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

摘要

Existing solutions to the boundary layer equations with helium injection and constant free stream pressure gradient are used to calculate the injection distribution on a hemisphere required to maintain a constant wall temperature. The method used is an extension of the wedge-matching technique of Stine and Wanlass. The fabrication and calibration of a wind tunnel model de¬signed on this basis is described. The model was tested in the Naval Supersonic Laboratory wind tunnel at Mach 3.53. The resulting distributions of wall temperature, insulated wall temperature and Stanton number are pre¬sented, and the variation of these quantities with injection rate, using air and helium as coolants. The design technique proved satisfactory. The insulated wall tem¬perature near the nose, for helium injection, is nearly ten per cent higher than the tunnel stagnation temperature. It is suggested that this may result from the thermal diffusion of the helium within the boundary layer.