Reynolds Number Effects on Flow Asymmetry Over a Slender Body at High Angles of Incidence

Slender-bodied vehicles that maneuver at high angles of attack, such as smart projectiles, experience significant aerodynamic side forces due to vortex asymmetry that occurs near the body’s surface. Although previous investigations have widely studied the influence of the angle of attack and nose geometry, the role of the Reynolds number on vortex asymmetry remains less understood, particularly in the incompressible regime. This study experimentally investigates Reynolds number effects on flow development over an 8° conical forebody at a fixed 45° angle of attack using planar particle image velocimetry (PIV) and force measurements using a six-component strain gauge. Reynolds numbers ranging from 0.2 × 105 to 3.5 × 105 were tested in the low-speed wind tunnel at the Florida Center for Advanced Aero-Propulsion (FCAAP) Laboratory. The results depend strongly on the Reynolds number, resulting in changes in vortex asymmetry and side force behavior. As the Reynolds number increases, side forces show a decreasing trend and an increasing trend. Results also suggest the presence of flow instabilities, which can lead to vortices moving closer to the model’s surface between 30-40m/s. These results help create a better understanding of the complex coupling between boundary layer state and vortex dynamics.