Discontinuity of lift on a hydrofoil in reversed flow for tidal turbine Application
Article dans une revue avec comité de lecture
Date
2017Journal
European Journal of Mechanics - B/FluidsAbstract
This work presents an experimental investigation of a hydrofoil in reversed flow configuration in the context of marine current turbine development. Experiments consist in hydrodynamic force measurements and PIV flow observations on a NACA 0015 hydrofoil, at 5 × 105 Reynolds number. The hydrofoil in reversed flow produces a higher lift than in the classical forward flow for very low angles of attack and proved to be relatively efficient for an angle of attack lower than 10°, despite a much higher drag than the same foil in direct flow. Moreover, the lift coefficient shows a discontinuity with an hysteresis effect when the angle of attack is varied up and down around zero-degree. It is shown that the sharp leading edge generates an early Leading Edge Separation Bubble on one side (suction side) even for vanishing angles of attack. This separation bubble triggers the transition to turbulence of the boundary layer on the suction side while the pressure side boundary layer remains laminar. As a consequence, separation on the rounded trailing edge occurs farther downstream on the (turbulent) suction side compared to the (laminar) pressure side. The Leading Edge Separation Bubble and the inherent up–down asymmetry in the boundary layer regime are responsible for the lift singularity.
Files in this item
Collections
Related items
Showing items related by title, author, creator and subject.
-
Article dans une revue avec comité de lectureThe interaction between a boundary-layer flow and an elastic plate is addressed by direct numerical simulation, taking into account the full coupling between the fluid flow and the flexible wall. The convectively unstable ...
-
Article dans une revue avec comité de lectureThe flow around a circular arc is governed by the effect of the sharp leading edge and the arc’s curvature. There is a range of incidences where a leading-edge separation bubble (LESB) is formed on the convex side of the ...
-
Communication avec acteThe spinnaker is the most powerful and one of the most used sails both in racing and cruising - yet its complex aerodynamics governed by flow separation is still not fully understood. While the flow around a spinnaker is ...
-
Article dans une revue avec comité de lecturePERALI, Paolo; SACHER, Matthieu; LEROUX, Jean-Baptiste;
WACKERS, Jeroen; AUGIER, Benoît;
BOT, Patrick (Elsevier BV, 2024-08-08)
As a first step toward a multi-fidelity optimization tool for hydrofoils, the present work assesses the ability of the in-house code PUFFIn to be used as a “low-fidelity” solver within the multi-fidelity framework. The ... -
Article dans une revue avec comité de lectureThe structural response of a rectangular cantilevered flexible hydrofoil submitted to various flow regimes is analyzed through an original experiment carried out in a hydrodynamic tunnel at a Reynolds number of 0.75 × 10 ...