Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Design and performance analysis of a Francis type hydraulic turbine impeller employing CFD
Submission Author:
Mateus Felipe Benicio Moraes , MA
Co-Authors:
Mateus Felipe Benicio Moraes, Dener Silva de Almeida
Presenter: Mateus Felipe Benicio Moraes
doi://10.26678/ABCM.COBEM2023.COB2023-1508
Abstract
The impeller is the component of the hydraulic turbine responsible for converting hydraulic energy into mechanical energy. It consists of a series of specially shaped blades that use the movement of water to create a torque that enables it to rotate. The device’s geometry is determined through the design process, but this procedure does not provide a satisfactory understanding of the flow properties such as velocity and pressure. Computation Fluid Dynamics (CFD) is a versatile and cost-effective tool for experimental tests that can analyse various impellers in different operating conditions. This work aimed at designing the impeller of a Francis turbine using the Bovet method and analysing flow (pressure and velocity) and performance (head, power, efficiency, torque, and characteristic curves) parameters through a simulation in the software Ansys Student 2023 R2. Turbomachinery Fluid Flow and its modules BladeGen, TurboMesh, CFX-Pre and CFX-Post were used to simulate fluid flow and obtain the impeller’s performance parameters. The simulations were carried out in nine meshes to investigate mesh convergence. A k-ε model and the high resolution advection scheme were used to calculate the fluid flow. The results showed that fluid particles collided with the blades and were projected in the rotation direction. Mesh convergence couldn’t be verified. Flow separation and vortex formation between the blades occurred. There was a low-pressure zone at the blade’s leading edge, a behaviour that tends to induce cavitation and damage Francis turbine impellers in this region. The head value was overestimated due to numerical instabilities. The efficiency was lower due to impact losses, flow separation, and vortices. Shaft power and torque presented close errors due to error propagation. The efficiency curve showed only increasing trends, not behaving as expected. The relative errors of the performance parameters were about 11%.
Keywords
Francis Turbine, Design, Simulation, performance
