Transmitting Voltage Response Research Articles

Design and evaluation of a new ultrasonic horn for viscosity reduction of heavy oil

Based on the basic principle of the sandwich piezoelectric transducer, a high-power ultrasonic horn which can be used for viscosity reduction of heavy oil and pour point reduction of crude oil with high pour point was proposed and designed. The basic frequency of the horn is 16.8 kHz, and the input electrical power is 1 kw. It can work continuously on the industrial scale. First, the impedance characteristic was derived for the simplified model of the sandwich piezoelectric horn on the basis of equivalent network method. Second, its properties such as the resonance frequency, conductance, and transmitting voltage response were simulated by using of ANSYSsoftware in air, water, and silicone oil, respectively. According to the simulation, a prototype was made and measured by an impedance analyzer. Its basic frequency is in good agreement with the simulation calculation. The result shows that this high-power ultrasonic horn is expected to be applied on the industrial scale in viscosity reduction of heavy oil and ultrasonic sludge disintegration.

Design and tests of an acoustoelectric logging tool

The acoustoelectric logging is a developing method, and the logging method can interpret the seepage properties of the pore formation especially, such as permeability and so on. A new acoustoelectric logging tool is presented. The tool is composed of two acoustic transmitting transducers, three acoustic receiving transducers, two excitation electrodes, and four receiving electrodes. The transmitting transducers can work in a phased mode, and more radiant energy can be effectively generated. The acoustic radiant energy is a very important factor for the acoustoelectric logging tool, and measurements are conducted in an anechoic tank with dimensions of 5.0 m × 5.0 m × 4.0 m. The pulse width of excitation signals is 70μs, and the peak value is above 3000 V. The main frequency of receiving waves is 9.52 kHz, sound pressure is 47.2 kPa, and transmitting voltage response level is 147.5 dB. The tool is tested in the experimental wells and exploration wells. While the acoustic transmitting transducers radiate acoustic excitation signals, acoustoelectric signals from interfaces and concomitant acoustoelectric signals with acoustic waves are all acquired in clastic rock formations.

Underwater characterizations of monolithic piezoceramic and 1–3 composite using a self-designed transducer

Underwater characterizations of (Pb 0.94 Sr 0.04 )(Zr 0.52 Ti 0.48 )O 3 (PZT) and PZT/araldite-F 1–3 composite were carried out through a self-designed transducer. Disc-shaped samples of bulk PZT and PZT/araldite-F composite were first characterized in air and then were assembled in the transducer individually. The transducer’s underwater voltage receiving sensitivity ( S h ) and transmitting voltage response ( S v ) were investigated in the frequency range of 10–200 kHz (well below thickness mode resonance) using a calibrated projector and receiver method with pulse technique. Results revealed that the transducer made with composite sample exhibited better ( S h ) values (−214 dB ref 1 V/ µ Pa) due to ~295% higher piezoelectric voltage coefficient g h (30 × 10 −3 Vm/N) of the composite compared to PZT. In addition, the transducer with the PZT sample showed better S v values (80 dB ref 1 µ Pa/1 V at 1 m) due to the presence of planar mode peaks in the frequency range of 10–200 kHz. These results indicate that the monolithic piezoceramic can exhibit underwater S v response in both planar and thickness resonance modes owing to the admittance peaks in these frequency regions.

COMSOL Multiphysics Modeling of Architected Acoustic Transducers in Oil Drilling

ABSTRACTIn the oil and gas industry, acoustic transducers have been found to provide valuable geological sonic information such as compressional wave velocity, shear wave velocity, and rock formation slowness. These data can be used to indicate lithology, determine porosity, detect over-pressured formation zones, and check well to well correlation. One category of such acoustic transducers is equipped with piezoelectric elements. Conventional piezoelectric transducers are packaged by epoxy resin. Because of the liquid nature of uncured epoxy resin, it is difficult to position the piezoelectric elements accurately. The introduction of polyether ether ketone (PEEK) as the packaging material solved this issue. Due to the ease of machining on solid form, architectures of the composite acoustic transducers can be devised with great flexibility and creativity. These designs can be modeled with finite element methods (FEM) and the best design for the oil drilling application can be finalized and fabricated.COMSOL Multiphysics® solves problems in a programming environment that integrates relevant physics. In this case, it includes electrical circuit, solid mechanics, acoustics, and piezoelectricity. Here a compete model and procedure to study the performance of an architected composite acoustic transducer is provided. The displacement analysis gives insights into the resonance modes of the piezoelectric elements. The acoustics analysis gives the necessary information on the acoustic performance of the transducers, such as acoustic pressure spatial distribution, acoustic pressure frequency response, transmitting voltage response, and directivity. These are important criteria to judge the effectiveness of an architected transducer.

