Ultrasonic Propagation Path Research Articles

Design of an ultrasonic flowmeter using a cow horn-shaped structure and secretary bird optimization algorithm-back propagation neural network algorithm

A novel dual-channel ultrasonic flowmeter based on the time-difference method is proposed, aiming at solving the measurement error due to the installation angle of the transducers and improving the measurement accuracy. The angle error is eliminated by optimizing the ultrasonic propagation path so that it is parallel to the fluid flow direction. The pipeline design is optimized to reduce the pressure loss to ensure high-precision measurements at different flow rates. In addition, in order to solve the measurement accuracy problem caused by the transducer position, the measurement results of the two channels are fused by Secretary Bird Optimization Algorithm-Back Propagation Neural network, which reduces the error of the measurements and improves the overall accuracy of the measurements. The results of system error analysis and uncertainty evaluation show that the calibrated flowmeter has a maximum relative error of 0.6% and a maximum repeatability of 0.7%, which proves its reliability and effectiveness in fluid measurement.

Longitudinal Wave Defect Detection Technology Based on Ablation Mechanism

For laser ultrasound in the thermoelastic mechanism, excitation of ultrasonic body wave signal is weak, it is not easy to realize the detection of deep defects inside the workpiece. While the ablation mechanism produces a high and practical ultrasonic signal-to-noise ratio, this paper is based on the generation mechanism of laser ablation excitation of ultrasonic waves, the establishment of laser ultrasound in the ablation mechanism in the aluminum plate excitation and propagation of ultrasonic numerical model, through the solution, obtained the ultrasonic acoustic field map, discussed the ablation mechanism of the laser ultrasonic body wave acoustic field directionality. Additionally, the preliminary verification of the validity of the model is presented. Then, in order to explore the application potential of high signal-to-noise ratio longitudinal waves in defect detection, defects of different depths are preset in the model for simulation calculations, and waveform and acoustic field analyses are performed on the simulation results to study the ultrasonic propagation paths inside the member and the interaction with the defects, and the transverse position and depth of the internal defects are judged by using B-scan imaging. Finally, experimental validation is carried out. The experimental results are highly consistent with the simulation model, and the defect experiments can qualitatively determine the location of internal defects and verify the practicality and accuracy of the model.

An Accelerated Post-processing Calculation Method of Curved Surface Profile Extraction Based on the Total Focusing Method of Ultrasonic Phased Array

Surface profile extraction is a significant process for determining the ultrasonic beam propagation path based on the Fermat’s principle while applying the total focusing method (TFM) of ultrasonic phased array on a curved component immersed in water. However, TFM calculation is time consuming due to the large amounts of data post-processing. Hence, a trade-off between computation cost and precision of result image is must to be made. In this paper, an accelerated total focusing method (ATFM) was proposed to extract the surface profile of an arc-shaped component. The experimental results show that compared with TFM, ATFM could shorten the imaging time by more than 70% under various conditions of grid spacing. Meanwhile, the maximal error of extracted surface profile compared to the practical profile curve is about 0.7mm and the surface extraction errors near the central area are less than 0.1mm. It shows that the proposed ATFM can significantly improve the computation efficiency while ensuring the accuracy of surface extraction.

Study on Ultrasonic Propagation Path in Nonuniform Temperature Field

Study on Ultrasonic Propagation Path in Nonuniform Temperature Field

FEA-Based Ultrasonic Focusing Method in Anisotropic Media for Phased Array Systems

Traditional ultrasonic imaging methods have a low accuracy in the localization of defects in austenitic welds because the anisotropy and inhomogeneity of the welds cause distortion of the ultrasonic wave propagation paths in anisotropic media. The distribution of the grain orientation in the welds influences the ultrasonic wave velocity and ultrasonic wave propagation paths. To overcome this issue, a finite element analysis (FEA)-based ultrasonic imaging methodology for austenitic welds is proposed in this study. The proposed ultrasonic imaging method uses a wave propagation database to synthetically focus the inter-element signal recorded with a phased array system using a delay-and-sum strategy. The wave propagation database was constructed using FEA considering the grain orientation distribution and the anisotropic elastic constants in the welds. The grain orientation was extracted from a macrograph obtained from a dissimilar metal weld specimen, after which the elastic constants were optimized using FEA with grain orientation information. FEA was performed to calculate a full matrix of time-domain signals for all combinations of the transmitting and receiving elements in the phased array system. The proposed approach was assessed for an FEA-based simulated model embedded in a defect. The simulation results proved that the newly proposed ultrasonic imaging method can be used for defect localization in austenitic welds.

