垂直射流混合的三维湍流数值模拟

CFD MIXING ANALYSIS OF VORTEX GENERATOR JETS INJECTED INTO CONFINED CROSSFLOW IN RECTANGULAR DUCT

关键词:  垂直气流  气体射流  混合  数值分析

Key words:  Vertical air current  Gas jet  Mixing  Numerical analysis

摘要:

采用三维ＳＩＭＰＬＥ程序和ｋ－ε双方程湍流模型对三维受限垂直射流进行数值模拟，研究了不同的几何变量和流动参数对射流穿透和混合的影响。模拟结果表明，三维垂直射流最显著的流动特征是形成了流向旋涡。射流与来流的混合程度取决于旋涡的位置、作用范围和强弱。单股射流随动量比、旋涡强度和尺度的增加，混合增强。对于单排多股射流，喷孔间距直接影响旋涡涡心位置。密排射流，旋涡过于靠近下壁面，旋涡无法影响上面来流；但喷孔排列也不能过于稀疏，否则涡对靠的太近，旋涡对侧面影响不大。Ｓ／Ｈ和动量比不变，改变孔径Ｄ对射流穿透几乎无影响。这一重要结论说明Ｓ／Ｈ和Ｊ是决定多股受限射流穿透深度的最重要的量。

Abstract:

A CFD study was performed using 3D SIMPLE program and k ε double equation turbulence model to analyse the effects of geometries and flow parameters on the penetration and mixing of transverse jet.It was found that the size and location of streamwise vortex has a significant effect on the mixing rates.Three jet configurations numerically tested were 1)single hole jet;2)slot jet;3)multile jets.Comparing single hole jet with slot jet,fast mixing rate could be acquired by Vortex Generator Jets,also streamwise vortex.For multiple jets,optimum location of streamwise vortex was found to enhance mixing quickly by adjusting the orifice spacing and momentum ratio.Orifice size has little influence on the jet penetration depth at constant orifice spacing and momentum ratio