monitored by the control microphone and fed back to the closed-loop sound control software to achieve closed-loop sound control. The heating device heats the measurement area, and the temperature is monitored by the thermocouple and fed back to the heating device to achieve closed-loop temperature control.

[0031] The derived acoustic sensing system includes an air intake pipe, a sound wave duct, a sensing system, and a signal measurement system. The air intake pipe leads the sound wave pulsation in the high-temperature jet device into the sound wave duct, and transmits it to the sensing system through the sound wave duct. The sensing system converts the sound signal into an electrical signal through the diaphragm of the built-in microphone and transmits it to the signal measurement system. The cooling device ensures that the temperature of the hot air entering the pipeline is reduced so as not to exceed the limit temperature of the microphone, thereby damaging the microphone.

[0032] The correction system includes a signal generator, a signal amplifier, a standard sound generator, a pipeline structure, and a temperature control module. The signal generator generates electrical signals corresponding to sine waves at each frequency according to the set frequency and frequency interval; the signal generator and the signal amplifier are connected by a data line. The signal amplifier amplifies the electrical signals generated by the signal generator and supplies them to the standard sound generator; the signal amplifier and the standard sound generator are connected by a data line. The standard sound generator converts the electrical signals into corresponding sine wave sound signals and emits them into the pipeline structure. The temperature control module heats the pipeline structure to maintain a certain temperature in the pipeline structure.

[0033] The method for correcting the influencing parameters of the derived acoustic sensing system in a high-temperature environment includes the following steps:

[0034] Step 1: Collect the target original acoustic signal at the high-temperature jet device through the derived acoustic sensing system, and simultaneously collect the reference acoustic signal under the same working conditions with a high-precision probe device.

[0035] Step 2: Perform a fast Fourier transform on the acquired target original acoustic signal and the reference acoustic signal to obtain the frequency-domain signals of the target original acoustic signal and the reference acoustic signal.

[0036] Step 2.1: Input the discrete time-domain signal measured in Step 1.

[0037] Step 2.2: Based on the Cooley-Tukey algorithm, divide the input sequence into two groups according to the parity of the time index, and recursively decompose it into smaller subsequences until it is decomposed into sequences of length 2.

[0038] Taking 4 points as an example, decompose the time-domain signal into 2 sequences of length 2:

[0039]

[0040] After decomposing 4 points into sequences of length 2, the frequency-domain signal can be directly calculated as follows:

[0041] X(1) = x(1) + x(2) + x(3) + x(4);

[0042]

[0043] Extended to the decomposition of N points into sequences of length 2, it is transformed into the following formula:

[0044]

[0045]

[0046] In the formula, x(n) is the time-domain signal and X(r) is the frequency-domain signal; is the rotation factor.

[0047] Step 2.4: Arrange the calculation results in bit-reversal order, that is, convert their position numbers into binary, reverse them, and reorder them after reversal, as follows:

[0048]

[0049] After arrangement, the frequency-domain signal is obtained. Since the calculated frequency-domain signal has conjugate symmetry, only the first half of the effective values needs to be taken.

[0050] The frequency-domain narrowband spectrum of the reference signal is as Figure 2 shown.

[0051] Step 3: Use the same set of derived acoustic sensing systems on the high-temperature jet correction system to collect the standard signals emitted by the standard acoustic transmitters to obtain test signals; adopt the direct comparison method to compare the measured test signals with the standard signals emitted by the standard acoustic generators, and then the frequency-domain compensation signals of this set of derived acoustic sensing systems can be obtained.

[0052] The same set of derived sensing systems mentioned above means that their air intake pipes and acoustic waveguide lengths are the same, and the microphone is the same as that in Step 1. The heating module on the pipeline structure can ensure that the inside of the pipeline of the correction system is in the same temperature environment as the high-temperature jet device, control the variables, and ensure the correct progress of the experiment.

[0053] Step 4: Synthesize the frequency-domain signals of the target original acoustic signals collected by the derived acoustic sensing system and the obtained frequency-domain compensation signals, and then the corrected acoustic signals of the measured target can be obtained.

