Effects of in-cylinder flow on local heat transfer to chamber wall in diesel combustion

Abstract

In order to reduce the heat loss of diesel combustion, it is important to clarify the effect of in-cylinder flow on heat transfer to the chamber wall．The experiments were conducted using the rapid compression machine (RCM) equipped with heat flux sensors fixed on chamber wall to measure local instantaneous wall temperature to investigate the effect of swirl flow on the local heat transfer in diesel flame．Injection angle of single hole nozzle and swirl were controlled to investigate the correlation of spray flame and in-cylinder flow characteristics on heat transfer to the chamber wall．The results show that, the local heat transfer at the impinging point was suppressed because of decreasing local flame temperature with reverse swirl. On the other hand, local heat transfer was increased by forward swirl with local flame temperature rises. The exponent of Reynolds number in the empirical equation of Nusselt number was decreased by the reverse swirl than without swirl. Meanwhile, the exponent of Reynolds number was increased by the forward swirl than without swirl.

Keywords

• diesel engine
• spray flame
• local heat transfer
• in-cylinder flow
• swirl
• heat flux