基于流固耦合的换热管道污垢超声回波检测数值模拟与实验

Numerical Simulation and Experiments of Fluid-solid Coupling-based Ultrasonic Echo Detection of Pipeline Fouling

对换热管道污垢的有限元建模、耦合边界处理进行了分析与讨论,以压力声学与固体力学为理论基础,基于COMSOL Multiphysics中的PDE模式构建平面辐射声源下的声波振动控制方程,采用超声回波法对换热管道污垢厚度进行无损检测,求解不同振动频率下的回波振型和响应时间历程,为检测多层管材时模态和频率选择提供理论依据。针对多组不同管材污垢厚度回波特性,将有限元仿真与测点检测结果进行对比,验证了模型的准确性。基于换热污垢动态模拟实验装置进行了污垢定量实验。结果表明:采用实验和有限元结合的方式实现换热管道污垢超声回波检测的方法是可行的,数值模拟与实验结果吻合,超声波对管道沉积污垢的检测误差在±4%左右,该结果对工程在役换热集输系统的运行和清管具有实际意义。

Analyses and discussion were provided on finite element modeling of heat exchange pipeline fouling and on the treatment of the coupling boundary.With pressure acoustics and solid mechanics as the theoretical basis,sound wave vibration control equations under plane wave source radiation were developed based on Comsol Multiphysics in PDE mode.Heat exchange pipes were nondestructively examined for their fouling thicknesses using ultrasonic echo technique,and the echo vibration mode and response time history were found for various vibration frequencies.The paper offers theoretical reference to the choice of mode and frequency in examining multi-layer pipes.With respect to the echo characteristics corresponding to the fouling thickness of sets of pipes made of various materials,a comparison was made with the results of the test points,which attested to the accuracy of this model.With heat exchange fouling dynamic simulation testing equipment,aquantitative testing study was performed on fouling.The results suggest：it is feasible to perform ultrasonic echo detection of heat exchange pipeline fouling by a method that combines testing and finite element technique,the numerical simulation is in agreement with the test results,and ultrasonic detection produces an error around ±4% in examining pipeline fouling deposit.These results have practical significances to the operations and pipe cleaning of in-service heat gathering and transportation systems.