A GENERAL METHOD FOR DETERMINING THE AERODYNAMIC CHARACTERISTICS OF FAN-IN-WING CONFIGURATIONS. VOLUME 1. THEORY AND APPLICATION

A general method is presented for the determination of aerodynamic characteristics of fan-in-wing configurations by means of incompressible potential-flow theory. The method is applicable to wings, flapped or unflapped, and to a wide variety of other potential-flow boundary-value problems. Arbitrary wing and inlet geometry, fan inflow distribution, thrust vectoring, angle of attack, angle of yaw, and flight speeds from hover through transition can be treated. The theoretical model is completely three dimensional, with no linearization of boundary conditions. The calculated results include pressure distributions, lift, induced drag and side force, pitching moment, rolling moment and yawing moment. The numerical potential-flow solution is obtained with source and vortex distributions on the boundary surfaces. The representation is composed of small, constant-strength source sheet panels distributed over the exterior wing surfaces, internal vortex filaments which emanate from the wing trailing edge to provide circulation and to produce the trailing vortex sheet, and a vortex lattice across the fan face and along the periphery of the fan efflux. Source and vortex strengths are obtained by satisfying boundary conditions at discrete points on the boundary surfaces. Velocities and surface pressures are calculated from the induced effects of the source and vortex distributions. Internal fan loads, based on pressure and momentum relations across the fan and an assumed fan exit flow distribution, are added to integrated wing surface pressures to determine total forces and moments on a fan-in-wing configuration. The method was programmed for use with a high- speed digital computer.
Task no. 1F125901A14234. See also Volume 2, AD667981.