CFD Simulation and Experimental Validation of a Diaphragm Pressure Wave Generator
Caughley, A. J.
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Industrial Research Ltd has been developing a low-cost diaphragm pressure wave generator for cryocoolers since 2004. Thermodynamic losses in the pressure wave generator can have a significant impact on the overall efficiency of a cryocooler. To help characterize the thermodynamic losses, a two-dimensional axisymmetric Computational Fluid Dynamics (CFD) model was developed to simulate oscillating fluid flow and heat transfer in the diaphragm pressure wave generator. The ANSYS-CFX commercial code was utilized for the 2-D model. A series of validation experiments were conducted on an apparatus consisting of a diaphragm pressure wave generator connected to four cylindrical spaces with the same volume but different diameters (40mm, 60mm, 80mm and 100mm). Volume and pressures at different locations were measured for both helium and nitrogen gas over a range of frequencies. The pressure and volume measurements were used to calculate hysteresis loss. Good agreement was achieved between the CFD simulations and the validation experiments. The model will be used to increase the efficiency and optimize the design parameters. Results obtained from CFD simulations and validation experiments are presented and discussed in this paper.