Ultrasonic Attenuation Coefficient Research Articles

Ultrasonic Non-Destructive Testing on Fast-Charging Lithium-Ion Battery’s Capacity Fading

Fast charging technology provides a solution to the issue of charging time for power supplies with long life requirements. However, it will shorten the charging period while also hastening the power battery’s capacity degradation, reducing its service life. The ultrasonic inspection technique has been widely used for the internal structure detection and reaction process characterisation of lithium-ion batteries because of its nondestructive testing properties. This paper presents a method for monitoring the capacity attenuation of a fast-charging battery by calculating the ultrasonic attenuation coefficient α. The experimental findings indicate that the battery’s capacity is more vulnerable to lithium plating during high-rate charging. The parameter α can be employed to illustrate the energy dissipation characteristics of sound as it propagates through the electrode. Moreover, the inhomogeneous ageing of battery electrode material is observed and quantified based on the differences in acoustic signals, which provides new insights into battery health management and uneven ageing assessment.

Multiple ultrasonic parametric imaging for the detection and monitoring of high-intensity focused ultrasound ablation

Numerous quantitative ultrasound imaging techniques have demonstrated superior monitoring performance for thermal ablation when compared to conventional ultrasonic B-mode imaging. However, the absence of comparative studies involving various quantitative ultrasound imaging techniques hinders further clinical exploration. In this study, we simultaneously reconstructed ultrasonic Nakagami imaging, ultrasonic horizontally normalized Shannon entropy (hNSE) imaging, and ultrasonic differential attenuation coefficient intercept (DACI) imaging from ultrasound backscattered envelope data collected during high-intensity focused ultrasound ablation treatment. We comprehensively investigated their performance differences through qualitative and quantitative analyses, including the calculation of contrast-to-noise ratios (CNR) for ultrasonic images, receiver operating characteristic (ROC) analysis with corresponding indicators, the analysis of lesion area fitting relationships, and computational time consumption comparison. The mean CNR of hNSE imaging was 10.98 ± 4.48 dB, significantly surpassing the 3.82 ± 1.40 dB (p < 0.001, statistically significant) of Nakagami imaging and the 2.45 ± 0.74 dB (p < 0.001, statistically significant) of DACI imaging. This substantial difference underscores that hNSE imaging offers the highest contrast resolution for lesion recognition. Furthermore, we evaluated the ability of multiple ultrasonic parametric imaging to detect thermal ablation lesions using ROC curves. The area under the curve (AUC) for hNSE was 0.874, exceeding the values of 0.848 for Nakagami imaging and 0.832 for DACI imaging. Additionally, hNSE imaging exhibited the strongest linear correlation coefficient (R = 0.92) in the comparison of lesion area fitting, outperforming Nakagami imaging (R = 0.87) and DACI imaging (R = 0.85). hNSE imaging also performs best in real-time monitoring with each frame taking 6.38 s among multiple ultrasonic parametric imaging. Our findings unequivocally demonstrate that hNSE imaging excels in monitoring HIFU ablation treatment and holds the greatest potential for further clinical exploration.

Relation between quadrupole ultrasonic resonance and shear viscoelasticity of polymer droplets with different glass transition temperatures

Abstract When observing the ultrasonic signal transmitted through a suspension of particles dispersed in a liquid, a peak is observed in the frequency spectrum of the attenuation coefficient of the ultrasonic energy. This peak mainly reflects shear elasticity, even though longitudinal ultrasound is used. Hence, the shear modulus of a single particle dispersed in a liquid can be obtained in a non-contact manner. In this study, we used ultrasound to analyze the process of polymer particle formation from an oil-in-water emulsion, in which a polymer solution containing an organic solvent is used as the oil phase, and the organic solvent is evaporated in water. Furthermore, the liquid-to-solid transition was quantified for microparticles consisting of various polymeric materials (liquid, rubber, and glass), and the relationship between the glass transition temperature, peak behavior of ultrasonic attenuation coefficient, and shear modulus was clarified.

