Fluid–Structure Interactions and Unsteady Kinematics of a Low-Reynolds-Number Rotor

Antonio Alguacil (1) , Thierry Jardin (1) , Nicolas Gourdain (1)

1 DAEP - Département Aérodynamique Energétique et Propulsion

Micro air vehicles are used for both civil and military applications, like rescue or surveillance. The aerodynamic performance of the rotor is known to be lower than for classical large rotors, due to increased drag at low Reynolds numbers. However, the rotor performance can be improved by taking advantage of the flow unsteadiness and considering unsteady rotor kinematics, like a periodic variation of the rotor pitch. To study such behaviors, it is necessary to develop numerical methods adapted to these fluid–structure interaction phenomena, which are the main objectives of this paper. The method relies on the implementation of fluid–structure interaction capabilities in a lattice–Boltzmann flow solver, which is implemented in a monolithic fashion using generalized coordinates. The validation is first conducted on a vortex-induced vibration test case. Then, numerical simulations are performed for a rotor test case 1) with a forced motion and 2) by coupling the flow with the equation of the dynamics. Some semianalytical models are derived and validated against the numerical simulations to predict the effects of pitching, flapping, and surging on the thrust. The results show that flapping and surging significantly increase the rotor thrust, but at the price of a penalty on the power consumption.

Mots clés: Rotor; Fluid-structure interaction; Low Reynolds number; Lattice-Boltzmann

Domaines: Mécanique des fluides [physics.class-ph]

Antonio Alguacil, Thierry Jardin, Nicolas Gourdain. Fluid–Structure Interactions and Unsteady Kinematics of a Low-Reynolds-Number Rotor. AIAA Journal, 2020, 58 (2), pp.955-967. ⟨10.2514/1.J058230⟩. ⟨hal-03079732⟩