Abstract: In view of the idea that the bionic nonsmooth surface can reduce the viscous drag of a body, the drag reduction potential was investigated for the bodies of revolution by controlling the surface boundary layer structure to form a certain nonsmoothness. An orthogonal test scheme with 6 factors and 3 levels for each factor was used to evaluate the effect of 6 major influencing factors on the drag of the bodies of revolution. The nonsmooth bodies of revolution with spherical convex domes, spherical dimples and riblets were tested in comparison with the original smooth body in a wind tunnel under low speed, subsonic and supersonic conditions to get the drag reduction rates of the nonsmooth bodies as the test targets. The test results indicated that all 3 kinds of nonsmooth surfaces can reduce the drag of bodies of revolution, the maximal reduction rate is about 5%. The extremum difference analysis was used to determine the influence order of the factors and their optimal levels. The impact of the different bionic surfaces on the viscous forebody drag (including the skin friction and the shockwave drag) and the base drag of bodies of revolution were discussed.

Key words: bionics engineering, boundary layer, drag reduction, bionic nonsmoothness, orthogonal test design, bodies of revolution