A detailed aerodynamic analysis of the cyclorotor using dynamic mesh in CFD

A numerical study with dynamic mesh technique has been conducted on a cyclorotor operating at Reynolds numbers about 20,000~90,000. The varying total thrust of cyclorotor , the force on blade during revolution and the aerodynamic characteristics of the unsteady flow field around cyclorotor and blade airfoil are investigated in detail. The instantaneous thrust, which are cyclically fluctuating with azimuth as an approximated sinusoidal curve, is found to have close relationship with the corresponding azimuth-varying resultant pitch angle of all blades; the average direction of thrust during revolution is found to remain almost constant as rotating speed change, which is very important for a cyclogiro's stability control; the curves of varying normal force and tangent force coefficients of a blade airfoil with pitch angle are clearly shown to be hysteresis loops both in one-and four-bladed cyclorotor, which indicate the strong unsteady aerodynamics of cyclorotor. The flow field around the blade airfoil of one-bladed cyclorotor and four-bladed cyclorotor are given to show the complex flow field with unsteady interactions between the blades and the wakes of other blades.