气氮调温器Y型喷嘴实验及数值研究

基于FLUENT软件离散相模型及气体助力雾化模型，采用欧拉-拉格朗日方法研究通过Y型喷嘴雾化液氮的雾化特性.由于液氮液滴的蒸发相变，与水相比喷雾锥角更清晰且明显减小，约为10°，喷雾距离缩短.分析喷嘴气液工作压力对液氮雾化索太尔平均直径（SMD）、液滴体积分数和数量分数的影响.结果表明：SMD沿喷射方向变化幅度极小；SMD主要受气相速度及气液比影响，气压低时气相速度影响较大，气压高时气液比影响较大；由于相变作用，液氮雾化粒径分布更为集中.数值研究Y型喷嘴用于不同流量需求的气氮调温器的调温效果，出口温度低于98K，进出口温差达到12K，且整个出口温差在±1K以内，能够实现精确控温要求.

Experimental and numerical study of Y-jet nozzle of LN2-spray temperature-adjusting system

Based on Euler-Lagrange method, the characteristic of LN₂ (liquid nitrogen) atomized by the Y-jet nozzle was studied by discrete phase model and air blast atomizer model of software FLUENT. Because of the evaporation effect of LN₂ droplets, the spray angle was about 10°, significant smaller than the spray angle of water, and the spray distance was shortened. The effect of operating pressure on the Sauter mean diameter (SMD) and the distribution of volume fraction and quantity percentage was analyzed. The results indicate that the SMD along the spray direction is essentially unchanged. The SMD is controlled by gas velocity and gas-liquid ratio, and gas velocity is the major factor in the low pressure conditions while gas-liquid ratio is the major factor in the high pressure conditions. The distribution of LN₂ droplets diameter is more concentrated than in the cases using water, due to the evaporation of droplets. The effect of temperature control of LN₂-spray temperature-adjusting system using Y-jet nozzles with different flow rate demands was also investigated. The temperature of outlet was lower than 98K with temperature difference of 12K between inlet and outlet, and the temperature difference of outlet was within ±1K, which could satisfy the temperature control requirements.