Engine ground thermal test pulsating thrust measurement system and method

Abstract

This invention provides a system and method for measuring the pulsating thrust of an engine during ground hot-fire testing. It solves the problem of insufficient accuracy in measuring pulsating thrust when the test stand is installed at a 45° angle on the test bench, due to the coupling interference of the axial and radial components of the thrust. By using a force component decomposition algorithm and a dedicated sensor layout, the lateral force interference caused by the 45° installation is eliminated, achieving precise separation of the axial component of the pulsating thrust with a measurement error ≤ ±0.5%. Simultaneously, it employs a Pacific6000 modular acquisition device, internally equipped with an n-channel synchronous data acquisition board (n≥8) and parameter design. Combined with an external double-layer electromagnetic shielding shell and an internal signal conditioning unit connected to an LC passive filter topology circuit, it can achieve distortion-free acquisition of 10-1000Hz pulsating signals, improving the sampling rate and signal bandwidth matching degree by 30%.

Description

Technical Field

[0001] This invention relates to a measurement system and method for engine ground hot test parameters, specifically to a measurement system and method for engine ground hot test pulsating thrust. Background Technology

[0002] With the rapid development of aerospace propulsion technology, higher requirements are placed on the accuracy and reliability of thrust measurement during hot-fire testing of high-thrust liquid rocket engines. In particular, high-precision dynamic measurement of pulsating thrust has become a key technical aspect for evaluating engine operational stability, combustion characteristics, and structural safety. Existing thrust measurement systems and methods have the following drawbacks:

[0003] (1) 45° test bench force decomposition error: Existing thrust measurement systems and methods are mostly adapted to horizontal / vertical test benches. When the test frame used for engine ground hot test is installed on the test bench at a 45° angle, the axial and radial components of the test frame thrust interfere with each other, and the lateral force introduces measurement deviation, resulting in distorted pulsating thrust signal. Especially under the 1000kN level high thrust condition, the structural deformation intensifies the coupling interference between axial thrust and radial thrust, making it impossible for the existing sensor layout to achieve accurate component separation.

[0004] (2) Disconnect between dynamic response and static verification: The conventional three-pass six-level verification only covers the static load range and does not consider the dynamic characteristics of high-frequency pulsation (10-1000Hz) during hot test. The verification results deviate from the actual working conditions, resulting in insufficient accuracy of pulsation signal amplitude and phase measurement.

[0005] (3) Insufficient adaptability of the acquisition system: Although the Pacific6000 acquisition device has the advantage of modularity, the board configuration in the current application is not optimized for pulsating signals. The signal conditioning module has weak resistance to electromagnetic interference and high temperature gas interference. There is a time delay error when multiple channels are acquired synchronously.

[0006] (4) Difficulty in extracting pulsating signals: Existing thrust measurement methods do not distinguish between the signal characteristics of steady-state thrust and pulsating thrust. Due to the superposition of interference signals such as high-temperature gas impact and test bench vibration with pulsating signals, it is difficult to extract effective signals and the measurement signal-to-noise ratio is low.

[0007] (5) The calibration process is incomplete: the static three-pass six-level calibration is not combined with dynamic load calibration, which cannot compensate for dynamic errors such as sensor dynamic response lag and signal conditioning module phase offset, and the reliability of the calibration results is limited. Summary of the Invention

[0008] The purpose of this invention is to solve the problem of insufficient accuracy in measuring pulsating thrust when the test frame is installed on the test bench at a 45° angle during engine ground hot testing, due to the coupling interference of the axial and radial components of the test frame thrust. Therefore, this invention provides an engine ground hot testing pulsating thrust measurement system and method.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] An engine ground hot test pulsating thrust measurement system is used to measure the dynamic frame pulsating thrust of the test frame mounted on a 45° inclined test stand. Its special feature is that it includes a dual-axis thrust sensor, a signal conditioning unit, a data acquisition unit, and a data processing unit.

[0011] The axial test end of the dual-axis thrust sensor is located on the inclined surface, and the radial test end is perpendicular to the inclined surface and faces upward. The housing of the dual-axis thrust sensor is connected to the fixed frame of the test frame. The axial test end and the radial test end are respectively used to connect to the axial end and the radial end of the moving frame of the test frame. The dual-axis thrust sensor is used to collect the raw signal of the pulsating thrust of the moving frame.

[0012] The input terminal of the signal conditioning unit is connected to the signal output terminal of the dual-axis thrust sensor, and is used to optimize the original signal and convert it into a pulsating signal that is adapted to the input requirements of the data acquisition unit.

[0013] The input end of the data acquisition unit is connected to the output end of the signal conditioning unit. The data acquisition unit is used for multi-channel synchronous acquisition of pulse signals and is deeply optimized according to the high-frequency characteristics of the pulse signals and the multi-channel synchronization requirements to achieve high-speed and synchronous transmission of pulse signals.

[0014] The input terminal of the data processing unit is connected to the output terminal of the data acquisition unit. The data processing unit is used to perform steady-state thrust stripping, interference signal filtering, and pulsation parameter extraction on the received pulsating signal.

[0015] Furthermore, the range of both the axial and radial test ends of the dual-axis thrust sensor is set to 0-1200kN, with a 20% redundancy reserved for the maximum range.

[0016] The sensitive surface of the dual-axis thrust sensor uses a force-transmitting steel ball to achieve point contact force transmission, and the material of the force-transmitting steel ball is a high-strength alloy material with a hardness ≥ HRC60.

[0017] The dual-axis thrust sensor contains a high-temperature heat-insulating coating, which is applied to the surface of the core components of the dual-axis thrust sensor using a plasma spraying process. The high-temperature heat-insulating coating is made of zirconium oxide-alumina composite ceramic material with a thickness of 0.8mm-1.2mm and a temperature resistance limit of ≥800℃.

