The transient heat transfer characteristics of diesel spray-wall impingement on a high temperature wall in a constant volume combustion chamber were studied by transient temperature measurement technique.Results show that as the initial surface temperature increases from 250 ℃ to 550 ℃,the heat transfer mode on the wall changes from film evaporation to nucleate boiling,and then to transition boiling.This transformation causes the surface heat flux and heat transfer coefficient first increases and then decreases,reaching maximum values at 440 ℃ and 400 ℃ respectively.Increasing injection pressure,decreasing impingement distance and ambient temperature can improve the surface heat flux and the heat transfer coefficient.An increase in initial surface temperature increases the effect of injection pressure and impingement distance on heat transfer characteristics,but reduces the effect of ambient temperature.The dimension of 1 surface heat flux expressed as Biot and Fourier numbers is highly similar.A dimension of 1 correlation was established to reveal the internal heat transfer mechanism of the spray-wall im-pingement.An accurate and wider applicable prediction dimension of 1 model was also established for predicting the maximum surface heat flux of the spray-wall impingement.
关键词
喷雾撞壁/高温壁面/表面热流密度/换热系数
Key words
spray-wall impingement/high temperature wall/surface heat flux/heat transfer coefficient
维普
万方数据