Bulb Turbine, Sand Erosion Study CFD Simulation, ANSYS Fluent

Description

The current project aims to simulate the operation of a Bulb Turbine using ANSYS Fluent software. The Bulb Turbine is a type of hydraulic turbine that is widely used in hydroelectric power plants. It consists of a rotor with several curved blades, which are positioned around the central axis of the turbine.

In this project, we consider a water flow with 2 m/s velocity, which passes through the turbine. The model is designed in three dimensions, taking into account the intricate details of the Bulb Turbine. The blades are first designed in SOLIDWORKS software, where their dimensions, angles, and distances from the central axis are carefully determined. Then, the blade design is imported into the Design Modeler software to construct the integrated blade model. To create a circulating water flow around the blades, a special cylinder is placed in the space around the turbine blades.

The meshing of the model is carried out using ANSYS Meshing software with an unstructured mesh type. To ensure high accuracy, the element number is set to 2,792,060. This helps to capture the intricate flow patterns and turbulence effects that occur around the blades during the operation of the turbine. Overall, this project provides a detailed and accurate simulation of the Bulb Turbine, which is essential for optimizing its performance and efficiency in hydroelectric power plants.

Methodology

In order to accurately simulate the rotation of the turbine blades, the Frame Motion technique is utilized. Specifically, for the cylindrical section, a mesh mode is defined by establishing a rotational speed of 572 revolutions per minute around the central horizontal axis of the turbine.

Additionally, the simulation involves the use of the Discrete Phase Model (DPM) module to account for the presence of sand particles and erosion/accretion effects. It is important to note that due to the nature of the Erosion/Accretion phenomena, a steady-state solver is employed.

Further, the Realizable-K-Epsilon model is selected to capture the turbulence characteristics of fluid flow accurately. Moreover, the simulation takes into account the effects of gravity in the Z direction, with a magnitude of -9.81 meters per second squared.

Conclusion

Upon concluding the solution process of the fluid dynamics simulation, a wealth of valuable data was obtained in the form of two-dimensional and three-dimensional contours, providing insight into various parameters such as pressure, velocity contours, and. The results revealed that the maximum velocity occurred near the rotating blades, which is a crucial finding in the field of fluid mechanics. Furthermore, the three-dimensional contours clearly depicted the effect of sand particles.

However, these results also highlighted the issue of erosion, which was evident over time, particularly over the blades. These findings are visible in erosion/accretion contours such as Oka, Mclaury, Finnie, etc.