Discrete Film Cooling in a Rocket with Curved Walls
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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This study quantified the effects of discrete wall-based film cooling in a rocket with curved walls. Simulations and experiments showed decreasing with wall radius of curvature, holding jet diameter constant, improves net heat flux reduction NHFR and adiabatic effectiveness eta for 90 compound injected cylindrical jets, though is reduced at the highest curvature. NHFR and eta improved further with a high favorable stream-wise pressure gradient K2.1x10-5 at all tested blowing ratios, but were not affected much by a high density ratio DR1.76 using carbon dioxide as the coolant. Experiments were run at a Reynolds number of 31K and a free-stream turbulence intensity of 26 with varying wall and jet radii. Simulations showed the Rannie transpiration model may be used to predict the cooling performance of a wall with full coverage film cooling using a correction formula based on the hole coverage area. Three improvements were made to the method of simultaneous acquisition of adiabatic wall temperature and heat flux coefficient solving for the needed variables via a multi-point non-linear least squares curve fit instead of a two-point direct solution correctly applying the free-stream fluid temperature boundary solving for the needed variables via a multi-point non-linear least squares curve fit instead of a two-point direct solution correctly applying the free-stream fluid temperature boundary condition to account for drifting temperature instead of assuming it to be constant and showing a repeatable way to reduce uncertainty in the test start time.
- Theoretical Mathematics