基于流固耦合的超声污垢检测数值模拟

NUMERICAL SIMULATION FOR ULTRASONIC FOULING DETECTION BASED ON FLUID-SOLID STRUCTURE INTERACTION

基于Comsol Multipysics仿真软件,建立了声发射耦合的板材-污垢多层有限元模型。以弹性动力学和压力声学为理论基础,推导了薄平板型试样在平面波辐射下的声波振动控制方程,研究了流相与固相区域超声传播特性规律,实现了二维平板污垢纵、横波分离的弹性数值模拟,通过分离后的波场提取,对薄层平板沉积污垢厚度进行高精度检测。数值模拟结果表明:流相区域服从微小声波波动方程传播规律,固相区域也能很好的实现弹性纵横波的完全分离提取;超声波对薄层平板沉积污垢的检测误差在5%以内,证明了数值模拟的可行性与准确性,对于实际换热系统的运行和清污具有很好的指导作用。

Based on simulation software of Comsol Multipysics,a launch coupling-board-fouling multilayer finite element model was established. In addition,by deeming elastokinetics and pressure acoustics as theoretical foundations,an acoustic vibration control equation was derived for the thin plates at the condition of plane wave radiation to study ultrasonic propagation rules in flow and solid phase zones and also implement elastic numerical simulation for longitudinal and transverse wave separation of two-dimensional flat fouling. Furthermore,a high-precision detection was carried out for the thickness of fouling deposited on the thin plate after the extraction of the separated wave field. The numerical simulation results indicated that complete separation and extraction of elastic P-and S-waves were also realized for the solid phase zone in a better manner according to the flow zone complies with micro acoustic wave equation propagation law; In addition,the detection error of deposited fouling on thin plate performed by the ultrasonic wave was within a range of about 5%. Such results not only proved both feasibility and accuracy of numerical simulation,but also played a role of guidance in the operation and clearing of the actual heat exchange system.