Numerical Study of Evaporation and Motion Characteristics of Liquid Nitrogen Droplet in High-Speed Gas Flow

[摘要] In the cryogenic wind tunnel, cooling the circulating gas to cryogenic temperature by spraying liquid nitrogen (LN2) is an efficient way to increase the Reynolds number. The evaporation and motion of LN2droplets in the high-speed gas flow is the critical process that determines the cooling rate, cooling capacity and the safe operation of the down-stream compressor. In this study, a numerical model of droplet motion and evaporation in high-speed gas flow is developed and verified against experimental data. The droplet evaporation rate, diameter and velocity are obtained during the evaporation process under different gas temperatures and flow velocities. The results show that the gas temperature has dominant influence on the droplet evaporation rate. High flow speed can increase droplet evaporation effectively at the beginning process. Evaporation of droplets with different diameters follows a similar trend. The absolute evaporation rate increases with the increase of droplet diameter while the relative evaporation amount is highest for the smallest droplet due to its high area-volume ratio. This numerical study provides insight for understanding the evaporation of LN2droplets in high-speed gas flow and useful guidelines for the design of LN2spray cooling.

[发布机构] State Key Laboratory of Multiphase Flow in Power Engineering, Xi'An Jiaotong University, Xi'an; 710049, China^1;Xi'An Jiaotong University Suzhou Academy, Suzhou; 215123, China^2

[效力级别] 物理学 [学科分类] 材料科学（综合）

[关键词] Cooling Capacity;Cryogenic temperatures;Cryogenic wind tunnels;Droplet diameters;Droplet evaporation;Evaporation process;Evaporation rate;Motion characteristics