Comparison of Overwing and Underwing Nacelle Aeropropulsion Optimization for Subsonic Transport Aircraft

Abstract

This research compares a forward-mounted overwing nacelle configuration to a conventional underwing nacelle for a single-aisle transport aircraft. We focus on characterizing the impact of the overwing placement on cruise fuel burn. To this end, we optimize both configurations under similar constraints and design processes. We use coupled computational fluid dynamics and propulsion cycle analysis with Gaussian process-based adaptive sampling in a multistage design process. The particular overwing design has a 4% higher fuel flow than the underwing design at cruise conditions. However, a postoptimization nacelle placement study illustrates that this fuel burn difference can drop to 2–3% if the overwing nacelle is moved farther forward in our design space without accounting for any resulting structural weight changes.

A Review of Novel and Non-Conventional Propulsion Integrations for Next-Generation Aircraft

“…It was found that the optimal overwing configuration exhibits at least a 2% increase in drag compared to the conventional installation, thus appearing to be unfavorable in aerodynamic terms. Similar analysis and general outcomes are also proposed in [86,87]. However, the potential benefits that can be obtained in other regards, such as propulsive efficiency, landing gear weight reduction, reduced risk of FOD (foreign object damage [88]) or simplification of high-lift systems, make the overwing assembly interesting for further investigation and successive detailed optimizations.…”