Numerical simulation of aerodynamic characteristics of a BWB UCAV configuration with transition models

Abstract

A numerical simulation for a nonslender BWB UCAV configuration with a rounded leading edge and span of 1.0 m was performed to analyze its aerodynamic characteristics. Numerical results were compared with experimental data obtained at a free stream velocity of 50 m/s and at angles of attack from -4 to <TEX>$26^{\circ}$</TEX>. The Reynolds number, based on the mean chord length, is <TEX>$1.25{\times}106$</TEX>. 3D multi-block hexahedral grids are used to guarantee good grid quality and to efficiently resolve the boundary layer. Menter's shear stress transport model and two transition models (<TEX>${\gamma}-Re_{\theta}$</TEX> model and <TEX>${\gamma}$</TEX> model) were used to assess the effect of the laminar/turbulent transition on the flow characteristics. Aerodynamic coefficients, such as drag, lift, and the pitching moment, were compared with experimental data. Drag and lift coefficients of the UCAV were predicted well while the pitching moment coefficient was underpredicted at high angles of attack and influenced strongly by the selected turbulent models. After assessing the pressure distribution, skin friction lines and velocity field around UCAV configuration, it was found that the transition effect should be considered in the prediction of aerodynamic characteristics of vortical flow fields.