Dynamic Pressure Measurements on a Model Turbine Runner and their Use in Preventing Runner Fatigue Failure

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Hydropower is a mature and cost-competitive renewable energy source and plays a central role in the European electricity system by providing flexibility, reserves, and grid stability. However, expanding hydropower generation capacity and operational capabilities is increasingly constrained by environmental regulations, competing water uses, and limited opportunities for new infrastructure development. This study explores the feasibility of deploying hydrokinetic turbines within tailrace channels downstream

Tip vortices generated at the tip of lifting surfaces pose significant challenges in fluid dynamics, causing induced drag, noise, and cavitation erosion risk across aerospace and hydraulic applications. Among the various mitigation strategies, porous tips have been explored with mixed results, showing limited effectiveness in diffusing concentrated vorticity. In this study, we introduce a gyroid-based porous tip as a novel passive flow control device for tip vortex mitigation. A gyroid is a triply periodic

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With increasing of hydrological data records and the development of technologies for flood discharge estimation, as well as higher requirements on dam safety issues, a large number of existing dams require spillway rehabilitation to improve their hydraulic capacity. For such projects, the Piano Key Weir (PKW) is an efficient alternative. When compared to standard labyrinth weirs, this structure provides a longer effective crest length for a given spillway width, with the advantage that a PKW can be mounted

Confluences are the nodes of the fluvial network. They are typically characterized by highly heterogeneous conditions that are favorable for a sound fluvial ecosystem, and play a key role in the connectivity of the river system. During the past centuries, many rivers and their tributaries have been channelized and regulated, often resulting in quasi-homogeneous flow and morphologic conditions, deficient flood safety, reduced natural dynamics, impoverished ecological value, and reduced connectivity. Marcelo

In this first part of a 2 papers series, we present the experimental procedure for onboard measurement of pressure and strain fluctuation in a model of low head Francis turbine. 28 miniature pressure sensors are fitted in the pressure and suction sides of two consecutive blades. A specific technique for sensors mounting has been developed allowing a direct manufacturing of the pressure sensors in the runner blades. This prevents from any geometry alteration of the hydraulic profile. Furthermore, miniature p

The flow in a Francis turbine runner (GAMM Turbine) is analysed numerically. Different operating points are calculated using two industrial software packages based respectively on a finite element method (N3S) and a finite volume method (TASCflow®) and compared to experimental results. The numerical results allow to observe physical phenomena in the runner that are important in the process of hydraulic turbomachinery design. Values of Cu and Cm velocity components, blade pressure distribution and recirculat

Three dimensional numerical tools are now commonly used in the design or analysis process of the internai flow of hydraulic machinery. As an illustration of the use of such tools to study the internai flow of a Francis turbine, the computational results obtained in all components of this turbine with an Euler equations solver and two Reynolds Averaged Navier Stokes equations solvers are discussed. The analysis process is illustrated and comparisons with experimental results obtained in the spiral casing and

The two techniques, vibratory monitoring and pit counting, show promising results for the prediction of prototype cavitation erosion from model tests of Francis turbines. These cavitation detection methods are compared in two set-ups at different power levels, a laboratory high velocity cavitation jet and a full scale 270 MW Francis turbine. Excellent quantitative correlations are obtained in the jet tests between erosion rate, volume pitting rate measured on polished metal surfaces of different hardness wi

The present article describes an ambitious research project being conducted jointly by EDF, HQ and EPFL, with the aim of developing a method suitable for industrial use for predicting cavitation in Francis turbines on the basis of scale model testing. Results concerning the notion of erosion aggressiveness, methods to measure it -accelerometer, pressure fluctuations and pitting measurements -, the correlation between measurements on models and erosion on prototypes, and validation testing done on an actual

An experimental study of flow in a Francis hydraulic turbine, especially designed for the GAMM Workshop, has been carried out. In order to provide a data base for the validation and comparison of computational fluid dynamics codes, a Francis turbine mode! and adequate instrumentation have been specially developed. Measurements of both global and local quantities have been performed for the best operating point of the turbine. A five-hole probe mounted on a remote traversing system provides static pressure a

Experimental flow analysis of hydraulic machines is of prime importance for improving the design of such a unit. Moreover, computational fluid dynamics codes need an experimental data reference in order to check their ability to simulate the main flow features. To obtain such an experimental data base a Francis turbine model and an associated instrumentation is specially developed. Measurements of both global and local quantities are performed for five different operating points of the turbine. A five-hole

Most of the severe erosion of hydraulic machines are found to be associated with the collapse of transient cavitation vortices downstream of a leading edge cavity. The dynamics of such a type of cavitation is investigated in a Cavitation Vortex Generator (CVG). By producing the cyclic growth and collapse of single cavitation vortex, this device provides a way to investigate the mechanisms involved in the final stage of the cavity collapse. Very high-speed visualization, at a rate of 500 '000 frames per seco

In order to investigate the dynamics of the vortex cavitation, which is found to be responsible of the cavitation erosion in hydraulic machinery, a cavitation vortex generator (CVG) is used. By producing the cyclic growth and collapse of cavitation vortex, this device provides a good simulation of the realistic hydrodynamics situation corresponding to the travelling cavities downstream a fixed leading-edge cavity. The simultaneous use of the shock and the pressure time-history recordings and the high speed

Dynamic Pressure Measurements on a Model Turbine Runner and their Use in Preventing Runner Fatigue Failure

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Expanding Hydropower Capabilities Using Hydrokinetic Turbines in Tailrace Channels: Feasibility, Site Optimization, and System Implications

Gyroid porous inserts as a novel flow control to mitigate tip vortex cavitation

Gondo Throttled Surge Tank Numerical Modeling and Design Review

Piano Key Weirs as efficient spillway structure

Influence of tributary widening on confluence morphodynamics

Onboard Measurements of Pressure and Strain Fluctuations in a Model of low Head Francis Turbine. Part 1 : Instrumentation

Numerical Flow Analysis of the GAMM Turbine at nominal and off-design Operating Conditions

Comparison of Flow Computation Results with experimental Flow Surveys in a Francis Turbine

Accelerometer and Pit Counting Detection of Cavitation Erosion on a Laboratory Jet and a Large Francis Turbine

Predicting Cavitation in Francis Turbines on the Basis of Scale Model Testing

Experimental flow study of the GAMM turbine model

Flow survey and blade pressure measurements in a Francis turbine model

Shock pressure generated by cavitation vortex collapse

Dynamics of vortex cavitation involved in the erosion of hydraulic machines