Ultrasonic Total Focusing Imaging Method of Multilayer Composite Structures Using the Root‐Mean‐Square (RMS) Velocity

Multilayer composite structures have been widely used in industrial manufacturing, and nondestructive testing of these multilayer structures is to ensure their reliable quality and performance. Currently, ultrasonic total focusing method (TFM) imaging using full‐matrix capture (FMC) technology has been proven to sense small defects in a single homogeneous medium and improve the imaging signal‐to‐noise ratio. However, these algorithms cannot be accurately applied to imaging of multilayer composite structures, due to the acoustic impedance variation and because reflection and refraction occur at the interface between the layers, which makes it very difficult to calculate the ultrasonic propagation path and time. To solve this problem, a root‐mean‐square (RMS) velocity algorithm for total focusing imaging of multilayer structures is proposed in the article. Based on the theory of RMS velocity for processing of seismic data, the approximated delays can be easily and quickly calculated by a hyperbolic time‐distance relationship under circumstances of short lateral distance and horizontal layers. The performance of the proposed algorithm is evaluated by total focusing imaging of a two‐layer medium with drilled holes and conducted by the finite element simulation. To further improve imaging efficiency, the partial data in the full‐matrix data were used for imaging which is the simplified matrix focusing method (SFM). The results verify that the proposed methods are capable of total focusing imaging of two‐layered structures. However, the imaging performance and efficiency of these algorithms are different.

An Improved Ultrasonic Imaging Method for Austenitic Welds Based on Grain Orientation Distribution Inversion Algorithm

Traditional ultrasonic imaging inspection does not perform well for austenitic welds, in which the defect locating accuracy is insufficient due to the distortion of propagation paths caused by the weld’s anisotropy and inhomogeneity. The distribution of grain orientation (DGO) contributes to the velocity distribution in austenitic welds and influences the ultrasonic propagation paths. An improved ultrasonic imaging method for austenitic welds based on a DGO inversion algorithm is proposed in this paper. A DGO model is established using an iterative disturbance method of local parameters. The model is optimized by an evolution strategy based on the model error evaluated by propagation times of known reflectors. Inspection experiments were carried out, in which a reference specimen was used to acquire the DGO inversion result and the inspection images of a target specimen were generated based on the optimized DGO model. Experimental results have proved that the improved ultrasonic imaging method can obviously increase the defect locating accuracy and effectively improve the imaging performance for austenitic welds.

A method for reconstructing two-dimensional surface and internal temperature distributions in structures by ultrasonic measurements

A new method for simultaneously reconstructing surface and internal transient temperature distributions in structures is presented by ultrasonic measurements. The principle of ultrasonic thermometry is based on temperature dependence of the velocity of ultrasonic wave (acoustic velocity) propagating through heated structures. Considering the bending effect of ultrasonic propagation path in non-uniform temperature field, an approach for predicting two-dimensional ultrasonic propagation path is developed using the Fermat theory. Combining the advantages of the ultrasonic pulse-echo measurements and an inverse analysis of thermo-acoustic coupling problem, a reconstruction algorithm is proposed to estimate two-dimensional surface and internal temperature fields. The presented approach is discussed in some detail and a number of examples are given as verification to demonstrate the feasibility and reliability of this method. The surface and internal temperature profiles determined by ultrasound agree well with the exact values. In addition, the influences of bending effect of wave propagation, measurement error of ultrasonic wave propagation time, number and position of measurement points on the reconstruction of temperature fields are analyzed in detail. It shows that the presented method is a promising means for high-accurately and nondestructively determining surface and internal transient temperature distributions in heated structures.

