基于时间模式不稳定性理论,研究了无黏静止气体中二维幂律流体液膜射流不稳定过程.在对幂律流体本构方程线性近似的基础上,通过对非对称模式和对称模式的色散方程的推导和求解,研究了广义雷诺数、韦伯数、气/液密度比以及幂律指数对于液膜破碎的影响.结果表明:在两种模式下,不论剪切变稀流体还是剪切变稠流体,液体的黏性和表面张力都会抑制液膜破碎,而气/液相互作用力则促进液膜破碎.而且,幂律指数越小,液膜射流越容易破碎.同时,尽管非对称模式在液膜破碎过程总是占据主导地位,但是当两种模式的最大扰动增长率的量级同阶时,对称模式对于液膜破碎也起着重要作用.%The temporal instability of a two-dimensional power law liquid sheet moving in a static inviscid gas medium was investigated theoretically.There were two kinds of disturbance modes for the sheet:varicose mode and sinuous mode.The corresponding dispersion relation between the growth rate and the wave number of disturbed interface waves for each mode was derived with a linear approximation.By solving the dispersion equations numerically,the effects of the generalized Reynolds number,the Weber number,the density ratio of gas to liquid and the power law exponent,on the instability of the sheet were studied.The results reveal that,for both the modes and for both the shearthinning and shear-thickening fluids,the viscosity and surface tension of the liquid prevent the sheet from breaking up while the aerodynamic interaction between the gas and the liquid promotes the breakup process.And a liquid sheet with a smaller power law exponent is easier to disintegrate.Moreover,although sinuous disturbances always dominate the instability process of the sheet,varicose disturbances also play an important role,especially when the maximum growth rate of varicose mode is the same order as that of sinuous mode.
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