喷水式超声检测的声−流耦合模型

Modeling of acousto-fluid interaction in water-jet ultrasonic testing

为研究超声波在射流水柱中的传播特性,提出了喷水式超声检测的声−流耦合建模方法。使用计算流体动力学方法得到喷水探头内部流场的湍动能、速度和压力,并通过弱形式偏微分方程将其映射到声学网格作为声场分析的边界条件,用线性纳维−斯托克斯方程求解湍动能、流速等引起的声学变化,建立了喷水式超声检测的声−流耦合模型。仿真计算了不同流速时工件内部的声压分布,进水口流速的变化不会改变工件中声压的分布规律,但空间声压幅值随着流速的增大而减小。仿真计算了不同流速时的平底孔回波,回波幅值随着流速的增大而减小,通过与实验结果对比,验证了本文方法的准确性。

A method for modeling of acousto-fluid interaction in water-jet ultrasonic testing is proposed to study the ultrasonic wave propagation characteristics in the water jet.The flow field of a water-jet probe is numerically calculated using computational fluid dynamics(CFD).The CFD results,including turbulent kinetic energy,flow velocity and pressure,are transferred to acoustic meshes as boundary conditions using weak formulations of the partial differential equations.The linear Navier-Stokes equations are used to solve for the acoustic changes caused by turbulent kinetic energy and flow velocity,thus modeling the acousto-fluid interaction in water-jet ultrasonic testing.Numerical calculations of the sound pressure distribution in the workpiece at different flow velocities are performed using the acousto-fluid interaction model.The results show that the sound field distribution is similar,but as the flow velocity increases,the pressure amplitude decreases.The echoes of the flat bottom hole are obtained using the proposed method and the echo amplitude decreases as the flow velocity increases.The accuracy of the proposed method is validated by comparison with experimental measurement results.