Experimental and numerical studies on a high head model Francis turbine were carried out over the entire range of operation. A complete Hill diagram was constructed pressure-time measurements performed at several operating conditions power generation by installing pressure sensors in rotating stationary domains turbine. Unsteady simulations five using two turbulent models, shear stress transport (SST) k-ω standard k-ε advection schemes, resolution second order upwind. There very small...

The penetration of intermittent wind and solar power to the grid network above manageable limits disrupts electrical grids. Consequently, hydraulic turbines synchronized experience total load rejection are forced shut down immediately. turbine runner accelerates runaway speeds in a few seconds, inducing high-amplitude, unsteady pressure loading on blades. This sometimes results failure components. Moreover, significantly affects operating life runner. Transient measurements were carried out...

Hydraulic turbines are frequently used to maintain electrical grid parameters. An angular movement of the guide vanes (GVs) during transients such as load acceptance and rejection within short time raised significant concerns for increased wear instabilities. The present work focuses on pressure variations in a high-head Francis turbine transients. Six transient conditions were investigated including time-domain rotor–stator interaction. measurements vaneless space runner indicated presence...

The present study aims to investigate the unsteady flow phenomenon that produces high energy stochastic fluctuations in a highly skewed blade cascade. A complex structure such as turbine is operated at runaway speed, where circumferential velocity dangerously high, and dissipation so significant it takes toll on operating life of machine. Previous studies showed large vortical changes spatial location very quickly interacts with secondary attached pressure-side. temporal inception rings...

Abstract Downstream hydropower plants, a change in water chemistry can lead to the occurrence of widely unknown problem: total dissolved gas (TDG) supersaturation. It takes place when air is entrained body and exposed high pressures, which leads dissolution water. Re-exposure atmospheric pressure downstream power plant results TDG This potential danger for aquatic environment living these waters, as increased saturation poses risk experiencing bubble disease (GBD). Studies about...

The global need for balance between energy generated from intermittent renewable sources and the actual demand has introduced severe operational challenges on hydropower, a steady source in current context. Although it some flexibility operation by varying flow, head, speed, entirety of its range must be optimized to more effective. non-optimal conditions caused these changes result flow separation runner blades that results low efficiency can mitigated with use vortex generators. generators...

Wave loads are one of the main contributors to fatigue tidal turbine blades. Because this, they a determinant parameter for calculation blade life time. To avoid cost associated with oversizing blades or replacing damaged blade, it is essential evaluate acting on turbine, and especially wave blades, best possible accuracy. Experience from wind industry valuable horizontal axis design can be estimated using same methods, even if different. This article presents features code written Matlab,...

Water passes freely through a hydraulic turbine in the absence of power requirements or during maintenance transmission lines, spillways, dam. Moreover, operates under no-load conditions prior to generator synchronization startup and after disconnection from grid load for shutdown. High-velocity swirling flow spin-no-load (SNL) induces unsteady pressure pulsations turbine, these cause fatigue blades. To investigate amplitude loading, transient measurements were carried out model Francis SNL....

Abrasive wear in the clearance gap of guide vanes (GVs) increases size, which deteriorates flow and causes loss efficiency. This paper investigates performance a Francis turbine including erosion-induced gaps on GVs. The effect is studied numerically, by using GV runner blade passages. results are compared with an experiment conducted single rig, developed for same model. Simulations performed GVs NACA0012, NACA2412 NACA4412 profiles each at 11 operating conditions. It found that induces...

Abstract Clearance gaps between guide vanes and cover plates of Francis turbines tend to increase in size due simultaneous effect secondary flow erosion sediment affected hydropower plants. The pressure difference the two sides vane induces leakage through gap. This enters into suction side with high acceleration, disturbing primary causing more losses downstream turbine components. A cascade rig containing a single passage has been built study clearance gap using sensors PIV (Particle Image...