Propeller Aerodynamic Interaction and Noise Characteristics in Distributed Propulsion

The transportation technology has greatly advanced in the past two decades, leading to rapid development in the area of Urban Air Mobility (UAM), which sees the unmanned aerial vehicles and short-haul electric aircrafts to gradually become an integral part of our daily life. The UAM market is currently projected to reach an industrial value of 1.5 trillion USD by 2040. Compared to the research efforts into conventional aircraft aerodynamics and aeroacoustics, research into electrical distribution propulsion (DP) and electrical Vertical Take-Off and Landing (eVTOL) which are the promising green (i.e. zero-emission) configurations for UAM, remains relatively scarce. This proposed research project aims to focus on the flow interactions associated with the distributed propulsion system, as well as their influence on the aerodynamically generated noise by implementing experimental measurements and numerical simulations. The study will focus on two main areas of interest: (a) the rotor-to-rotor interaction; (b) the rotor to airframe interaction. With the comprehensive and high-fidelity flow field and noise information, the project will significantly improve our knowledge and understanding of distribution propulsion configurations. Therefore, the project is timely and essential as U.K. embraces on its 'Build Back Greener' initiatives, including the FlightZero and NetZero programmes. The project leverages upon the strong numerical and experimental expertise in Bristol. The numerical simulations will be carried out using Lattice Boltzman method (LBM) for scale-resolved and efficient simulation of complex geometrical configurations (i.e., multi-propeller) and the experimental measurements will be performed in the aeroacoustic wind tunnel with highly instrumented set-up to unravel the fundamental flow and noise generation mechanisms. The project is also aligned well with several large-scale EPSRC and H2020 research initiatives in novel propulsion configurations such as ENODISE and SilentProp, which the study will learn and work with the partners in those projects for greater impact and dissemination of the results, leading to prospective project collaborations. Moreover, from the obtained results, three to four high quality research papers are expected to be published on the leading journals, as well as presented in domestic and international conferences and seminars to further explore potential opportunities to collaborate with interested institutions and industrial partners.
Aims and Objectives: The proposed research will shed light on understanding of the aerodynamic interaction and the related noise characteristics in DP configurations, and are expected to:
1. Establish an extensive set of numerical and experimental datasets in DP system with a focus on blade-to-blade and blade-to-airframe interactions.
2. Provide assessment of the Lattice-Boltzman based solver on complex configurations.
3. Investigate and understand the modifications of the near-field aerodynamics and their physical relation to the radiated noise with varying parameters in DP configurations.
Research Methodologies: The project will utilise the state-of-the-art numerical tool and experimental techniques. For numerical simulations, wall-resolved simulations based on LBM will be carried out. The solver has inherent advantages on complex configurations. The experiments will be carried out in the national wind tunnel facility at Bristol. The instrumented airframes and the noise localisation arrays are designed and built with sensor techniques developed in-house. Alignment with EPSRC: The research falls under Aerodynamics and Fluid Dynamics which is a strategic research area under EPSRC engineering theme. Project Partners: Vertical Aerospace acts as an industrial advisor of the project to provide guidance to the DP configurations with an industrial perspective.