Computational study of the effect of Reynolds number on a body of revolution at high angles of attack

Compressible, turbulent, viscous computations have been performed for a complex aerodynamic configuration consisting of an axisymmetric fuel tank with an attached pylon, and two triangular sway braces. Additional computations have been performed for a simplified configuration consisting only of the axisymmetric fuel tank. The free-stream Mach number was 0.7 for all computations. Six solutions were computed for the complex configuration at angles of attack in the -25 to -55 degree range and a unit Reynolds number of 0.186 million based on maximum tank diameter. The aerodynamic loads from these solutions were compared to experimental data and are in good agreement. These calculations were used to verify the ability of the Navier-Stokes CFD code, XAIR, to predict forces and moments on a complex configuration at high angles of attack. Twenty computations were performed on the axisymmetric configuration at angles of attack ranging from 0 to 55 degrees. Eleven of these solutions were performed at a sub-flight unit Reynolds number of 0.186 million based on maximum tank diameter and eleven were performed at a flight scale unit Reynolds number of 13.5 million. The sub-flight Reynolds number was chosen to correspond to a 1/15 scale wind tunnel simulation, and the flight Reynolds number was chosen to correspond to sea-level conditions at full scale. Fourteen of these solutions were performed to study Reynolds number effects, two were performed to examine the validity of the high Reynolds number solutions based on axial force comparisons with flat plate theory, and the remaining four solutions were performed to study asymmetric effects. Results presented include: comparisons of the computed and experimental loads on the complex configuration with the tank and pylon, differences in aerodynamic loads caused by varying the Reynolds number from the sub-flight to flight condition on the tank alone configuration, flow visualization of the tank alone solutions, and a brief examination of the effect of asymmetric shedding on the total aerodynamic loads for the tank alone configuration.