Scaling Film Cooling Adiabatic Effectiveness with Mass Transfer and Thermal Experimental Techniques
Abstract
With increasing engine temperatures, it is becoming more important to design effective film cooling schemes. Low temperature, large scale tests are often implemented in the design process to reduce cost and complexity. A nondimensional adiabatic effectiveness can be used as an indication of the performance of a film cooling scheme. However, the coolant flow rate must be properly scaled between the low temperature tests and engine temperatures to accurately predict film cooling effectiveness. This process is complicated by gas property variation with temperature. Tests are commonly conducted using thermal measurement techniques with infrared thermography (IR), but the use of pressure sensitive paints (PSPs) can be used implementing the heat-mass transfer analogy. Thus, the question arises whether mass transfer methods can be used as a surrogate to thermal methods. In this study, a thermal technique with IR was compared to a heat-mass transfer method with PSP. A new method for collecting large datasets with PSP was implementing in this study to account for paint degradation. Results indicate that adiabatic effectiveness is best scaled by accounting for specific heat with the advective capacity ratio (ACR) using thermal techniques. Results also indicated that the mass flux ratio (M) is an appropriate parameter to scale adiabatic effectiveness results between gases using the mass transfer technique. This has significant implication for engine designers that rely on experimental data to predict engine behavior.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 21, 2019
- Accession Number
- AD1073903
Entities
People
- Luke J. Mcnamara
Organizations
- Air Force Institute of Technology