Exchanging data between computational fluid dynamic and thermodynamic models for improving numerical analysis of Stirling engines

Abstract

AbstractIn a numerical analysis of a Stirling engine, the thermal and flow fields in the cylinder are three‐dimensional and periodically varying. Therefore, a computational fluid dynamic (CFD) analysis may provide detailed solution but it takes a long computation time to simulate enough number of cycles toward the final stable oscillatory regime. On the contrary, a thermodynamic model is relatively time‐effective; however, it is not sufficiently accurate because it is built under some ideal assumptions. In this study, a method of exchanging data between the two models is proposed to facilitate the simulation of Stirling engines. In this method, the CFD model provides some coefficients required by the thermodynamic model. The simulation is then advanced to the stable oscillatory regime by the thermodynamic model. The information of the stable oscillatory regime predicted by the thermodynamic model is introduced back to the CFD model to renew its initial guesses. Then, the CFD model corrects the required coefficients for the thermodynamic model. The iteration of prediction‐and‐correction continues until the exchanged information converges. Since the predicted initial guesses of the CFD analysis by the thermodynamic model are actually very close to the solutions in the stable oscillatory regime, the CFD model can achieve detailed solutions for the stable oscillatory regime in just a finite number of cycles. In this manner, the overall time consumption can be dramatically reduced and accuracy of the CFD analysis can be improved as well.