同轴旋转可压缩流动中液体射流稳定性

摘要

基于线性稳定性理论,建立了描述同轴旋转可压缩流动中超空化条件下液体射流稳定性的数学模型,并对数学模型及其求解方法进行了验证;在此基础上,对模型中考虑的射流及气体可压缩性、气体同轴旋转以及超空化等因素对射流稳定性的影响进行了分析.分析结果表明,模型中考虑射流及气体的可压缩性后,与不考虑可压缩性相比,计算得到的射流稳定性明显变差,最小液滴直径减小,分裂液滴直径变化范围变宽,且小液滴数量增多.气体的同轴旋转在轴对称与非轴对称扰动下对射流稳定性的影响完全相反;轴对称扰动时,气体旋转使射流稳定性增强,而非轴对称扰动时则正好相反;气体旋转有可能导致影响射流稳定性的扰动模式发生根本性变化.超空化使射流稳定性变差;超空化程度较弱时,超空化使分裂液滴最小直径减小,分裂液滴直径变化范围增大;而超空化达到一定程度后,进一步提高超空化程度,分裂液滴最小直径几乎保持不变.%In this paper,a mathematical model is presented for studying on the stability of compressible liquid jet in a coaxial swirling compressible airstream.The mathematical model and its solving method are verified by the data in literature,and the influences of compressibility,swirling gas and supercavitation on the stability of liquid jet are investigated,respectively.The results show that compressibility plays an important role in the instability of liquid jet.The range of wave numbers,the drop distributions and the drop diameters are changed due to compressibility.The effects of swirling gas on the stability of liquid jet are different in various disturbance modes.However,gas swirling has little impact on drop diameters.It is also found that the liquid jet becomes more unstable due to the greater supercavitating condition.Supercavitation with a small void fraction gets the greater wave numbers and the smaller drop diameters,while it draws different conclusion when void fraction reaches a certain value.