关键词: 工程仿生学, 仿生射流表面, 数值模拟, 减阻, 边界层

Abstract: Numerical simulation is carried out to study the drag reduction characteristics of porous bionic jet surface according to RNG k-ε turbulence model. The results show that there exists a linear dependency of the drag reduction on the rate of velocity, that is, the higher the rate of the velocity, the better the effect of drag reduction. The maximal efficiency of drag reduction is 59.02%. Friction coefficient decreases at first, and then increases along with the central line of the bionic jet surface with single hole. The efficiency of drag reduction in local region can be up to 111.8%. Furthermore, the more the number of jet holes, the better the drag reduction effect. The mechanism of the drag reduction of the bionic jet surface is studied. It is found that the jet-flow increases the thickness of the viscous sublayer in the boundary layer by changing the structure of the flow field in the vicinity of the jet surface. As a result, the gradient of normal velocity, perpendicular to the surface, is decreased, which contributes to remarkable drag reduction. Meanwhile, the gradient of normal velocity generates streamwise vortex structure and develops small secondary vortex on the surface, which results in inhibiting momentum exchange between fluids, thus, reducing the friction on the jet surface.

Key words: engineering bionics, bionic jet surface, numerical simulation, drag reduction, boundary layer