ACOUSTIC RESONNANCE IN CAVITATION FREE AND CAVITATING FLOWS

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We propose a two-fold approach to model reduction of fluid-structure interaction. The state equations for the fluid are solved with reduced basis methods. These are model reduction methods for parametric partial differential equations using well-chosen snapshot solutions in order to build a set of global basis functions. The other reduction is in terms of the geometric complexity of the moving fluidstructure interface. We use free-form deformations to parameterize the perturbation of the flow channel at res

Systematic investigations on positive and negative surge waves from upstream have been conducted in a 40 m long channel with a mean bed slope of 1.14? and non-prismatic bank geometries. The channel banks included macro-roughness elements, namely various cavities. In total, 41 different geometrical configurations have been investigated. The surge wave experiments confirmed the applicability of the elementary surge wave theory including secondary waves and wave breaking in the prismatic reference configuratio

In this work we use the Smoothed Particle Hydrodynamics methodology (SPH) to simulate incompressible viscous flows of Newtonian fluids. The SPH is a meshfree Lagrangian method which simulates the flow like a set of moving fluid particles that interact one with others by hydrodynamics forces. The forces acting on each particle are evaluated using a spatial filtering process, taken over a certain region in the neighborhood of the particle which is defined by a smoothing length, h. The filter kernel function a

Fourier Domain OCT proved to be an outstanding tool for measuring 3D retinal structures with high sensitivity, resolution, and speed. We extended the FDOCT concept towards functional imaging by analyzing the spectroscopic tissue properties, polarization contrast and Doppler velocity imaging. Differential spectral contrast FDOCT allows optical staining of retinal tomograms and to contrast tissue of high pigmentation such as the retinal pigment epithelium (RPE). The latter shows strong correlation if compared

Piezoresistive pressure sensors using classical deformable structures such as membranes progressively run into difficulties at very high pressures (above 1 to 2 kbar), due to the decreasing ratio between the available sensing strain on the outer membrane surface and the maximal materials strain experienced on the pressurised side. Therefore, a novel "isostatic" pressure sensor concept, whereby the sensing element is immersed in the pressure fluid, has been developed. This method in principle allows the meas

Measurement of key plasma jet properties, such as the Mach number, electron density and temperature, in a low pressure environment, were performed using double Langmuir probes and Mach probes. In particular, under-expanded jets are studied in detail by performing complete mappings of plasma jet properties at chamber pressures of 10 and 2 mbar. These results show that the measured physical properties are consistent with the jet flow phenomenology, such as the presence of periodic expansion and compression zo

A novel implicit cell-vertex finite volume method is presented for the solution of both the Navier-Stokes equations and the governing equations for certain viscoelastic fluids. The key idea is the elimination of the pressure term from the momentum equation by multiplying the momentum equation with the unit normal vector to a control volume boundary and integrating thereafter around this boundary. The resulting equations are expressed solely in terms of the velocity components and, where appropriate, the com

The current work intends to improve the cavitation erosion prediction methodology in hydro turbines by the use of onboard vibration measurements taken on the rotating shaft. For that, a measuring campaign in two similar Francis turbine prototypes has been carried out. In particular, one machine is a well known case of severe erosion on all the blades meanwhile the second machine does not present any erosion at all. A miniature telemetry system has been mounted on the shaft in both cases to transmit the sign

At this time, a large number of hydraulic turbomachinery installations are ageing, so that they need refurbishement to increase their efficiency and their associated output power. The items that need refurbishement are mainly the runner and the guide vanes. The draft tube and the spiral casing are generally not modified, for cost and safety reasons. An unsuitable match between the new runner and the old draft tube can lead to an unfavourable flow behavior and an efficiency drop when the hydroelectric plant

An experimental investigation of the flow and heat transfer characteristics in internal coolant passages of gas turbine airfoils has been conducted. The PIV method was employed for the flow measurements. A stereoscopic PIV system was used and automated. The stereoscopic method allowed measuring the three velocity components in measurement planes. The system was capable of measuring 100 planes in each configuration. Each measurement plane was composed of 30*30 measurement points. The transient liquid crystal

The Aosta plain like any intra-ridge alluvial valley, is it hydrogeological system where a multilayer detritic aquifer is recharged by several subwatersheds. In such valleys the preservation of the chemical (mass transfert) and hydraulic (pressure transfert) signals from upstream (input) to downstream (output) can no longer be accepted. Considering the fact that vertical heterogeneities engender hydraulic and chemical discontinuities, in Aosta plain the occurrence of lateral discontinuities in the same sedi

An analytical approach allowing modelling transient phenomena in pipes, valves, surge tanks and Francis turbines based on impedance method is developed. These models are implemented in a software called “SIMSEN”, which simulates the behaviour of complex applications in the domain of adjustable speed drives and electrical power networks. This program is based on a modular structure, which enables the numerical simulation of transient modes of systems exhibiting arbitrary topologies. The numerical simulation

ACOUSTIC RESONNANCE IN CAVITATION FREE AND CAVITATING FLOWS

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Reduced formulation of a steady fluid-structure interaction problem with parametric coupling

Unsteady flow in a channel with large scale bank roughness

SMOOTHED PARTICLE HYDRODYNAMICS APPLIED TO THE SIMULATION OF LOW REYNOLDS NUMBER FLOWS

Measurement of retinal physiology using functional Fourier domain OCT concepts

LTCC ultra high isostatic pressure sensors

Characterization of supersonic low pressure plasma jets with electrostatic probes

A numerical investigation using a novel finite volume method of some flow instabilities

Cavitation Erosion Prediction in Hydro Turbines from Onboard Vibrations

Analyse du champ de pression pariétale d'un diffuseur coudé de turbine Francis

Experimental investigation of heat transfer and flow characteristics in various geometries of 2-pass internal cooling passages of gas turbine airfoils

Complexité des circulations dans l'aquifère alluvial de la plaine d'Aoste (Italie) : mise en évidence par l'hydrogéochimie [Complexity of the groundwater flow in the alluvial aquifer of the Aosta plain (Italy): Study with hydrogeochemistry]

New Tool for the Simulation of Transient Phenomena in Francis Turbine Power Plants.