3D numerical simulation of interaction between aligned Vertical-Axis Turbines within a farm: The case of Tidal Turbines

Abstract

Vertical Axis Turbines (VATs) are devices used to extract kinetic energy from natural flows and convert it to electricity. In the past, VATs received less attention than Horizontal Axis Turbines (HATs). Recently, considerable research has focused on this type of turbine for applications in both wind and tidal power due to their distinct advantages over HATs. Understanding the interaction between the VATs within an array remains a complex issue, particularly regarding wake interactions and flow recovery downstream of each turbine. This paper presents the results of research on the interaction between Vertical Axis Tidal Turbines (VATTs) within an array. Turbines are modeled using the Actuator Cylinder theory. Simulations are conducted in ANSYS Fluent employing the standard k–ε turbulence model. First, a single turbine model is validated by comparing the normal and tangential forces acting on its blades with experimental data from Strickland’s study. Then, the interaction between two aligned turbines is analyzed. The distances considered are 3D, 7.5D, 15D, and 20D (where D represents the turbine diameter). The research results show that increasing the distance between turbines leads to faster recovery of flow energy for the downstream turbine. The flow velocity recovers to 42% of the free-stream velocity at a distance of 7.5D, and reaches 70% at 15D. The results of the research indicate that a 15D spacing is an appropriate distance for enhancing flow energy recovery for the downstream turbine. These findings are important for determining the optimal spacing between aligned VATTs within an array to ensure maximum efficiency in energy extraction from the flow