[0018] The housing of the dual-axis thrust sensor is a sealed structure with a protection rating of IP67.

[0019] The signal output terminal of the dual-axis thrust sensor outputs a standard current signal of 4mA-20mA, with a signal linearity error ≤ ±0.1% and zero drift ≤ 0.05%FS / ℃.

[0020] Furthermore, the signal conditioning unit includes a double-layer electromagnetic shielding shell and an LC passive filter topology circuit, a gain adaptive adjustment circuit, an opto-isolation circuit, and a temperature compensation circuit with a built-in compensation algorithm disposed within the double-layer electromagnetic shielding shell. The input terminal of the LC passive filter topology circuit is connected to the signal output terminal of the dual-axis thrust sensor, and the output terminal of the LC passive filter topology circuit is sequentially connected to the input terminal of the gain adaptive adjustment circuit, the opto-isolation circuit, the temperature compensation circuit, and the data acquisition unit. The LC passive filter topology circuit, the gain adaptive adjustment circuit, the opto-isolation circuit, and the temperature compensation circuit are respectively used to filter, amplify, electrically isolate interference, and correct temperature drift error of the gain adaptive adjustment circuit for the original signal.

[0021] The inner layer of the double-layer electromagnetic shielding shell is made of copper shielding mesh, and the outer layer is made of aluminum alloy shielding shell.

[0022] The shielding effectiveness of the double-layer electromagnetic shielding shell is ≥80dB.

[0023] Furthermore, the cutoff frequency of the LC passive filter topology is set to 50kHz;

[0024] The gain adaptive adjustment circuit is a gain adaptive adjustment circuit based on microcontroller control;

[0025] The isolation voltage of the opto-isolation circuit is ≥2500V;

[0026] The temperature compensation circuit includes an integrated PT100 temperature sensor.

[0027] Furthermore, the data acquisition unit adopts a Pacific6000 modular acquisition device with a built-in 1TB high-speed solid-state drive;

[0028] The Pacific6000 modular acquisition device is equipped with an acquisition board for n-channel synchronous data, where n≥8. The acquisition board uses a 16-bit AD converter with a resolution of 0.38μV / LSB.

[0029] The sampling rate of each channel of the acquisition board is 2MHz, and the synchronization accuracy of the n channels is ≤1μs;

[0030] The signal conditioning unit includes n signal conditioning channels, each of which is connected to a channel of a data acquisition board.

[0031] Furthermore, the data processing unit includes a pulsation signal separation algorithm module, a force component compensation algorithm module, a pulsation parameter calculation module, and a data anomaly detection and correction module connected in sequence.

[0032] Furthermore, it also includes a static calibration unit and a dynamic correction unit;

[0033] The static calibration unit includes a standard force source and a static calibration processor. The standard force source is used to apply loads to the axial and radial test ends of the biaxial thrust sensor. The static calibration processor is used to acquire the output signal from the signal output end of the biaxial thrust sensor, calculate the static error correction coefficient based on the applied load and the output signal, and write the correction coefficient into the Pacific6000 modular acquisition device.

[0034] The dynamic calibration unit includes an electromagnetic vibrator, a standard force sensor, and a dynamic calibration processor. The electromagnetic vibrator is connected to the axial and radial test ends of the biaxial thrust sensor, respectively, or to the standard force sensor to apply pulsating loads. The dynamic calibration processor is used to record the dynamic response signal output from the signal output end of the biaxial thrust sensor, as well as to acquire the actual response signal of the standard force sensor. By comparing the dynamic response signal with the actual response signal, a dynamic response model is established, the dynamic response coefficient is calculated, and the data is written into the Pacific6000 modular acquisition device.

[0035] Meanwhile, the present invention also provides a method for measuring the pulsating thrust of an engine during ground hot-fire testing. Its unique feature is that, based on the aforementioned engine ground hot-fire testing pulsating thrust measurement system, it includes the following steps:

[0036] Step 1: Set the axial test end of the dual-axis thrust sensor on the inclined surface of the 45° inclined test bench, and the radial test end is perpendicular to the inclined surface and facing upwards. The housing of the dual-axis thrust sensor is connected to the fixed frame of the test frame, and the axial test end and the radial test end are connected to the axial end and the radial end of the moving frame of the test frame, respectively.

[0037] Step 2: The raw signal of the moving frame pulsating thrust is collected using a dual-axis thrust sensor. The signal conditioning unit optimizes the raw signal and converts it into a pulsating signal that matches the input requirements of the data acquisition unit.

[0038] Step 3: The pulse signal is acquired synchronously through multiple channels using the data acquisition unit, and then transmitted at high speed and synchronously.

[0039] Step 4: The data processing unit is used to perform steady-state thrust stripping, interference signal filtering and pulsation parameter extraction on the pulsating signal to obtain the pulsating thrust.

[0040] Furthermore, in step 1, after the dual-axis thrust sensor is installed, the following steps are also included: using a static calibration unit and a dynamic correction unit to perform static calibration and dynamic calibration on the dual-axis thrust sensor respectively, and writing the static error correction coefficient and dynamic response coefficient obtained from the calibration into the Pacific6000 modular acquisition device;

[0041] Step 3 specifically involves: using the Pacific6000 modular acquisition device to perform multi-channel synchronous acquisition of the pulsating signal and high-speed, synchronous transmission.

[0042] Furthermore, step 4 specifically involves:

[0043] Step 4.1: Use the pulsation signal separation algorithm module to separate the pulsation signal;

[0044] Step 4.1.1: Decompose the pulsating signal into 10 layers of wavelet coefficients, including low-frequency coefficients and high-frequency coefficients. The low-frequency coefficients correspond to the steady-state thrust component at the level of 1000kN, and the high-frequency coefficients correspond to the pulsating thrust component and the interference signal.

