Particle velocity and acoustic impedance density of the ultrasonic field by the circular flat transducers

概要

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Particle velocity and acoustic impedance density of the ultrasonic field on the axis of a circular flat transducer are computed together with sound pressure. In nearfield range, interference pattern with transducer distance is investigated. The phase delay of acoustic impedance density jumps always from -π/2 to π/2, where amplitude becomes zero. But, this regular jump is not the case for sound pressure. Next, the ultrasonic field off the axis of the circular flat transducer is investigated. It is revealed that the case on the axis is the extremity of the general ultrasonic field around the axis. The mean value over a model of receiving coaxial circular flat transducer is also computed changing the ratio of the radius (a) of the circular flat transducer to the wavelength (λ) of the ultrasonic wave. Computed amplitude of sound pressure, particle velocity and acoustic impedance density are tabulated with the normalized distance (Zλ/a^^2). The mean amplitude of Z-component of particle velocity is always less than 1. 0 and seems to be an appropriate response for the ultrasonic system of a pair of circular flat transducers.
社団法人日本音響学会の論文