Shape Optimizing Nacelle near Flat-Plate Wing Using Multiblock Sensitivity Analysis

摘要

A major design task in reducing the overall aircraft drag is the integration of the engine nacelles and the airframe. With this impetus, a methodology was demonstrated to optimize nacelle shapes with and without the presence of a flat-plate nearby to account for the wing interference. Overly simplified shapes notwithstanding, this process requires multiblock grids not only for its aerodynamic analysis, but also for its optimization. Although the former is a standard practice, the latter has only recently been possible for the gradient-based optimizations with the development of the sensitivity analysis with domain decomposition scheme. The analyses were obtained by solving the three-dimensional, compressible, thin-layer Navier-Stokes equations using an implicit, upwind-biased, finite volume scheme. In addition to demonstrating the present method's suitability for automated shape optimization of interfering aircraft components, such as a nacelle and a wing, the results verified two important issues. First, accounting for the aerodynamic mutual interference between components in close proximity manifested itself in a shape different than that obtained when a component was assumed to be isolated. Secondly, even for isolated-component designs, neglecting the viscous effects compromised not only the flow physics but also the optimized shapes.