Exploring the influence of flexibility on rotor performance in turbulent flow environments

Abstract

Flexibility plays a crucial role in the design and performance of modern rotors. Its impact on rotor performance and its ability to adapt to external flow disturbances are well-established. In this study, we employ numerical simulations to explore the behavior of a flexible rotor submerged in a turbulent flow, aiming to forecast the influence of its flexibility on performance metrics. The rotational motion of the rotor and the forces imposed by the flow induce deformations in the blades, including bending and twisting. These deformations not only disrupt the flow patterns (vortices) in the turbulent wake but also modify the aerodynamic profiles, thereby affecting essential performance aspects such as thrust, drag, and lift. Our objective is to uncover the relationships between blade deformations, rotation frequencies, and rotor performance in a turbulent flow with a Reynolds number, $Re=O\left(10^4\right)$, and for a tip speed ratio in the range $[0,18]$. We demonstrate that the mean blade bending angle can be effectively expressed using a modified Cauchy number, revealing a scaling law. We also examined how the aerodynamic performance of the rotor blade is affected by variations in the tip speed ratio, either amplifying or reducing it. Through this research, we advance our understanding of the interplay between rotor flexibility, deformation, and performance, contributing to the optimization of rotor design and operational efficiency.