Optimizing Engine Placement on an Aircraft Wing using Bio- mimetic optimization and FlightStream~(TM)

摘要

This paper describes the development of an automated engine placement capability using FlightStream to solve for aircraft aerodynamic loads, Vehicle Sketch Pad (VSP) to produce outer mold line geometry, and the Numerical Propulsion System Simulation (NPSS) tool for engine performance modeling and for setting boundary condition for the flow solver. FlightStream is a robust, fast prediction tool based on vorticity computations using an unstructured surface mesh representing the outer mold line of an aircraft, and is capable of producing high fidelity solutions for aerodynamic loads for aircraft in subsonic flight. VSP is a NASA funded open source geometry generator and NPSS has become an industry standard tool for engine modeling in conceptual and preliminary design phases. A high-bypass ratio engine has been placed along the wing under a pylon. The pylon geometry is driven by a genetic algorithm to determine the optimized location and design of the engine pylon relative to the wing geometry. The pylon geometric parameters are fed to VSP which in turn produces the outer mold line surface mesh for FlightStream. A genetic algorithm internal to FlightStream directs the geometry development and solutions to obtain an optimal configuration. Results are presented for modeling a typical commercial aircraft with a varying engine placement to minimize thrust specific fuel consumption. It is shown that a reduction of 2.3% in fuel flow rate can be obtained by the optimum design and placement of the engine and pylon on the wing as compared to a nominal starting configuration.