Darrieus Wind Turbine CFD Simulation using Dynamic Mesh 6DOF method, ANSYS Fluent Training

Description

The Darrieus wind turbine is a type of vertical axis wind turbine (VAWT) used to generate electricity from wind energy. The turbine consists of several curved aerofoil blades mounted on a rotating shaft or framework. The curvature of the blades allows the blade to be stressed only in tension at high rotating speeds.

The blades of a Darrieus turbine can be canted into a helix, e.g., three blades and a helical twist of 60 degrees. Since the wind pulls each blade around on both the windward and leeward sides of the turbine, this feature spreads the torque evenly over the entire revolution, thus preventing destructive pulsations.

In this case, a Darrius wind turbine with 6blade is exposed to wind with a speed of 23 m/s. The rotation of the turbine is modeled with the Dynamic Mesh 6DOF method.

The present model in the 3-D domain of this simulation has been designed in ANSYS Design Modeler. Domain has two parts: flow domain and body of influence around the turbine. The domain contains a velocity inlet, pressure outlet, and wall for the earth.

The meshing of this present model has been generated by ANSYS Meshing software. The mesh grid is unstructured; the total cell number is 2,966,928 elements and 720300 nodes. The figure below shows an overview of the performed mesh.

Methodology: Darrieus Wind Turbine CFD Simulation using Dynamic Mesh 6DOF method

In this simulation, the rotation is modeled with the Dynamic Mesh 6DOF method, which simulates the turbine rotation based on its moment force.

Conclusion

In the simulation results, the turbine’s rotation is clear. The vortices resulting from the collision of the flow and the turbine in motion are known in the speed contour. In the created vortex velocity contour, the same Van Karman vortices can be seen.

The presented pressure contour also shows the pressure changes in the domain and the environment around the blades. Also, The leading edge of the turbine wall suffers from the highest-pressure gradient, which is logical since the velocity has just met zero.

Additionally, the streamlines vectors illustrate the quality of the flow streams resolved in the wake section, which is the core challenge of aerodynamic simulation. The provided turbulence contour accurately shows the resulting turbulence.