Detection of turbulent error by helicity in an ultrasonic flowmeter

Turbulence generated by invading structures in pipes introduces uncertainties into measurements using ultrasonic flowmeters. A numerical model based on large eddy simulation (LES) is developed here to study the features of turbulent errors in a typical U-shaped ultrasonic flowmeter. According to the flow structures obtained by LES, a one-dimensional turbulent spectrum and probability density function of helicity along the effective ultrasonic propagation path are calculated. It can be seen that the turbulent error is dominated by the large-scale anisotropic vortices in a specific range on the sampling line, and the anisotropic vortices have the common largest fluctuating scales in the error-dominated area in which the Reynolds number ( Re) exceeds 15,000. The results provide possibilities for reducing the turbulent error by limiting the largest fluctuating scale through structure optimization. The probability density function of streamwise helicity is first introduced to unveil the continuous turbulent development in an ultrasonic flowmeter, which has the potential to contribute to turbulent analyses.

A combined marching and minimizing ray-tracing algorithm developed for ultrasonic array imaging of austenitic welds

In order to improve the performance of defect sizing and locating in the ultrasonic inspection of austenitic welds, it is important to predict ultrasonic propagation paths using ray-tracing algorithms considering the anisotropy and inhomogeneity of the weld. An effective ray-tracing algorithm is proposed in this paper, which predicts rays in a P2M mode (from a point to a target matrix). The algorithm combines the marching ray-tracing strategy and the minimizing ray-tracing strategy to improve the computing efficiency and accuracy. The performances of both two ray-tracing strategies were analyzed, based on which the parameters of the proposed algorithm were optimized. The propagation times of all the target points were acquired by the algorithm and applied for ultrasonic array imaging. Images generated using inspection experimental signals can prove that the proposed algorithm can achieve P2M ray-tracing efficiently and realize good imaging performance.

Acoustic waveguides: An attractive alternative for accurate and robust contact thermometry

We report a robust and very precise method of measuring temperature using ultrasonic waves. Solid stainless steel waveguides are used to provide well-defined and stable ultrasonic wave propagation paths. Ultrasonic wave velocity is strongly temperature dependent. The arrival times of the ultrasonic wavepackets along a waveguide are used to infer the average temperature of the waveguide. Our ultrasonic temperature measurements exhibit a high precision (i.e. ±0.015 °C) that is more than two times better than the quoted accuracy of 1/10 DIN resistance temperature detectors (RTDs). The responsiveness of the waveguides was also investigated. While ultrasonic measurements can be made at very high frequencies, the responsiveness is limited by the heat transfer into the active sensing area. The waveguides make it easy to customise the dimension of the active sensing area and a shorter response time than those of RTDs has been demonstrated. The technique presented in this paper is a robust and cost effective alternative to other contact temperature measurements.

Energy transfer model and its applications of ultrasonic gas flow-meter under static and dynamic flow rates.

Most of the ultrasonic gas flow-meters measure the gas flow rate by calculating the ultrasonic transmission time difference between the downstream and upstream. Ultrasonic energy attenuation occurs in the processes of the ultrasonic generation, conversion, transmission, and reception. Additionally, at the same time, the gas flow will also affect the ultrasonic propagation during the measurement, which results in the ultrasonic energy attenuation and the offset of ultrasonic propagation path. Thus, the ultrasonic energy received by the transducer is weaker. When the gas flow rate increases, this effect becomes more apparent. It leads to the measurement accuracy reduced, and the measurement range narrowed. An energy transfer model, where the ultrasonic gas flow-meter under without/with the gas flow, is established by adopting the statistical analysis and curve fitting based on a large amount of experimental data. The static sub model without the gas flow expresses the energy conversion efficiency of ultrasonic gas transducers, and the dynamic sub model with the gas flow reflects the energy attenuation pattern following the flow rate variations. The mathematical model can be used to determine the minimum energy of the excitation signal for meeting the requirement of specific measurement range, and predict the maximum measurable flow rate in the case of fixed energy of excitation signal. Based on the above studies, a method to enhance the excitation signal energy is proposed under the output power of the transmitting circuit being a finite value so as to extend the measurement rage of ultrasonic gas flow-meter.

