Characterization of Non-constant Aerodynamic Load Changes in the Vortex Ring State of a Quadrotor Aircraft
This study investigated the characteristics of unsteady aerodynamic loads on quadrotor helicopters under vortex ring conditions using a combination of separated vortex (DES) and nested grid techniques.The analysis focused on the impact of aerodynamic interference between quadrotors on vortex ring characteristics and the underlying mechanisms.The results indicated that during hover and vortex ring initiation phase,aerodynamic interference between the rotors caused significant,non-steady fluctuations in the thrust of each rotor,with a fluctuation ratio reaching 12％.In the vortex ring maturation phase,due to the interference and dissipation of vortices within the rotor-to-rotor region,no obvious vortex ring was observed in this region.However,the detached vortices rolled up and re-entered the rotor,resulting in a reduction in rotor thrust of 31％ and an increase in non-steady fluctuation amplitude to 16％.In the later stage,or as the windmill state,vortices between neighboring rotors collided,stretched,and ruptured.The rotor root vortices also rapidly ruptured,forming fine-scale vortices above the rotor disc,causing a significant increase in the cycle of rotor non-steady fluctuations and a 41％ increase in thrust.
vortex ring statequadrotoraerodynamic characteristicsnon-steady
万方数据
维普
