FLOW VISUALIZATION DURING MULTIPLE-AXIS MOTIONS USING A WIND-DRIVEN MANIPULATOR

This article explores the problem of capturing vortex flow interaction s that occur during coupled-axis maneuvers at finite rates. A wind-dri ven dynamic manipulator (WDM) has been developed to perform simultaneo us motions repetitively about two degrees of freedom under open-loop o r feedback control in a low-speed wind tunnel. The concept of the WDM is examined and support interference is shown to be small compared to that in conventional approaches to maneuver simulation. Vortex flow in teractions occurring near the vertical fins of a 1/32-scale fighter co nfiguration during pitch, yaw, and coupled pitch-yaw motions are explo red using quantitative laser sheet videography. Large asymmetry and co mplex interactions are observed in the flowfield. Vortices generated b y the forebody, wing leading edge, wingtip, and vertical fins are seen to interact during the coupled pitch-yaw maneuver, Maneuvers are limi ted to reduced frequencies below 0.036, based on wingspan. Vortex loca tions are seen to be accurately reproducible and to be independent of rate as expected in this regime. Even at such low rates, several trans ient interaction phenomena are observed, involving vortices and contro l surfaces. Quantification of such phenomena is demonstrated.