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The purpose of this paper is to examine the details of the air mass flow and aerodynamical phenomena across a channel containing a large vertical axis wind turbine. The considered model reproduces as closely as possible the real assembly of the Sistan-type wind-mill whose top is open. The technical results of this work could be used for the restoration and operation of this assembly whose historical and architectural values are recognized.

Several inlet velocities into the channel are considered, taking into account the possible local wind resources. Calculations corresponding to Reynolds number varying between 8×10⁵ and 4×10⁶ are made by means of the finite volume method and turbulence is treated with the realizable k-ε model. The mesh consists of a fixed part associated to the contour of the channel, interfaced with a moving one linked to the turbine itself, equipped with nine partly filled wings.

The relative pressure and velocity fields are presented for various dynamic and static conditions. Calculation results clearly show that the vortex phenomena present in some cases are not a source of degradation of the wind turbine’s aerodynamical performances, given its location, intensity and rotation direction. Particular attention is devoted to the air mass flow and its distribution between the inlet and the outlet sections of the channel.

The present work provides technical information useful to consider the restoration and modernization of this installation whose architecture and technical performance are very interesting. This survey complements a previous one examining the aerodynamical phenomena occurring in a modified version of this assembly with a closed top channel.