Numerical study on parametrical design of long shrouded contra-rotating propulsion system in hovering

Abstract

The parametrical study of Shrouded Contra-rotating Rotor was done in this paper based on 2D axisymmetric simulations. The calculations were made with an actuator disk as double rotor model. It objects to explore and quantify the effects of different shroud geometry parameters mainly using the performance of power loading (PL), which could evaluate the whole propulsion system capability as 5 Newton total thrust generation for hover demand. The numerical results show that: The increase of nozzle radius is desired but limited by the flow separation, its optimal design is around 1.15 times rotor radius, the viscosity effects greatly constraint the influence of nozzle shape, the divergent angle around 10.5° performs best for any chosen nozzle length; The parameters of inlet such as leading edge curvature, radius and internal shape do not affect thrust greatly but play an important role in pressure distribution which could produce most part of shroud thrust, they should be chosen according to the reduction of adverse pressure gradients to avoid the risk of boundary separation.