Aerodynamic Analysis of a Vertically Landing Lifting Body

摘要

The vertical landing lifting body (VLLB) is a new concept for reusable launch vehicles, which launches vertically, but re-enters the atmosphere at a high angle of attack (alpha) for its entire flight. The VLLB remains at high angles of attack through all Mach numbers under aerodynamic control until shortly before touchdown. One of the important risk areas for the VLLB concept concerns flight below Mach 2 at high angles of attack where the flow is dominated by separated, highly vortical behavior. The CFD study reported in this paper represents the beginning of a comprehensive effort. The purpose of this study is to investigate the aerodynamic characteristics and control effectiveness of the high-alpha flow of the Hot Eagle Vertically Landing Lifting Body geometry. Several test cases were performed utilizing Detached Eddy Simulations (DES) to both analyze and control the flow over Hot Eagle geometry at different flow conditions. According to results of the time-dependent DES computations, the flow is symmetric and steady at both subsonic and transonic Mach numbers for both 45 and 60 degrees angle of attack. As the angle of attack or the Mach number increases, the vortices get stronger; but the flow remains steady and symmetric. This is probably because of the blunt nature of the nose and its cross-section. Symmetric and asymmetric blowing cases were performed to control the flow structure around the body. Different blowing rates have been investigated, and the vehicle is found to be controllable with reasonable amounts of blowing.