Hypersonic, Turbulent S kin-F riction and Heat-Transfer Measurements on a Sharp Cone
Turbulent skin-friction coefficients directly measured on an axisymmetric 5° half-angle sharp cone by two floating-element skin-friction balances at a freestream Mach number of 7.90 are presented. Heat-transfer distributions are obtained simultaneously. These results yield directly the Reynolds analogy factor. On the basis of measured skin-friction coefficients, which covered a range of wall-to-stagn ation temperature ratios (Tw/To) of 0.24 to 0.41 and Reynolds numbers at the location of the skin-friction balance of 1.45 x 107 to 2.17 x 107, we conclude that the method of Van Driest and that of Clark and Creel predict the measurements within about 10%. The methods of Spalding and Chi and of Sommer and Short underpredict the data by about 30% and 20%, respectively. Except for the relatively low-Reynolds-number case, the directly measured sharp-cone Reynolds analogy factor is between 1.01 and 1.07, which is in good agreement with the recent flat-plate measurements of Keener and Polek. Finally, results indicate that the Stanton number is essentially constant for Tw/To between 0.20 and 0.36, whereas it decreases by about 10% at Tw/To = 0.11.