Measurement of transitional flow in pipes using ultrasonic flowmeters

The accuracy of an ultrasonic flowmeter depends on the ratio k of average profile velocity of pipe and average velocity of an ultrasonic propagation path. But there is no appropriate method of calculating k for transition flow. In this paper, the velocity field of the transition flow in a pipe is measured by particle image velocimetry. On this basis, the k of U-shaped and V-shaped ultrasonic flowmeter is obtained when Reynolds number is between 2000 and 20 000. It is shown that the k is constant when the Reynolds number is in the range of 2000–2400 and 5400–20 000, and the k decreases with the increasing of Re when the Reynolds number is 2400–5400. The results of study can be used to improve the measurement accuracy of ultrasonic flowmeters when flow is transition flow and can provide help for the study of pipe flow.

Numerical Simulating Nonlinear Effects of Ultrasonic Propagation on High-speed Ultrasonic Gas Flow Measurement

The effects of nonlinear ultrasonic propagation on high-speed ultrasonic gas flow measurement are analyzed based on the sound line equation derived from Snell's geometric acoustic law. A math ematical model for the ultrasonic propagation path in ultrasonic flowmeter pipe is built, and the relationship between x and r is calcula ted by MATLAB programming and ode45 simulating. The ultrasonic propagation path at the flow rate of 3 � 30m/s is simulated in the assumed boundary conditions of the pipeline, transducer installation and fluid state. It shows that the nonlinear propagation characte ristics cause the large deviations of the position of received ultrasonic waves in conditions of different flow rates, which strongly aff ects the stability and accuracy of flow measurement. The simulated offset data of the receiving position are useful for the high-s peed gas ultrasonic flowmeter installation and dry calibration on clamp-on ultrasonic flowmeters.

The direct numerical simulation of pipe flow

The conservative difference scheme and the third-order Runge-Kutta scheme in combination with the the Crank-Nicholson scheme are used to directly simulate the flow field in a pipe with the Reynolds number of 2 600. The flow field, including the velocity distribution and the turbulence intensity, is obtained by the direct numerical simulation. From the calculated results, the ratio of the linear average velocity along the ultrasonic propagation path to the profile average velocity on the pipe cross-section is also obtained in an ultrasonic flow meter. It is concluded that the direct numerical simulation method can be used to study the ratio of the profile-linear average velocity at low Reynolds number conditions in the transition region and to improve the measurement accuracy of the ultrasonic flow meter.

High heat flux point source sensitivity and localization analysis for an ultrasonic sensor array

State estimation procedures using the extended Kalman filter are investigated for a transient heat transfer problem in which a high heat flux point source is applied on one side of a thin plate and ultrasonic pulse time of flight is measured between spatially separated transducers on the opposite side of the plate. This work is an integral part of an effort to develop a system capable of locating the boundary layer transition region on a hypersonic vehicle aeroshell. Results from thermal conduction experiments involving one-way ultrasonic pulse time of flight measurements are presented. Uncertainties in the experiments and sensitivity to heating source location are discussed. One key finding is that sensitivity to heating source location is greater in the direction normal to the ultrasonic pulse propagation path. Scaled sensitivities to boundary conditions and thermal conductivity are presented and analyzed for all possible source locations using a square sensor grid. While sensitivity to the primary heat flux was determined to be the highest, sensitivity to the other parameters is either on the same order of magnitude or one order of magnitude less. Two different measurement models are compared for heating source localization: (1) directly using the one-way ultrasonic pulse time of flight as the measurement vector and (2) indirectly obtaining distance from the one-way ultrasonic pulse time of flight and then using these obtained distances as the measurement vector in the extended Kalman filter. Heating source localization results and convergence behavior are compared for the two measurement models. Two areas of sensitivity analyses are presented: (1) heat source location relative to sensor array position, and (2) sensor noise. The direct measurement model produced the best results when considering accuracy of converged solution, ability to converge to the correct solution given different initial guesses, and smoothness of convergence behavior.

