Local Heat Transfer on a Combustion Chamber Wall of a Spark-Ignition Engine

Instantaneous local heat transfer coefficients on the wall surface of combustion chamber were estimated experimentally using a four cycle, L-type, single cylinder, spark-ignition engine. The effects of gas flow and flame propagation on the heat transfer coefficients were investigated. Local heat flux was measured at twenty four positions on the cylinder head using a fast-response heat flux sensor developed by the authors, and the pressure in the combustion chamber was measured simultaneously. The burned- and unburned gas temperatures were calculated from a two-zone model. The flame arrival time at a position of cylinder head surface was also measured and flame velocity was calculated. The results showed that the maximum heat flux decreases as the flame arrival time increases. An empirical correlation between Nusselt number based on the local heat transfer coefficient and Reynolds number based on the flame velocity is derived from the experimental investigation of spark-ignition engine.