| The flow-induced oscillation caused by fluid flowing through cavity structures widely exists in pipeline,fluid machinery,aerospace and large span flexible building structures.The combination of piezoelectric technology and the use of flow-induced oscillation phenomenon that is easy to generate in the environment for energy collection can enrich the utilization of environmental fluid kinetic energy,and is expected to form a passive energy supply system for low-power electronic equipment in special occasions.In this paper,the fluid kinetic energy utilization method of resonant flow-induced oscillation is studied by numerical simulation and experiment.The main research work is as follows :(1)The basic theory and calculation method of aeroacoustics involved in cavity flow-induced oscillation are introduced,and the energy of sound source is calculated and analyzed.The impedance analysis of the convection-acoustic conversion system and the acoustic-electric conversion system was carried out.(2)The main parameters affecting the fluid-resonant cavity flow-induced oscillation are studied.Through the simulation calculation and experimental test of cavity flow-induced oscillation under different resonant cavity lengths and width sizes and fluid conditions,the coupling relationship between flow field,vortex and sound field is analyzed from the aspects of its flow field and sound field distribution characteristics : instantaneous vorticity,hydraulic mode,acoustic mode and sound pressure distribution.The internal mechanism of cavity resonance is explained,and the influence law of cavity structure size on sound field characteristics is obtained.At the same time,through the calculation and analysis of Strouhal number and sound source energy,the influence of flow velocity on cavity acoustic oscillation is explored.Because the flow-induced cavity oscillation has the characteristics of state mutation and multi-stable state,the hysteresis phenomenon of flow-induced oscillation under forward and reverse speed conditions with specific structure size is simulated and experimentally studied,and the causes of hysteresis phenomenon are preliminarily explored.(3)The main influence parameters of acoustic field on power conversion in the acoustic-electric conversion system are analyzed.The COMSOL software is used to realize the three-dimensional modeling of the piezoelectric transducer,and the modal analysis of the piezoelectric transducer is carried out.The acoustic field simulation results are used as the fluid-solid interaction surface of the piezoelectric transducer model,and the electric field output characteristics driven by the acoustic field are obtained.The influence of the acoustic oscillation of the resonant cavity on the electric field output characteristics is analyzed.Select the appropriate cavity structure to install piezoelectric transducer to achieve the initial acoustic-electric energy conversion process. |
PDF Full Text Request