A Multiphysics Simulation Method for Vibration Excitation and Detection in Coriolis Flowmeters

Abstract

Coriolis flowmeters rely on vibration to conduct their measurements, where the vibration is normally excited and detected by electromagnetic means. The excitation or detection system typically includes a coil and a permanent magnet to apply the excitation force or sense the vibration velocity on the measuring tube. This paper presents a multiphysics simulation method including both structural and electromagnetic finite element (FE) models together with a simplified single degree of freedom (SDOF) model to simulate the electromagnetic excitation and detection system. The finite element models of coil and permanent magnet were established through ANSYS Maxwell, which can represent either the excitation or the detection system. The measuring tube model of a U-shaped Coriolis mass flowmeter was established by ANSYS Mechanical, where the resonant frequency of the measuring tube and the frequency response at the detecting point were obtained. Combined with the established SDOF system model, the equivalent mass and equivalent stiffness of the measuring tube at the detecting point were also solved. By transferring the equivalent data of the SDOF system to the detection device established in Maxwell, the induced voltage by the detecting coil can be obtained. The experimental data of a single U-shaped Coriolis mass flowmeter (DN2) were collected for comparison with the simulation results. It has been demonstrated that the multiphysics simulation method can simulate the excitation force and induced voltage. The relative errors between the finite element calculation results and the experimental data are within 6%. This numerical method can be advantageously used to optimize the excitation and detection system design for Coriolis flowmeters.