[0045] Step 4.1.2: Denoise the high-frequency coefficients by setting a threshold;

[0046] Step 4.1.3: Perform inverse transformation on the low-frequency coefficients and the denoised high-frequency coefficients to separate the steady-state thrust from the interference signal and obtain the time-domain waveform of the pulsating thrust.

[0047] Step 4.2: Compensate the time-domain waveform of the pulsating thrust using the force component compensation algorithm module;

[0048] Step 4.2.1: Obtain the axial force signal F1 and radial force signal F2 based on the time-domain waveform of the pulsating thrust;

[0049] Step 4.2.2: Establish a mathematical model of force components based on a 45° inclined test stand, and calculate the pure pulsating thrust; the expression of the mathematical model of force components is:

[0050] F = F1 × cos45° - F2 × sin45°;

[0051] Where F represents pure pulsating thrust;

[0052] Step 4.2.3: Obtain the time-domain waveform of the pure pulsating thrust based on the pure pulsating thrust;

[0053] Step 4.3: Extract characteristic parameters from the time-domain waveform of the pure pulsating thrust using the pulsating parameter calculation module to obtain the amplitude parameter composed of peak value, valley value, effective value, peak factor, and waveform factor, as well as the frequency parameter composed of fundamental frequency, harmonic frequency, and frequency spectral density.

[0054] Step 4.4: The data anomaly detection and correction module compares whether the jump between the current amplitude parameter and the amplitude parameter of the previous second exceeds 5% of the amplitude parameter of the previous second. If so, the interpolation algorithm is used to correct the abnormal amplitude parameter, and the corrected amplitude parameter and frequency parameter are output; if not, the current amplitude parameter and frequency parameter are output.

[0055] The beneficial effects of this invention are:

[0056] 1. This invention provides a system and method for measuring the pulsating thrust during engine ground hot-fire testing. By using a force component decomposition algorithm and a dedicated sensor layout, the lateral force interference caused by 45° installation is eliminated, achieving accurate separation of the axial component of the pulsating thrust with a measurement error ≤ ±0.5%.

[0057] 2. This invention provides an engine ground hot test pulsating thrust measurement system and method, which adopts the Pacific6000 modular acquisition device, internally equipped with an n-channel synchronous data acquisition board, n≥8 and parameter design, combined with an external double-layer electromagnetic shielding shell and an internal signal conditioning unit connected to an LC passive filter topology circuit, which can achieve distortion-free acquisition of 10-1000Hz pulsating signals, and the matching degree of sampling rate and signal bandwidth can be improved by 30%.

[0058] 3. This invention provides an engine ground hot test pulsating thrust measurement system and method. Based on the existing three-pass six-level static calibration, a dynamic load calibration link is added to construct a two-level system of "static accuracy assurance + dynamic response calibration". The calibration coverage is extended from static to the dynamic range of the entire operating condition.

[0059] 4. This invention provides a pulse thrust measurement system and method for engine ground hot test, which integrates a pulse signal separation algorithm module, a force component compensation algorithm module, a pulse parameter calculation module, and a data anomaly detection and correction module. It simultaneously completes steady-state thrust stripping, interference signal filtering, and pulse parameter extraction, with a data processing delay of ≤10ms, meeting the real-time monitoring requirements of the test. Attached Figure Description

[0060] Figure 1 This is a schematic diagram of an embodiment of an engine ground hot test pulsating thrust measurement system according to the present invention.

[0061] The attached figures are labeled as follows:

[0062] In the figure, 1-dual-axis thrust sensor; 2-signal conditioning unit; 3-data acquisition unit; 4-data processing unit; 401-pulsation signal separation algorithm module; 402-force component compensation algorithm module; 403-pulsation parameter calculation module; 404-data anomaly detection and correction module; 5-moving frame of the test stand. Detailed Implementation

[0063] 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.

[0064] This invention provides an engine ground hot test pulsating thrust measurement system for measuring the pulsating thrust of a test frame mounted on a 45° inclined test stand. Figure 1 As shown, it includes a dual-axis thrust sensor 1, a signal conditioning unit 2, a data acquisition unit 3, a data processing unit 4, a static calibration unit, and a dynamic correction unit arranged in sequence.

[0065] As the signal source of the measurement system, the performance of the sensor directly determines the measurement accuracy. In this embodiment, a dual-axis thrust sensor 1 is used. The axial test end of the dual-axis thrust sensor 1 is located on the inclined surface, and the radial test end is perpendicular to the inclined surface and faces upwards. The housing of the dual-axis thrust sensor 1 is connected to the fixed frame of the test stand. The axial and radial test ends are used to connect to the axial and radial ends of the moving frame 5 of the test stand, respectively. The dual-axis thrust sensor 1 is used to collect the raw signal of the pulsating thrust of the moving frame 5 of the test stand. The following design is implemented for the 45° inclined installation condition of the test stand for a 1000kN-class high-thrust engine:

[0066] Range adaptation: The axial and radial ranges of the dual-axis thrust sensor 1 are both set to 0-1200kN, with a 20% redundancy reserved for the maximum range. This not only fully covers the total load range after the superposition of the engine's steady-state thrust (1000kN) and pulsating thrust (0-200kN), but also avoids damage to the dual-axis thrust sensor 1 due to overload, ensuring the safety of the equipment during the test.

[0067] Optimized Installation Structure: The dual-axis thrust sensor 1 is precisely positioned along the axial and radial directions of the 45° inclined test bench, with point-contact force transmission achieved using force-transmitting steel balls on the sensitive surface. This design effectively eliminates unavoidable minor gaps during the installation of the dual-axis thrust sensor 1, structurally blocking the transmission path of lateral forces and completely resolving the core issue of mutual interference between axial and radial force components when the test bench is installed at a 45° angle. Simultaneously, the transmission steel balls are made of high-strength alloy material with a hardness ≥ HRC60, ensuring no deformation or wear under heavy loads and guaranteeing the stability and accuracy of force transmission.

