Synthesis of Aero-Propulsive Interaction Studies Applied to Conceptual Hybrid-Electric Aircraft Design

Abstract

This paper presents a synthesis of aero-propulsive interaction studies performed at Delft University of Technology, applied to conceptual aircraft designs with distributed hybrid-electric propulsion (DHEP). The studied aero-propulsive interactions include tip-mounted propulsion, wing leading-edge distributed propulsion and boundary-layer ingestion, combined with different primary propulsion-system arrangements. This paper starts with a description of the applied design framework and an overview of the aero-propulsive interactions. Subsequently, the different aircraft configurations are sized for a set of top-level requirements covering the range between regional turboprop to typical narrow-body turbofan aircraft. Results indicate that lower shaft power ratios show better performance, with the unoptimized DHEP concepts showing values of maximum take-off mass (MTOM) and payload-range energy efficiency (PREE) comparable to their reference aircraft. It was shown that beyond 20% shaft power ratio, the PREE decreases and MTOM increases much more than between 10% and 20%, indicating a possible local optimum between these values since even lower values did not yield any significant improvements. The benefits of tip-mounted propulsion are found to be constrained by the propeller blade tip Mach number in this particular analysis for the selected reference blade loading distribution. At the high range case for Mach 0.5, it can be seen that the distributed propulsion systems show the largest improvement.