超声波流量计中反射装置的声-固耦合分析

Analysis of the reflection device in ultrasonic flowmeter based on acoustic-structure coupling method

对超声波流量计中的反射装置进行有限元模拟计算,利用声-固耦合的方法将流体域内的声压和固体域中的结构变形联系起来。在流体域内求解Helmholtz方程,得到的声压作用于固体表面使得超声波反射装置受到载荷,而结构变形在固体边界的法向上产生结构化加速度。选取一款超声波流量计的反射装置并将其置于无限大空间中,通过一个球体对计算区域进行分割得到有限元计算区域,将超声波换能器简化为垂直入射计算区域的平面波。通过对硬边界、铝材料和不锈钢的模拟结果进行对比,分析3种情况下超声波传播过程中3条路径上的声压级变化,得出固体域的结构变形对超声波传播过程中声压分布产生影响;不锈钢材料宜作为反射装置的材料。

The finite element method （FEM） is introduced in this paper to study the reflection device of ultrasonic flowmeter, which adopts the acoustic-structure coupling method to connect the sound pressure in fluid domain and the structural deformation in solid domain. The Helmhohz equation is solved in fluid domain, the obtained acoustic pressure acts on the solid surface as a boundary load for the reflection device, which causes the structural deformation and generates the structural acceleration on the normal direction of the solid boundary. The reflection device of an ultrasonic flowmeter was selected and immersed in infinite space, which is truncated as a sphere that is divided and represents the computational region of the FEM. The ultrasonic transducer output is simplified as a plane wave perpendicularly incident to the computational region. The sound pressure level along the three paths were analyzed, with the sound-hard boundary, aluminum and stainless steel were used as the boundary conditions for the reflection device. The result shows that the structural deformation has an impact on the sound pressure distribution in the ultrasonic wave propagation process, and the stainless steel is suitable for the material of the reflection device.