Molecular Interaction Study in the Binary Liquid Mixture of PEO and DMF by Ultrasonic Technique

The non‐destructive ultrasonic technique is a great employ for knowing the solute–solvent interaction in the polymer blend. By the ultrasonic velocity and attenuation evaluation, the visco‐elastic behaviors of the polymer solution have been assessed and compared with the results of conventional dynamic mechanical analysis. In the present research work, a comprehensive ultrasonic investigation of molecular interaction in a polymeric mixture of Poly (ethylene oxide) PEO and dimethyformamide (DMF) at 333 K has been executed by using the information provided by the literature. For this purpose, ultrasonic waves of two different frequencies such as 2 and 5 MHz have been implemented. Several acoustical parameters such as adiabatic compressibility, acoustic impedance, relaxation time, and ultrasonic attenuation coefficient (𝛼/𝑓2) are explored. Thermodynamic parameters like relative association and intermolecular free path length are also estimated. The evaluated values have been associated with the previous experimental results. The non‐ideal approach of the solution is analyzed and discussed in detail.

Effects of porosity on ultrasonic attenuation coefficient, shear properties and failure mechanisms of CF/EP laminates

Carbon fiber reinforced epoxy composite (CF/EP) laminates with porosity ranged from 0% to 2.5% were prepared under inadequate curing pressures, and then applied to ultrasonic, metallographic and mechanical testings. Porosity was evaluated using an ultrasonic attenuation model, which was established by taking consideration of surface losses, material attenuation coefficient and void attenuation coefficient. Shear properties were determined via short beam shear (SBS) method and porosity-related failure mechanisms were characterized using ultrasonic B-Scan and metallographic analysis. The results show that there is a third-order polynomial correlation between porosity level and ultrasonic attenuation coefficient. The shear strength approximately drops by 15%, 30%, 40% and 45% with porosity level up to 1.0%, 1.5%, 2.0% and 2.5% respectively. The detrimental effects of Porosity can be attributed to the reduced bonding area between plies or among fiber-resin area as well as the crack initiation and propagation.

Experimental Investigation on Pore-Fracture Variations in Coal Affected by Carbon Disulfide.

Solvent treatment is an effective technique to stimulate pore and fracture growth in low-permeability coal seams and improve the efficiency of methane extraction. Adopting the nuclear magnetic resonance test, liquid nitrogen adsorption analysis, ultrasonic test, and CT scanning, pore variation and fracture development in lignite, bituminous coal, and anthracite after carbon disulfide treatment were analyzed. Full-scale pore size distribution characteristics were obtained. The Frenkel-Halsey-Hill model was adopted to analyze pore fractal properties. Experiment results show that carbon disulfide could increase coal porosity. Lignite showed the best pore alteration effect, with a porosity increase of 34.10%, followed by bituminous coal with a porosity increase of 14.55%, while anthracite had a slightly weaker change with only 0.91% porosity growth. The pore diameter distribution range of treated coal expanded from 0-450 to 0-1000 μm. The average pore diameter rose from 316 to 483 μm, with better connectivity between pores. After treatment, the proportions of micropore specific surface areas (SSA) in three coal samples decreased but the ratios of small pore and medium pore SSA increased. Fractal dimension D1 of lignite and bituminous coal decreased by 5.669 and 0.054%, while D1 of anthracite increased by 22.407%. D2 reduced by 0.599, 3.143, and 1.262%, respectively. Raw coal had the maximum porosity near both ends of the CT section. Porosity of lignite was the largest at the ends after treatment. Surface porosity inside coal samples also rose from about 0.1 in raw coal to approximately 0.4 after treatment. Ultrasonic velocity in lignite decreased by 50.16% due to solvent treatment. Increases in ultrasonic attenuation coefficient α and ultrasonic attenuation ratio β indicate good fracture development. Furthermore, development degrees of lignite and bituminous coal are higher than that of anthracite. Results of the above methods verify with each other, indicating the effectiveness of carbon disulfide treatment in improving pore and fracture structures. The outcomes of this research could offer a theoretical basis for chemical permeability-enhancement technology.

Theoretical Investigation on Thermal, Mechanical and Ultrasonic Properties of Zirconium Metal with Pressure

Zirconium (Zr), a metal with an hcp structure, has been investigated for the transmission of acoustic wave in the 0 to 25 GPa operating pressure. For this, the Lennard-Jones interaction potential approach has been used to estimate the higher order elastic coefficients (SOECs and TOECs). This model is used to calculate the 2nd and 3rd order elastic parameters for zirconium metal. With the help of SOECs, other elastic moduli such as bulk modulus (B), Young’s modulus (Y) and shear modulus (G) have been calculated for Zr metal using Voigt-Reuss-Hill (VRH) approximations. Later, applying SOECs as well as zirconium density under the same pressure range, three orientation dependent acoustic velocities, comprising Debye average velocities, have been studied. Basic thermal characteristics such as specific heat at constant volume, thermal conductivity associated with lattice, thermal energy density, thermal relaxation time as well as acoustic coupling coefficients of zirconium metal have been also calculated at same pressure range. The computation is also satisfactory in estimating the ultrasonic attenuation coefficients, arises due to the interaction of phonons, hardness as well as melting temperature under various pressures in this research work.

