Accession Number : AD0278447

Title :   HEAT TRANSFER RATES AND INSULATED WALL TEMPERATURES FOR A TRANSPIRATION COOLED HEMISPHERE

Corporate Author : AIR FORCE OFFICE OF SCIENTIFIC RESEARCH ARLINGTON VA

Personal Author(s) : GOLLNICK,ALBERT F. JR.

Report Date : DEC 1960

Pagination or Media Count : 1

Abstract : Existing solutions to he bou dary layer equations with helium injection and constant free stream pressure gradient are used to calculate the injection distribution on a hemisphere re uir d to maintain a constant wall temperature. The method used is an extension of the wedgematching technique. The fabrication and calibration of a wind tunnel model designed on this basis is described. The resulting distributions of wall temper ture, insulated wall temperature and Stanton number are presented, and the variation of thes quantities with injection rate, using air and helium as coolants. The design technique proved satisfactory. The insulated wall temperature near the ose, for helium injection, is nearly ten per cent higher than the tunnel stagnation temper ture. It is suggested that this may result from the thermal diffusion of the helium within the boundary layer. The Stanton numbers obtained with air and helium agree with theoretical predictions, and the corresponding heat fluxes demonstrate that mass transfer cooling on a blunt body is very effective. On the other hand, the anticipated superiority of helium over air does not occur, since the adverse effec of helium injection on the insulated wall temperature negates the corresponding reduction in heat transfer coefficient. (Author)

Descriptors :   ABLATION, COOLING, FLUID FLOW, HELIUM, HEMISPHERICAL SHELLS, TEMPERATURE, WIND TUNNELS

Distribution Statement : APPROVED FOR PUBLIC RELEASE