Forebody flow physics due to rotary motion.

摘要

An experimental investigation of the aerodynamic behavior of an isolated forebody undergoing rotary motion was conducted in a small-scale wind tunnel. Force balance, surface pressure, and flow visualization data was acquired over a range of AOA, for a round and chined configuration of a generic tangent ogive shape. The nature of the fixed location of separation of the chined forebody develops a strong, symmetrical leeward side flowfield. In comparison, the round forebody develops a lateral asymmetry, as a function of AOA, from the naturally occurring separated flow. Quantifying the side force behavior due to the rotary motion of the two distinctively different forebody configurations will lead to a better understanding of the flowfield which plays a primary role in the overall stability and control of an air vehicle.; For the round forebody, the side force behavior due to the rotary motion ($CYW$) is dependent upon flow speed (Re_D), AOA, as well as the direction and magnitude of rotation ($W=wLV$). In the low AOA range, the rotary-induced flowfield is insufficient in promoting a side force development. In the high AOA range a damping in side force behavior is a result of the “moving wall” effect where the flow along the windward region of the forebody is the predominant influence. In the AOA range where an asymmetrical flowfield is established in a static environment, the rotary motion does not disrupt the natural asymmetric state of the vortices. Additionally, neither the presence of a static side force nor its direction is apparently sufficient in determining the $CYW$ behavior from the axially-varying flowfield.; The $CYW$ behavior of the chined forebody is related to the leeward side vortices' vertical trajectory, which is a function of AOA. A slight propelling side force behavior develops in an AOA range where an increased suction develops from the upwind vortex. In the high AOA range there is a diminishing influence from the leeward side vortex suction resulting from the increased vertical displacement of the vortices. Consequently, the flow along the windward region of the forebody is again the predominant influence developing a damping $CYW$ character.