In film cooling experimental studies, due to the difficulty in measuring the surface heat flux variation, a Heat Flux Ratio (HFR) equation originally derived by Mick and Mayle [1], has been widely employed to calculate the surface heat flux distribution using the measured adiabatic film effectiveness and surface temperature. A close examination of the derivation process and applications of the ...

It is found in many film-cooling experiments and computational analyses that a heated surface is employed to simulate the actual film-cooling condition with a cooling jet and a hot main flow. Considering that the dominant energy passage in turbine airfoil film cooling is always from the hot combustion gas flowing into the airfoil, employing a heated surface to simulate the actual film cooling c...

Film cooling is a cooling technique widely used in highperformance gas turbines to protect the turbine airfoils from being damaged by hot flue gases. Motivated by the need to further improve film cooling in terms of both cooling effectiveness and coolant coverage area, the mist/air film cooling scheme is investigated through experiments in this study. A small amount of tiny water droplets (7% w...

Effects that two different compound-angle film-hole configurations have on film cooling effectiveness are investigated. Effectiveness measurements have been made downstream of a single row of compound-angle cylindrical holes with a diameter of 7.5 mm, and a single row of compound-angle, diffuser-shaped holes with an inlet diameter of 7.5 mm. Both geometries were inclined with respect to the cov...

An experimental investigation of the local film cooling effectiveness and heat transfer coefficient downstream of a row of elongated holes in a simulated axial turbine blade tip is presented. Film cooling is needed to protect the turbine blade tip region from high heat transfer rates, especially when cooling by convection is insufficient to keep the temperature distribution of the blade within ...

Cooling of gas turbine hot section components such as combustor liners, combustor transition pieces, turbine vanes (nozzles) and blades (buckets) is a critical task for improving the life and reliability of hotsection components. Conventional cooling techniques using air-film cooling, impingement jet cooling, and turbulators have significantly contributed to cooling enhancements in the past. Ho...

Maximization of film-cooling effectiveness in an idealized film-cooling flow is accomplished using a gradientbased control strategy. The state equations are the two-dimensional unsteady incompressible Navier-Stokes equations along with the temperature equation. The control is a spatially and temporally varying normal velocity boundary condition subject to a constraint of zero mass and energy fl...

We report results from a computational study of film cooling from cylindrical holes inclined at 35 degrees with respect to a flat surface using Large Eddy Simulations (LES). The hole length is L/d = 3.5, distance between the holes is P/d = 3, boundary layer above the flat surface is turbulent with Reθ = 938, density ratio = 0.95, velocity ratio = 0.5. All pertinent components of geometry, namel...

An experimental investigation was conducted to study the effects of blowing ratio and the existence of lands on the film cooling effectiveness of a turbine blade trailing-edge model. Instead of using a temperature-based technique, a mass transfer analogywas used to quantify the film cooling effectiveness. This was done through themeasurement of the distribution of oxygen concentration over the ...