Numerical investigation of hydraulic load and stress induced in Savonius hydrokinetic turbine with the effects of augmentation techniques through fluid-structure interaction analysis

Abstract

The objective of the present study is to estimate hydraulic load, induced stress and factor of safety of the Savonius hydrokinetic turbine when operating under free stream velocity of 0.3 m/s to 4 m/s at rotor angle 0° to 360°. Hydraulic load evaluated from CFD analysis, whereas the induced stress computed from FEM analysis based on the computed hydraulic load through CFD in ANSYS 14. The effects of deflector and duct augmentation technique on the hydraulic load and induced stress have also been investigated. The maximum hydraulic load and von-Mises stress on rotor are found as 0.57 Mpa and 153.41 Mpa respectively in case of duct with single deflector augmentation techniques at rotor angle 0°, 180° and 360° at 4 m/s free stream velocity. In Savonius rotor with augmentation techniques, at higher free stream velocity the factor of safety reached very low, somewhat equal or less than minimum specified limit of failure. Computation results show that front area of shaft rotor from inlet side experiences zone of high von-Mises stress and has minimum factor of safety that leads to chances of fatigue crack, when applied for a free stream velocity greater than 2 m/s.