[0068] Environmental Adaptability Design: The dual-axis thrust sensor 1 features a built-in high-temperature thermal insulation coating made of zirconia-alumina composite ceramic material, prepared using a plasma spraying process. The coating thickness is controlled between 0.8 mm and 1.2 mm, with a temperature resistance limit of ≥800℃. This effectively blocks the thermal radiation and heat conduction effects of high-temperature exhaust gases (600-750℃) during engine hot runs on the core components of the dual-axis thrust sensor 1. Furthermore, the dual-axis thrust sensor 1's housing employs a sealed structure with an IP67 protection rating, resisting the corrosion of dust, water vapor, and other impurities in the exhaust gas, thus extending the service life of the dual-axis thrust sensor 1.

[0069] Signal output characteristics: The dual-axis thrust sensor 1 outputs a standard current signal of 4mA-20mA, with a signal linearity error of ≤±0.1% and zero drift of ≤0.05%FS / ℃, ensuring the stability and reliability of the output signal under wide temperature range and large load fluctuations.

[0070] The signal conditioning unit 2 includes a double-layer electromagnetic shielding shell and an LC passive filter topology circuit, a gain adaptive adjustment circuit, an opto-isolation circuit, and a temperature compensation circuit with a built-in compensation algorithm, all housed within the double-layer electromagnetic shielding shell. The input terminal of the LC passive filter topology circuit is connected to the signal output terminal of the dual-axis thrust sensor 1, and the output terminal of the LC passive filter topology circuit is sequentially connected to the input terminal of the gain adaptive adjustment circuit, the opto-isolation circuit, the temperature compensation circuit, and the data acquisition unit 3. The LC passive filter topology circuit, the gain adaptive adjustment circuit, the opto-isolation circuit, and the temperature compensation circuit are used to filter, amplify, electrically isolate interference, and correct temperature drift error of the original signal, respectively. The inner layer of the double-layer electromagnetic shielding shell uses a copper shielding mesh, and the outer layer is an aluminum alloy shielding shell. The shielding effectiveness of the double-layer electromagnetic shielding shell is ≥80dB, which can effectively suppress electromagnetic interference generated by gas ionization during engine ignition, electromagnetic coupling interference during cable transmission, and radiation interference from other electrical equipment at the test site.

[0071] The cutoff frequency of the LC passive filter topology circuit is set to 50kHz; it can filter out high-frequency noise signals above 1000Hz without attenuating the target pulsating signal (10Hz-1000Hz), thus achieving precise blocking of interference signals.

[0072] The gain adaptive adjustment circuit is a microcontroller-based gain adaptive adjustment circuit. The microcontroller is an STM32F103, which dynamically adjusts the amplification factor (adjustment range 1-100 times) by real-time acquisition of the amplitude of the output signal of the dual-axis thrust sensor 1. When the amplitude of the pulsating signal is small (≤2kN), it automatically switches to the high gain level (50-100 times) to ensure that the signal amplitude meets the resolution requirements of the acquisition device. When the signal amplitude is large (≥100kN), it switches to the low gain level (1-10 times) to avoid signal saturation distortion. In the intermediate amplitude range, the algorithm automatically matches the optimal gain to achieve high-fidelity amplification of the signal across the entire range.

[0073] The isolation voltage of the opto-isolation circuit is ≥2500V; it can effectively block the potential difference interference between the dual-axis thrust sensor 1 and the data acquisition unit, and protect the back-end data acquisition unit from high voltage impact.

[0074] The temperature compensation circuit includes an integrated PT100 temperature sensor. It monitors the operating temperature of the signal conditioning unit 2 in real time (measurement range -20℃ to 85℃) and corrects the temperature drift error of the gain adaptive adjustment circuit in real time through a built-in compensation algorithm. This ensures that the accuracy of the optimized signal is not affected under fluctuating temperature conditions at the test site, with an additional temperature error ≤ ±0.05%FS.

[0075] Data acquisition unit 3 uses a Pacific6000 modular acquisition device, with its input end connected to the output end of signal conditioning unit 2. It is used for multi-channel synchronous acquisition of pulsating signals and is deeply optimized according to the high-frequency characteristics of pulsating signals and the requirements of multi-channel synchronization.

[0076] Selection and configuration of the acquisition board: An 8-channel synchronous data acquisition board (model: PCI-6039B) is used. This acquisition board uses a 16-bit AD converter with a resolution of up to 0.38μV / LSB, which can accurately capture weak pulsating signals.

[0077] Sampling parameter optimization: Each channel of the acquisition board has a sampling rate of 2MHz. According to the Nyquist sampling theorem, this sampling rate can achieve at least 2000 times oversampling for pulsating signals up to 1000Hz, not only completely restoring the time-domain waveform of the signal but also effectively improving the signal-to-noise ratio. Simultaneously, the sampling triggering method uses hardware triggering, and the trigger threshold can be flexibly set according to experimental requirements (0-50kN), ensuring accurate data acquisition initiation at the moment of engine ignition.

[0078] Synchronization Performance Guarantee: The built-in GPS time synchronization function of the Pacific6000 modular acquisition device ensures 8-channel synchronization accuracy ≤1μs, guaranteeing complete synchronization of all 8 channels on the time axis and completely resolving the time delay issue in acquiring raw axial and radial force signals under 45° operating conditions. Furthermore, the device supports multi-device cascading synchronization. When the experiment requires expanding the acquisition channels, multiple Pacific6000 devices can work collaboratively via the synchronization bus, with synchronization errors still controlled within 1μs.

