Experimental Investigation of the Downstream Influence of Stagnation-Point Mass Transfer

Summary This report presents the results of an experimental investiga­ tion of the downstream influence of localized mass transfer in the stagnation region of a blunt body under hypersonic flow con­ ditions. The coolant is injected through a porous plug coaxial with the centerline of symmetry of the model. The tests were carried out in a wind tunnel with a Mach number of 6.0, stagna­ tion temperatures of approximate^ 1,600°R., and a stagnation pressure of approximately 600 psia. Four different gases were injected over a range of mass flows. The heat transfer on the im­ permeable section was measured under isothermal wall con­ ditions; for the higher rates of mass flow, adiabatic surface tem­ peratures were also determined. The theoretical analysis of the boundary-layer flow is investigated in order to establish the simi­ larity parameters for the flow system. These parameters permit the extrapolation of the test results to other flow conditions, provided that laminar flow prevails. Helium is found to be the most efficacious coolant.