A liquid-fuel sheet injected into the combustor of gas turbine engines is deformed and atomized as a result of the complex interactions between the liquid and air flows. However, the effects of the fluid properties and velocities of the gas and liquid on liquid sheet oscillation have not been clarified yet. In this paper, we performed two-dimensional (2-D) numerical simulations of an oscillating liquid sheet using a volume tracking method to investigate the effects of densities, velocities, viscosities and momentums of the gas and liquid phases on the growth rate and wavelength of the liquid sheet oscillation. As a result, we obtained the following conclusions. The oscillation of a liquid sheet is suppressed by the atomizer lip, which forms a wake in its downstream. The gas velocity gradient at the gas-liquid interface is a dominant factor in the growth of liquid sheet oscillation, which depends not mainly on gas velocity but on liquid velocity due to the lip. Gas and liquid viscous forces slightly reduce liquid sheet oscillation. The wavelength of the oscillation is in inverse proportion to the square root of the momentum flux ratio.

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A liquid fuel sheet injected into the combustor of gas turbine engines is deformed and atomized by the complex interactions between the liquid sheet and air flows. Aiming at improving the control technology of a fuel spray, the oscillation phenomenon and the primary break-up process of a planar liquid sheet with air flows have been studied for many years. Based on the previous studies, we propose a new correlation on the longitudinal wavelength λ Lon given by λ = � and that on the oscillation frequency f Lon of a liquid sheet given by f = ′ � / � , where MR Lip is the lip momentum ratio defined in this study. In addition to previous visualization experiments of a planar liquid sheet and parallel air flows with various densities of gas and liquid, gas and liquid velocities, liquid sheet thicknesses and lip thicknesses, we carry out an additional experiment with various gas velocities and liquid viscosities to cover all the effects of fluid properties, injector geometries including gas and liquid boundary layers on the deformation and the atomization characteristics of the oscillating liquid sheet. Image analysis is conducted to obtain f Lon . As a result, we confirm that liquid viscosity does not affect f Lon and λ Lon of the liquid sheet in a wide range of liquid Reynolds number. Finally, we verify the validity of the correlations of λ Lon whose constant c is 14.3 and f Lon whose constant c' is 0.095.

The Steam turbine is widely used for generating electricity, in the thermal, nuclear and geothermal power generation systems. A wet loss is known as one of the degrading factors of the performance. To reduce the amount of liquid phase generated by condensation and atomization from nozzles, the prediction of the distribution of liquid mass flow rate inside the turbine is important. However, the quantitative understanding and the prediction method of the liquid flow inside the turbine remain unclear because physics inside a turbine is consisting of complex multiscale and multiphase events. In the present study, we proposed a theoretical model predicting the motion of droplet particles in gas flow based on Stokes number whose model does not require numerical simulation. We also conducted the numerical validation test using three-dimensional Eulerian-Lagrangian simulation for the problem with turbine blade T106. The numerical simulation shows that the particle motion is characterized by the Stokes number, that is consistent with the assumption of the theoretical model and previous studies. When Stokes number is smaller than one, the particle trajectory just follows the gas flow streamline and avoids the impacts on the surface of T106. With increasing Stokes number, the particles begin to deviate from the gas flow. As a result, many particles collide with the surface of T106 when the Stokes number is approximately one. When the Stokes number is extremely larger than one, particles move straight regardless of the background gas flow. The good agreements between the theoretical predictions and numerical experiment results justify the use of our proposed theoretical model for the prediction of the particle flow around the turbine blade.