Numerical Simulation Of The Brownout Of A Helicopter Rotor In Hige Conditions By Coupling A Free-Wake Methodology To A Particle Lagrangian Approach

Abstract

This work presents numerical simulations of the brownout phenomenon produced by the Bo105 helicopter's rotor in HIGE conditions, at a height equal to one rotor blade radius. A Lagrangian approach is implemented in the CIRA free-wake aerodynamic solver RAMSYS to model both the direct entrainment and the bombardment mechanisms of the simulations use silica dust and sand of granulometry, ranging from 1to , and density of . The results indicate that particles of are easily uplifted, while particles are never mobilized because the friction velocity produced by the rotor flow is not sufficient to break the high inter-particle forces. A toroidal cloud forms around the rotor, which, however, even in the most severe condition, does not obscure the pilot's visibility. Preliminary results are also shown for the brownout produced by coaxial and side-by-side rotors.