冷流率对大口径涡流管性能影响分析

Influence of Cooling Rate on Performance of Large-Caliber Vortex Tube

为了探究冷流率对大口径涡流管节流降压效果的影响,基于Fluent改变冷流率值,对比模拟计算结果发现:主管段区内外旋气体存在能量损耗,轴向位置出现压力滞止点和速度方向折点,径向位置r=28 mm处出现分界层。冷流率0.1至0.5,外旋气体温度上升趋势平缓,制热效果不明显;冷流率0.6至0.9,外旋气体温度上升趋势明显,制热效果加强;冷流率增大过程中,内旋气体温度下降趋势平缓,制热效果减弱。热端出口气体压力随冷流率增大而增加,大部分气体流至冷端出口,导致冷端压力变化梯度明显;冷流率过大,热端出口节流降压效果降低,无法满足节流需求。冷热端出口压差变大,外旋气体流动受阻,速度减小;内旋气体流动加快,速度增大。综合分析得出:冷流率0.5时,大口径涡流管节流降压效果最佳,节流区间3 MPa左右,冷热端出口气体温降区间均为5 K,忽略传热损失,节流前后气体温降区间几乎为零,满足后续工艺温度要求。

In order to discuss on the influence of cooling rate on the throttling depressurization effect of large-caliber vortex tube,the throttling depressurization effects under different cooling rates are simulated.The results show that in main pipe,there will be pressure stagnation point and speed direction turning point in the axial direction,and the boundary layer appears at the radial position r=28 mm.When the cooling rate is 0.1~0.5,the temperature rising trend of external swirl gas is gentle,and the heating effect is not obvious.When the cooling rate is 0.6~0.9,the temperature of external swirl gas increases obviously,the heating effect is strengthened.In the process of increasing the cooling rate,the downward trend of the internal swirl gas temperature is gentle,and the heating effect is weakened.The gas pressure at the hot end increases with the increase of the cooling rate,most of the gas flows to the cold end,resulting in a significant pressure gradient at the cold end.If the cooling rate is too great,the throttling effect at hot end is reduced,which can not meet throttling demand.If the pressure difference between the hot end and cold end increases,the flowing of external swirl gas is blocked and its velocity is decreased;the flowing of internal swirl gas is accelerated and its velocity is increased.The comprehensive analysis shows that when the cooling rate is 0.5,the throttling depressurization effect of the largecaliber vortex tube is the best.The throttling pressure is about 3 MPa,the temperature drop of gas at the cold and hot ends is 5 K.Ignoring heat transfer loss,the temperature drop of gas before and after throttling is almost zero,which meets the requirements of subsequent process temperature.