Numerical Modeling of Liquid Film Cooling Heat Transfer Coupled to Compressible Gas

Liquid film cooling is a widely adopted method for restricting the solid wall temperature within allowable limits in a combustor. In most of the earlier works, the hot gas and coolant is treated as incompressible, however, in many practical applications such as in rocket propulsion systems, hot gas is compressible. In this study, a numerical model for coupled heat transfer between the compressible hot combustion gas and the incompressible liquid film injected along the wall is presented. Interface energy balance and mass balance are modeled along with phase change of liquid and diffusion of vapor into the gas flow, to investigate the extent of cooling along the solid wall. Validation of turbulence-based in-house code with literature data for nozzle flow is also included in the study. Effects of initial liquid film thickness, film temperature, film velocity, and vapor mass fraction on wall-cooling are studied. The film cooled length obtained from the present numerical model is compared with experimental results available in the literature.