UNSTEADY AERODYNAMIC ANALYSIS OF SPACE SHUTTLE VEHICLES Part Ⅲ: BOOSTER INTERFERENCE EFFECTS

摘要

An investigation of the interference flow field on the space-shuttle boost configuration has been made. The results show that the interference effects can dominate the shuttle aerodynamics. Furthermore, vortices shed from shock-induced flow separations on the forward portion of the vehicle affect the aerodynamic loads on the aft portion of the booster. Thus, the forebody and aft-body flow fields are coupled. This coupling and the associated time lag due to the finite convection speed of the vortices furnish a mechanism whereby the unsteady aerodynamics can cause undamping of certain low frequency elastic modes of the booster. A preliminary order-of-magnitude analysis of the aeroelastic stability of the shuttle booster indicates that negative aerodynamic damping could occur for at least one bending mode and be of sufficient magnitude to dominate the structural damping. The implication of these results (i.e., the possibility of undamped oscillations leading to structural failure), is serious enough to warrant further, more detailed analysis.