Abstract

To be representative of engine conditions, a measurement of film cooling behavior with an experiment must involve matching certain nondimensional parameters, such as freestream Reynolds number. However, the coolant flow rate must also be scaled between the experiments and engine conditions to accurately predict film cooling effectiveness. This process is complicated by gas property variation with temperature. Additionally, selection of the appropriate coolant flow rate parameter to scale from low to high temperatures is a topic of continued uncertainty. Furthermore, experiments are commonly conducted using thermal measurement techniques with infrared thermography (IR) but the use of pressure sensitive paints (PSPs) implementing the heat-mass transfer analogy is also common. Thus, the question arises of how the adiabatic effectiveness distributions compare between mass transfer experimental methods and thermal experimental methods and whether these two methods are sensitive to coolant flow rate parameters in different ways. In this study, a thermal technique with IR was compared to a heat-mass transfer method with a PSP on a flat plate model with a 7-7-7 film cooling hole. While adiabatic effectiveness is best scaled by accounting for specific heats with the advective capacity ratio (ACR) using thermal techniques, results revealed that PSP measurements are scaled best with the mass flux ratio (M). The difference in these methods has significant implications for engine designers that rely on PSP experimental data to predict engine thermal behavior as PSP is fundamentally not sensitive to the same relevant physical mechanisms to which thermal methods are sensitive.

This content is only available via PDF.
You do not currently have access to this content.