Breakup of Volatile Liquid Jet in Hot Cross Flow

Abstract

Liquid jet in cross flow has been a widely studied subject although most of the experimental work has been carried out at ambient conditions. The present study involves the investigation of the behavior of an ethanol jet injected into a cross flowing air at elevated temperatures up to 428K. Spray parameters such as the trajectory and drop size distributions are measured and compared for cold and hot flow conditions. Experiments are conducted for a range of liquid-to-air momentum ratios (Q) ∼ 4 – 13 and for Aerodynamic Weber numbers (We) ∼ 15. Though most of the existing literature attributes the effect of elevated temperature on the effective change in Q due to density variation, the present study shows interesting observations where the results vary in spite of maintaining similar magnitudes of Q between cold and hot flow conditions. It is observed that a higher trajectory is consistently manifested by the ethanol jet at elevated temperatures as compared to that found at ambient temperatures. It is proposed that the physical parameter,density ratio, needs to be considered as an additional parameter to account for these differences. Therefore, a new trajectory correlation is proposed which is observed to match experimental data at different temperatures. The drop size measurements indicate considerable amount of evaporation of the fine droplets formed at the leeward portion of the resultant spray of ethanol jet in cross flow.