Notes on the progress of free-flight trials to measure heat transfer at Mach numbers up to 5

Abstract

A summary of the first ten flights made with a heat-transfer vehicle is given together with some of the salient features of the results relative to conical and hemispherical heads. The method of reducing the temperature data is outlined. The turbulent heating rates to a cone were overestimated by about 12% on the average by a theory based on 'intermediate' enthalpy, a Reynolds analogy factor of 1.22 and a cone form factor of 1.18. The data relative to hemispherical heads indicate the following results. (i) Fair agreement is obtained with the theory of Stine and Wanlass at the stagnation point and some agreement at those stations identified with laminar flow. (ii) On the whole predictions for turbulent heat transfer on the basis of Peattie and Wild 3 are closer than those on the basis of Van Dries but neither give a satisfactory correlation of all the data. (iii) The roughness of the surface finish can give rise to an appreciable increase in turbulent heat transfer rate. A 10 inch diameter hemisphere with a C.L.A. finish of 200 microinches was found to have turbulent heat-transfer rates about 30% greater on the average than those of a similar smooth one. (iv) The distance of the boundary between laminar and turbulent flow from the nose was not the same along different streamlines radiating from the stagnation point. Further experiments planned are briefly described.