Aerodynamic Influence of a Helicopter on a Jettisoned Missile

摘要

The effect of the presence of a helicopter fuselage on the aerodynamic behavior of an unthrusted, jettisoned missile with forward strakes and tail control surfaces is explored. The investigative tool used for this purpose is a production-oriented, Euler, Computational Fluid Dynamics (CFD) methodology Titled Euler Tunnel Analysis (ETA). Initially, comparison of CFD computations with wind tunnel measurements for the isolated missile are used to anchor the computations in reality and provide an evaluation benchmark. The ensuing study is assumed to be sufficiently fast so as to convect rotor downwash effects downstream of the region of interest. Further, the calculations are performed in steady-state mode for each scenario. As expected, it is found that even without downwash the presence of the fuselage significantly modifies the aerodynamic properties of the missile. In addition, the vorticity confinement method (which conserves field and surface vorticity) is shown to preserve the vorticity created by the forward strakes as it convects downstream to the tail controls.