旋转气体介质对环膜液体射流破碎不稳定性影响的研究

利用线性不稳定性理论研究了旋转气体介质对黏性环膜液体射流破碎的影响。研究结果表明，无论是轴对称模式还是非轴对称模式，由液体环膜内部气体介质旋转所产生的离心力是液体射流的失稳因素，有助于液体射流的破碎。另外，由液体环膜外部气体介质旋转所产生的离心力是液体射流的促稳因素，不利于液体射流的破碎。当相同强度的旋转同时存在于内部和外部气体介质中时，对于轴对称模式，内部气体介质的影响显著，而对于非轴对称模式，则外部气体介质的影响更为明显。通常情况下，非轴对称模式的扰动增长率强于轴对称模式的扰动增长率，因此会在环膜液体射流的破碎中占据主导地位。

The Instability Analysis of Gas Rotations on the Breakup of an Annular Liquid Jet

A temporal linear instability analysis on a viscous annular liquid jet subject to two gas streams with different velocities and swirls is presented in this paper, and the effect of swirls from the inner and outer gas streams on the instability of the annular liquid jet is studied numerically. The study shows that, for both para-varicose and para-sinuous modes, the centripetal force induced by the swirl in the inner gas stream is a destabilizing factor to the instability of the annular liquid jet. Meanwhile, the centripetal force arising from the swirl of the outer gas stream is a stabilizing factor to the jet. When swirls are existed in both inner and outer gas streams simultaneously, for para-sinuous mode disturbance, the effect of the inner gas swirl will dominate the breakup. In the contrary, for the para-varicose mode disturbance, the effect of the outer gas swirl will become a predominant factor. In general, the growth rate for the para-sinuous mode is much larger than the corresponding para-varicose mode under the same flowing condition. This implies that in real air-assist or air-blast atomization, the para-sinuous mode will dominate the breakup process of the annular liquid jet.