The main purpose of this study is to investigate film instability and hence the entrainment mechanisms of the liquid film of cooling flow by computational fluid dynamics (CFD) techniques. In the modelling, a two-layer k-ε turbulence model is used with a high Reynolds number k-ε turbulence model away from the walls while the near-wall viscosity-affected layer is resolved with a one-equation model. So as to accommodate the two-phase interface, the Scalar Equation (Volume of Fluid) Method was used. In addition to the investigation of entrainment mechanisms, the nature of the film-coolant released into the atmosphere, with and without chemistry (combustion) included is examined. The transient numerical simulations indicate the generation of disturbance waves at the liquid-gas interface for coolant flows above a critical value and their growth result in liquid entrainment. The film-coolant flow was found to persist into the wake, which has environmental implications, in that if afterburning is not used, then cracked large-molecule hydrocarbons are then the primary product instead of soot formation.
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