RESEARCH ON DELTA WING UNSTEADY HIGH ANGLE OF ATTACK AERODYNAMICS

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This research is to study the basic physical details of the fluid dynamic phenomena associated with the wing rock observed at hjgh angles of attack on delta wings. A specially designed forced roll oscillation method with a two-components balance was introduced to take the aerodynamic force and moment ; not adopting the conventional free rotation methods. The success of the method depends on the accurate separation of the inertial and aerodynamic forces from the measurement. Use of light weight models, low rate of oscillation and elaborate calibration of balances made it possible to get data up to the non-dimensional roll rate of 0.1.Two delta wing models of 14 and 7 degree semi-apex angle, respectively, are put to the tests and the model with a smaller apex angle shows very complicated aerodynamics. The reason of these changes are mode clear in relation to the vortex breakdown and vortex splitting by comparing the blance outputs with the flow visualization pictures.