Description

This simulation is about Kaplan hydro turbine evaluation via ANSYS Fluent software. We perform this CFD project and investigate it by CFD analysis.

The Kaplan turbine is a propeller-type water turbine that has adjustable blades. Also, the Kaplan turbine is an inward flow reaction turbine, which means that the working fluid changes pressure as it moves through the turbine and gives up its energy.

Power is recovered from the hydrostatic head and the flowing water's kinetic energy. The design combines features of radial and axial turbines. In this project, we will study Kaplan turbine hydrodynamics. For the rotating motion of the turbine, we determined an angular velocity equal to  16.5 RPM.

For our boundaries, we set a constant mass flow of 1000 kg/s as our inlet, a zero gauge pressure as our outlet, and finally, we considered all the side walls symmetrical since they are far from the domain of interest.

In this study, we have also investigated the performance of the current Kaplan turbine by evaluating the drag force.

The geometry of the present model is drawn by Design Modeler software. The geometry included a small Kaplan turbine. The model is then meshed by ANSYS Meshing software. The model mesh is unstructured, and 9861922 cells have been created.

Kaplan Method

In this simulation, the MRF (Frame Motion) option has been activated to model the rotation of the turbine. It is assumed that the fluid around the turbine blades is rotating instead of the turbine blades.

Therefore, a cylindrical zone has been separated from the whole computational zone due to having a turbomachinery simulation. The rotational velocity of this fluid is equal to the rotational velocity of the turbine. To do this, the MRF tool is used in Cell Zone Conditions.

Kaplan Conclusion

After simulation, 2D and 3D contours of pressure, velocity, and surface pressure are obtained. Also, the velocity vector and streamlines around the turbine are obtained. Velocity vectors and streamlines show the rotational motion of the fluid around the turbine blades.

As depicted in the contours, the leading edge of the turbine wall corresponding to the lowest pressure is entirely logical since the velocity has the highest value on the tip of the turbine blade.

Also, the contours of velocity show that as we go farther from the turbine axis, the rotational velocity and the influence of our source terms would be increased. As depicted in the pressure contours, the pressure distribution adjacent to the turbine walls formed two significant sections.

The first section corresponds to the high-pressure zone before the flow interacts with the Kaplan turbine. The low-pressure zone, however, is the zone behind the Kaplan geometry.

Additionally, the flow vectors illustrate the quality of the flow resolved in the wake section, which is the core challenge of aerodynamic simulation.

Understood from the flow vectors, we have observed the suction mechanism at the lower parts of the turbine, while we have illustrated the blowing mechanism for the upper section.

Moreover, we have given the core vortex adjacent to the turbine body to inform us how the flow field would be manipulated close to our rotary walls.