Publications de Mohamed Farhat

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Experiments on vortex shedding from a blunt trailing edge symmetric hydrofoil operating at zero angle of attack in a uniform high speed flow, Re-h = 16.1 . 10(3) - 96.6 . 10(3), where the reference length h is the trailing edge thickness, are reported. The ...

Cloud cavitation induces intense underwater radiation noise, with complex spectral characteristics that remain insufficiently understood. This study explores the underlying mechanisms through experiments and simulations on a twisted hydrofoil. Beyond the well-known harmonic tones linked to cavity shedding frequency, two key spectral characteristics were identified: a series of lock-in frequency features and a consistent high-frequency decay rate. Experimental and numerical results reveal that tunnel acousti

The tip-leakage vortex (TLV) cavitation is a challenging issue for a variety of axial hydraulic turbines and pumps from both technical and scientific viewpoints. The flow characteristics of the TLV cavitation were widely studied in the past decades, but th ...

In the present paper, a new control method for tip-leakage vortex (TLV) cavitation is proposed. This method, which combines the effects of grooves and winglets, is made of overhanging grooves (OHGs) fitted at the tip of a hydrofoil. Experimental and numeri ...

Background Conflicting reports in the literature have raised the question whether radial extracorporeal shock wave therapy (rESWT) devices and vibrating massage devices have similar energy signatures and, hence, cause similar bioeffects in treated tissues. ...

Pumped storage power plants are key components for the development of new renewable CO2-free primary energies and the security enhancement of electricity supply. They also offer interesting business opportunities in nowadays liberalized electricity market. ...

In centrifugal pumps, the interaction between the rotating impeller and the stationary diffuser generates specific pressure fluctuation patterns. When the pump is operated at off design conditions, these pressure fluctuations increase. The resulting rise o ...

The shedding process of the Kármán vortices at the trailing edge of a 2D hydrofoil at high Reynolds numbers is investigated. The focus is put on the effect of the cavitation on the vortex street morphology. A direct insight is also provided on the role of ...

ObjectiveWall shear stress (WSS) and its derived spatiotemporal parameters have proven to play a major role on intracranial aneurysms (IAs) growth and rupture. This study aims to demonstrate how ultra-high field (UHF) 7 T phase contrast magnetic resonance ...

The influence of leading edge sheet cavitation and supercavitation on the added mass effects experienced by a 2-D NACA0009 truncated hydrofoil has been experimentally investigated in a hydrodynamic tunnel. A non-intrusive excitation and measuring system ba ...

One-dimensional stability analysis of a hydraulic system composed of a penstock, a runner, and a draft tube was carried out to determine the cause of the full load draft tube surge. It is assumed that the cavity volume at the runner exit is a function of t ...

Flow induced vibration on a hydrofoil may be significantly reduced with a slight modification of the trailing edge without alteration of the hydrodynamic performance. Particularly, the so called Donaldson trailing edge shape gave remarkable results and is ...

This paper presents a validation of numerical simulations in case of a forced oscillating hydrofoil. As a representative case study for vibrating blade in hydraulics machines, a 2D NACA 0009 oscillating hydrofoil is considered. Pressure coefficients from e ...

Anewcavitation erosion testing procedure in high-speed cavitation tunnel is presented. The method is based on surface-mounted obstacles on a plane-convex hydrofoil leading edge. This experimental set-up is able to accelerate the accumulation of damage on specimens located behind the obstacles and presents several advantages. Measurable cavitation erosion damage has been obtained for a thermal spray coating and a stainless steel 13.4 after 75 h of operation. The hydrodynamic operating conditions have been an

The efficiency of centrifugal pumps drops sharply when the flowrate is reduced below a threshold value. This is due to a profound change in the flow structure, characterized by a large of portion flow separation near the impeller blades and the formation o ...

This paper deals with flow investigations using endoscopes in a single-injector reduced scale Pelton turbine performed with a CMOS high-speed camera. Both onboard and external visualizations techniques of the flow in a bucket are presented. The flow observ ...

We realized an experimental setup to study the dynamics of cavitation bubbles inside spherical water drops produced in microgravity (8th Student Parabolic Flight Campaign, European Space Agency ESA). Water volumes of up to 8 ml (25 mm diameter) were expelled through a specially designed injector tube. The latter contained a porous hydrophilic foam and was particularly coated to ensure a stable and attached water drop. Single cavitation bubbles were then generated by an electrical discharge inside the drop.

The work presented in this paper is part of a comprehensive research effort aimed at understanding the influence of flow unsteadiness on leading edge cavitation. Pressure measurements are made on the suction side of an oscillating hydrofoil in the High-Speed Cavitation Tunnel. Leading edge roughness effects are investigated for both cases of fixed and oscillating hydrofoils. The cavity that detaches on the rough leading edge is thicker while its length is approximately the same as for the smooth configurati

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

Numerical simulation of tip vortex cavitation (TVC) remains a challenging task in a variety of applica-tions, such as axial turbines and pumps as well as marine propellers. Although it is well known that TVC is highly sensitive to gas content, be it dissol ...

Mohamed Farhat

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The Effects of a Tripped Turbulent Boundary Layer on Vortex Shedding from a Blunt Trailing Edge Hydrofoil

New insights into cloud cavitation noise spectrum 关于云空化噪声频谱的新认识

A review of cavitation in tip-leakage flow and its control

Suppressing tip-leakage vortex cavitation by overhanging grooves

Radial Shock Wave Devices Generate Cavitation

Experimental investigation of a pump-turbine at off-design operating conditions

Experimental Investigation of Flow Instabilities and Rotating Stall in a High-Energy Centrifugal Pump Stage

Cavitation in Kármán Vortices and Flow Induced Vibrations

Near-wall hemodynamic parameters quantification in in vitro intracranial aneurysms with 7 T PC-MRI

Experimental investigation of added mass effects on a hydrofoil under cavitation conditions

One-Dimensional Analysis of Full Load Draft Tube Surge

Effect of trailing edge shape on hydrodynamic damping for a hydrofoil

2D Oscillating Hydrofoil

Cavitation Erosion Tests on a 2D Hydrofoil using surface-mounted Obstacles

Onset of Flow Separation Phenomenon in a Low-Specific Speed Centrifugal Pump Impeller

High Speed Flow Visualisation of an Impinging Jet on a Pelton Turbine Bucket

Water drops and cavitation bubbles in microgravity

Physical Investigation of the Cavitation Phenomenon

Cavitation Erosion Prediction in Hydro Turbines from Onboard Vibrations

A new Euler-Lagrangian cavitation model for tip-vortex cavitation with the effect of non-condensable gas