Abstract:

Taking supersonic separator as the research object, five models are established based on the ratio of the gap size of the discharge port(δ) to the diameter of the throat tube(D), which is 0.3, 0.4, 0.5, 0.6 and 0.7. The SST(shear stress transport) κ-ω turbulent model is used to numerically simulate the fluid flow characteristics in the separator. The variation of pressure distribution, temperature distribution, shock wave position, nucleation rate and droplet radius with δ is analyzed. The results show that the diffusion section of the supersonic separator has the largest extremely low pressure range, maximum expansion capacity, more uniform temperature field distribution, and a larger range of extremely low temperature when δ=0.5D; by optimizing δ, the shock wave position can be moved down, and the induced coagulation nucleus can be generated earlier to promote droplet generation and growth. Under the conditions of inlet pressure of 84.8 kPa, inlet temperature of 279.6 K, and water vapor volume fraction of 0.75%, the highest nucleation rate of the separator is 318 kg^-1·s^-1 and the droplet diameter reaches 996.8 nm at δ=0.5D, which is higher than other models and is also conducive to improving its separation performance.

Key words: supersonic separator, structural optimization, pressure distribution, pressure loss, temperature distribution, nucleation rate, Mach number, gap of the discharge port

摘要：

以超音速分离器为研究对象，分别按排液口间隙尺寸δ与喉管直径D之比为0.3,0.4,0.5,0.6,0.7建立了5个模型。采用SST(剪切应力输运)κ-ω湍流模型对分离器内部流体流动特性进行了数值模拟，考察了压力分布、温度分布、激波位置、成核率与液滴半径等参数随δ的变化规律。结果表明：δ=0.5D时超音速分离器扩散段的极低压范围最大，膨胀能力最大，温度场分布更均匀，极低温范围也更大；优化δ值使激波位置下移，可更早产生诱导凝结核而利于液滴生成与增长；在分离器入口压力84.8 kPa、入口温度279.6 K、水蒸气体积分数0.75%条件下，δ=0.5D时分离器的成核率最高为318 kg^-1·s^-1、液滴直径达到996.8 nm,均高于其他模型，有利于提高其分离性能。

关键词: 超音速分离器, 结构优化, 压力分布, 压力损失, 温度分布, 成核率, 马赫数, 排液口间隙