Heat release and heat flux in a spray-guided direct-injection gasoline engine

Abstract

Heat flux measurement and pressure-based heat release analysis have been performed on a spray-guided direct-injection spark-ignition single-cylinder research engine. A two-dimensional model of the heat flux sensor has been used to calculate the heat flux from the measured surface temperature. The effects of the ignition timing, air-fuel ratio, and mixture preparation on the engine heat flux and heat release have been investigated at a specific operating condition. An engine thermodynamic simulation code has been used to predict the gas-to-wall heat transfer using different heat transfer correlations. It was found that both the heat release rate and the heat flux are strongly influenced by ignition timing and air-fuel ratio. The results also show that late direct injection has a faster initial burn rate even compared with the plenum injection mode. The modelled heat transfer has been compared with the measured results and a modified Woschni correlation has been proposed.