气体旋转运动对类反对称模式下环膜液体射流破碎尺度的影响

Effect of Gas Swirl on Breakup Scale of Annular Liquid Jet for Para-Sinuous Disturbances

利用线性不稳定性理论研究了气体介质旋转运动对类反对称模式下黏性环膜射流破碎不稳定性的影响.通过对描述黏性环膜射流不稳定性色散方程的推导和数值求解,研究了气体介质的旋转运动对环膜射流破碎尺度模式的影响.研究表明,对于类反对称模式的液体环膜射流,内气体介质的旋转运动对射流的不稳定性有极强的促进作用,能使射流迅速从大尺度破碎模式转换为小尺度破碎模式;外气体介质的旋转运动是环膜射流破碎的促稳因素,不能改变环膜射流的破碎尺度模式.研究结果证明了类反对称模式主要与环膜射流的内气-液界面相关联.在此条件下,内气体介质的失稳作用控制射流的破碎尺度特征,而外气体介质的促稳作用在"穿透"液体射流后被大大衰减.

A linear temporal instability analysis was carded out for a viscous annular liquid jet moving in two swirl- ing gas streams of unequal velocities and densities. From numerical results of dispersion equation, it can be seen that for para-sinuous mode disturbances, the swirl of inner gas phase is a positive factor for the instability of annular liquid jets, and it can make the jet change from large-scale breakup mode to small-scale breakup mode. On the other hand, the swirl of outer gas phase is a negative factor for the instability of jets, and it cannot lead to any change of the breakup mode of liquid jets. The results also prove that the para-sinuous mode mainly relates to inner liquid-gas interface, and the effect of swirl of inner gas phase plays the key role in breakup of liquid jet, whereas the effect of swirl of outer gas phase is weakened a lot after penetrating liquid jets.