The Pelton wheel, a vital component in hydroelectric power generation, is an advanced impulse turbine design that necessitates complex computer analysis to achieve peak performance. Engineers can now correctly model the fluid-structure interactions within these turbine systems using ANSYS Fluent’s Six Degrees of Freedom (6DOF) Dynamic Mesh CFD modeling technology. This advanced computational approach allows for exact tracking of the turbine’s rotational dynamics, bucket-jet interactions, and consequent flow patterns, which typical static mesh methods cannot capture. The ANSYS Fluent tutorial shows how 6DOF simulation capabilities can help engineers optimize Pelton wheel design by analyzing critical performance parameters like jet impingement angles, sheet formation characteristics, and momentum transfer efficiency under different operational conditions. This comprehensive CFD modeling technique, aided by ANSYS Fluent‘s dynamic mesh capabilities, has become an essential tool for modern hydropower engineering analysis and design optimization.

Figure 1: Pelton wheel schematic

Simulation Process

The CFD simulation framework uses a thorough technical method with a 2D block-structured mesh made up of 145,432 cells that are mostly quadrilaterals. By using smoothing and remeshing methods, dynamic mesh features keep the integrity of the mesh even when the geometry changes. Six Degrees of Freedom (6-DOF) modeling lets you precisely track three translational and three rotational motion components, which is more accurate than standard 3-DOF methods. The Volume of Fluid (VOF) model makes it easier to handle interactions between water and air by calculating volume fractions. Block-structured meshing, dynamic adaptation, and motion tracking work together to make a strong platform for simulating fluid-structure interactions. This technical framework shows that it can handle a wide range of difficult engineering tasks. It makes sure that the solutions are correct while also making the best use of computer resources by carefully considering mesh quality metrics, cell count requirements, and phase interface treatment methods.

Figure 2: Hybrid grid over Pelton wheel CFD Simulation using 6DOF dynamic mesh

Post-processing

The velocity magnitude contours show important flow features in the star-shaped rotor configuration, with top speeds of 180 m/s close to the blade tips. The flow field clearly speeds up through the spaces between the blades, creating complicated wake structures behind the rotor. The pattern of velocity distribution from blue to red really shows how secondary flows and turbulent mixing areas form. This is especially clear in the post-rotor region, where uneven wake formations and vertical structures appear.

Figure 3: Velocity field around Pelton wheel CFD simulation

The volume fraction outlines show in great detail how the multiphase flow behaves, with the blue and red colors clearly showing the water and air phases, respectively. The VOF method does a good job of capturing a distinct boundary between phases, showing complicated interactions like splash formation, air entrainment, and unstable interfaces in high-shear zones. The patterns of phase distribution are especially clear in the mixing areas farther downstream of the rotor, where there is a lot of phase interaction and rapid dispersion. This shows that the numerical method works well for solving these complicated multiphase problems.

Figure 4: Volume fraction of water around Pelton wheel CFD simulation