Session: 02-03-02: Aeroacoustics, Dynamic Loads, Wave Propagations, Response, Vibration, Control, and Alleviation of Aerospace Structures and Vehicles

Paper Number: 183314

183314 - Forced Vibration Analysis of Distributed Propulsion Wings 

Unlike traditional helicopters and fixed-wing aircraft, emerging electric aircraft concepts often employ distributed propulsion systems consisting of multiple, independently controlled electric rotors. These rotors operate through variable RPM control, providing precision and agility in flight operations. However, this control strategy also introduces new challenges, particularly the risk of exciting structural resonances during critical flight phases such as hover–forward flight transitions or high-speed cruise. The small, rigid nature of the propellers intensifies these vibratory effects and hence operation near resonant frequencies can amplify structural loads, leading to increased vibration, fatigue, and reduced passenger comfort.  

To ensure safe and efficient design of distributed propulsion wings, it is essential to accurately characterize their forced vibration response. This response depends on two aspects: the structural dynamics of the wing and the unsteady aerodynamic loads generated by the propellers. Obtaining reliable dynamic loading information is particularly challenging because the propellers are aerodynamically coupled but mechanically independent, often operating at distinct rotational speeds and thus exciting multiple frequency components. High-fidelity CFD simulations can in principle capture these effects but are computationally impractical for design iterations, while lower-order models such as Blade Element Momentum theory lack the fidelity to predict dynamic interactions accurately.

This study presents the application of a mid-fidelity aerodynamic tool to evaluate the dynamic loading induced by distributed electric propulsors. DUST, an open-source solver based on panel and vortex particle formulations, are developed for complex rotor analysis. It allows aerodynamic interaction of propellers to propellers, wings, and airframes and their wakes by implementing steady or transient rotor dynamics. The interactional effects are captured in the form of deviations in local, skewed airflow orientations, and their resulting oscillations in aerodynamic loads at a particular point of interest. The computed aerodynamic loads are subsequently transferred to a finite element structural model to assess the wing’s forced vibration response. The approach demonstrates a practical balance between computational efficiency and physical accuracy, enabling improved prediction of vibration characteristics and structural loads in distributed propulsion configurations.

Presenting Author: Aykut Tamer University of Bath

Presenting Author Biography: Having as background in BSc and MSc in Aerospace Engineering From Middle East Technical University and PhD from Politecnico Di Milano, and currently working as an assistant professor at the University of Bath.