Abstract: The complicated atomization process of liquid fuels, in particular, the initial atomization process, in the aero-engine combustor hinders the establishment of accurate primary atomization models. We apply the linear instability analysis to the study on the breakup mechanism of inviscid liquid (water) without considering the jet viscosity. The jet breakup is predicted according to the growth rate of the surface wave and the unstable wave number range by establishing the dispersion equation. When the Weber number of the air or the liquid increases, the growth rate of the jet surface wave increases significantly, while the optimal wavelength decreases significantly. When the liquid to air momentum ratio is larger than the critical value, K-H instability is dominant; otherwise, R-T instability is dominant. The two-dimensional shear airflow has a velocity gradient in the jet direction, changing only the effect of transverse aerodynamic force on the jet surface wave. When the jet flow rate is constant, the negative gradient shear airflow can accelerate the jet breaking.

Key words: two-dimensional shear airflow, liquid jet in crossflow, dispersion equation, R-T instability, K-H instability