Special issue

1 Research progress of ultrasonic temperature measurement technology in ultra-high temperature extreme environments

WANG Gao , LIANG Haijian , WEI Yanlong , WANG Xinhui , ZHAO Jian , LI Xin

2024, 44(5). DOI: 10.11823/j.issn.1674-5795.2024.05.01

[Abstract](636) [HTML](247) [PDF 12.36 M](635)

Abstract:
This paper introduces the principles of contact ultrasonic guided wave temperature measurement technology, ultrasonic internal temperature gradient temperature measurement technology, and cross-beam ultrasonic temperature measurement technology. It describes the research status of ultrasonic temperature measurement technology, and the application cases and test results of ultrasonic temperature measurement technology in engine combustion chamber temperature measurement. This review analyzes the technical characteristics and potential problems of various ultrasonic temperature measurement techniques. It is pointed out that the study of high temperature oxidation resistant waveguide materials is the top priority in the development of ultrasonic guided wave temperature measurement technology. It is proposed that the temperature measurement range can be extended and the temperature measurement accuracy can be improved by developing new materials, new processes and new equipment, and constantly iterating the feature signal recognition algorithm model. This provides reference for further development of acoustic temperature measurement technology.

2 Time delay estimation method of ultrasonic thickness measurement signal based on fuzzy variable step size LMS

WANG Nian , YANG Dingqiang , ZHENG Zhiyang

2026, 46(3):77-88. DOI: 10.11823/j.issn.1674-5795.2026.03.09

[Abstract](88) [HTML](32) [PDF 8.91 M](57)

Abstract:
In the time delay estimation (TDE) of ultrasonic signals, the traditional fixed step size least mean square (LMS) algorithm struggles to balance convergence speed and steady-state accuracy. Moreover, existing variable step size algorithms often rely on instantaneous errors and fixed function models, leading to poor adaptability under non-stationary echo signals. To address these issues, a TDE method using a fuzzy variable step size LMS algorithm is proposed for ultrasonic thickness measurement in this paper. Based on the time-varying characteristics of ultrasonic echo signals, the conventional single-error feedback mechanism is discarded. Instead, the local correlation coefficient error between the output and desired signals, along with its variation, are extracted as the dual inputs for a fuzzy controller. A zero-order Sugeno fuzzy inference system is then designed to establish a nonlinear mapping rule between these input features and the step size, enabling adaptive dynamic adjustment of the step size. Numerical simulations are presented using simulated echo signals under different signal-to-noise ratios. The results demonstrate that the proposed method yields better overall performance compared to the fixed step size LMS, the hyperbolic tangent variable step size LMS, and the instantaneous error-based fuzzy variable step size LMS. It significantly reduces the steady-state misadjustment while ensuring fast convergence, thereby offering higher measurement accuracy and noise robustness. This is further verified using measurements made on standard gauge blocks with a laboratory ultrasonic thickness measurement platform. The experimental results show that the relative measurement errors of the proposed method for gauge blocks of varying thicknesses are consistently smaller than those of the other three LMS algorithms, with a maximum relative error of 0.710%. Ultimately, the fuzzy variable step size LMS method for TDE provides vital technical support for high-precision ultrasonic time-of-flight (TOF) calculations. It facilitates the development of ultrasonic non-destructive testing technologies and holds significant practical value in engineering applications.

3 Research progress and prospects of ultrasonic velocimetry reconstruction algorithms for complex flow fields

LI Xinhao , WANG Yi , ZHANG Shuting

2026, 46(2):78-89. DOI: 10.11823/j.issn.1674-5795.2026.02.06

[Abstract](110) [HTML](107) [PDF 5.35 M](81)

Abstract:
This paper introduces mainstream ultrasonic velocity measurement methods, and details the fundamental principles and calculation formulas of the transit-time method and the Doppler method. It focuses particularly on the ill-posed inverse problem inherent in ultrasonic velocity field reconstruction, and provides an in-depth analysis of the mechanisms, strengths, and inherent ill-posedness of classical inversion algorithms including the least squares method, Tikhonov regularization, and truncated singular value decomposition (TSVD). The paper summarizes key physical-signal joint processing strategies for mitigating significant ultrasonic beam drift and low signal-to-noise ratio (SNR). Prospectively, it proposes that the integration of physics-informed deep learning, computational fluid dynamics (CFD)-acoustics simulation coupling, and system-on-chip integration are core directions for advancing the technology towards high precision, adaptability, and miniaturization. This work aims to provide a reference for further breakthroughs and the engineering application of ultrasonic velocity measurement technology.

