共查询到19条相似文献,搜索用时 143 毫秒
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本文通过设计纵向水声换能器辐射头的形状及利用其弯曲振动模,实现宽带宽波束辐射特性,采用后质量块的嵌套结构有效缩小了换能器的长度。利用ANSYS有限元软件模拟了小型宽带宽波束纵向水声换能器的电声特性。研制了换能器样品,实现了与有限元模拟计算结果相一致的电声参数:谐振频率14kHz,最大发射电压响应141.9dB,-3dB带宽为11.3~18.7kHz,-3dB带通Q值为1.9,在14kHz频率下波束宽度为132°,比通常纵向换能器波束宽度宽23%。 相似文献
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高频宽波束换能器已广泛应用于潜水员探测、海港监测以及水下避障等多方面。通过解析法以及有限元法分析,设计制作了一种球冠形复合材料换能器,其300 kHz的水平及垂直指向性均大于46°,制作工艺简单,具有高频宽波束的技术优势。 相似文献
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无障板圆形活塞换能器波束特性建模 总被引:2,自引:0,他引:2
针对ka<π时无障板活塞声源波束特性不能用无限平面障板活塞换能器理论进行描述的问题,提出一种基于有限元方法结合曲线拟合的简便数学建模方法.模型采用了无限平面障板活塞换能器理论的基本函数表达,通过增加修正因子函数来改变模型的细节部分,用曲线拟合方法给出了较准确的两个修正因子函数的数学表达式。最终建立了无障板圆形活塞换能器波束特性经验公式模型,模型在ka为0.03~5.2范围内与有限元方法给出的波束曲线相一致,并且在ka取更大值时与无限平面障板活塞换能器理论公式等效. 相似文献
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本文中介绍了一个可以实现大角度波束扫描的宽带平面声基阵,设计了纵向振动与换能器前盖板弯曲振动相复合的宽带换能器作为基元,保证了基阵具有较好的宽带性能。针对基元的自然指向性难以满足平面阵进行大角度波束扫描的要求,本文中采用通道型橡胶反声障板技术来拓宽阵上换能器的单元指向性,从而实现平面声基阵的大角度、宽带波束扫描。在有限元和边界元进行优化设计的基础上,制作了实验样阵。测试数据表明:在工作频段内换能器响应起伏不超过3 dB,12 kHz时阵上基元指向性达到了140°,基阵-3 dB波束覆盖范围可以达到144.4°,最大旁瓣不超过30%。 相似文献
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为了处理水声信号,声纳阵列通常需要形成宽频带恒定束宽的波束。采用两种阵元加权方法分析二维圆弧形恒定束宽换能器声纳阵列:球面Legendre函数加权方法和柱面Legendre函数加权方法。分别对球面阵、柱面阵和平面阵这三种几何结构的声纳阵列进行分析,并且计算波束宽度和波束方向。结果表明,在宽频带范围内,除了柱面Legendre函数加权的球面阵之外,其余Legendre函数加权的声纳阵列均能利用简单的、不随频率变化的阵元权重和阵元延时,形成恒定束宽的波束,并且具有较小的旁瓣,此外波束方向与预设方向也较为一致。相对于其他恒定束宽波束形成方法,Legendre函数加权方法能利用较低的计算复杂度来实现良好的宽频带恒定束宽的波束特性。 相似文献
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文章综述了几种典型结构水声换能器近些年的新发展,包括:弯张换能器、圆柱面辐射型换能器、纵向换能器等等,主要介绍这些结构类型水声换能器的设计新思想和多方面优化改进的新成果。 相似文献
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L.A.A. Warnes 《Ultrasonics》1982,20(4):184-188
A simple acoustic Fresnel lens is described, which, when used with a plane array of sonar transducer elements, produces a wide beam in azimuth. Test results are compared to computed beam plots and good agreement between theory and measurement was found when all the array elements were in phase. When alternate zones are 180° out of phase, the lens can be reduced in thickness as the step height is halved; however, more careful placing of the transducer elements is required. Such a reduction in lens thickness could be desirable at low operating frequencies, or if a very wide sound beam is desired. 相似文献
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A nonparaxial multi-Gaussian beam model based on the rectangular aperture is proposed in order to overcome the limitation of paraxial Gaussian beam model which losing accuracy in off-axis beam fields. With the method, acoustical field generated by an ultrasonic linear phased array transducer is calculated and compared with the corresponding field obtained by Rayleigh-Sommerfeld integral, paraxial multi-Gaussian beam model, and Fraunhoffer approximation method. Simulation examples show that nonparaxial multi-Gaussian beam model is not limited by the paraxial approximation condition and can predict efficiently and accurately the acoustical field radiated by a linear phased array transducer over a wide range of steering angles. 相似文献
13.