The research on piezoelectric cylindrical oscillating transducer for dipole acoustic logging

Acoustic transducer, which is a core component of acoustic logging tool, determines the development of acoustic logging technology. In order to realize the goal of dipole acoustic logging transducer with the features of low frequency, broadband and high radiation power, a cylindrical oscillating dipole acoustic transducer using an actuator of a group of different trilaminar piezoelectric bending bars is designed and studied. Modal and harmonic response analyses of the whole transducer are conducted by using the finite element method, including analyses of input conductance of transducer in air and water, transmitting voltage response and directivity patterns. Besides, the proposed transducer is fabricated and tested to compare with numerical simulation results. Moreover, the numerical results of the proposed transducer are compared with that of traditional dipole transducer. The comparison result indicates the proposed dipole transducer is characterized by low frequency, broadband, and high radiation power, which is feasible in the application of dipole acoustic logging.

A comparison between flexible disk transducer cavitation measurements and predictions

An investigation of the threshold of cavitation of flexible disk transducers used as underwater acoustic sources was conducted. The principal task was the estimation of the cavitation threshold in sound pressure level (SPL) of an individual transducer as a function of operating depth and the actual measurement of the cavitation threshold. The transducers under test were driven at a series of voltage levels, using CW pulse lengths of 50 and 100 ms. these drive voltages were increased in steps and the received signals were analyzed for total harmonic distortion (THD), transmitting voltage response (TVR), output SPL, and voltage-current phase angle, all as a function of depth. The onset of cavitation on the flex disk is well defined in terms of THD. Comparing the measured values for the onset of cavitation to those predicted by an expression recommended by Sherman and Butler, a value of the cavitation parameter, gamma, was determined to be about 0.36, consistent with, and bracketed by, their values, for a number of transducer shapes. predictions of cavitation threshold versus depth for the flexible disk transducer were within 1 to 2 dB of measured results.

Research and experimental testing of a new kind electrokinetic logging tool

We designed a new downhole electrokinetic logging tool based on numerical simulations and petrophysical experiments. Acoustic and electric receivers cannot be arranged at the same depth, and the proposed composite electrokinetic logging tool offers a solution to this problem. The sound field characteristics of the detectors were tested in a water tank in the laboratory. Then, we calculated the sound pressure of the radiated acoustic field and the transmitting voltage response of the transmitting transducers; in addition, we analyzed the directivity and application of the acoustic transmitting probe based on linear phased array. The results suggest that the sound pressure generated at 1500 mm spacing reaches up to 47.2 kPa and decreases with increasing acoustic source frequency. When the excitation signals delay time of adjacent acoustic transmitting subarrays increases, the radiation beam of the main lobe is deflected and its energy gradually increases, which presumably enhances the acoustoelectric conversion efficiency.

A Flextensional Transducer Prototype with PVDF Piezoelectric Film

This paper presents a prototype of a new flextensional transducer with PVDF (Polyvinylidene Fluoride) piezoelectric film instead of metallic shell. Resonance frequency, bandwidth, transmitting voltage response, and horizontal directivity of the flextensional transducer with PVDF piezoelectric film were respectively measured by using laser-scanning vibrometer, and underwater acoustic measurement system. Experimental results showed that the new transducer features effectively conversion from longitudinal vibration of piezoelectric stack into radial vibration of PVDF piezoelectric film.

Optimization of the Monopole Acoustic Transducer for Logging-while-Drilling

A new design idea for a monopole acoustic transducer which increases the frequency band and improves electromechanical performance is proposed with a focus on the lowest order of the radial and flexural modes. Numerical modeling of the resonance frequencies and electrical conductance are conducted with respect to the dimensions and material parameters of the proposed transducer. The transmitting voltage response level with respect to the density and velocity of the fluid media is calculated. The numerical simulation is validated through experiments. The frequency band and the electromechanical performance of the monopole acoustic transducer can be optimized by the given methods concluded from the numerical results.

