Film cooling effectiveness in single row of holes:First moment closure modeling

The present article focuses on the evaluation of a first-moment closure modelapplicable to film cooling flow and heat transfer computations. The present firstmomentclosure model consists of a higher level of turbulent heat flux modeling inwhich two additional transport equations for temperature variance kθ and itsdissipation rate εθ are considered. It not only employs a time scale that ischaracteristic of the turbulent momentum field, but also an additional time scaledevoted to the turbulent thermal field. The low Reynolds number k-ε turbulencemodel is combined with a two-equation kθ-εθ heat flux model to simulate the flow andheat transfer in a three-dimensional single row of cylindrical holes film coolingapplication. Comparisons with available experimental data show that the twoequationheat flux model improves the over-predictions of center-line film coolingeffectiveness caused by the standard simple eddy diffusivity (SED) model with a fixedvalue of turbulent Prandtl number. This is due to the enhancement of turbulent heatflux components in the first-moment closure simulations. Also, the span wisedistributions of effectiveness are computed with more accuracy due to betterpredictions of coolant jet spreading. However, the limitations of first-moment closuredue to its isotropic approach should be taken into consideration

Keywords:

Film Cooling , First-Moment Closure , Two-Equation kθ-εθ Heat Flux Model , Turbulent Heat Flux Modeling