[0079] The Pacific6000 modular data acquisition device features a built-in 1TB high-speed solid-state drive, supporting real-time storage of acquired data in binary file format, balancing storage speed and data compression ratio. It also includes a gigabit Ethernet interface, enabling real-time transmission of acquired data to the back-end data processing unit 4 at a transmission rate ≥100MB / s, meeting the data transmission requirements for real-time monitoring during experiments. Furthermore, the device supports local data caching; when the network is interrupted, data is automatically stored locally and automatically retransmitted after network recovery, ensuring no data loss.

[0080] The input end of the data processing unit 4 is connected to the output end of the data acquisition unit 3. The data processing unit 4 includes a pulsation signal separation algorithm module 401, a force component compensation algorithm module 402, a pulsation parameter calculation module 403, and a data anomaly detection and correction module 404; it is used to perform steady-state thrust stripping, interference signal filtering, and pulsation parameter extraction on the received pulsation signal.

[0081] The static calibration unit and the dynamic correction unit serve as calibration units, forming a two-level calibration system. This system retains the advantages of traditional static calibration while supplementing dynamic calibration, achieving error compensation across the entire operating range.

[0082] Static Calibration: The existing mature three-pass, six-level static calibration process is retained. Calibration load points are set at 0, 200, 400, 600, 800, and 1000 kN, covering the full range of engine steady-state thrust. During calibration, the input of the static calibration unit is connected to the signal output of the dual-axis thrust sensor 1. A standard force source (accuracy ≤ ±0.01%) is used to sequentially apply loads at each level to the axial and radial test ends of the dual-axis thrust sensor 1. Each load point is held for 30 seconds. The output signal of the dual-axis thrust sensor 1 is collected, and the relationship curve between the output signal and the standard load is fitted using the least squares method. Static error correction coefficients (including linearity error, hysteresis error, and repeatability error) are calculated and written into the Pacific6000 modular acquisition device to achieve real-time correction of static measurements. The measurement error after static calibration is ≤ ±0.1%FS.

[0083] Dynamic calibration: The input of the dynamic calibration unit is connected to the signal output of the biaxial thrust sensor 1. The axial and radial test ends of the biaxial thrust sensor 1 are connected to an electromagnetic vibrator (maximum excitation force 300kN, frequency range 5Hz-2000Hz) and a pulsating load is applied to simulate the pulsating load environment during engine hot testing. During calibration, the excitation frequency is set to 10-1000Hz (step 10Hz), and a standard force signal of 0-200kN (step 20kN) is applied at each frequency point. The dynamic response signal output by the signal output of the biaxial thrust sensor 1 is recorded. The biaxial thrust sensor 1 is replaced with a standard force sensor, and the actual response signal is acquired. By comparing the dynamic response signal with the actual response signal, a dynamic response model is established, the dynamic response coefficient is calculated, and the data is written into the Pacific6000 modular acquisition device. Dynamic calibration covers the full frequency and full amplitude range of the pulsating signal, and can effectively compensate for dynamic errors such as the dynamic response lag of the dual-axis thrust sensor 1 and the phase shift of the signal conditioning unit 2. The phase error after dynamic calibration is ≤ ±0.5° and the amplitude error is ≤ ±0.2%.

[0084] In this embodiment, calibration data is stored in a database, recording information such as the time, ambient temperature, calibration personnel, and standard force source number for each calibration, facilitating traceability and retrieval. The calibration cycle is set to perform a complete calibration (static + dynamic) every 30 tests. If the biaxial thrust sensor 1 is replaced, equipment is repaired, or test conditions change during this period, calibration must be performed in advance. Calibration data is written to the calibration parameter library of the Pacific6000 modular acquisition device in real time. During measurement, the corresponding parameters are automatically called for data correction without manual intervention, ensuring the effective application of the calibration results.

[0085] This embodiment also provides a method for measuring the pulsating thrust of an engine during ground hot testing. The method for measuring the pulsating thrust of a test frame mounted on a 45° inclined test stand includes the following steps:

[0086] Step 1: Set the axial test end of the dual-axis thrust sensor 1 on the inclined surface of the 45° inclined test bench, and the radial test end is perpendicular to the inclined surface and facing upwards. The housing of the dual-axis thrust sensor 1 is connected to the fixed frame of the test frame, and the axial test end and the radial test end are respectively connected to the axial end and the radial end of the moving frame of the test frame.

[0087] During installation: The installation angle of the biaxial thrust sensor 1 is adjusted using a high-precision level (accuracy 0.02mm / m) to ensure that the sensor axis is aligned with the 45° axis of the test bench, with a deviation ≤ ±0.1°. The height of the biaxial thrust sensor 1 is adjusted using a wire-locking mechanism. The coaxiality of the sensor's sensitive surface center with the engine thrust axis is calibrated using a laser alignment instrument (measurement accuracy ±0.01mm) to ensure a coaxiality error ≤ ±0.2mm, avoiding measurement errors caused by force line misalignment. After installation, the sensor is checked for tightness. All fixing bolts are tightened to the specified torque (50N·m) using a torque wrench (accuracy ±5%) to prevent loosening during testing.

[0088] Parameter Configuration and Self-Test: Start the Pacific6000 modular acquisition device, signal conditioning unit 2, and data processing unit 4. Load the preset acquisition board, signal conditioning unit 2 (filter frequency 50kHz, etc.), and algorithm parameters (pulse signal separation algorithm module 401, force component compensation algorithm module 402, etc.) using dedicated configuration software. After configuration, execute the device self-test process: First, check the power supply status and communication connection status of each unit to ensure there are no hardware faults; then, perform a signal path test by outputting a standard signal (4-20mA, 1-5V) through a signal generator to verify whether the signal transmission link of the dual-axis thrust sensor 1, signal conditioning unit 2, and data acquisition unit 3 is unobstructed, and the signal distortion is ≤±0.1%; finally, perform an algorithm self-test by inputting a simulated raw signal to verify the operational stability and calculation accuracy of algorithms such as pulse signal separation and force component compensation, ensuring that the algorithm output results meet expectations. After passing the self-test, the device enters standby mode, waiting for calibration instructions.

