Articles | Volume 2, issue 1
Research article
19 Jun 2017
Research article |  | 19 Jun 2017

Vortex particle-mesh simulations of vertical axis wind turbine flows: from the airfoil performance to the very far wake

Philippe Chatelain, Matthieu Duponcheel, Denis-Gabriel Caprace, Yves Marichal, and Grégoire Winckelmans

Abstract. A vortex particle-mesh (VPM) method with immersed lifting lines has been developed and validated. Based on the vorticity–velocity formulation of the Navier–Stokes equations, it combines the advantages of a particle method and of a mesh-based approach. The immersed lifting lines handle the creation of vorticity from the blade elements and its early development. Large-eddy simulation (LES) of vertical axis wind turbine (VAWT) flows is performed. The complex wake development is captured in detail and over up to 15 diameters downstream: from the blades to the near-wake coherent vortices and then through the transitional ones to the fully developed turbulent far wake (beyond 10 rotor diameters). The statistics and topology of the mean flow are studied. The computational sizes also allow insights into the detailed unsteady vortex dynamics and topological flow features, such as a recirculation region influenced by the tip speed ratio and the rotor geometry.

Short summary
Vertical axis wind turbines (VAWTs) operate through inherently unsteady aerodynamics, unlike their horizontal axis counterparts (HAWTs). This greatly affects the structure of the wake, i.e., the region of velocity deficit and increased turbulence downstream of the machine. In this work, we use an advanced vortex method to identify the flow structures and instabilities at work in the decay of a VAWT wake, a crucial step if one wishes to optimize this decay or perform the design of VAWT farms.
Final-revised paper