Numerical and experimental study on liquid sheet deformation by air flow

A liquid fuel sheet injected into the combustor of gas turbine engine is deformed and atomized by the complex interactions between the liquid and high-speed air flows. However, the detailed atomization process remains unknown. Various factors such as densities, velocities, viscosities, momentums, kinematic energies of gas and liquid, surface tension and instabilities of a gas-liquid interface affect the atomization process. In this study we investigated the effects of these factors on the growth rate and the wavelength of the primary liquid sheet oscillation induced by high-speed air flows. We performed two-dimensional numerical calculations using a volume tracking method and visualization experiments of a liquid sheet with high-speed air flows. As a result, we confirmed that gas velocity gradient at the interface is dominant for the growth of liquid sheet perturbation, which depends not on gas velocity but on liquid velocity due to the lip. The wavelength is in inverse proportion to the square root of momentum flux ratio. We measured the wave velocity using high speed images to confirm that liquid is not accelerated so much by air stream in the near wake.