Three-dimensional Euler solutions for long-duct nacelles

A three-dimensional Euler-equation computational technique has been developed to solve for the transonic flow past flow-through nacelles. The technique employs an approximately-factored alternating-direction implicit numerical algorithm and a radiation treatment of the outflow boundary. Studies are presented which show that the radiation treatment gives better numerical convergence than the condition of specifying the pressure at the outflow boundary. Calculations made with the technique are presented for a long-duct turbofan engine nacelle at a Mach number of 0.80 and angles of attack of 0 deg and 4 deg. Good agreement is shown between the computational results and wind-tunnel data. Problem areas are identified and recommendations are made for further numerical studies.