Numerical Calculations Of Liquid Jet Stability In Sprays

This paper calculates the input parameters based on the relationship between different parameters.Then writing programs and performing numerical calculations by Fortran language and Muller method,and drawing and analyzing the?_rk-curves under different conditions,waveforms and waveform superposition graphs separately according to the dispersion relation of the plane liquid film in the compressible downstream airflow,the circular jet flows in the incompressible downstream airflow,the annular liquid film in the incompressible downstream airflow and the annular liquid film in the compressible composite airflow,and the three-stage surface wave perturbation amplitude function and the circular frequency formula of the space-time mode of the plane liquid film.The numerical results show that the jet surface wave growth rate decreases first and then increases with the increase of gas-liquid velocity ratio difference,increases with the increase both of Weber number and Reynolds number,and increases with the increase of Euler number and Mach number.In the process of fragmentation of planar liquid film,the para-sinuous waveform dominate when the gas-liquid velocity is relatively small,but in the compressible flow,the waveform has little effect on the fragmentation of liquid film.In the process of atomization of circular jet,in the laminar zone where the jet velocity is small,the flow velocity is the stabilizing factor of the jet,while in the transition zone where the jet velocity is large,the flow velocity turns into the unstable factor of the jet.The instability of the varicose waveform is slightly greater than that of the sinuous waveform,and the growth rate of the surface wave increases with the decrease of the Ohnesorge number.When the jet velocity is in the same interval and the difference is small,the influence of order is small,but it can still be seen that the higher the order,the more stable the jet.For the annular liquid film in the downstream flow,in the low-speed flow,the influence of the velocity of one side of the outer ring on the growth rate of surface wave is the greatest,followed by that of the one side of the inner ring,and that of the two sides of the equal-velocity flow is the smallest.In high-speed airflow,the conclusion is opposite.The amplitude ratio of surface wave increases with the increase of gas-liquid velocity ratio.The growth rate of surface wave decreases with the increase of gas-liquid density ratio in the case of constant velocity bilateral flow,while the opposite trend occurs when the velocity of both sides is unequal.The growth rate of surface wave always decreases with the increase of Weber number when the velocity of both sides is constant and the Weber number is small,while the growth rate of surface wave decreases first and then increases with the increase of Weber number when the velocity of both sides is unequal.For the annular liquid film in the composite airflow,regardless of the eddy current mode and waveform,the growth rate of surface wave increases with the increase of the gas-liquid velocity ratio in the inner and outer rings,the vortex strength in the inner rings and the gas-liquid density ratio.In the mode of rigid vortex,the para-sinuous waveform is more unstable.Regardless of the waveform,the growth rate of surface wave decreases with the increase of the rigid vortex strength in the outer ring,and decreases first and then increases with the increase of Weber number and Reynolds number.In the mode of potential vortex,the effect of waveform is negligible;the growth rate of surface wave increases with the increase of potential vortex intensity in the outer rings,and the liquid Weber number and Reynolds number increase together,and the effect of potential vortex intensity of the outer rings is greater than that of the inner rings.In the absence of rotating airflow,the surface wave growth rate and the surface wave number increase with the increase of Mach number of downward airflow in the inner and outer rings,regardless of the waveform.For the analysis of the non-linear stability of planar liquid film,the breakup time and length of the sinuous waveform are shorter than that of the varicose waveform under the same flow conditions.This is because the sinuous waveform usually appears in the transition section of the jet,while the varicose waveform usually appears in the laminar section of the jet.