Experimental investigations of test gas effects on the hypersonic flow field around large angle blunt cone in shock tunnel

The effect of the test gas on the flow field around 120°-apex angle blunt cones has been investigated in a shock tunnel at a nominal Mach number of 5.75. The shock stand-off distance around the blunt cone is measured by electrical discharge technique using both carbon dioxide and air as test gases. The fore body laminar convective heat transfer to the blunt cone is measured using platinum thin film sensors in both air and carbon dioxide environments. An increase of 10-15 in the measured heat transfer values is observed with carbon dioxide as the test gas compared to air. The measured thickness of the shock layer along the stagnation streamline is 3.57±0.17 mm in air and 3.29±0.26 mm in carbon dioxide. The computed thickness of the shock layer for air and carbon dioxide are 3.98 mm and 3.02 mm respectively. The observed increase in the measured heat transfer rates in carbon dioxide compared to air is due to the higher density ratio across the bow shock wave and the reduced shock layer thickness. © 2000 The American Institute of Aeronautics and Astronautics Inc. All rights reserved.