Development of an engine model for an integrated aircraft design tool

Abstract

This thesis describes the development of a new engine weight surrogate model and High Pressure Compressor (HPC) polytropic efficiency correction for the propulsion module in the Transport Aircraft OPTtimization (TASOPT) code. The goal of this work is to improve the accuracy and applicability of TASOPT in conceptual design of advanced technology, high bypass ratio, small-core, geared and direct-drive turbofan engines. The engine weight surrogate model was built as separate engine component weight surrogate models using least squares and Gaussian Process regression techniques on data data generated from NPSS/WATE++ and then combined to estimate a "bare" engine weight-including only the fan, compressor, turbine, and combustor-and a total engine weight, which also includes the nacelle, nozzle, and pylon. The new model estimates bare engine weight within +/-10% of published values for seven existing engines, and improves TASOPT's accuracy in predicting the geometry, weight, and performance of the Boeing 737-800. The effects of existing TASOPT engine weight models on optimization od D8-series aircraft concepts are also discussed. The HPC polytropic efficiency correction correlation, which reduces user-input HPC polytropic efficiency based on compressor exit corrected mass flow, was implemented based on data from Computational Fluid Dynamics (CFD). When applied to TASOPT optimization studies of three D8-series aircraft, the efficiency correction drives the optimizer to increase engine core size.