Flow control for the steering of supersonic fin-stabilised projectiles using pin-based micro-actuators

This study focuses on a novel steering method for supersonic fin-stabilised projectiles using pin-based mechanical micro-actuators implanted at the rear of the ammunition. When supersonic cross-flows and aerodynamic structures generated by the neighbouring tail fins are acting on the projectile, complex interactions between the boundary layer and the pin-induced shockwaves will occur around the actuator. To understand the underlying physical phenomena and to determine how these flow structures could be simulated with steady-state CFD simulations, fundamental wind tunnel investigations have first been performed on a flat plate by means of pressure sensitive paints (PSPs) and particle image velocimetry (PIV) measurements. The resulting conclusions have then been applied to the controlled ammunition. Parametric CFD calculations determined the optimal area where the actuator should be implanted. Six degrees of freedom (6DoF) simulations provided the resulting trajectory. These predictions have finally been compared to free-flight deviation measurements to validate the steering methodology and to quantify the prediction error resulting from successive aerodynamics and flight mechanics simulations.