The development of a fully reusable vertical-takeoff-and-vertical-landing (VTVL) rocket is indispensable for reducing space transportation costs. However, there are many technical issues associated with such vehicles, such as the safe execution of a turnover maneuver during return flight. It is known that a relatively desirable pitching moment characteristic for turnover can be accomplished by employing a slender body configuration, but the reason for this is not well understood. In this study, we carried out a delayed detached-eddy simulation (DDES) on the aerodynamic characteristics of such a slender-bodied reusable rocket for angles of attack between 0 and 180 degrees using unstructured compressible computationalfluid-dynamics (CFD). We also conducted inviscid calculations in order to distinguish the pitching moment contribution of the body configuration itself from the effects of viscosity and turbulence. It was found that two types of vortices were formed at 0-90 degrees, and also these vortices affected the pitching moment distribution. We also observed three types of vortices generated at 90-180 degrees. Combined with the results of the inviscid simulation, we concluded that the pitching moment characteristic is greatly impacted by the behaviors of these vortices and bubbles.
The Post Limiter (simple a posteriori slope limiter) is an anti-slope-limiting mechanism to preserve nominal second order in space as much as possible. This technique has been demonstrated to increase resolutions of two-dimensional simulations up to four times in each dimension [Kitamura and Hashimoto,
The development of a fully reusable vertical-takeoff-and-vertical-landing (VTVL) rocket is indispensable for reducing space transportation costs. However, there are many technical issues associated with such vehicles, such as turnover maneuvers during return flight where the pitching moment plays a key role. It is known that aerodynamic characteristics can be controlled by installing aerodynamic devices, but the relationship between the aerodynamic characteristics and the flowfields has not been explored. To clarify this relationship using computational fluid dynamics (CFD), we investigated these flowfields and aerodynamic characteristics, in the case where we install such devices (fins) in the nose part of a reusable rocket. We found that vortices form downstream of the aerodynamic devices. For angles of attack between 0 and 90 degrees (in which the fins are located in the upstream portion), these vortices significantly affect the surface pressure on the rocket and increase the pitching moment. On the other hand, for AOAs between 90 to 180 degrees (in which the fins are in the downstream portion), the effect of these vortices on the on-surface pressure is negligible, and only vortices formed near the surface of the fins increase the pitching moment.
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