The unburned end-gas temperatures in a combustion chamber of a conventional 4-cylinder DOHC spark-ignition engine were measured using the broadband CARS temperature measurement technique. The test engine was fueled with primary reference fuel 80 and gasoline with research octane numbers of 70.9, 83.4, 91.5 and 100.4. The measured CARS temperatures were compared with the adiabatic core temperatures calculated from the measured pressures. Significant heating by pre-flame reaction in the end gas zone was observed in the late part of compression stroke under both knocking and non-knocking conditions. The measured CARS temperatures when the cylinder pressures were above 1 400 kPa were higher than the calculated adiabatic core temperatures. These results indicate that some exothermic reactions exist in relatively low pressure and temperature regions. The CARS temperatures began to be higher than the adiabatic core temperature when the end-gas temperatures reached 700 K. The temperature elevation due to the pre-flame reaction correlated well with the unburned gas CARS temperature for different research octane number fuels tested.
|Number of pages||6|
|Journal||JSME International Journal, Series B: Fluids and Thermal Engineering|
|Publication status||Published - 2002 Aug|
All Science Journal Classification (ASJC) codes
- Mechanical Engineering
- Physical and Theoretical Chemistry
- Fluid Flow and Transfer Processes