H-Type Vertical Axis Wind Turbine (VAWT), Mesh Motion

H-Type Vertical Axis Wind Turbine (VAWT) CFD Simulation Applying ANSYS Fluent Mesh Motion Method, Tutorial

This simulation is about an H-type vertical axis wind turbine (VAWT) via ANSYS Fluent software. We perform this CFD project and investigate it by CFD analysis.

Nowadays, turbines are a reliable, clean energy source that generates electricity using the induced rotation by wind flow. However, turbine wind farms face challenging issues such as low efficiency at lower diameters for horizontal axis turbines (HAWT), disruption of the natural view of valleys, and low wind conditions.

These three problems can be solved using Vertical Axis Turbines (VAWT), where diameters as large as 200 m, commonly used in HAWTs, do not need. VAWTs are widely used offshore. Disruption of natural view is overcome, and wind conditions are more predictable and reliable in offshore wind farms.

The H-type turbine analyzed in the present work has six blades with three blades closer to the center of rotation. The turbine rotates in a -Z direction with an angular velocity equal to 14.17 rad/s. Air velocity at the inlet is equal to 5.3 m/s.

Airflow in the domain is dominantly affected by turbine rotation. Maximum air velocity in the domain is equal to 45 m/s, which is captured downstream of the turbine.

The geometry of the present model is drawn by Design Modeler software. The model is then meshed by ANSYS Meshing software. The model mesh is unstructured, and 1546624 cells have been created.

H-type Turbine Method

In this simulation, the rotational motion of the turbine blades must be defined. But instead of applying rotational motion to the blades, rotational motion is applied to the field around the blades. So, it is necessary to separate a distinct zone as the moving zone from the total computing zone. Since this turbine is one of the vertical axis turbines, the behavior of the fluid is dependent on time; because the position of the turbine blades varies over time. Then the Mesh Motion is used in cell zone conditions. In this method, the rotation axis and rotation speed must be determined.

H-type Turbine Conclusion

After simulation, the contours of velocity and pressure are obtained. Also, velocity vectors and pathlines around the turbine blades are obtained. The results show that the wind flow around the turbine blades has a rotational movement. The air mass flow rate at the inlet is equal to 272.685 kg/s.

The turbine blade’s tip speed ratio (TSR) is almost equal to 6, where tip speed and free stream velocity are equal to 30 and 5.3 m/s. According to rotation and free stream flow direction, there is a stagnation point in the minus Y direction of the turbine, which also represents the maximum pressure zone.

The combined effect of free stream flow and flow generated due to rotation differs on the inner and outer blades. On the internal blades, the pressure difference is less than on the outer blades. This can result from the higher linear velocity of the outer blades than the inner blades.