Aerodynamic and aero-optic computation of a lateral jet-controlled high-speed vehicle operating at medium altitudes

Lateral thrust jets exhibit better maneuverability performance than control surfaces such as conventional fins for attitude control or the orbital transfer of guided weapons. In the supersonic region, however, jet interaction phenomena occur due to the lateral jet during flight and a complicated flow structure is generated by the interaction of the shock wave, boundary layer flow, and vortex flow. In particular, high-speed vehicles using hit-to-kill strategy require precise control and maneuvering, so it is necessary to analyze the effect of the jet interaction flow accurately. Infrared sensing system is often used to correct the attitude and orbit of the vehicle controlled by lateral jets. Sensors inside the vehicle's head detect electromagnetic waves radiated from the target, and the control system determines whether the attitude or orbit needs to be changed based on the image data from the sensors. However, incident waves are propagated through an inhomogeneous density field, resulting in wavefront aberration, change of propagation trajectory, and reduction of intensity. This aero-optic phenomena acts as an external noise to the sensor, so it is necessary to separate aero-optic noise from the observed data. A number of conventional jet interaction analyses have been performed under low-altitude conditions, but there are not many cases with respect to medium-altitude conditions. Unlike low-altitude conditions, jet interaction flows at medium-altitude conditions have different flow characteristics. Moreover, strong flow structres from jet interaction has the possibility to to affect the density field around the head, enlarging the aero-optic noises. In this study, a jet interaction flow analysis is performed on a lateral jet-controlled high-speed vehicle operating at medium altitudes. Based on the results, the characteristics of the flow structure and the changes in the aerodynamic coefficients are analyzed. Furthermore, infrared wave propagation is numerically simulated to observe aero-optic errors.