Development of Broadband Utrasonic Transducer for High Temperature Use

一种超声波换能器，它可以从一个振动板发射一个具有任意特定频率的超声波，用于其高温用途。铁磁板是由静磁体和交变感应磁场之间的交变吸引力和排斥力电磁驱动的。用于此目的的典型材料是具有770 ℃的高磁居里点的矩形铁板，与用于超声换能器的常规压电弹性材料相比，该磁居里点相当高。在其中心具有小而强的钕磁体（例如0.4t）的板被放置在电磁极的前面，该电磁极被施加具有40-80 W的高频交流电。电磁振荡板可以发射具有相同频率的超声波。使用超声波测量仪或麦克风测量辐射声的强度和频率。FFT分析表明，声音具有相同的频率。研究了频率、电流、振动板的厚度和距离对声强的影响。通过使用高分辨率热观察仪远程观察板中的发热情况，试图找到共振情况下的振动模式。在水浴中作为熔融金属也可以间接产生具有20 kPa水平的声音。虽然新开发的超声波装置的高温使用的基本原理进行了研究和报告，我们还需要进一步的研究，如冷却液体的系统，通过超声波将被传输。在这份报告中，基于声的关键技术和更好地设计预期的系统，利用辐射力和声空化进行了讨论。

An ultrasonic transducer which can emit an ultrasound with arbitrarily specified frequency from a vibrating plate has bee developed for its high temperature use. A ferromagnetic plate is electromagnetically driven by alternative attractive and repulsive forces between static magnet and alternatively induced magnetic field. A typical material for the purpose is a rectangular iron plate with high magnetic Curie point of 770 ℃ that is fairly high compared with normal piezo-elastic material for ultrasonic transducer. The plate with a small yet strong neodymium magnet (say 0.4t) in its center was placed in front of an electromagnetic pole which was imposed with a high frequency alternative current with 40-80 W. The electromagnetically oscillating plate can emit an ultrasound with the same frequency imposed. The intensity and frequency of the irradiated sound was measured with the use of an ultrasonic meter or a microphone. FFT analysis indicated that the sound had the same frequency. The various effects of frequency and current imposed, and thickness and distance of the vibrating plate on the sound intensity were investigated. The vibrating modes for the resonant situations were tried to find by the remote-observation of heat generation in the plate by using a high resolution thermo-viewer. The sound with a level of 20kPa could be also indirectly generated in the water bath as a molten metal. Although the fundamentals of the newly developed ultrasonic device for high temperature use were investigated and reported here, we further need additional research such as a system for cooling liquid through which an ultrasound would be transmitted. In this report, sound based key technologies and the better designing of expected systems using radiation force and acoustic cavitation are discussed as well.