Water Wheel CFD Simulation Training by ANSYS Fluent

Water Wheel (Pelton Wheel), ANSYS Fluent CFD Simulation Training

The present problem is Water Wheel CFD Simulation Training (Pelton Wheel) by ANSYS Fluent software. We perform this CFD project and investigate it by CFD analysis to analyse the performance.

The water wheel is an example of a Pelton turbine. Most water wheels are mounted vertically on a horizontal axis and can also be mounted horizontally on a vertical shaft. In order to solve the fluid flow equations, the averaged form of the Navier-Stokes equation is used by applying ANSYS Fluent software.

The turbine’s diameter is 0.7 m, and the free surface’s boundary is 0.2 m below the center of the water wheel. Water velocity is considered 3 to 5 m / s depending on the average river velocity.

And accordingly, the turbine’s rotational speed should be calculated with no drag or bump in the flow. In this CFD simulation, the turbine rotational speed is 60 rpm.

Water Wheel Methodology

The wheels are perpendicular to certain turbine parts due to reduced friction force and increased nozzle thrust. The other part of the turbine is out of the water. Therefore, the wheels are in two different phases of water and air, rotating around their axis.

The two-phase model also uses the VOF model. We designed the geometry of the turbine by SOLIDWORKS and divided it into smaller sections to improve the geometry and mesh of the turbine.

We split the geometry into two general rotaries (Rotor) sections and one stationary unit (Stator). The rotor part consists of the turbine and the cylinder that is located around the turbine. The static part surrounds the rotary cylinder.

We use ICEM software to generate the mesh. The rotor section first meshes unstructured. Parts such as the turbine leading-edge use a larger number of meshes (smaller elements) due to the complexity of the flow and the high gradient in that area.

We use the structured mesh for the stationary zone. Structured mesh causes the number of mesh to decrease and the quality of the mesh to be very high. After meshing the two parts separately by two different methods, we couple the two parts together to mesh the total geometry.

The rotation of the impeller at each time step can have different values. In this simulation, we have 3 degrees of rotation of the impeller at each time step, which we should consider much smaller for more accurate simulations.

For the present issue, we should use the MESH MOTION. Static and rotary meshes slide with common boundaries (INTERFACE) and simulate the problem.

Water Wheel Conclusion

The results show well the rotational motion around the body of Pelton’s water wheel.