In order to perform a scaled film cooling experiment, fluid dyamicists understand that there are certain fundamental nondimensional parameters that influence the flow conditions, such as the Reynolds number and freestream turbulence intensities. However, there is debate regarding the proper parameter by which to scale coolant flow rates in film cooling experimentation. Often, researchers attempt to match the density ratio (DR) between engine and laboratory conditions, and vary the coolant blowing ratio (M) or momentum flux ratio (I). Density, however, is not the only transport property that must be accounted for between engine and laboratory conditions. Specific heat, thermal conductivity, and dynamic viscosity abo vary, and the introduction of other gases adds an additional level of complexity, in particular, with the considerations that must be made for the diffusion of species from the coolant plume into the freestream. Binary pressure sensitive paint (PSP) and infrared thermography (IR) experiments were performed with several inert gases in order to explore the effects of gas property variation on film cooling adiabatic effectiveness. Coolant jet plume position was found to be scaled with I for both experimental techniques, and the effectiveness magnitude was found to be related to the advective capacity ratio (ACR) in IR experiments.
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