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

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.