Investigation of surface roughness on aerodynamics properties

This paper describes the effects of surface finish models on aerodynamic coefficients for constructed wind-tunnel testing models. Three models were evaluated. These models were fabricated from aluminum 2024-T4 by computer numerical control (CNC) machining. The roughness of surfaces for each model was 6.3,60, and 150 mu m, which was determined by PERTHOMETER2. A wing-body-tail configuration was chosen for the actual study. Testing covered the Mach range of Mach 0.3 to 1.2 at an angle-of-attack range of +6 to +26 deg at zero sideslip and an angle-ofsideslip range of -8 to +8 deg at a 16-deg angle of attack; the coefficients of normal force, axial force, pitching moment, and lift over drag are shown at each of these Mach numbers. Results from this study show that surface finish does have an effect on the aerodynamic characteristics in general; the data differ between the three models by less than 5 %. The surface finish does have more effect on the aerodynamic characteristics when the Mach number is decreased and has the most effect on the aerodynamic characteristics of axial force and its derivative coefficients.