Evaluation of corrosion resistance of 316L stainless steel by laser ultrasonic nondestructive testing technology

At present, the corrosion resistance of materials such as 316L stainless steel is mainly tested by electrochemical testing, which is time-consuming, laborious and environmentally unfriendly. In this paper, the laser ultrasonic detection technology, which is a rapid, non-destructive, pollution-free microstructure and corrosion resistance evaluation method is used for the detection of 316L stainless steel, and the ultrasonic signals are filtered by the wavelet threshold denoising method. The results show that the laser ultrasonic attenuation coefficient obtained by the wavelet threshold denoising signal processing method has a good correlation with the corrosion resistance of 316L stainless steel. A laser ultrasonic potential evaluation model was established based on the passivation film rupture potential and ultrasonic attenuation coefficient. The average relative error of the evaluation model for corrosion resistance of 316L stainless steel is less than 5.00%. The relative error of corrosion resistance evaluated by the laser-receiving method is lower than that by the probe-receiving method. It is feasible to nondestructive evaluation of the corrosion resistance of 316L stainless steel by laser ultrasonic technology.

Simultaneous imaging of ultrasonic relative backscatter and attenuation coefficients for quantitative liver steatosis assessment

Prevalence of liver disease is continuously increasing and nonalcoholic fatty liver disease (NAFLD) is the most common etiology. We present an approach to detect the progression of liver steatosis based on quantitative ultrasound (QUS) imaging. This study was performed on a group of 55 rats that were subjected to a control or methionine and choline deficient (MCD) diet known to induce NAFLD. Ultrasound (US) measurements were performed at 2 and 6 weeks. Thereafter, animals were humanely euthanized and livers excised for histological analysis. Relative backscatter and attenuation coefficients were simultaneously estimated from the US data and envelope signal-to-noise ratio was calculated to train a regression model for: (1) fat fraction percentage estimation and (2) performing classification according to Brunt’s criteria in grades (0 <5%; 1, 5–33%; 2, >33–66%; 3, >66%) of liver steatosis. The trained regression model achieved an R^2 of 0.97 (p-value < 0.01) and a RMSE of 3.64. Moreover, the classification task reached an accuracy of 94.55%. Our results suggest that in vivo QUS is a promising noninvasive imaging modality for the early assessment of NAFLD.

Ultrasonic characteristics and equivalent crack width of coal and rock bodies around boreholes during progressive failure.

The ultrasonic characteristics of the coal and rock bodies around boreholes during failure are closely related to the crack propagation law. To investigate the ultrasonic characteristics and crack propagation law of coal and rock bodies around boreholes, different grouting samples with boreholes were taken to carry out ultrasonic test during progressive failure. The ultrasonic amplitude, velocity and attenuation coefficient of the samples were analyzed. According to the ultrasonic time difference formula, the equivalent crack width of the sample during the failure process is calculated. The influence of grouting material on the crack propagation law is quantitatively analyzed. The results show that: (1) The peak stress, elastic energy at the peak, ultrasonic parameters and crack propagation of the coal and rock bodies around boreholes show obvious differences influenced by the strength of the grouting material. (2) During the loading process, the arrival time of the first wave of the sample with holes is 5μs later than that of the grouting sample, and the ultrasonic energy attenuates fastest in the time domain, and the coda wave is not developed. (3) During the progressive failure, the ultrasonic velocity and attenuation coefficient of all show three stages of stability(0~0.6σp), slow change(0.6σp~0.8σp) and rapid change(0.8σp~1.0σp). According to the "sudden decrease" of velocity and the "sudden increase" of attenuation coefficient to judge the crack propagation of sample. (4) The equivalent crack width of the sample increases exponentially with the increase of stress level. At the time of reaching the peak stress, the equivalent crack width of SH-BH increases about 0.027mm~0.032mm, SH-PU about 0.01mm~0.014mm, and SH-CEM about 0.002mm~0.006mm.

Evaluating acoustic and thermal properties of a plaque phantom.

