加热条件下液体燃料射流破碎机理的研究

Study on the Mechanism of Liquid Jet Breakup under Heating Conditions

利用线性热不稳定性理论,对黏性液体射入高温气体介质模型所对应的色散方程进行了数值求解。利用所得到的计算结果,研究了加热条件下轴对称模式扰动液体射流破碎机理,探讨了表征各种影响射流破碎作用力的无量纲Weber数(We)、密度比(Q)、Marangoni数(Ma)和Ohnesorge数(Z)对液体射流破碎最大扰动增长率及占优波数的影响。研究结果表明,液体和气体介质之间的温度梯度对液体射流稳定性有着非常显著的影响,表明热毛细力对于液体射流的破碎有促进作用,这种作用对处于Taylor模式下的液体射流尤为显著,并且这种热力作用可使液体射流从一种模式进入另一种模式,并可以大大改变射流的破碎尺度。

A temporal linear instability analysis on a viscous liquid jet with temperature gradient subjected to a gas stream is presented in this paper, and the effects from various dimensionless numbers, including Weber number （We）, Density ratio （Q）, Marangoni number （Ma） and Ohnesorge number （Z）, on the growth rate and dominant frequency of surface wave of a liquid jet was numerically studied. It was found that the thermo-capillary force induced by the temperature gradient was a significant destabilizing factor for the breakup of a liquid jet. The results also showed that the influence by Taylor regime was more remarkable to liquid jet than by Rayleigh regime, and the breakup dimension of a liquid jet decreased dramatically with the increase of temperature gradient.