Low-speed wind-tunnel tests were conducted to investigate the parallel blade-vortex interaction. Flowvisualization tests of vortex generation performed before the pressure tests showed that a well-defined starting vortex was generated by an impulsively pitched wing. Time history of the pressure distribution on a pressuretapped wing model was acquired as the starting vortex passed over the wing. These pressure tests revealed that a substantial pressure change near the leading edge was induced by

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... the encountering vortex. The effects of vortex proximity, reduced frequency, and maximum pitch angle of the vortex generator on the pressure change were also investigated. Nomenclature c = chord length of instrument wing c vg = chord length of vortex generator wing Q = section lift coefficient of instrumented wing C p = pressure coefficient of instrumented wing, (P-P*)/q k = reduced frequency, ctc vg / VP -local static pressure P ini = initial local static pressurê max = maximum local static pressurê min = minimum local static pressure Pa, = freestream static pressure q = freestream dynamic pressure Re = Reynolds number T = time elapsed after vortex generation V w = freestream velocity x = longitudinal distance from instrumented wing leading edge to pressure tap x v = longitudinal distance from instrumented wing leading edge to vortex center y v = vortex generator height above wing a. = pitch angle of vortex generator «max = maximum pitch angle of vortex generator a = pitch rate of vortex generator fi m = freestream viscosity F = vortex strength Po, = freestream density