Horizontal Axis Tidal Turbine, Paper Numerical Validation

Horizontal Axis Tidal Turbine, Paper Numerical Validation, ANSYS Fluent CFD Simulation Training

The current project simulates a horizontal-axis water turbine using ANSYS Fluent software. The CFD simulation results are compared and validated with the article “Performance of horizontal axis tidal current turbine by blade configuration.”

The water flows at a velocity of 1 m.s-1 and passes the water turbine; Therefore, by colliding the water flow to the turbine blades and creating a torque force on the blades, a rotational motion is obtained in the turbine blades, which causes a rotational flow for the surrounding water around the blades.

The present model is designed in three dimensions; Thus, the sections related to the turbine blades are in the form of airfoil type S814.

Since the airfoil section of the edges decreases or increases at different blade lengths by a certain scale (based on the length of the airfoil chord), each airfoil section as a set of points with coordinates is imported and drawn in SOLIDWORKS software at a certain angle and distance from the central axis.

These sections, including 16 units, are then imported to the Design Modeler software for integrated blade design.

In design modeler software, modeling is done so that for the desired turbine, 3 blades are drawn. In the space around the turbine blades, a special cylinder is created to make a circulating water flow, and a rectangular cube space is designed as a space for free water flow.

Geometrical information about turbine blades, including the chord size of each airfoil section of the blade and its angle of an inclination concerning the central axis, is presented in Table 3 of the mentioned paper.

The meshing was done using ANSYS Meshing software, and the mesh type is unstructured. To increase the meshing accuracy, the boundary layer mesh is used on the surfaces of the turbine blades, and the element number is 4270222.

Horizontal Axis Methodology

The Frame Motion (MRF) technique is used to simulate the rotation of the turbine blades. Therefore, for the cylindrical region, the frame motion mode is defined by defining a rotational speed of 191 rpm around the central horizontal axis of the turbine.

Horizontal Axis Conclusion

At the end of the solution process, the amount of turbine power (P) is calculated based on the amount of torque applied to each of the turbine blades (T) and, consequently, the amount of pressure coefficient applied to its blades (Cp) is obtained by the software.

Then, it was compared and validated with similar values in the article. This comparison and validation process is based on the data in Table 2 of the article. Some of the data in the table are input or reference values, and based on them, the final value of torque and pressure coefficient is obtained.

The power and pressure coefficient formulas based on the article are as follows. The comparison of the present CFD work results with the paper results is presented in the table below.