Acoustooptic Bragg diffraction without overemodulation (i.e., with the extended high-efficiency region on the diffraction
efficiency dependence vs. sound amplitude) is studied theoretically and experimentally. It is found that this effect appears
in the case of a symmetrically nonuniform acoustic field and is due to the equality of additional opposite phase shifts of
light beams passing through symmetric regions of the acoustic field. The situation is considered when an acoustic field is
excited by a three-section phased-array transducer. The conditions are determined, in which reverse optical power transfer
from the diffracted beam to transmitted beam (overemodulation) in the case of a high (close to 100%) diffraction efficiency
is considerably suppressed. In the case of a phased array, the effect weakly depends on the frequency of sound and the size
of transducer sections, which makes it possible to observe it in a wide range of acoustooptic interaction parameters. 相似文献
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Bragg’s acoustooptic diffraction in an acoustically anisotropic medium is considered taking into account the two-dimensional
spatial diffraction structure of the acoustic beam. The conditions are determined under which reverse transfer of optical
power from the diffracted to the transmitted beam in the regime of 100% efficiency of diffraction is considerably suppressed.
It is shown that this effect is due to diffraction bending of wave fronts of the acoustic beam in the acoustooptic diffraction
plane. The problem of optimization of the piezoelectric transducer size and the spatial position of the input light beam is
solved using the criterion of the minimal required power of the acoustic field. The results of simulation in a wide range
of the acoustooptic interaction parameters for a Gaussian light beam are reported. The correctness of the model is confirmed
experimentally. Recommendations for designers of acoustooptic devices are formulated. 相似文献
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This paper presents the design, fabrication, operating characteristics and applications of a wideband, high-frequency, line-focus beam transducer we constructed using a 9 microm thick piezoelectric polyvinylidene fluoride (PVDF) film. This transducer possesses a focal length of 2.38 mm and an aperture angle of 84 degrees. The frequency spectrum of the signal measured at the focal point indicates that the transducer has a wide frequency response which extends from 10 MHz to over 100 MHz. When compensated for the frequency-dependent attenuation of the coupling medium, the operational frequency exceeds 150 MHz. The transducer can be operated in a time-resolved pulse mode or in a radio-frequency (rf) tone burst mode. An application of the transducer to determine the anisotropic elastic property of a silicon wafer is demonstrated. The phase velocities of surface acoustic waves (SAW) propagating along various directions on the (001) surface of cubic silicon are measured and compared to computed values. 相似文献
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To date, ultrasonic measurement models have primarily treated systems where circular transducers are used. Recently, however, a highly efficient ultrasonic beam model for a rectangular transducer has also become available where the transducer is represented as a superposition of a relatively few Gaussian beams. Thus, using the multi-Gaussian beams, we developed ultrasonic measurement models for systems where a rectangular transducer is employed. In this paper, we describe the developed models including the beam model, the efficiency factor for a rectangular transducer and far-field scattering models for some standard scatterers. Furthermore, the accuracy of the proposed model is verified by the comparison of the model-based predictions to the experimental measurements. 相似文献
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Temperature rise induced by an annular focused transducer with a wide aperture angle in multi-layer tissue 下载免费PDF全文
In order to improve the operability and accuracy of high-intensity focused ultrasound(HIFU), an annular focused transducer, whereby a B-ultrasound probe is placed in its center, is used to realize the real time monitoring and control of the treatment. In this paper, the spheroidal beam equation(SBE) was used to calculate the sound field by an annular focused transducer with a wide aperture angle to first derive the heat deposition and the Pennes equation was used to calculate the temperature field in multi-layer tissue. We studied the effect of different parameters on the temperature of the tissues. The result shows that the focal length has a significant influence on both maximum liver temperature rise and skin temperature rise, and both increase with the increase in the focal length. When the frequency increases, the temperature rise first undergoes a rapid increase before gradually reaching a maximum, and then finally decreasing. The temperature rise increases while the inner radius decreases or the sound pressure increases. By choosing suitable parameters, the proper temperature rise both on the target tissue and skin via an annular focused transducer with a wide aperture angle can be obtained. 相似文献
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使用双面同相振动的弯曲圆盘换能器驱动双Helmholtz共振腔,既放大了弯曲圆盘换能器弯曲共振频率以下频段的声输出,又利用两个Helmholtz共振腔的同相声源辐射模型实现了在Helmholtz共振频率处的"∞"字形垂直指向性,实现了低频指向性声发射。阐述了换能器实现"∞"字形低频指向性发射的机理,研究了腔体长度、金属圆片厚度及弯曲圆盘边缘简支厚度等关键结构参数对Helmholtz共振频率的影响,求解了换能器的发送电压响应、指向性等参数。依据仿真结果制作了实验样机,在消声水池中进行了电声性能测试。测试结果显示,指向性形状及液腔共振频率与仿真结果基本相符。这种由弯曲圆盘驱动的双Helmholtz共振腔水声换能器为实现水声换能器小尺寸、低频指向性发射提供了一种技术手段。 相似文献
19.
S. Lees 《Ultrasonics》1978,16(5):229-232
The sonic beam of a weakly focused transducer can be represented by a cone with apex on the transducer. The focal spot diameter and the beam divergence are calculated from O'Neil's expression for the pressure distribution at the focus and the appropriate criterion defining the edge of the beam. Confirmation with experimental results is given. 相似文献