Verification and Optimisation of Distributed Propulsion Using High-Fidelity CFD Method

Abstract

This work presents CFD verifications and comparisons related to distributed propulsion concepts. The work started with validation studies using experimental data from the NASA Workshop for Integrated Propeller Prediction (WIPP) and the folding conformal high lift propeller (HLP) projects. The high fidelity CFD results from HMB3 for isolated and installed configurations at different forward flight speeds were compared with experiments. Expanding from that, the second part of the paper examined several configurations of propellers similar to the ones used in modern eVTOL designs to identify performance differences for propellers located at different positions around a lifting wing. Results from different methods show that distributed propellers with a small radius have much stronger interference with the lifting wing compared to the tip-mounted propeller. The interference also depends on the location of the propellers, with propellers placed ahead of the leading edge showing slightly better performance than propellers placed on top of the wing. However, both methods indicate that the wing's performance improved significantly after optimizing the propeller from a traditional tractor configuration to a novel over-wing configuration. More specifically, the fully resolved results show that the wing lift-to-drag ratio has totally increased by 69%.