Inverse Design Method for Designing Isolated and Wing-Mounted Engine Nacelles

Abstract

This report summarizes the results of the joint partnership Inverse Design of Isolated and Installed Engine Nacelles between Rolls-Royce Deutschland (former BMW Rolls-Royce) and DLR Braunschweig. The main objective of the partnership was the development of an inverse design method for the design of engine nacelles. A second objective, the development of an actuator disk boundary condition, has been achieved, too. While the results of the second objective are published in a separate report [1], this document will focus on the achievements related to the inverse design procedure. The inverse design method presented in this report is based on the inverse design algorithm for airfoils and wings already implemented into the block-structured DLR flow solver FLOWer. The method uses a residual-correction type approach to design a geometry which satisfies the user-prescribed target pressure distribution. During this project the design method has been adapted for the design of engine nacelles. Results are shown for the inverse design of axial-symmetric nacelle profiles and for isolated 3D nacelles. The results are obtained using a block-structured DLR flow solver FLOWer. Due to the time-consuming process for generating complex block-structured grids and because of the achieved results in the field of flow calculations using arbitrary grids, the objectives of the partnership have been modified. A new Inverse Design System has been developed being capable of handling flow field calculations on arbitrary grids. The flow solver used is the DLR TAU Code while the inverse design step is done using the procedures of the before mentioned design code. Using this new system, results are presented for the inverse design of isolated 3D nacelles and wing-mounted engine nacelles under consideration of the pylon. These results have also been presented at the 40th AIAA Aerospace Science Meeting and Exhibit, Reno (NV), January 2002 [2].