In the present study, numerical simulations have been conducted to investigate the primary breakup
of the liquid film in the gas-liquid pintle injector, using the volume of fluid (VOF) method with
the adaptive mesh refinement to capture the gas-liquid interface. The film breakup and atomization
characteristics in the pintle injector are studied by changing the structure parameters and the momentum
ratio. The results show that increasing the radial liquid flow rate to raise the momentum
ratio promotes the atomization performance, while decreasing the axial gas flow rate deteriorates the
atomization performance. The two methods of altering the momentum ratio both cause the spray
angle to increase with the momentum ratio, but the first routine leads to a slower increase. With the
increase of opening distance, the velocity of the liquid flow decreases, and the thickness of the liquid
film increases significantly, making the film hard to break up. The skip distance negatively influences
the film breakup and atomization when the skip distance exceeds one. Moreover, the hollow region of
the spray is decreased with a longer skip distance, which is detrimental to fuel combustion.