[0089] The biaxial thrust sensor 1 was calibrated using a static calibration unit and a dynamic correction unit, and the resulting structure was written into the Pacific6000 modular acquisition device; specifically:

[0090] Static Calibration: Initiate the static calibration program. The standard force source applies static loads sequentially at preset load points (0, 200, 400, 600, 800, 1000 kN). During the application of each load point, control the loading rate to ≤10 kN / s to avoid impact loads damaging the sensor. Hold each load point for 30 seconds. After the output signal of the biaxial thrust sensor 1 stabilizes (signal fluctuation ≤±0.05%FS), record the output value of the biaxial thrust sensor 1 and the actual load value of the standard force source. Repeat the above procedure three times for static calibration, calculating the linearity error, hysteresis error, and repeatability error for each calibration. Take the average of the three calibration results as the final static error correction coefficient. If the error at any load point exceeds the allowable range (≤±0.1%FS), check the installation status of the biaxial thrust sensor 1 or the working status of the standard force source. After troubleshooting, recalibrate until the errors at all load points meet the requirements.

[0091] Dynamic Calibration: After successful static calibration, initiate the dynamic calibration program. Connect the electromagnetic exciter to the sensitive surface of the sensor being calibrated, ensuring a secure connection free from additional interference. Apply standard pulsating loads sequentially according to the preset frequency range (10-1000Hz, 10Hz step) and amplitude range (0-200kN, 20kN step). For each frequency-amplitude combination, apply the load continuously for 30 seconds, simultaneously acquiring the output signal of the standard force sensor and the response signal of the calibrated biaxial thrust sensor 1. Calculate the amplitude ratio and phase difference between the two, generating the amplitude-frequency response curve and phase-frequency response curve of the biaxial thrust sensor 1. Obtain the dynamic response coefficients through curve fitting. If the amplitude error at a certain frequency point is ≥±0.2% or the phase error is ≥±0.5°, adjust the filtering parameters or gain settings of the signal conditioning unit 2 and recalibrate at that frequency point. After dynamic calibration, integrate the dynamic response coefficients and static error correction coefficients to generate a complete calibration parameter file, which is then written into the calibration library of the Pacific6000 modular acquisition device.

[0092] Step 2: Ten minutes before engine ignition, start the data acquisition unit 3 to enter the preheating state and ensure the equipment operating temperature is stable (20-30℃). After the engine ignition command is issued, the acquisition system automatically starts data acquisition through a hardware trigger mechanism. The dual-axis thrust sensor 1 synchronously acquires the raw signals of the axial and radial pulsating thrust of the moving frame. The signal conditioning unit 2 optimizes the raw signals and converts them into pulsating signals that are compatible with the input requirements of the data acquisition unit 3.

[0093] Step 3: Data acquisition unit 3 performs multi-channel synchronous acquisition and high-speed synchronous transmission of the pulsating signal;

[0094] Step 4: The data processing unit 4 decomposes, compensates, and calculates parameters of the pulsating signal to obtain the pulsating thrust. Specifically:

[0095] Step 4.1: Use the pulsation signal separation algorithm module 401 to separate the pulsation signal;

[0096] Step 4.1.1: The wavelet transform algorithm of the db4 wavelet basis decomposes the pulsating signal into 10 layers of wavelet coefficients, including low-frequency coefficients and high-frequency coefficients. The low-frequency coefficients correspond to the steady-state thrust component at the level of 1000kN, and the high-frequency coefficients correspond to the pulsating thrust component and the interference signal.

[0097] Step 4.1.2: Denoise the high-frequency coefficients by setting a threshold to filter out interference signals such as high-temperature gas impact and test bench vibration;

[0098] Step 4.1.3: Perform inverse transform on the denoised wavelet coefficients to separate the steady-state thrust from the interference signal and obtain the time-domain waveform of the pulsating thrust. The signal separation accuracy of this algorithm is ≥99.5%, which can effectively separate the steady-state thrust from the interference signal and accurately extract the target pulsating signal.

[0099] Step 4.2: The force component compensation algorithm module 402 is used to compensate the time-domain waveform of the pulsating thrust;

[0100] Step 4.2.1: Obtain the axial force signal F1 and radial force signal F2 based on the time-domain waveform of the pulsating thrust;

[0101] Step 4.2.2: Establish a mathematical model of force components based on a 45° inclined test stand, and calculate the pure pulsating thrust; the expression of the mathematical model of force components is:

[0102] F = F1 × cos45° - F2 × sin45°;

[0103] Where F represents pure pulsating thrust;

[0104] The algorithm eliminates measurement errors caused by lateral force coupling by using a mathematical model of force components. It incorporates a real-time calibration mechanism that automatically corrects the trigonometric coefficients based on the installation angle deviation (≤±0.5°) of the dual-axis thrust sensor 1, ensuring accurate compensation of force components even with minor installation deviations.

[0105] Step 4.2.3: Obtain the time-domain waveform of the pure pulsating thrust based on the pure pulsating thrust;

[0106] Step 4.3: Extract characteristic parameters from the time-domain waveform of the pure pulsating thrust within the pulsating parameter calculation module 403 to obtain amplitude parameters composed of peak value, valley value, effective value, peak factor, and waveform factor, as well as frequency parameters composed of fundamental frequency, harmonic frequency, and frequency spectral density.