The aim of this study is to evaluate the acoustic and thermal properties of a plaque phantom. This is very important for the effective implementation of ultrasound not only in diagnosis but especially in treatment for the future. An evaluation of acoustic and thermal properties of plaque phantoms to test their suitability mainly for ultrasound imaging and therapy was presented. The evaluation included measurements of the acoustic propagation speed using pulse-echo technique, ultrasonic attenuation coefficient using through transmission immersion technique, and absorption coefficient. Moreover, thermal properties (thermal conductivity, volumetric specific heat capacity and thermal diffusivity) were measured with the transient method using a needle probe. It was shown that acoustic and thermal properties of atherosclerotic plaque phantoms fall well within the range of reported values for atherosclerotic plaque and slightly different for thermal diffusivity and volumetric specific heat capacity for soft tissues. The mean value of acoustic and thermal properties and their standard deviation of plaque phantoms were 1523 ± 23m/s for acoustic speed, 0.50 ± 0.02W/mK for thermal conductivity, 0.30 ± 0.21db/cm-MHz for ultrasonic absorption coefficient and 1.63 ± 0.46db/cm-MHz for ultrasonic attenuation coefficient. This study demonstrated that acoustic and thermal properties of atherosclerotic plaque phantoms were within the range of reported values. Future studies should be focused on the optimum recipe of the atherosclerotic plaque phantoms that mimics the human atherosclerotic plaque (agar 4% w/v, gypsum 10% w/v and butter 10% w/v) and can be used for HIFU therapy.

Rheometeric, ultrasonic and acoustical shielding properties of Cu-alloy/silicone rubber composites for electronic applications

Silicone rubber (SR) is a highly adaptable material that is attractive for a variety of applications, including electronics, construction, and aerospace. In general, adding Cu-Al-Zn alloy to the SR matrix improved the mechanical properties of rubber composites and noise attenuation. The mechanical, magnetic, ultrasonic, and acoustic characteristics of the resulting SR-composites were characterized. According to variations in treated Cu-alloy loading, ultrasonic measurements were performed as the ultrasonic velocities, Poisson’s ratio, Young’s modulus, acoustic impedance, ultrasonic attenuation coefficient, and micro-hardness. Results indicated that adding treated Cu-alloy to SR-composites improves them significantly. They showed that curing time decreases gradually, tensile strength increases constantly and elongation at break of SR-composites has maximum value at 15% treated Cu-alloy. The coupling agent 3-(Trimethoxysilyl) propyl methacrylate (TMSPM) improves the mechanical properties of the composites by forming a network structure in the SR matrix and enhancing the interfacial interaction between the Cu-alloy and the SR matrix. The acoustic sound absorption coefficient, reflection coefficient, and damping factor calculations were studied in addition to the decibel drop ranging from 0.4–4.9 dB. The composite sample SR-4 is considered to have the optimal percentage of the selected acoustic properties studied. Thus, the shielding efficiency of SR-composite increased with increasing content of Cu-alloy which makes it applicable in ear plugs and electronic applications.

Study on ultrasonic attenuation characteristics in air-droplet two-phase flow

The wetness of exhaust steam in nuclear power plant steam turbine is an important index to evaluate the safety and economy of nuclear power plant and the ultrasonic attenuation method has the advantages of quick response and non-contact in the steam wetness measurement of nuclear power plant steam turbine. The saturated steam-droplet medium and the air-droplet medium have many similar thermal fluid characteristics, in order to simplify the experiment, the air-droplet two-phase flow is used to simulate the wet steam discharged from steam turbine of nuclear power plant, and the ultrasonic attenuation coefficient in the air-droplet two-phase flow is measured. The correlation between wetness and ultrasonic attenuation coefficient was studied by calibrating the wetness of the air-droplet two-phase flow and measuring the ultrasonic attenuation coefficient under different wetness conditions. Meanwhile, the static characteristics of ultrasonic transducer and the influence of flow velocity on attenuation coefficient are studied experimentally. According to the results of experiment and numerical calculation, the ultrasonic attenuation coefficient is very sensitive to the change of wetness. The ultrasonic attenuation coefficient and wetness has a good linear relationship in the wetness range (0–16%), the ultrasonic attenuation method is appropriate for the wetness measurement of turbine steam exhaust and has high precision when the droplet size is stable.

