Experimental Study And Simulation Analysis On The Resistance Characteristics Of Regenerator In Pulse Tube Cryocooler

The regenerator is a key component of pulse tube cryocooler.The loss of regenerator accounts for large proportion of the total loss of pulse tube cryocooler.Its performance affects the efficiency of the pulse tube cryocooler directly.The loss mechanism of regenerator has not been well resolved,especially the resistance characteristics of the regenerator,including resistance coefficient,viscosity resistance coefficient and inertance resistance coefficient.The resistance coefficients are the keys to resolve the control equation of regenerator for numerical simulation.In this paper,a benificial research on the resistance characteristics of regenerator at low temperature is made.1.The performance characteristics of regenerator at low temperature are studied experimentally.Based on the phase theory of regenerator,the calculation formulas of the pressure wave,mass flow and velocity in regenerator are deduced.Experimental platfom for measuring pressure wave directly and mass flow indirectly at the hot and cold end of regenerator is built.Pressure wave,mass flow rate and velocity of regenerator are studied experimentally.2.Resistance coefficient of regenerator at low temperature is studied.Based on the heat conservation equation of porous medium and acoustic theory,the viscousity resistance coefficient and inertance resistance coefficient are analyzed.the experimental platform for resistance coefficient of the regenerator at low temperature is established.Combined with the experimental results of the oscillating flow in the regenerator and based on the momentum equations of working fluid,theoretical analysis of the resistance term,viscous and inertial terms are carried out,the pressure drop vs.velocity is set up into a related model using Matlab cftool model.The viscocity resistance coefficient and inertance resistance coefficient under different working conditions are analyzed.The experimental results show that the viscous term is larger than inertial term.The visicosity resistance coefficient decreases and the inertance resistance coefficient increases as the cooling temperature increases;the visicosity resistance coefficient and the inertance resistance coefficient decrease as the initial pressure increases;viscosity resistance coefficient increases and the inertial resistance coefficient decreases as the wire mesh increases.3.the use of resistance coefficient in two-dimensional numerical simulationA two-dimensional numerical simulation model of pulse tube cryocooler is built.In the porous medium model,the viscousity resistance coefficient and inertance resistance coefficient measured by experiment are used as the input parameters.Based on User Define Function in Fluent,a compressor entrance boundary and the pulse tube crycooler boundary conditions are compiled completely.The momentum equation of oscillatry flow in regenerator is solved.The two-dimensional numerical simulation is completed.The simulation results agrees to the experiment results.