| As one kind of non-contact supporting technology,ultrasonic standing wave suspen-sion technology has been widely used to simulate the microgravity and non-contact characteristics of space environment,and provide experimental conditions close to ideal state in biochemistry and materials science.In field of biology research,the non-contact separation,extraction,suspension and other operations of the cells provide a intact en-vironment,so that the cells can be preserved intact,and provide more pure and energetic biological cells for biological experiments,reagent preparation and biomedical treat-ment.The development and development of ultrasonic composite sound field theory has pushed the application of acoustic suspension to a new level,extending the frontier research of contactless drug transportation,contactless cell transportation,and ultra-sound surgery.In the transmission and operation of ultrasound drugs or cells,the dy-namic control of the sound field is mainly used to achieve object control.However.most of the current theory of acoustic suspension research is aimed at static suspension,and the stability of suspended particles in ultrasonic suspension is studied.In order to solve the current urgent problem,this thesis conducts theoretical and experimental research on the motion stability of suspended particles in dynamic suspended sound field,and finally obtains the optimization scheme of dynamic sound field suspension to improve the suspension stability.The research content of this paper are as follows:(1)Relationship between the environmental parameters of acoustic suspension and the variation of acoustic pressure are critical elements in research.This paper introduces the definition of standing wave,the linear wave equation of sound wave propagation in fluid,and the classical ultrasonic radiation force theory of King and Gor ’kov,and ana-lyzes the influence of physical factors such as the medium,the distance between the transmitting surface and the reflecting surface,and the geometry of the reflecting sur-face on the acoustic pressure intensity and distribution.The influence of suspended solids on the intensity and distribution of sound field was analyzed by COMSOL simu-lation of static acoustic suspension model.(2)Study on dynamic stability of acoustic suspended particles.The linear dynamic model of dynamic acoustic suspended particles is established.Through COMSOL simulation test,the mechanical characteristics of suspended particles near the nodes in dynamic acoustic suspension field are calculated,and the linear characteristics of dy-namic acoustic suspension system are studied.The dynamic acoustic suspension stabil-ity experiment was built.Foam ball,glass ball and droplet with equal diameter were taken as the research objects.The acoustic radiation force of dynamic acoustic suspen-sion was measured by using high precision measurement system,and the suspension stability of dynamic acoustic suspended particles was observed.Based on the discussion and analysis of the experimental results,an optimization scheme for the occurrence of oscillations in linear motion of suspended particles is proposed.(3)Research objective is to improve the anti-noise ability of static suspension.The nonlinear motion characteristics of the ultrasonic suspended ball under different dis-turbance frequencies are studied by using the wave superposition property to input the disturbance frequency into the suspension system.Based on the linear dynamic model,the damping force and disturbing force are introduced to guide the nonlinear dynamic model of the suspended ball.Based on the Duffin oscillator model,the irregular vibra-tion of the suspended ball in the disturbed environment is discussed,and the optimiza-tion method for the suspension stability under the disturbance factors is proposed. |
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