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Abstract: Aerodynamic heat-transfer measurements were at six stations on the 40-inch-long 10° total-angle conical nose of a rocket-propelled model which was flight tested at Mach numbers up to 5.9. The range of local Reynolds number was from 6.6 x 106 to 55.2 x 106. Laminar, transitional, and turbulent heat-transfer coefficients were measured, and, in general, the laminar and turbulent measurements were in good agreement with theory for cones. Experimental transition Reynolds numbers varied from less than 8.5 x 106 to 19.4 x 106. At a relatively constant ratio of wall temperature to local static temperature near 1.2, the transition Reynolds number increased from 9.2 x 106 to 19.4 x 106 as Mach number increased from 1.57 to 3.38. At Mach numbers near 3.7, the transition Reynolds number decreased as the skin temperature increased toward adiabatic wall temperatures.
Heat-transfer data from four wind-tunnel experiments and two free-flight experiments with turbulent boundary layers have been examined to see whether or not they are well represented by the Reynolds analogy or a modification thereof. The heat-transfer results are put into the form of dimensionless Stanton numbers based on fluid properties at the outer edge of the boundary layer and are compared with skin-friction coefficients for the same Mach numbers and wall to free-stream temperature ratios as obtained from an interpolation of the existing skin-friction data. The effective Reynolds number is taken to be the length Reynolds number measured from the effective turbulent origin, a position which differs importantly from the leading edge of the test surface in some cases.
A preliminary investigation has been made of the effects of heat transfer on boundary-layer transition on a body of revolution at a Mach number of 1.61 and over a Reynolds number range of 7,000,000 to 20,000,000, based on body length. The body had a parabolic-arc profile, blunt-base, and a fineness ratio of 12.2 (NACA RM-10). The results indicated that, by cooling the model an average of about 50 degrees F, the Reynolds number for which laminar boundary-layer flow could be maintained over the entire length of the body was increased from the value of 11,500,000 without cooling to over 20,000,000, the limit of the present tests. Heatig the model an average of about 12 degrees F on the other hand decreased the transition Reynolds number from 11,500,000 to about 8,000,000. These effects of heat transfer on transition were considerably larger than previously found in similar investigations in other wind tunnels. It appears that, if the boundary-layer transition Reynolds number for zero heat transfer is large, as in the present experiments, then the sensitivity of transition to heating or cooling is high; if the zero-heat-transfer transition Reynolds number is low, then transition is relatively insensitive to heat-transfer effects.