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 26°. The Reynolds number, based on the mean chord length, is 1.25×106. 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 (γ-Reθ model and γ 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.

CFD Analysis of the Sideslip Angle Effect around a BWB Type Configuration

“…We investigated the highly nonlinear behaviors of the aerodynamic force and moment coefficients in more detail from a physics perspective by analyzing flow field parameters including contours and streamlines. Figures 8,11,and 12 show the contours of the pressure coefficient and skin friction line, which we calculated streamline from the wall shear stress at three angles of attack (0°, 12°, and 16°) and three sideslip angles (0, 8, and 20°). We observed symmetric skin friction lines and pressure contours with respect to the wing root at a sideslip angle of zero (Figures 8(a), 11(a), and 12(a)), which is consistent with the simulation results of Park et al [24] which considered the geometry with half of the body irrespective of the sideslip angle.…”

“…The behavior of the vortex on this type of planform is sensitive to some parameters such as the swept angle [2,3], the sharp or rounded leading edge [4,5], the angle of attack and angle of sideslip, and the Reynolds number. Many experimental [4,6,7] and CFD (computational fluid dynamics) studies [5,[8][9][10][11] were conducted to understand the flow behavior including the leading edge vortex around the low swept delta wings. The vortical flow around the SACCON configuration was investigated through both wind tunnel experiments and numerical simulation by Schütte et al [12].…”

Weight assessment for a blended wing Body-Unmanned aerial vehicle implementing boundary layer ingestion

“…Chandrasekhara [10] assessed experimentally, in a wind tunnel, the aerodynamics of a UCAV (wingspan = 9 in). Jo et al [11] evaluated, through numerical simulations, the aerodynamic characteristics of a BWB-UCAV (wingspan = 0.7 m). The same BWB-UCAV used by Jo [11], has been tested experimentally in a wind tunnel in Shim and Park's work [12].…”

“…Jo et al [11] evaluated, through numerical simulations, the aerodynamic characteristics of a BWB-UCAV (wingspan = 0.7 m). The same BWB-UCAV used by Jo [11], has been tested experimentally in a wind tunnel in Shim and Park's work [12]. These works have focussed on the aerodynamics characterization of BWB-UAVs and UCAVs; however, they neither address the propulsion system integration with the airframe, nor BLI integration features.…”