Nose Tip Shape Optimization for Minimum Transpiration Coolant Requirements.
Final rept. 1 Aug 76-30 Jun 78,
AEROSPACE CORP EL SEGUNDO CA VEHICLE ENGINEERING DIV
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Expressions for the total heat transfer to a nose tip for a realistic reentry trajectory have been obtained by using local laminar and turbulent convective heat transfer relationships and extending the trajectory integration procedures of earlier investigators. Then, employing approximate relationships for the boundary layer edge properties along the nose tip surface, a variational calculus approach to determine nose tip shapes which minimize the total trajectory heat transfer coolant requirements for fixed fineness ratio and reentry parameters is utilized. The calculated minimum heat transfer shapes found have a flat nose with an expansion corner followed by an afterbody with monotonically decreasing slope. The height of the flat nose relative to the base radius decreases as the fineness ratio decreases. However, for fineness ratios greater than 0.2, the laminar and turbulent solution shapes were found to be very similar to one another. For fineness ratios approaching zero i.e., slender bodies, the laminar and turbulent minimum heat transfer shapes are 12 and 813 power law bodies, respectively. The relative heat transfer rate to a particular one of the minimum heat transfer shapes was found to be a factor of up to three times lower than that for other body shapes having the same fineness ratio.
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