Experimental investigation on pores and permeability variation characteristics of coal treated by chemical solvents

Enhancing coal permeability by adopting chemical solvents treatment is one of the most effective methods to improve coalbed methane production efficiency in deep coal reservoirs with low permeability. However, coal pores and permeability variation characteristics affected by chemical solvents is not quantitatively determined. In this study, after being treated with carbon disulfide (CS2), acetone (C3H6O) and N-methyl pyrrolidone (NMP), changes in coal ultrasonic characteristics were investigated. Relationship between ultrasonic parameter variations and coal fracture development was revealed. Meanwhile, through adopting nuclear magnetic resonance (NMR) and permeability testing equipment, coal pore structure, porosity and permeability changes were studied. Results show that after treated by three chemical solvents, ultrasonic velocity in coal reduces by 7.7%–51.2%, while ultrasonic attenuation coefficient increases by 4.22dB/m-123.8 dB/m, indicating that coal fractures experience good development. Moreover, NMR signal quantity of treated coal under saturated state rises significantly, with big growth in mesopore and macropore peaks. Compared with NMP and acetone, CS2-treated coal porosity experiences the maximum increase of 7.71%, while the corresponding permeability growth is also the largest of 69.565 × 10−15m2. Permeability changes obtained from NMP calculation model is basically consistent with that acquired by lab measurement. Furthermore, changes in extraction rate, ultrasonic parameters, pore fracture characteristics and permeability results of solvent-treated coal are mutually consistent. This verifies that chemical solvents could dissolve molecular substances in coal, effectively increase primary fractures and change small pores to mesopores and macropores, as well as improving pore connectivity. As a result, coalbed methane extraction performance is expected to be enhanced due to increased coal permeability.

Preparation of polyvinyl acetate composite as a new backing material for the manufacture of ultrasonic transducers

Polyvinyl acetate (PVAc) composites were loaded with varying amounts of nano-metal alloy (Ag–Sn–Cu–Pt) and stearic acid. They are used as backing materials for ultrasonic transducers to prevent back-echoes from reverberating into the piezoelectric element and to reduce noisy echoes. The novelty of this work is the usage of these newly prepared PVAc/alloy composites as backing material in ultrasonic transducers with a polyvinylidene fluoride (PVDF) active element. The X-ray diffraction (XRD) technique was used to examine the structure of the composites. The ultrasonic technique investigated the ultrasonic attenuation coefficient, the acoustic impedance, the mechanical properties, and other parameters. The transducers with the new backing composites gained high sensitivity, broadband, short ringing, and so on. These characteristics were improved by increasing the nano-metal alloy content in the backing composites. The study also proved the efficiency of the PVAc/alloy composite as new backing material in ultrasonic transducers.Graphical abstractSketch of fabricated ultrasonic transducers with backing materials from PVAc/alloy composites (B1, B2, B3, B4, B5, and B6) and their important features (BW is transducers’ band width and S is transducers’ sensitivity).

An ultrasound-based monitoring of kaolinite flocculent settling processes

In order to implement real-time monitoring of flocculent settling processes, an ultrasonic method based on the ECAH model was proposed and studied, particularly by considering the influence of particle irregularity on sound attenuation. Numerical simulations were conducted to evaluate the influence of critical physical parameters’ variation on the attenuation coefficient. Meanwhile, an integrated experimental system including ultrasonic measurement, interface settling velocity measurement, microscopic imaging and online sampling methods was established. The experiments of kaolinite particle suspensions with four different initial mass concentrations were carried out, and the phenomenon of flocculation and settling was observed accordingly. The duration of each settling stage and its change rate were analyzed simultaneously by both the interface settling velocity and ultrasonic attenuation coefficient. The analysis results show that for the same flocculent settling stage, the relative deviation of duration obtained by two methods above were 0%, 7.32%, −10.57%, 1.62% and 1.63%, respectively. The mechanisms and characteristics of each stage in the precipitation process were discussed in detail. At the same time, the volume concentrations obtained by ultrasonic method were compared with the results of weighing after on-line sampling. The deviations under the four initial mass concentrations were 18.6%, 12.1%, 11.0% and 13.2% respectively. The correlation between the process of flocculation and ultrasonic parameters was established accordingly, which provided data support for the application of ultrasonic technique to the online detection of kaolinite particle flocculent settling processes.

