Simulation Research On Oscillating Characteristics Of Thermoacoustic Engine

Thermoacoustic heat engines are a new type of heat engine that utilizes the thermoacoustic effect to convert between heat and acoustic energy.Thermoacoustic heat engines advantages are no moving parts,high reliability,high potential thermal efficiency,availability of low-grade heat,and using environmentally friendly inertia gas.Among all the energy utilization technologies,thermoacoustic technology has great potential and application prospects.The main components of the thermoacoustic engine are resonant tubes,regenerators and heat exchangers.The resonant tube plays the role of influencing the resonance frequency,maintaining the plane acoustic field and storing part of the acoustic energy.The regenerator is the core component to realize the thermoacoustic effect in the thermoacoustic engine.These two components are the focus and difficulty of thermoacoustic heat engine research.In this paper,Fluent software is used to simulate the oscillation characteristics of resonant tube and regenerator.The main contents are as follows.Study on the acoustic field of thermoacoustic resonator.The five kinds of thermoacoustic resonance tubes,straight,conical,sinusoidal,exponential and hyperbolic,were simulated and the pressure waveforms and spectral analysis charts were drawn.Study and analyze the role of variable-section tapered thermoacoustic resonator in suppressing higher harmonics.Research on the factors affecting the pressure amplitude in resonance tube.In this paper,the working pressure and the tube as a variable to explore its impact on the pressure amplitude of the tube.The research shows that the distribution of the pressure amplitude in the resonance tube is related to the tube type.The high working pressure in the resonance tube helps to increase the pressure amplitude in the resonance tube.The standing wave thermoacoustic engine plate stack type regenerator was taken as the research object to simulate and analyze the alternating flow characteristics of the working fluid in regenerator.The research shows that the pressure,velocity and temperature in the regenerator all show alternating flow characteristics,changing periodically,following the regular chord law,and the tube is not an ideal standing wave sound field.The influence of plate stack gap on the oscillation characteristics in regenerator was analyzed.Studies have shown that there is a periodically varying thermal boundary layer in the regenerator fluid channel with a larger temperature gradient in the thermal boundary layer.The optimal stack gap is related to the thickness of the thermal boundary layer.Analysis of the influencing factors of thermal boundary layer thickness.The main influencing factors of thermal boundary layer thickness are inflation pressure,working frequency and working fluid.Research shows that when the inflation pressure is lower,the thermal boundary layer is thicker,When the working frequency is lower,the thermal boundary layer is thicker,When the working fluid is air,nitrogen,helium,helium heat boundary layer thickness is the largest.