A study on the performance prediction of 4 cycle 4 cylinder S.I. engine considering the unsteady flow in the intake and exhaust pipes

흡배기 관내의 비정상 유동을 고려한 4사이클, 4기통 전기.점화 기관의 성능 예측에 관한 연구

In this study, the analytic investigation of the unsteady flow in the intake and exhaust pipes has been carried out using the method of characteristics in one direction to predict volumetric efficiency. Based on the calculated volumetric efficiency, three zone predictive analysis using Wiebe function was applied to predict the engine performance and the results were compared with experiment. Mixture in the cylinder is subdivided into three zones during combustion process in this analysis; adiabatic core zone, thermal boundary layer zone and unburned zone. In each zone, pressure, temperature and gas composition have been calculated. In conclusion, it is possible to take account of the intake and exhaust pipe tuning effect in predicting the engine performance, by the analytic solution of the unsteady flow in the pipes, and comparison of prediction with experimental results shows a good agreement on the pressure variation in the intake and exhaust pipes which has a direct influence on the volumetric efficiency and performance of the engine.