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从一维平面波理论入手分析了超声波声压分布特性。依据多普勒频移原理,在声场的运动方程,连续性方程,波动方程的基础上,建立一个超声波在流动的液体中传播的控制方程。根据轴对称模型的实际特点,简化了所得方程,并求出解析解。结果表明流动液体可以产生声波的衰减。液体的黏滞性是产生超声波衰减的重要原因。超声波的频率较高,液体的黏滞性对超声波衰减影响明显。依据黏滞力与速度梯度的关系,建立一个超声波在黏滞液体传播的控制方程,并依据边界条件求出解析解,反映了媒质黏滞性对超声波传播尤其是衰减特性的影响。
Based on one-dimensional plane wave theory, the ultrasonic sound pressure distribution characteristics are analyzed. Based on the principle of Doppler frequency shift, a governing equation of ultrasonic propagation in flowing liquid is established based on the motion equation, continuity equation and wave equation of sound field. According to the actual characteristics of the axisymmetric model, the resulting equation is simplified and an analytical solution is obtained. The results show that the flowing liquid can produce sound wave attenuation. The viscosity of the liquid is an important cause of ultrasonic attenuation. The higher the ultrasonic frequency, the viscosity of the liquid has a significant effect on the ultrasonic attenuation. According to the relationship between viscous force and velocity gradient, a control equation of ultrasonic propagation in viscous liquid is established, and the analytic solution is obtained according to the boundary conditions, which reflects the influence of medium viscosity on ultrasonic propagation, especially the attenuation characteristics.