Author(s): Marija Lazarevikj; Zoran Markov

Linked Author(s): Marija Lazarevikj, Zoran Markov

Keywords: Hydraulic torque; Guide vane axis; CFD; FSI

Abstract: Hydraulic turbines often operate at off-design conditions according to the energy demand which imposes variation of the guide vanes static loads at different turbine operating conditions. Francis turbine guide vanes' mechanical behavior depends on the magnitude of hydrodynamic forces and the location of the pivot axis both influencing the hydraulic torque. Therefore, it is significant to study the guide vane torque changes. Most suitable position of the guide vane axis can be determined aiming to obtain as low stresses and deformations as possible. For that purpose, the structural performance of a guide vane is predicted by simulating fluid and structure interaction (FSI). The Francis-99 model from the Waterpower Laboratory at NTNU is used as a test case. Water flow in the Francis turbine guide vanes cascade is modeled and simulated for different turbine conditions to determine the hydraulic torque variation for the actual axis location. A methodology for determining the guide vane pivot axis based on the criteria to obtain zero hydraulic torque at selected turbine operating condition (i.e. for lower guide vane opening) is presented. The structural behavior of the guide vane at the actual axis location and the proposed location using the presented methodology is compared for wider range of guide vane openings to confirm the improvement.

DOI: https://doi.org/10.3850/IAHR-39WC2521711920221028

Year: 2022