Rotor-Fuselage-Intake Aerodynamics and Icing Using Vortex and Eulerian-Lagrangian Computational Fluid Dynamics Methods

Abstract

Rotorcraft rotor-fuselage-intake aerodynamics and icing present unique challenges associated with rotor-wake dynamics and the interaction of rotor wake with the fuselage and the intake. The effects of the rotor wake are dominant in low forward flight, and performing high-fidelity simulations of the rotor-fuselage-intake simultaneously is expensive. This study presents a novel hybrid nonlinear vortex-computational fluid dynamics (CFD) approach to rotor-fuselage-intake aerodynamics and icing. The method combines nonlinear vortex-lattice, Lagrangian vortex-particle, and Eulerian CFD methods on airflow and droplet impingement with a PDE-based ice-accretion model. The Lagrangian description of rotor wake preserves the wake structure independently of the Eulerian grid, whereas the Eulerian description of the flowfield naturally computes nonlinear flow phenomena and surface properties. The algorithm allowed the ice accretion to be computed much faster than existing methods. The method was validated by considering airflow, surface pressure, and ice accretion around a model rotorcraft. We investigated ice accretion with strong rotor wakes for different advance ratios and rotor thrust coefficients. We also investigated the effects of the suction of airflow in the intake and the differences between with and without the rotor. It was found that the advance ratio had a dominant effect compared to the rotor thrust coefficient.