A nacelle design method for turbofan engines

Abstract

The purpose was to develop a preliminary nacelle design method to evaluate the impact of the nacelle's geometry on the net propulsive force of an engine in multiple flight conditions. The 2D axisymmetric nacelle is parameterised and analysed for the cruise and take-off conditions using an Euler solver to find the optimum Pareto front. Several test cases were optimised, where every case analysed 700 geometries within two days. It was found that a higher and rounder lip, and more forward maximum diameter at the fan cowl improve the performance in both conditions. Longer and steeper bypass ducts improve the pressure force in take-off. The test cases did not converge completely due to the randomly generated initial population. Especially the stricter hot & high take-off condition converged to a local Pareto front. A better and larger initial population with lower crossover and mutation operators are recommended to speed up the convergence.