Numerical Investigation on a Rotor Tip-Vortex Instability in Very Low Advance Ratio Flight

摘要: Helical tip vortex is known as stable structure, however the specific frequency component of far wake perturbation induces pairing in hover and axial flight. It expected that phenomena may happen transition flight very low advance ratio so inflow be most nonuniform The objectives this paper are a tip-vortex instability during from into forward numerically predicted to understand physics by using time-marching free-wake method. To achieve objectives, numerical method firstly validated typical flights cases. Present scheme with trim routine can predict airloads distribution good accuracy. Then, condition calculated. rotor used calculation small-scale AH-1G model. By trajectory tracking method, process clearly observed transient flight(μ=0.03) disappears at slightly higher ratio(μ=0.05). According steady simulation μ=0.03, it confirmed continued rear part disk not occurs front part. Time averaged case smooth distribution.