Research On Flow-Acoustic Interaction And The Related Issues For The Gas Ultrasonic Flowmeter

As an emerging flowmeter,ultrasonic flowmeter has been developing rapidly in recent years.For ultrasonic flowmeter,an important category is based on the transit time principle.The flow velocity is obtained by measuring the ultrasonic transit time of downstream and upstream,and the measurement principle is based on the influence of flow on ultrasound beam.Therefore,one of the unavoidable problems for gas ultrasonic flowmeter study is the interaction between flow and sound propagation.Therefore,through the in-depth analysis for the flow-sound coupling and the related issues,the measurement performance of gas ultrasonic flowmeter can be improved significantly.For these reasons,in this paper,the flow-acoustics coupling is mainly studied for the gas ultrasonic flowmeter.Meanwhile,other important issues such as sound source forming,transducer features,sound features in medium with various parameters are also studied.The main works are as follows.In order to analyze the influence factors of sound source and sound field,and to verify the simulation scheme,the point source combination are studied.Firstly,the sound field of point source combination with complex and changeable feature is obtained by using the finite element scheme.Then,for the point source,as well as the piston source,the sound field features in gas medium with different parameters are analyzed.Lastly,the frequency domain and time domain sound fields are analyzed for single factor,as well as factors combination.In order to compare the commonly used real ultrasonic transducer with the classical transducer,the surface vibration experiment,and acoustic field simulation are implemented by using laser vibrometer,microphone,and finite element method,respectively.As a result,the surface vibration velocity and sound pressure distributions of the transducers are compared comprehensively.In order to deepen the latest research,also be closer to the real condition,the new scheme is designed for study.By using the combination of computational fluid dynamics and wave acoustics,the velocity profile variation caused by the vortex near transducer,and the impact on the acoustic beam are analyzed.Then,the influences of flow regimes on the sound propagation,receiving,and flowmeter performance are comprehensively analyzed.For the further development of flow-acoustic coupling mechanism research for gas ultrasonic flowmeter,except for computational fluid dynamics and wave acoustics,the ray acoustics is used to form the new hybrid scheme.The influences of flow regime on ray propagation trajectory,receiving features,sound pressure distribution,and instrument performance are comprehensively analyzed.Overall,the new hybrid scheme makes the analysis of the flow-acoustic coupling mechanism more thorough.The working process of ultrasonic flowmeter is divided into two stages.Firstly,in flow-acoustic coupling stage,for the geometry issues of product produced by manufacturers,the main factors that influence the sound pressure are obtained.Secondly,in the sound-force-electric coupling stage,the multi-physical field coupling simulation of ultrasonic flowmeter is realized.