Aerodynamic Modelling of Unconventional Rotorcraft

Abstract

This doctoral thesis presents an examination of electric vertical take-off and landing aircraft, with a focus on their design optimisation, and aerodynamic interactions. The study begins by reviewing existing eVTOL aircraft, discussing population growth and design challenges, as well as highlighting modal propulsion system choices. The thesis then presents a methodology for selecting the number of rotors in wingless multirotor aircraft and uses it to estimate the effect of propulsion group size on aircraft weight based on a typical urban air mobility mission profile. The analysis suggests that if redundancy is taken into consideration, it is advantageous to increase the number of rotors in the propulsion group. The research also develops a reduced-order aerodynamic model for Rotor-on-Rotor interference which offers a significant reduction in computational time compared with well-established mid-fidelity free-vortex wake methods, while maintaining an accuracy of within ten percent. The proposed model is verified through comparison with experimental data and other numerical methods, limitations are established and discussed, and use-case scenarios are explained. Finally, an optimisation methodology based on a global optimisation algorithm and the newly developed interference model is presented to search for the optimal rotor configuration in an arbitrary multirotor system. The optimisation study of up to ten rotors found a distinct formation pattern that reduced the overall power requirements of the rotor formation, resembling an inverse V pattern, which was preserved across a range of considered multirotor systems and operating conditions. The analysis was limited to two-dimensional, unconstrained domains due to computational limitations. However, it can be extended to three-dimensional spaces. Overall, this research contributes to the advancement of electric multirotor aircraft design and technology, providing a basis for further research in this field. The presented analysis can be used by engineers and researchers to design more efficient eVTOL aircraft propulsion systems. The research findings can be applied to the development of novel electric vertical lift aircraft or to improve their performance, which will help to promote the adoption of urban air mobility and contribute to the development of sustainable transportation systems.

Date of Award	31 Dec 2023
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Antonino Filippone (Supervisor) & Nicholas Bojdo (Supervisor)