Theoretical Study On Nonlinear Thermoacoustic Engine

Thermoacoustic engine is a new type of heating equipment,compared to traditional device,which has specific advantages such as simple structure,no-moving parts,high reliability,long service life and so on.Due to utilizing inert gases without any pollution to the environment as working medium,at the same time it can use the low grade energy as heat source,Therefore,the study of thermoacoustic engine is one of the most attractive project in the refrigeration field.First,in this paper the author makes a detailed review on the historical development of the thermoacoustic engine,and introduces the development of the numerical simulation and the nonlinear thermoacoustic theory.The main reseaches include the following sections: 1.Research on the Linear Simulation of Thermoacoustic EngineThe Rott linear thermoacoustic theory is the mathematical model of simulation calculation and it adopts weighted residual method of finite element method to solve the mathematical model.The calculation programing is based on the numerical simulation of the calculation block diagram,respectively,the numerical simulation is carried on for travelling wave and standing wave thermoacoustic engine.According to the calculated results,some conclusions has been obtained that are about the sound field and the flow field characteristics in the two types of thermoacoustic engine system and the effects of the resonance tube length on the thermoacoustic system.2.Second-order Nonlinear Thermoacoustic Theory ModelOne dimension second-order nonlinear thermoacoustic theory is built which is based on the three equations of hydrodynamics and the gas equation of state,including the two order pressure gradient equation,the two order volumetric flow rate gradient equation and the two order temperature equation and the second-order acoustic wave equation is established.3.Research on the Nonlinear Simulation of Thermoacoustic EngineAccording to the model of one dimension second-order nonlinear thermoacoustic theory,weighted residual method of finite element method could get access to solve the nonlinear mathematical model.By independently compiling calculating programs,respectively,the numerical simulation is carried on for travelling wave and standing wave thermoacoustic engine.According to the calculated results,some conclusions has been obtained that are about the second-order sound field and the flow field characteristics in the two types of thermoacoustic engine system and the existence of second-order time averaged velocity U2.0 in the resonance tube is analyzed.