The Study on Broad Directivity Characteristic of Piston Transducer with Finite Baffle

Transducer with large directivity and high transmitting sensitivity is designed and fabricated. It is a sandwich transducer with composite horn and it has a finite baffle. A novel model considering the dimension of baffle is deduced, the directivity of transducers are calculated under different conditions. The computations of models agree with the experimental data well. The maximum transmitting voltage response level of the sandwich transducer is 143dB (1V/μPa) and the directivity is up to 99°(-3dB) at the resonance frequency of 75.6kHz.

12 주파수의 48 tonpilz 진동소자를 이용한 광대역 초음파 모자이크 변환기의 대역폭 확장

This article describes the design and performance characteristics of a broadband ultrasonic mosaic transducer. We focus on the improved bandwidth in the high frequency band of a previously designed broadband ultrasonic transducer (Lee et al., 2014). The improvement in the pulse-echo bandwidth was achieved by employing twelve <TEX>$2{\times}2$</TEX> element subarrays, operating at different resonance frequencies, and utilizing the mosaic array concept. We found that the -6 dB and -12 dB bandwidths of the newly developed broadband ultrasonic mosaic transducer, were up to 155% and 170% of the previously designed model, with a quality factor of 1.71 and 1.25, respectively. The averaged TVR (transmitting voltage response), SRT (receiving sensitivity), and FOM (figure of merit) values in a nearly flat transmitting response band, from 45 to 105 kHz providing a -12 dB bandwith of 60 kHz, were 163.3 dB (re <TEX>$1{\mu}Pa/V$</TEX> at 1 m), -192.8 dB (re <TEX>$1V/{\mu}Pa$</TEX>), and -30.9 dB, respectively.

40-75 kHz의 주파수 범위에서 동작하는 광대역 초음파 변환기의 설계 및 개발

The objective of this study was to design and develop a broadband ultrasonic transducer that has both wide bandwidth and high sensitivity to measure broadband echoes related to identifying fish species. A broadband ultrasonic transducer providing a nearly flat transmitting response band of 40.2-75.5 kHz with a -12 dB bandwidth of 35.3 kHz was achieved by integrating 12 tonpilz transducer elements operating at different resonance frequencies. The average transmitting voltage response, receiving sensitivity, and figure of merit values in this frequency band were 168.4 dB (re <TEX>$1{\mu}Pa/V$</TEX> at 1 m), -196.8 dB (re <TEX>$1V/{\mu}Pa$</TEX>), and -28.4 dB, respectively. The results suggest that bandwidth and sensitivity can be widened and improved by adjusting the array pattern and the structure of tonpilz transducer elements.

Low frequency broadband submarine acoustic actuator based on cymbal transducer

Based on planar cymbal transducer array, a low frequency broadband submarine acoustic actuator is presented and analysed. Several kinds of prototype of cymbal transducer are fabricated, and the properties of this transducer are tested. Three prototypes of planar cymbal transducer array, with thickness <20 mm, used as acoustic actuator are built and tested. The measured transmitting voltage response of acoustic actuators are >130 dB re 1 μPa/V@1m and flat over the frequency range of 3–15 kHz. It is shown that this kind of acoustic actuator has thin, low frequency broadband; thus, it can be used as a high power submarine actuator with a working frequency <10 kHz. The experiment system of active control for attenuating acoustic reflection of underwater target is built and tested. The results show that the cymbal actuator acts as an active sound absorption device that can attenuate acoustic reflection on underwater target effectively.

수중 음향 트랜스듀서의 송수신 감도를 고려한 1-3형 압전복합체의 구조 최적화

The optimal structure of 1-3 piezocomposites has been determined by controlling polymer properties, ceramic volume fraction, thickness of composite and aspect ratio of the composite to maximize the TVR (transmitting voltage response), RVS (receiving voltage sensitivity) and FBW (fractional bandwidth) of underwater acoustic transducers. Influence of the design variables on the transducer performance was analyzed with equivalent circuits and the finite element method. When the piezocomposite is vibrating in a pure thickness mode, inter-pillar resonant modes are likely to occur between lattice-structured piezoceramic pillars and polymer matrix, which significantly deteriorate the performance of the piezocomposite. In this work, a new method to design the structure of the 1~3 type piezocomposite was proposed to maximize the TVR, RVS and FBW while preventing the occurrence of the inter-pillar modes. Genetic algorithm was used in the optimal design.

