Breakup Of R-T Surface Waves Of Plane Liquid Film In A Composite Gas Stream

In this paper,the physical model of the viscous planar liquid film jet into the compressible composite gas flow is established,and the linear stability analysis of breakup of R-T surface waves of plane liquid film in a composite gas stream is carried out.Firstly,the dimensionless dispersion relation is derived by the continuity equation,the momentum conservation equation,the kinematic boundary condition,the additional boundary condition and the dynamic boundary condition,and compared with the existing Rayleigh wave derivation results.The R-T wave derivation process proved to be correct.Secondly,the program is written in Fortran language,and the dispersion relation is numerically calculated to obtain the relationship between the surface wave growth rate (?)and the surface wave number(?).According to the derived dispersion relation,the R wave is the main wave,and the T wave is the secondary wave.The R wave plays a leading role in the breakup process of the liquid film.When the T wave does not exist,the R wave still exists;but when R wave does not exist,the T wave will cease to exist.The Fortran program calculation results show that:(1)For R wave,the surface wave growth rate increases first and then decreases with the increase of the wave number.As the displacement extends,the amplitude of the jet increases and the wavelength gradually decreases until the wave number and the surface wave growth rate are the largest.For T wave,the surface wave growth rate decreases as the wave number increases until it reaches zero.The wavelength in the middle position is the largest and the amplitude is also the largest.As the displacement extends to both sides,the wavelength and amplitude are continuously reduced.At the edge position of the planar liquid film,the wavelength of the surface wave is the shortest and the amplitude is no longer increased.(2)Dimensionless parameters such as flow Weber number Wel and Reynolds number Rel,gas-liquid flow ratio (?)and (?),gas flow Mach number Magj,liquid flow Euler number Eul are unstable factors of planar liquid film breakup.The surface wave growth rate increases as these parameters increase.(3)In the case of only axial airflow or only lateral airflow,the lateral airflow is more likely to cause liquid film breakup than the axial airflow;but in the case of a composite gas stream with both axial and lateral airflow,it is axial airflow has a greater impact on liquid film instability than lateral airflow.