4 Porous parameter inversion based on irregular sound incidence

LIAO Yunhong , WANG Chenchen , FU Qiang

2025, 45(6):95-104. DOI: 10.11823/j.issn.1674-5795.2025.06.08

[Abstract](170) [HTML](120) [PDF 3.46 M](261)

Abstract:
Research was conducted for porous parameter inversion based on irregular acoustic incidence model to address the limitation of normal incidence case. A theoretical model was established for relating material porous parame- ters to the irregular incidence absorption coefficient. The acoustic response of porous materials under irregular incidence case was simulated to obtain the reference absorption data. The inversion study was conducted by using the established theoretical model and genetic algorithm, and the accuracy and astringency of inversed parameters was further analyzed. Results show a good agreement between theoretical and simulated outcomes and demonstrate high accuracy and astringency with relative errors of the inversed parameters below 9.0% and relative standard deviations less than 1 × 10?3. This study provides a novel theoretical approach for porous parameter inversion that presents considerable potential for both academic research and engineering applications.

5 Research on wide-area low-frequency acoustic localization method

ZHANG Chenwen , YANG Jun , LIAO Yunhong , ZHANG Runze

2025, 45(4):141-148. DOI: 10.11823/j.issn.1674-5795.2025.04.10

[Abstract](256) [HTML](126) [PDF 19.48 M](437)

Abstract:
Traditional location methods based on microphone arrays have certain limitations in locating wide-area low-frequency acoustic signals at kilometer-scale distances. To improve location accuracy , field experiments were conducted using a 32-element acoustic array to investigate the locating performance of the time delay minimum variance (TDMV) method and the beamforming (BF) method in a 5 km outdoor environment, focusing on low-frequency sound signals from the same source. Experimental results indicate that compared to the traditional BF method, the TDMV method exhibits a significant advantage in location accuracy over wide-area ranges, achieving an improvement of more than 2.1% in precision. These findings extend the effective range of sound source location and provide a feasible solution for the accurate location of low-frequency sound sources.

6 Monitoring method for wall thickness of variable-temperature pipelines based on ultrasonic guided waves

PAN Shuhua , WU Jianbo , XIA Hui , WANG Zhe , HUANG Ganghua , GONG Yuxuan

2025, 45(4):66-73. DOI: 10.11823/j.issn.1674-5795.2025.04.05

[Abstract](278) [HTML](189) [PDF 6.51 M](384)

Abstract:
Aiming at the problem of the decline in the accuracy of ultrasonic wall thickness measurement caused by temperature fluctuations during the operation of high-temperature petrochemical pipelines, a measurement method based on the inversion of temperature and the compensation of wall thickness by ultrasonic guided wave signals is proposed. A two-dimensional steady-state heat transfer model was established, the temperature field distribution of the waveguide strip was analyzed, an ultrasonic flight time prediction model was constructed, the quantitative relationship between the pipe temperature and the ultrasonic flight time in the waveguide was characterized, and the real-time measurement of the temperature of high-temperature pipes was achieved. On this basis, the ultrasonic guided wave thickness measurement data was compensated to improve the accuracy of pipe wall thickness monitoring. An ultrasonic guided wave measurement platform was built and experiments were performed. The results show that within the range of 15 ~ 500 ℃, this method can achieve precise measurement of the temperature change of the pipeline, and the measurement error of the wall thickness after compensation is ± 0.1 mm. This method breaks through the application bottleneck of the existing guided wave thickness measurement devices in variable-temperature environments, providing technical support for the safe operation of petrochemical plants.

