CFD simulation and investigation on the operating mechanism of a beta-type free piston Stirling engine

In order to study the operating mechanism of a beta-type free piston Stirling engine, a two-dimensional axisymmetric CFD model is established. Then the model reliability is verified by experiments. The periodic variation of temperature field and flow field in the expansion chamber and compression chamber can be obtained by the model. The motion of gas parcel in heat exchangers can be tracked by appropriate post-processing method which can achieve the transformation of Euler method to Lagrange method. The results present that each gas parcel in the oscillating flow has different thermodynamic process, which is different from the traditional thermodynamic cycle. Due to the elevating of the temperature gradient of gas parcel and the enhancement of the ability of pumping heat, the p-v work of parcels increases with the decreasing of distance between the corresponding gas parcel and the hot end. The regenerator is the main working component of the heat exchangers in that the thermodynamic process of gas parcel is similar to that of a micro-generator.