Unsteady aerodynamics of a twist bladed H-Darrieus rotor in low Reynolds number flow

Abstract

In this paper, an attempt is made to investigate the unsteady aerodynamics of a two-bladed H-Darrieus rotor having blade twist of 30° at the trailing edge when placed in low Reynolds number flow. The effect of low Re flow on the unsteady blade-fluid interactions has been studied in some details to understand the high power coefficient of such twist bladed rotor in low wind speed condition. Two-dimensional unsteady Reynolds-averaged Navier–Stokes equations are solved using Fluent 6.0 CFD software. The computational domain comprises of a large static domain and a rotating sub-domain, both are connected by a sliding mesh interface. The blade-fluid interactions have been investigated at different rotor azimuthal positions. The effect of low Reynolds number flow from dynamic stall is shown in the velocity profiles, pressure and torque-coefficients distributions. The combination of interactions of vortices on the leading edge and interactions of the same on the trailing edge of the returning blade increases torque coefficient of the rotor during its power stroke compared to untwisted rotor. The present numerical model could be built into a 3D CFD model to investigate the effect of different blade aspect ratios on the stall vortex interactions at trailing edge so as to improve the unsteady performance of such twist bladed rotor in low Re flow.