7 Optimization method for acoustic temperature measurement signal delay

LI Shuyuan , ZHAO Jian , ZHAO Yijun

2024(1). DOI: 10.11823/j.issn.1674-5795.2024.01.07

[Abstract](740) [HTML](235) [PDF 1.39 M](901)

Abstract:
This research is dedicated to the optimization of time delay processing for acoustic temperature measurement signals within engine combustion chambers, aiming to significantly enhance the precision and reliability of temperature determinations. A novel signal processing methodology is introduced, integrating wavelet packet decomposition transformation recombination with the isolation forest algorithm. This approach promises to refine the quality of temperature data by effectively mitigating noise interference and extracting pivotal information. Firstly, the acoustic temperature probe was thermally calibrated in a wind tunnel to obtain the data in a high temperature airflow environment. Secondly, the wavelet packet decomposition transformation and reorganization method combined with the isolated forest algorithm was used to filter and reconstruct the temperature data to eliminate noise and extract effective information. At the same time, outliers in the reconstructed data was detected to improve data quality and accuracy. The results of thermal calibration wind tunnel experiments show that the data distribution after signal processing is smoother and more symmetrical, the standard deviation is significantly reduced, and the data is more concentrated on the mean, so as to improve the accuracy and stability of temperature measurement. The research provides an effective technical solution for acoustic temperature measurement.

8 Study on optimization of acoustic pyrometer topological structure

ZHAO Yijun , ZHAO Jian , CHEN Xinhu

2023(5). DOI: 10.11823/j.issn.1674-5795.2023.05.03

[Abstract](836) [HTML](256) [PDF 10.78 M](1352)

Abstract:
Acoustic pyrometers still have such problems as insufficient probe temperature tolerance, poor temperature measurement stability, and susceptibility to the impact of airflow velocity. In order to improve the temperature measurement reliability of acoustic pyrometer, this paper establishes a corresponding airflow temperature field and sound propagation model in Virtual.Lab. The optimal topological parameters to reduce sound pressure level attenuation were analyzed and studied by changing the topological structure such as the acoustic probe distribution diameter, orientation, and tilt angle of an existing set of acoustic pyrometers, and experimental comparison was carried out. Finally, it was found that the topology structure with a diameter of 15 cm and an inclination angle of 30 degrees between the acoustic probe and the horizontal plane had the smallest comprehensive sound pressure level reduction value in the airflow temperature field environment with temperature from normal atmospheric temperature to 900 ℃ and Mach number from 0 to 0.3. The topology structure with a diameter of 20 cm and an inclination angle of 15 degrees took the second place. In conclusion, both topology structures reduce the standard deviation of data by more than 17% compared to existing topology structure, which improve the performance of acoustic source signal reception, therefore, improving the reliability of acoustic pyrometer temperature measurement in the airflow temperature field environment of temperature from normal to 900 ℃ and Mach number from 0 to 0.3.

9 Research on torque measurement based on surface acoustic wave resonators

HUANG Mingjing , CHEN Zhijun , SUN Cong , ZHONG Ming , SU Piqiang

2024, 44(5). DOI: 10.11823/j.issn.1674-5795.2024.05.07

[Abstract](417) [HTML](157) [PDF 7.50 M](608)

