超音波能量的使用日新月異，其在工業上的發展始於藍杰文式壓電換能器的出現，在近期已經成為表面機械處理、超音波萃取與降解等技術的核心，但是限於換能器僅能產生縱向的超音波能量，因此有了不同類型的發射器的研製。本文使用有限元素分析與基因演算法設計一個浸水式超音波發射系統，以特定頻率驅動自製的藍杰文壓電換能器並結合階梯型變幅桿放大能量，再藉由徑向發射器的幾何設計使能量傳遞由縱向轉變成徑向的超音波能量發射，對置於發射器同軸心位置之圓型管件表面產生集中的聲壓場。實驗結果與COMSOL模擬分析顯示，不同的共振頻率能夠產生不同分佈的聲壓場，若是以更高功率之放大器驅動，則可以進一步透過管件表面因空蝕氣泡反覆崩裂時產生的敲擊效應，探討超音波發射系統對材料表面機械處理的效果。

Applications of ultrasonic energy based on Langevin-type transducer have been in progress. Recently, the ultrasonic energy is used by many technologies, including mechanical surface treatment, ultrasonic extraction, ultrasonic degradation, and so on. Because the transducers can only produce longitudinal ultrasonic energy, there are many different developments of ultrasonic radiator. In this research, I employ COMSOL finite element method associated with genetic algorithm to optimize ultrasonic transducer and radial-type radiator and build ultrasonic radiate system in water tank. By driving homemade Langevin-type transducer with specific frequency and utilizing radiator to convert longitudinal energy to radial energy, the ultrasonic radiate system can produce radial and concentric ultrasonic energy to tube surface, which located in the coaxial core of ultrasonic radiator. The results of experiments and COMSOL simulations show that different resonant frequencies can produce various acoustic fields. If driving the ultrasonic radiate system with higher power amplifier, we can investigate the effect of mechanical surface treatment through the peening action of the tube generated by ultrasonic cavitation.

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