S-Space College of Engineering/Engineering Practice School (공과대학/대학원) Dept. of Mechanical Aerospace Engineering (기계항공공학부) Theses (Master's Degree_기계항공공학부)
Development of quasi-dimensional combustion model of SI engines equipped with variable valve actuation
가변밸브가 장착된 가솔린 엔진의 성능 예측을 위한 유사차원 연소모델 개발
- 공과대학 기계항공공학부
- Issue Date
- 서울대학교 대학원
- Fuel economy; Quasi-dimensional combustion model; Variable valve actuation; Turbulent Intensity; Residual Gas Fraction; Burning rate
- 학위논문 (석사)-- 서울대학교 대학원 : 기계항공공학부, 2014. 2. 민경덕.
- Variable valve actuation technology has great potential of improving both fuel economy and performance of SI engines. However, due to numerous valve profiles and excessive calculation time, optimization of valve actuation under various engine operation conditions can hardly be achieved by experimental method or 3D engine simulation tools. Therefore, in this work, a quasi-dimensional combustion model for fast simulation of SI engines equipped with VVA was developed.
MIT quasi-dimensional combustion model was used as the base code. It was modified to reflect the effect of VVA on burning rate prediction which is mainly affected by turbulent intensity and residual gas fraction. STAR-CD and GT-POWER were used to obtain base data of turbulent intensity and residual gas fraction under various valve lift, duration and timing. Using these base data, the turbulent flow energy model and boundary conditions of gas exchange process were modified to improve the accuracy of turbulent intensity and residual gas fraction prediction.
Model calibration based on experimental data was carried out. Simulation results showed that the modified model can predict burning rate with acceptable degree of accuracy under various valve lift, duration and timing. Finally, using the modified quasi-dimensional combustion model, the effect of VVA on fuel economy improvements was verified.