Blade twist effects on rotor behaviour in the vortex ring state

Brown, R.E., Newman, S.J., Perry, F.J. and Leishman, J.G. (2002) Blade twist effects on rotor behaviour in the vortex ring state. 28th European Rotorcraft Forum, Bristol, UK. 16 - 19 Sep 2002. 14 pp .

Abstract

Results are shown that give a better understanding of the factors that influence the initiation and subsequent development of the vortex ring state (VRS). It is suggested that the onset of VRS is associated with the collapse of the orderly structure of the rotor wake into a highly disturbed, irregular, aperiodic flow state. An analysis of the stability of the wake is presented to show that the location of the boundary of the VRS is influenced by the detailed structure of the rotor wake prior to its breakdown. Time-accurate calculations of the evolution of the rotor wake in the VRS are then presented to obtain more insight into the flows experienced by the rotor in the VRS. These calculations suggest that the location of the boundary of the VRS, and the depth of the VRS regime, is sensitive to the blade spanwise loading distribution, which is influenced by blade twist. The effects are significant even at low disk loading, but at high thrust where rotor stall may be encountered, rotors with and without significant blade twist show marked, and somewhat counterintuitive, differences in their behaviour under VRS conditions.

This record has no associated files available for download.

Contributors

Download statistics