Abstract:
In view of the current status and existing problems of the surface acoustic wave (SAW) torque measurement technology in theoretical analysis, algorithm design and experimental test, the torque measurement technology based on the SAW resonator (SAWR) is studied. According to the feature that the torque on the shaft is transmitted to the SAWR by the strain, the theory model of the strain loading in the Lagrange coordinates is established. The torque coefficient of frequency is defined as an important indicator for cuts optimization, and four SAWRs are designed and produced according to the principle of frequency division multiple access (FDMA). On the basis of the echo characteristics of the SAWR, the measurement methods of the SAWR resonance frequency and their characteristics are summarized. The wireless measurement system for static and dynamic torque are built respectively. The static system utilizes the method of frequency sweep for the signal strength measurement, which combines big step for rough sweep with small step for fine sweep for the purpose of enhancing real-time performance and improving the frequency measurement accuracy. The dynamic system employs the carrier frequency measurement method, and solves the problems of insufficient spectrum resolution and low torque measurement accuracy by the cubic spline interpolation in the frequency domain. The results show that the maximum measurement error of the static system does not exceed 1 N·m when the wireless distance exceeds 20 cm and the torque range is from -80 to 80 N·m; The maximum measurement error of the dynamic system does not exceed 3 N·m when the wireless distance exceeds 20 cm, the torque range is between 0 and 80 N·m, and the rotational speed does not surpass 600 r / min. The results validate the effectiveness of the torque measurement system based on the SAWRs, which provided a new approach for high-precision torque measurement.

10 Research on the test method of quantitative evaluating near surface region Brinell hardness of alloy steels by ultrasonic critical refracted longitudinal wave

MEN Ping , DENG Dan , WU Lingyuan

2024, 44(3). DOI: 10.11823/j.issn.1674-5795.2024.03.07

[Abstract](573) [HTML](263) [PDF 1.90 M](664)

Abstract:
In order to solve the problem of non-destructive, online, and in-service quantitative monitoring / testing of Brinell hardness of alloy steel component, by building and using an advanced critical refractive longitudinal wave parameter testing device, we have carried out experiments on quantitatively evaluating the near surface Brinell hardness of alloy steel using ultrasonic critical refracted longitudinal waves, measured the critical refracted longitudinal wave propagation characteristic parameters in alloy steel calibration specimens, and calculated the detection parameters required for evaluating Brinell hardness, namely acoustic velocity and attenuation coefficient. In the experiment, we altered the front edges distance between the receiving and transmitting probes and the calibrating specimen microstructure, studied the influence of above changes on the ultrasonic propagation characteristic parameters, confirmed the sensitive detecting parameter for evaluating alloy steel calibration specimen Brinell hardness, and finally established the calibration mapping relationship models between the near surface Brinell hardness of 45^# steel calibration specimens and the critical refractive longitudinal wave characteristic parameters, verified its hardness prediction accuracy. The test result shows that the wave detection parameters are different in sensitivity to the calibrated specimen Brinell hardness, there is a strong correlation relationship between the acoustic velocity and the Brinell hardness, and the error of the establishing Brinell hardness prediction model is less than 10%. The attenuation coefficient cannot be used to evaluate the near surface Brinell hardness of 45^# steel specimens. This study provides some reference for evaluating the Brinell hardness of alloy steel components by ultrasonic non-destructive testing methods.

11 Research progress on flexible wearable piezoelectric ultrasound transducers

ZHANG Min , XIU Kunhao , SUN Jingyao , WANG Ziying , ZHAO Libin

2024, 44(3). DOI: 10.11823/j.issn.1674-5795.2024.03.05

[Abstract](1021) [HTML](275) [PDF 6.97 M](3367)

Abstract:
The structural design and material selection of the piezoelectric layer, backing layer, matching layer, encapsulation layer, and interconnecting electrodes of flexible wearable piezoelectric ultrasound transducers are introduced, the advantages of the simulation design of the transducers using finite element analysis (FEA) technology are discussed, and key technologies in the transducers fabrication, such as electrode patterning, are described. The applications of this type of sensors in the fields of deep tissue imaging, haemodynamic monitoring, promoting the recovery of bone damage, and assisting transdermal drug delivery are analysed. The development direction of the sensors is outlooked, and it is pointed out that in the future, the measurement accuracy, safety and integration degree of flexible wearable piezoelectric ultrasound sensors can be further improved through the application of high-performance signal processing technology, improvement of ultrasound detection and imaging algorithm, and optimisation of the sensor structural design scheme, etc., so as to promote the marketable and industrial development of this kind of sensors.