Experimental study on heat transfer to rough walls

Experimental results of heat transfer to rough walls are given for sphere cone models at Mach number 5. The nose radius of the models is 27.4 mm and its base diameter is 60 mm. Five models were tested and the different roughness in its bend diameters are separately 0,0.3,0.5,0.7 and 0.9 mm. The tests were conducted in a conventional hypersonic wind tunnel at total pressures pt of 10-45 kg/cm squared and Reynold's numbers Rep of (0.8-3.6) x one million. The test results indicate that the smooth wall model heating is the laminar flow heating, its heat flux stagnation point is quite close to the laminar flow theoretical data, and the influence of roughness at low total pressure (10kg/cm squared) occurs mainly to promote the transition and development of a boundary layer.