| Popis: |
The paper analyzes the aerodynamics benefits of above-wing mounting of turbofan engines and performs a trade-off study of the structural limitations with this mounting method. This research is based on the US Patent #6,308,913, aiming to quantify the actual benefit derived from the drag reduction measure described in the patent. The paper focuses on the analysis of a turbofan engine, which when installed above an aircraft’s wing creates a flow field optimized to reduce the overall drag experienced by the wing nacelle assembly. This installation is designed to reduce wave drag during transonic cruise and therefore the wing-nacelle geometry was analyzed at a CL value of 0.4 and Mach number of 0.75. An aerodynamically ideal location for the nacelle was ascertained, and drag characteristics calculated. A multidisciplinary optimization study, considering the effects of drag, structural weight and aircraft mission was performed. This study does not, and was not intended to have the fidelity necessary for detailed design of an airframe-engine installation, but is instead intended to provide guidelines for use in the preliminary-design field. |