[0107] In this embodiment, the parameter calculation employs a sliding window algorithm, with the window length flexibly adjustable (10-100ms) according to the signal frequency characteristics. The calculation delay is ≤5ms, ensuring the real-time nature of the parameter output. Simultaneously, it supports real-time plotting of time-domain waveforms and frequency-domain spectra, providing experimental personnel with an intuitive display of signal characteristics.

[0108] During the measurement process, relevant test information was recorded simultaneously, including engine model, test date, ambient temperature (measurement range -10℃ to 40℃, accuracy ±0.5℃), ambient humidity (measurement range 20% to 80%RH, accuracy ±5%RH), ignition time, and test duration. This information was stored in conjunction with the measurement data to provide a basis for subsequent data traceability and analysis.

[0109] Step 4.4: In the data anomaly detection and correction module 404, compare whether the jump between the current amplitude parameter and the amplitude parameter of the previous second exceeds 5% of the amplitude parameter of the previous second. If it exceeds, use an interpolation algorithm to correct the abnormal amplitude parameter and output the corrected amplitude parameter and frequency parameter; if not, output the current amplitude parameter and frequency parameter.

[0110] Data integrity check: Check the integrity of the raw signal and amplitude and frequency parameters, including whether the start and end times of the raw signal acquisition cover the entire test process, whether the data file is missing or corrupted, and whether the characteristic parameters have been completely extracted. If data is missing or corrupted, check the equipment log, analyze the cause, and take remedial measures (such as restoring cached data, supplementing measurements, etc.).

[0111] Report Generation and Archiving: After successful data verification, a pulsed thrust characteristic report is automatically generated. The report includes basic test information, measurement system configuration parameters, calibration data, raw signal waveforms, time-domain / frequency-domain analysis graphs of the pulsed thrust, a summary table of characteristic parameters, and error analysis results. The report supports export in multiple formats (Word, PDF, Excel) for easy access and submission by test personnel. Simultaneously, all relevant files, including raw data, processing results, calibration data, and test reports, are archived to the server database according to a unified naming convention, establishing a complete test data archive for subsequent retrieval, traceability, and data analysis.

[0112] 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 ground thermal test engine pulsating thrust measurement system for measuring the dynamic frame pulsating thrust of a test frame installed on a 45° inclined test stand, characterized in that, It includes a dual-axis thrust sensor (1), a signal conditioning unit (2), a data acquisition unit (3), and a data processing unit (4); The axial test end of the dual-axis thrust sensor (1) is located on the inclined surface, and the radial test end is perpendicular to the inclined surface and upward. The housing of the dual-axis thrust sensor (1) is connected to the fixed frame of the test frame. The axial test end and the radial test end are respectively used to connect to the axial end and the radial end of the moving frame (5) of the test frame. The dual-axis thrust sensor (1) is used to collect the original signal of the pulsating thrust of the moving frame. The input end of the signal conditioning unit (2) is connected to the signal output end of the dual-axis thrust sensor (1) to optimize the original signal and convert it into a pulsating signal that meets the input requirements of the data acquisition unit (3). The input end of the data acquisition unit (3) is connected to the output end of the signal conditioning unit (2). The data acquisition unit (3) is used for multi-channel synchronous acquisition of pulse signals, and is deeply optimized according to the high-frequency characteristics of the pulse signals and the multi-channel synchronization requirements to achieve high-speed and synchronous transmission of pulse signals. The input end of the data processing unit (4) is connected to the output end of the data acquisition unit (3). The data processing unit (4) is used to perform steady-state thrust stripping, interference signal filtering and pulsation parameter extraction on the received pulsating signal.

2. The system of claim 1, wherein, The range of the axial and radial test ends of the dual-axis thrust sensor (1) is set to 0-1200kN, with a 20% redundancy reserved for the maximum range. The sensitive surface of the dual-axis thrust sensor (1) is made of a force-conducting steel ball to achieve point contact force transmission, and the material of the conducting steel ball is a high-strength alloy material with a hardness ≥ HRC60. The dual-axis thrust sensor (1) contains a high-temperature heat insulation coating, which is applied to the surface of the core component of the dual-axis thrust sensor (1) by plasma spraying. The high-temperature heat insulation coating is made of zirconium oxide-alumina composite ceramic material with a thickness of 0.8mm-1.2mm and a temperature resistance limit of ≥800℃. The housing of the dual-axis thrust sensor (1) is a sealed structure with a protection level of IP67. The dual-axis thrust sensor (1) outputs a 4mA-20mA standard current signal at its signal output terminal, with a signal linearity error ≤ ±0.1% and zero drift ≤ 0.05%FS / ℃.

3. The fluctuating thrust measurement system for ground thermal run of an engine of claim 1, wherein, The signal conditioning unit (2) includes a double-layer electromagnetic shielding shell and an LC passive filter topology circuit, a gain adaptive adjustment circuit, an opto-isolation circuit, and a temperature compensation circuit with a built-in compensation algorithm disposed inside the double-layer electromagnetic shielding shell. The input end of the LC passive filter topology circuit is connected to the signal output end of the dual-axis thrust sensor (1), and the output end of the LC passive filter topology circuit is connected in sequence to the input end of the gain adaptive adjustment circuit, the opto-isolation circuit, the temperature compensation circuit, and the data acquisition unit (3). The LC passive filter topology circuit, the gain adaptive adjustment circuit, the opto-isolation circuit, and the temperature compensation circuit are respectively used to filter, amplify, electrically isolate interference, and correct the temperature drift error of the gain adaptive adjustment circuit for the original signal. The inner layer of the double-layer electromagnetic shielding shell is made of copper shielding mesh, and the outer layer is made of aluminum alloy shielding shell. The shielding effectiveness of the double-layer electromagnetic shielding shell is ≥80dB.

4. The system of claim 3, wherein, The cutoff frequency of the LC passive filter topology is set to 50kHz. The gain adaptive adjustment circuit is a gain adaptive adjustment circuit based on microcontroller control; The isolation voltage of the opto-isolation circuit is ≥2500V; The temperature compensation circuit includes an integrated PT100 temperature sensor.

