Interactional aerodynamics could significantly affect the rotary wing performance, the airframe loads, as well as the handling qualities of aircraft. It has become necessary for the nature of the vortical slipstream and its interference with aircraft components to be understood over a wide range of flight operating conditions. The propeller/wing aerodynamic interaction phenomena have been experimentally investigated at low subsonic speeds on a propeller/nacelle/half-wing configuration (P/N/W2). The P/N/W2 ensemble has been studied under different wind-tunnel flow configurations to simulate different conditions of the whole flight envelope including axial, conversion/reconversion, and hovering flights. The experimental investigation has been based on extensive overall and local data measurements performed on the propeller, the wake geometry, and the half-wing. The results exhibited the considerable influence of the flow configuration and the tilt angle parameter on the nature of the wake distortion due to the half-wing. It is also shown that such tip vortex trajectories distortions strongly affect both the instantaneous and mean lift and drag distributions along the half-wing span.
Nomenclaturep x )/pn 2 D 2 c = wing chord section, 1.02 m Dr, Li = drag and lift airloads of the half-wing, N d = distance between the propeller disk and the leading edge of the wing, Q.6R LI = half-wing span, 0.75 m L2, L3, L4 = lengths defined in Fig. 3, L2 = 0.25 m, L3 -0.10m, L4 = 0.20m M = pitching moment of the half-wing, mN n = propeller rotational frequency, rps OXYZ = coordinates system defined in Fig. 1 P, T = power and thrust of the propeller p, p n p^ = static pressure, total pressure, and pressure at infinity, Pa R = propeller radius, 0.425 m r = radial coordinate from the axis of rotation, m r t = radial coordinate of tip vortex, m t = time, s U, V, W = velocity components defined in Fig. 1, m/s V x = velocity at infinity, m/s Presented as Paper 94-1921 at the AIAA 12th Applied Aerodynamics Conference, Colorado Springs, COX = spanwise coordinate of the nacelle/wing ensemble, m Z, = axial coordinate of tip vortex, m a = geometric incidence of the propeller/ nacelle/wing configuration, deg « 0 = mean pitch angle at rlR = 0.70 of the propeller blade, deg «! = wing geometric incidence at zero lift line, -2 deg j8 = tilt angle of propeller/nacelle around the half-wing, deg y = propeller operating parameter, VJnD 17 = propeller efficiency, yr/x v = kinematic viscosity, m 2 /s p = air density, kg/m 3 T = propeller thrust coefficient, T/pn 2 D 4 (f>i = i.d. circle of the octagonal test section, 3 m X = propeller power coefficient, P/pn 3 D 5 i/>, «/f r = age of the vortex, deg *l/ b = blade azimuth angle, flf deg H = propeller rotational frequency, rad/s (*)t = phase of the period, deg Subscripts /, ind Superscript relative to induced quantities relative to uniform flow conditions = time-averaged quantities over a rotational period