Ultrasonic Attenuation of Ceramic and Inorganic Materials Using the Through-Transmission Method

Ultrasonic attenuation coefficients of ceramic and inorganic materials were determined for the longitudinal and transverse wave modes. Sample materials included hard and soft ceramics, common ceramics, ceramic-matrix composites, mortars, silicate glasses, rocks, minerals and crystals. For ceramic attenuation measurements, a standardized method has existed, but this method based on a buffer-rod arrangement was found to be inconsistent, producing vastly different results. Resonant ultrasound spectroscopy was also found to be unworkable from its sample preparation requirements. Experimental reevaluation of the buffer-rod method showed its impracticality due to unpredictable reflectivity parameters, yielding mostly negative attenuation coefficients. In this work, attenuation tests relied on a through-transmission method, which incorporated a correction procedure for diffraction losses. Attenuation exhibited four types of frequency (f) dependence, i.e., linear, linear plus f4 (called Mason-McSkimin relation), f2 and f3. The first two types were the most often observed. Elastic constants of tested materials were also tabulated, including additional samples too small for attenuation tests. Observed levels of attenuation coefficients will be useful for designing test methods for ultrasonic nondestructive evaluation and trends on ultrasonic attenuation are discussed in terms of available theories. However, many aspects of experimental findings remain unexplained and require future theoretical developments and detailed microstructural characterization. This study discovered a wide range of attenuation behaviors, indicating that the attenuation parameter can aid in characterizing the condition of intergranular boundaries in combination with imaging studies.

In Vivo Measurements of the Bulk Ultrasonic Attenuation Coefficient of Breast Tissue Using a Novel Phase-Insensitive Receiver.

This study describes the first in vivo acoustic attenuation measurements of breast tissue undertaken using a novel phase-insensitive detection technique employing a differential pyroelectric sensor. The operation of the sensor is thermal in nature, with its output signal being dictated by the acoustic power integrated over its surface. The particularly novel feature of the sensor lies in its differential principle of operation, which significantly enhances its immunity to background acoustic and vibration noise. A large area variant of the sensor was used to detect ultrasonic energy generated by an array of 14 discrete 3.2-MHz plane piston transducers, transmitted through pendent breasts in water. The transduction and reception capability represent key parts of a prototype Quantitative Ultrasound Computed Tomography Test Facility developed at the National Physical Laboratory to study the efficacy of phase-insensitive ultrasound computed tomography of breast phantoms containing a range of appropriate inclusions, in particular, the measurement uncertainties associated with quantitative reconstructions of the acoustic attenuation coefficient. For this study, attenuation coefficient measurements were made using 1-D projections on 12 nominally healthy study volunteers, whose age ranged from 19 to 65 years. Averaged or bulk attenuation coefficient values were generated in the range 1.7-4.6 dBcm ^-1 at 3.2 MHz and have been compared with existing literature, derived from in vivo and ex vivo studies. Results are encouraging and indicate that the relatively simple technique could be applied as a robust method for assessing the properties of breast tissue, particularly the balance of fatty (adipose) and fibroglandular components.

Roughness correction method for the measurement of attenuation coefficient using contact transducers

The surface quality of a material significantly affects the accurate measurement of the ultrasonic attenuation coefficient. In this research, a roughness correction method for experimental calculation of the attenuation coefficient using contact transducers is proposed. Firstly, the losses due to the scattering from a rough interface are analysed. According to the mechanism of ultrasonic waves reflected from a thin layer between two solid media, the frequency-dependent reflection coefficient of the coupling interface involving a roughness parameter is derived based on the phase-screen approximation theory. Then, a compensation model is established to correct the error caused by the surface roughness. 304 stainless steel and 45 steel specimens with different levels of surface roughness are prepared and ultrasonic measurements are implemented using both the through-transmission and pulse-echo methods. The experimental results show that the proposed correction method can effectively eliminate the losses caused by surface roughness and improve the measurement accuracy of the attenuation coefficient.

Flow Pattern Identification of Oil-Water Two-Phase Flow Based on SVM Using Ultrasonic Testing Method.

A flow pattern identification method combining ultrasonic transmission attenuation with an ultrasonic reflection echo is proposed for oil–water two-phase flow in horizontal pipelines. Based on the finite element method, two-dimensional geometric simulation models of typical oil–water two-phase flow patterns are established, using multiphysics coupling simulation technology. An ultrasonic transducer test system of a horizontal pipeline with an inner 50 mm diameter was built, and flow pattern simulation experiments of oil–water two-phase flow were carried out in the tested field area. The simulation results show that the ultrasonic attenuation coefficient is extracted to identify the W/O&O/W dispersion flow using the ultrasonic transmission attenuation method, and the identification accuracy is 100%. By comparison, using the ultrasonic reflection echo method, the echo duration is extracted as an input feature vector of support vector machine (SVM), and the identification accuracy of the stratified flow and dispersed flow is 95.45%. It was proven that the method of the ultrasonic transmission attenuation principle combined with the ultrasonic reflection echo principle can identify oil–water two-phase flow patterns accurately and effectively, which provides a theoretical basis for the flow pattern identification of liquid–liquid multiphase flow.