Effects of ambient and injection conditions on local heat transfer of impinging flame and spray to chamber wall

Abstract

This study experimentally investigates the effect of the impinging spray flame on the local heat transfer to the impinging wall. The experiments were conducted using the rapid compression machine (RCM) equipped with heat flux sensors installed into impinging wall to measure local instantaneous wall temperature. The injection pressure, the ambient density and the impinging distance between the injector nozzle and the impinging wall were varied independently as experimental parameters. The results show that when the liquid spray impinged on the wall, the local heat transfer at the impinging point was suppressed due to reduction of temperature gradient between the wall and the high temperature burned gas. The relationship between the local Reynolds number and the local Nusselt number was different from the time series plot and the average plot. The exponent n of the local Reynolds number in the empirical equation of the Nusselt number was increased by increasing impinging distance at the impinging point and the offset point. Furthermore, with increasing impinging distance, the value of exponent n of the local Reynolds number at the offset point approached the value of the exponent n at the impinging point.

Keywords

• local heat transfer
• impinging spray
• impinging distance
• ambient density
• injection pressure