5. The fluctuating thrust measurement system for ground thermal run of an engine of claim 1, wherein, The data acquisition unit (3) adopts a Pacific6000 modular acquisition device with a built-in 1TB high-speed solid-state drive; The Pacific6000 modular acquisition device is equipped with an acquisition board for n-channel synchronous data, where n≥8. The acquisition board uses a 16-bit AD converter with a resolution of 0.38μV / LSB. The sampling rate of each channel of the acquisition board is 2MHz, and the synchronization accuracy of the n channels is ≤1μs; The signal conditioning unit (2) includes n signal conditioning channels, each of which is connected to a channel of a data acquisition board.

6. The fluctuating thrust measurement system for ground thermal run of an engine of claim 1, wherein, The data processing unit (4) includes a pulse signal separation algorithm module (401), a force component compensation algorithm module (402), a pulse parameter calculation module (403), and a data anomaly detection and correction module (404) connected in sequence.

7. The system of claim 5, wherein, It also includes a static calibration unit and a dynamic correction unit; The static calibration unit includes a standard force source and a static calibration processor; the standard force source is used to apply loads to the axial test end and radial test end of the biaxial thrust sensor (1); the static calibration processor is used to acquire the output signal of the signal output end of the biaxial thrust sensor (1), calculate the static error correction coefficient based on the applied load and the output signal, and write the correction coefficient into the Pacific6000 modular acquisition device. The dynamic calibration unit includes an electromagnetic vibrator, a standard force sensor, and a dynamic calibration processor. The electromagnetic vibrator is connected to the axial test end and radial test end of the biaxial thrust sensor (1) respectively, or connected to the standard force sensor to apply pulsating loads. The dynamic calibration processor is used to record the dynamic response signal output by the signal output end of the biaxial thrust sensor (1), and to acquire the actual response signal of the standard force sensor. By comparing the dynamic response signal with the actual response signal, a dynamic response model is established, the dynamic response coefficient is calculated, and the data is written into the Pacific6000 modular acquisition device.

8. A method of measuring pulsating thrust during ground hot run of an engine, characterized in that, Using the engine ground hot test pulsating thrust measurement system according to any one of claims 1-7 includes the following steps: Step 1: Set the axial test end of the dual-axis thrust sensor (1) on the inclined surface of the 45° inclined test bench, and the radial test end is perpendicular to the inclined surface and facing upward. The outer shell of the dual-axis thrust sensor (1) is connected to the fixed frame of the test frame, and the axial test end and the radial test end are respectively connected to the axial end and the radial end of the moving frame (5) of the test frame. Step 2: Use a dual-axis thrust sensor (1) to collect the original signal of the moving frame pulsating thrust. The signal conditioning unit (2) optimizes the original signal and converts it into the pulsating signal required by the data acquisition unit (3). Step 3: The pulse signal is synchronously acquired through multiple channels and transmitted at high speed and synchronously through the data acquisition unit (3); Step 4: Use the data processing unit (4) to perform steady-state thrust stripping, interference signal filtering and pulsation parameter extraction on the pulsating signal to obtain the pulsating thrust.

9. The method of claim 8, wherein, In step 1, after the dual-axis thrust sensor (1) is installed, the following steps are also included: using a static calibration unit and a dynamic correction unit to perform static calibration and dynamic calibration on the dual-axis thrust sensor (1) respectively, and writing the static error correction coefficient and dynamic response coefficient obtained from the calibration into the Pacific6000 modular acquisition device; Step 3 specifically involves: using the Pacific6000 modular acquisition device to perform multi-channel synchronous acquisition of the pulsating signal and high-speed, synchronous transmission.

10. The method of claim 8, wherein, Step 4 specifically involves: Step 4.1: Use the pulsation signal separation algorithm module (401) to separate the pulsation signal; Step 4.1.1: Decompose the pulsating signal into 10 layers of wavelet coefficients, including low-frequency coefficients and high-frequency coefficients. The low-frequency coefficients correspond to the steady-state thrust component at the level of 1000kN, and the high-frequency coefficients correspond to the pulsating thrust component and the interference signal. Step 4.1.2: Denoise high-frequency coefficients by setting a threshold; Step 4.1.3: Perform inverse transformation on the low-frequency coefficients and the denoised high-frequency coefficients to separate the steady-state thrust from the interference signal and obtain the time-domain waveform of the pulsating thrust. Step 4.2: Use the force component compensation algorithm module (402) to compensate the time-domain waveform of the pulsating thrust; Step 4.2.1: Obtain the axial force signal F1 and radial force signal F2 based on the time-domain waveform of the pulsating thrust; Step 4.2.2: Establish a mathematical model of force components based on a 45° inclined test stand, and calculate the pure pulsating thrust; the expression of the mathematical model of force components is: F = F1 × cos45° - F2 × sin45°; Where F represents pure pulsating thrust; Step 4.2.3: Obtain the time-domain waveform of the pure pulsating thrust based on the pure pulsating thrust; Step 4.3: Extract characteristic parameters from the time-domain waveform of the pure pulsating thrust using the pulsating parameter calculation module (403) to obtain the amplitude parameter composed of peak value, valley value, effective value, peak factor and waveform factor, and the frequency parameter composed of fundamental frequency, harmonic frequency and frequency spectral density. Step 4.4: The data anomaly detection and correction module (404) compares whether the jump between the current amplitude parameter and the amplitude parameter of the previous second exceeds 5% of the amplitude parameter of the previous second. If so, the interpolation algorithm is used to correct the abnormal amplitude parameter, and the corrected amplitude parameter and frequency parameter are output; if not, the current amplitude parameter and frequency parameter are output.

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