超声微粒检测换能器的分析与设计

Analysis and Design of the Ultrasonic Micro Particle Detecting Transducer

利用超声波在传播过程中遇障碍物会产生散射信号的特性进行微粒检测时,超声换能器的设计非常关键.通过对平面圆形活塞声源和凹球面聚焦声源的轴向声场分布比较分析,完成了超声微粒换能器的选型;基于一个假设的应用实例,对影响换能器性能的三个重要参数(焦距D、晶片半径a、和谐振频率f)的确定原则进行了理论研究和仿真分析,给出了一种超声微粒检测换能器的设计思路,并研制了二套高强度聚焦超声换能器,运用在所开发的超声波液体颗粒检测装置上.

Micro particles can be detected according to the characteristic that the scattering wave is produced while the ultrasonic propagates encountering a small obstacle. It is pivotal to design a suitable ultrasonic transducer. The type of the detecting transducer was determined by means of comparing the sound pressure distribution of the plane circle piston sound source with that of the concave focusing sound source. On the basis of a hypothetical application example the determining ways of three principal parameters （the focal length D, radius of the spherical crystal a, and the resonant frequency f） that influence the performance of the ultrasonic transducer were presented through theoretical research and simulation analysis. Two sets of high intensity focusing transducers were developed and applied to the ultrasonic liquid particle detecting equipment.