Temperature distribution and wind vector measurement using ultrasonic CT based on the time of flight detection

In this paper, a measurement method for cross-sectional temperature and wind velocity distribution is addressed. A novel method based on an acoustic computer tomography (CT) technique is proposed. Specifically, the temperature and the wind velocity distributions are estimated simultaneously using the time of flight data of many ultrasonic propagation paths. The temperature and the wind velocity effects can be distinguished by considering sum and difference in the times of the flight data. Two types of projection data, temperature-oriented data and wind-velocity-oriented data, components are obtained. A filtered back-projection (FBP) method and iterative method are applied to reconstruct the temperature and the wind velocity distributions, respectively. An experimental system is designed and fabricated to realize simultaneous temperature and wind velocity distribution measurements. Through this system, the effectiveness of the proposed measurement method is confirmed.

A study of ultrasonic propagation for ultrasonic flow rate measurement

For the purpose of accurate flow measurement, an automatic three-dimensional (3D) sound field measurement system has been developed, and an experimental study has been conducted on ultrasonic properties. By using this system, ultrasonic sound pressure distributions and radiation angles in water have been measured. According to Snell’s law, the ultrasonic transmission properties can be obtained on the basis of incidence angle, acoustic impedance, basic frequency of ultrasound, and material and thickness of the metallic plate. However, this law cannot be applied to certain cases where an ultrasonic incident wave passes through a metallic plate and turns into a longitudinal wave, a shear wave and a Lamb wave. Consequently, the ultrasonic propagation paths have been investigated experimentally at various angles of incidence. From the experiments, it was confirmed that the ultrasonic beam paths change with incidence angles. Hence, the most suitable incidence angle has been determined from the result of measurements. Velocity measurements using an ultrasonic velocity profiler were made at various incidence angles. The accuracy of measuring flow rates changed with the incidence angles. The optimal incidence angle determined from 3D field measurements was found to yield the most accurate flow rates.

21416 超音波流速分布式流量計測法に関する基礎研究 : 金属平板透過における超音波伝播特性(せん断流の計測,OS.4 流れの計測と制御)

The purpose of this study is to measure flow rates with high accuracy by using ultrasound. Experimental study has been conducted on ultrasonic properties which are necessary for the measurement. An automatic measurement system which can measure spatial-temporal sound pressure distributions has been developed. According to Snell's law, the ultrasonic propagation paths can be obtained on the basis of incidence angle, acoustic impedance, basic frequency of ultrasound, and material and thickness of metallic plate. However this law can't be applied to certain cases where an ultrasonic incident wave passes through a metallic plate and turns into a longitudinal wave, a shear wave and a Lamb wave. Consequently the ultrasonic propagation paths have been investigated experimentally at various angles of incidence and plate thickness. The most suitable incidence angle has been determined from the result of measurements, and flow rates will be measured.

Quantitative evaluation of trigger‐pulse reflected waves in supersonic extracorporeal shock‐wave lithotriptor

AbstractAs one method to prevent the mis‐shot in the supersonic extracorporeal lithotriptor, there is a system in which the trigger pulse is emitted to ensure that a calculus exists in the focal region. This paper discusses the propagation of the trigger pulse within the body in this type of system, using the finite‐difference time‐domain method.In this paper, the scattering and reflection of the pulse is analyzed when a calculus is placed in the focal region of the ultrasonic propagation paths. Then, a calculus is assumed to be shifted gradually from the focal region and the change of the reflection is examined in relation to the operation of the trigger‐pulse systems.Finally, the case is considered where a calculus exists in the focal region and there exists a bony structure (called bone) near the pulse propagation paths. the propagation, scattering and reflection of the pulse is examined, and the effect of the position of the bone on the behavior of the trigger pulse is evaluated quantitatively and investigated.