Numerical Study on Interactional Aerodynamics of a Quadcopter in Hover with Overset Mesh in OpenFOAM

TL;DR

This study uses overset mesh simulations in OpenFOAM to analyze the unsteady aerodynamics of a quadcopter in hover, revealing how rotor interactions and fuselage effects influence flow structures and unsteady airloads.

Contribution

It introduces a numerical approach using overset mesh in OpenFOAM to investigate interactional aerodynamics of quadcopters, highlighting rotor-fuselage and rotor-rotor effects on unsteady loads.

Findings

Rotor-rotor interactions produce Ω-shaped vortices.

Fuselage deflects rotor wake towards the vehicle center.

Quadcopters experience 8/rev thrust variations due to aerodynamic interactions.

Abstract

Interactional aerodynamics of a quadcopter in hover is numerically investigated in this study. The main objective is to understand major flow structures associated with unsteady airloads on multirotor aircraft. The overset mesh approach is used to resolve flow structures in unsteady simulation using the flow solver OpenFOAM. The current computational study demonstrates that aerodynamic interaction between quadcopter components strongly affects the rotor wake, generating interesting vortical structures. Multiple rotors in close proximity generate $\Omega$-shaped vortical structures merged from rotor-tip vortices. The fuselage of the current quadcopter deflects the wake flow of the four rotors towards the center of the vehicle. Such interactional aerodynamics, i.e., rotor-rotor and rotor-fuselage interaction, varies the inflow condition of a rotor blade during the rotor revolution. Therefore, the quadcopter experiences unsteady airloads per rotor revolution. Our study indicates that a typical quadcopter would experience 8/rev thrust variations, which are a combined outcome from 4/rev thrust variations on the rotor and 2/rev fluctuations on the fuselage. The current understanding of interactional aerodynamics could help to design reliable and efficient multicopter aircraft.