Measurement of Turbulent Heat Transfer Rates on the Aft Portion and Blunt Base of a Hemisphere Cylinder in the Shock Tube

Abstract

Turbulent heat transfer rates on the aft portion and on the blunt base of a hemisphere cylinder were measured in the 2-7/8 x 2-7/8 GALCIT shock tube over a range of shock Mach numbers between 3. 25 and 5. 1 and initial pressures between 3 and 17 em. Hg. The local Reynolds numbers on the cylindrical afterbody varied between 3.5 x 10^4 and 3.0 x 10^5 per em. A side support was used for the model in order to eliminate the disturbing effect of a rear sting support. The measured turbulent heat transfer rates on the cylindrical portion agreed very well with previous flat plate measurements for small temperature differences, although the ratio of stagnation to surface enthalpy varied between 3 to 8 in the present tests. Only a slight effect of this large variation in h_s/h_w was detected in this range of local Mach numbers, i.e., 1.25 < M_e < 1.5. The measured heat transfer rate on the base indicated that at the center of the base the heat transfer rate is comparable to that on the surface just ahead of the base, while the heat transfer rate falls off to 1/2 to 1/3 of this value towards the rim of the base. This unexpected distribution of heat transfer rate over the base, and particularly the high value at the center, shows the necessity for a careful study of wake phenomena.