[0054] For the original acoustic signals measured in Step 1, after the transformation in Step 2 and then through Step 4, the corrected signal frequency-domain narrowband spectrum is as Figure 3 shown, Figure 2 Compared with Figure 3 it can be seen that the corrected signals and the reference signals have little difference in the frequency domain, and the correction effect is good.

[0055] The upper limit of the measurement temperature range of the high-precision probe is 550 °C. However, due to the protection of the circulating water cooling device, the derived acoustic sensing system described in this embodiment can work normally at 1200 °C in a certain formal test, and can be used for noise measurement in high-temperature environments. But without the method of this embodiment, the accuracy cannot be guaranteed. After the method of this embodiment is proposed, it can be effectively applied to the occasion of noise measurement in high-temperature environments.

[0056] In addition, for aero-engines, there may be no small holes suitable for the size of the probe microphone. If the measurement is carried out near a large hole, the measurement results of the probe will be affected by the pore energy leakage. The derived acoustic sensing system of this embodiment can be flexibly designed, adapted by using the existing air film holes on the aero-engine, and the method described in this embodiment can be used to test the aero-engine noise.

[0057] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope defined by the claims of the present invention.

Claims

1. A method for correcting influencing parameters of a derived acoustic sensing system in a high temperature environment, characterized in that: Used to perform frequency domain signal correction on the acoustic signal measured by the derived acoustic sensor system, the method is assisted by a high-temperature jet correction system including a signal generator, a signal amplifier, a standard sound generator, a pipeline structure, and a temperature control module; the signal generator generates an electrical signal corresponding to a sine wave at each frequency according to a set frequency and frequency interval; the signal generator and the signal amplifier are connected by a data line, the signal amplifier amplifies the electrical signal generated by the signal generator, and provides it to the standard sound generator; the signal amplifier and the standard sound generator are connected by a data line, the standard sound generator converts the electrical signal into a corresponding sine wave sound signal, and then sends it to the pipeline structure; the temperature control module heats the pipeline structure to maintain a certain temperature in the pipeline structure; The correction method specifically includes the following steps: Step 1: The target original acoustic signal is collected at the high-temperature jet device by using a derived acoustic sensing system, and the reference acoustic signal under the same working condition is collected by using a high-precision probe device at the same time; Step 2: Performing a fast Fourier transform on the collected target original sound signal and the reference sound signal to obtain frequency domain signals of the target original sound signal and the reference sound signal; Step 3: Using the same set of derived acoustic sensing system on the high-temperature jet correction system to collect the standard signal emitted by the standard sound emitter to obtain a test signal; using a direct comparison method, the measured test signal and the standard signal emitted by the standard sound generator are compared to obtain a frequency domain compensation signal of the derived acoustic sensing system; Step 4: Synthesize the frequency domain signal of the target original sound signal collected by the derived acoustic sensing system with the obtained frequency domain compensation signal to obtain a corrected sound signal of the measured target.

2. According to the method for correcting influencing parameters of a derived acoustic sensor system in a high temperature environment in claim 1, it is characterized in that: The specific method of step 2 is: Step 2.1: Input two discrete time domain signals, the target original sound signal and the reference sound signal measured in step 1, and the input sequence length is n; Step 2.2: Based on the Cooley-Tukey algorithm, the input sequence is divided into two groups according to the parity of the time index, and recursively decomposed into smaller subsequences until the time domain signal is decomposed into several sequences of length 2; Step 2.3: After the n-point time domain signal is decomposed into a sequence of length 2, the frequency domain signal is directly calculated; the time domain signal is expanded to N points and decomposed into a sequence of length 2, which is transformed into the following formula: Where x(n) is the time domain signal and X(r) is the frequency domain signal; is the rotation factor; Step 2.4: Arrange the calculation results bit by bit, that is, convert the position sequence into binary, reverse it, and re-arrange it after reversal to obtain the frequency domain signal.

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