Development of Underwater Acoustic Transducer Using 1-3-2 Piezoelectric Composite

The flat transducer is composed of 1-3-2 piezoelectric composite and copper shell. The structure of transducer was determined according to design requirement and finite element analysis by ANSYS. The transducer was prepared by using a 25mm×25mm×4.8mm 1-3-2 composite chip, rigid foam backing, copper shell, polyurethane layer and acoaxial cable. The voltage response, source level, receiving voltage sensitivity and other performance were measured. The resonant frequency of transducer is 294kHz, the maximum transmitting voltage response is 159.6dB, 3dB bandwidth is 32kHz, source level is 208dB, receiving voltage sensitivity of the transducer is -203 ± 3dB in the frequency range of 50-250kHz frequency, the beam width of -3dB is 11º in the directivity.

도플러 속도계(DVL)를 위한 광대역 수중 음향 트랜스듀서

A broad-band underwater acoustic transducer that uses thickness vibration mode, derived from a disk type piezoelectric ceramic, has been proposed and designed for DVL (Doppler Velocity Log). Three different types of acoustic transducer were evaluated with respect to the transmitting voltage response, receiving voltage sensitivity and bandwidth of the transducer. The effect of the acoustic impedance matching layer and backing layer is discussed. The results demonstrated that three matching layer with lossy backing layer is the best configuration for underwater transducer. The trial underwater acoustic transducer with three matching layer has a frequency bandwidth of 55%, maximum transmitting voltage response of 200 dB and a maximum receiving voltage sensitivity of -187.3 dB.

Finite Element Analysis of Flextensional Transducer with Slotted Shell

The study of low frequency, small size transducer was an important aspect for the development of the underwater acoustic transducer. The Class Ⅳ flextensional transducer was a typical low frequency, high-power and small size transducer. For decreasing its resonant frequency in the case of small size, a flextensional transducer with slotted shell was analyzed using finite element software ANSYS. A comparison between the flextensioanl transducer with slotted shell and the Class Ⅳ flextensional transducer was made. The maximum size of the shell is 200mm. The transmitting voltage response of the transducer reaches to 131dB with resonant frequency 600Hz in water. The transducer could radiate at low frequency with small size of the shell.

Numerical analysis on the acoustic well logging transducers with various fluid load

It is numerically analyzed how the acoustic attributions of monopole well logging transducer change when excited in different fluid load media, such as water, silicone oil and mud with different components. The logging transducer is a radially polarized piezoelectric cylindrical tube with both ends shielded, being used as either transmitter or receiver. For the radially resonant mode of the transducer, the resonant frequency, transmitting voltage response and receiving sensitivity of the transducer are affected by the medium density and velocity. When the medium density is constant, the resonant frequency and the transmitting voltage response increase with the increasing of medium velocity, while the receiving sensitivity decrease with the increasing of medium velocity. When the medium velocity is constant, the resonant frequency decrease with the increasing of medium density, while the transmitting voltage response and receiving sensitivity increase with the increasing of medium density. For the given acoustic impedance, medium with different density and velocity have different effect on the transducer, which implies that the acoustic impedance of fluid load can't independently affect the acoustic attributions of transducer. The analysis results above have certain reference significance for the site operations of acoustic logging.

A free-flooded flextensional transducer with tube-beam coupling structure

The transducer consists of two annulus steel end plates, a tube stacked by piezoelectric rings as the driving element and a dual slotted concave aluminum shell coupled one end plate to the other. The shell has two concave parts and an annulus ring between them; and each part is equally slotted into several beams with gaps between each other. The tube and the beams form the tube-beam coupling structure. A sealing boot is covered on both inner surface of the stack and outer surface of the shell so that the water could freely flood through the ring stack. Some vibrating modes of the transducer including a cavity resonance are used to broaden the band. A prototype is fabricated and measured. The cavity resonant frequency is about 1250Hz with the transmitting voltage response of 130dB and the TVR fluctuates less than 6dB from 1800Hz to 5700Hz. This work was supported by the National Natural Science Foundation of China (No. 11074276).

Low frequency broadband monopole transducer based on trilaminar bender bar structures

A transducer which is produced by a skeleton and four Trilaminar bender bar vibration elements is presented in the paper. Four vibration elements formed a square array are excited by the same signal to realize monopole radiation. The influence of the skeleton is taken into account: flexural mode of vibration of the skeleton is used to extend the bandwidth. The transmitting voltage response of a modeling result shows that there are two peaks existed close to 1.8 kHz, which correspond to the 2nd order flexural mode of the Trilaminar bender bar and the 1st order flexural mode of the skeleton. The -3dB operational frequency range from 16.6kHz to 20.2kHz. The directivity patterns reflect that transducer can realize a monopole radiation in the horizontal plane before 13kHz.