• 오토저널
• /
• 제8권2호
• /
• pp.31-42
• /
• 1986

The prediction of performance, exhaust emissions and EGR effect is made by the SI engine cycle simulation. In this simulation several models are employed - two zome, thermodynamic combustion, mass fraction burned, heat transfer, chemical equilibrium, chemical kinetics for NOx, laminar flame speed for ignition delay. The chemical species in burned gas considered are 13 species-CO$_{2}$, CO, $O_{2}$, H$_{2}$O, H$_{2}$,OH, H, O, N$_{2}$, NO$_{2}$, N, Ar - and the cylinder pressure, burned and unburned zone temperature and composition of gas are calculated at each crank angle through the compression, ignition delay, combustion and expansion process. To check the validity of the model, experimental study is done for measuring emissions, combustion pressure and engine output. The predicted values for pressure and emissions show qualitative agreement with the measured data and the EGR effect also shows similar tendency.

• 한국추진공학회지
• /
• 제14권5호
• /
• pp.72-83
• /
• 2010

본 연구는 구형으로 전파하는 합성가스-공기 화염의 셀 불안정성에 있어서 헬륨, 이산화탄소, 질소의 희석제 첨가효과에 관하여 실험을 수행하였다. 층류화염속도와 Markstein Length는 여러 희석제 농도와 당량비에서 측정된 쉴리렌 이미지를 분석함으로써 측정하였다. 실험결과 반응혼합물에 희석제를 첨가했을 경우 층류화염속도와 Markstein Length는 두드러진 감소를 보였다. 희석제로 헬륨을 첨가한 합성가스-공기화염에서의 유효 루이스 수는 증가했지만 이산화탄소와 질소를 첨가시킨 혼합물에서는 희석제의 첨가량이 증가할수록 유효 루이스 수는 감소하였다. 또한, 헬륨으로 희석시킨 경우 셀 형성은 현저하게 억제된 경향성을 보였으나 이산화탄소나 질소를 첨가했을 경우 셀 불안정성이 완화되는 효과는 없었다.

• International Journal of Automotive Technology
• /
• 제6권4호
• /
• pp.323-332
• /
• 2005

A cylindrical constant volume combustion chamber was used to investigate the flow characteristics at the spark electrode gap and the combustion characteristics of a homogeneous charged methane-air mixture under various overall charge pressures, excess air ratios and ignition times. The flow characteristics, including the mean velocity and turbulence intensity, were analyzed with a hot wire anemometer. Combustion pressure development measured by piezoelectric pressure transducer, a flame propagation image acquired by ICCD camera and exhaust emissions measured by 2-valve gas chromatography were used to investigate effects of initial pressures, excess air ratios and ignition times on the combustion characteristics. It was found that the mean velocity and turbulence intensity had the maximum value around 200-300 ms and then decreased gradually to a near-zero value after 3000 ms and that the combustion duration was shorten and the flame speed and laminar burning velocity had the highest value under the condition of an excess air ratio of 1.1, an overall charge pressure of 0.15 MPa and an ignition time of 300 ms in the present study. The $CO_2$ concentration was proportional to the ignition time and overall charge pressure, the $CO_2$ concentration was proportional to the excess air ratio, and the UHC concentration was inversely proportional to the ignition time and overall charge pressure.