Investigation of the Reynolds Number on the performance of a cycloidal rotor

Abstract

The Reynolds number has great influence on the provided lift and requested power of a cycloidal rotor. The aim of the present paper is to determine lift, power and efficiencyof a three bladed cycloidal rotor in relation to the Reynolds number. The investigated range of Reynolds numbers reaches from Re=10x10^3 to Re=600x10^3. For the parameter study, a cycloidal rotor under stationary hovering conditions, using a instationary, incompressible 2D URANS CFD simulation has been investigated. To interpret the rotation averaged data, field solutions are provided. Two different flow regimes can be distinguished: For the first regime (10x10^3≤Re≤100x10^3), two dynamic flow detachments occur, the first one at a maximum pitch angle of Ψ=270° and the second shortly afterwards. The second flow regime (200x10^3≤Re≤600x10^3) avoids the first detachment due to the increased Reynolds number. Both detachments are perceptible in the flow field solution as well as in the azimuthal lift distribution. The rotation averaged lift and power follow the proportionalities obtained by momentum theory.