Experimental Study of Cavitation Unsteadiness and Erosion on a Plane Convex Hydrofoil. - Archive ouverte HAL Accéder directement au contenu
Communication Dans Un Congrès Année : 2022

Experimental Study of Cavitation Unsteadiness and Erosion on a Plane Convex Hydrofoil.

Résumé

Cavitation is a major issue in hydraulic machinery, it causes performance drop, vibrations increase, and damage due to erosion. This research is dedicated to the identification of different cavitation erosion mechanisms and proposes tools to quantify the erosive potential of a cavitating flow close to a moving boundary. Experiments were conducted on a plano-convex hydrofoil placed in the center of a cavitation tunnel where the fluid velocity, the overall pressure, and the angle of attack of the hydrofoil can be varied. Fast imaging recording and stereo particle image velocimetry were used to identify the characteristics of the flow. Previously, it has been shown that in steady conditions, cavitation exhibits three different regimes depending on the cavitation number and the angle of attack. In this work, we recreated the conditions for each cavitating regime and added a rapid motion to the hydrofoil, which starts from a steady position at a given angle of attack and goes rapidly to a null inclination where it stops. The three mentioned regimes are characterized by the size and shedding behavior of the cavitation cloud, and these characteristics change when the hydrofoil is moving. Three modes of cavitation collapse were identified depending on the acceleration of the hydrofoil. For relatively small angular accelerations a soft collapse of the cavity is observed (mode I). The cavity remains attached to the hydrofoil leading edge and collapses by the upstream movement of its closure region towards the leading edge. For larger accelerations, the leading-edge cavity turns into a cloud that is entrained by the flow and collapses in a symmetrical way (mode II). Mode III is the post-motion collapse mode that is observed for the largest values of the angular acceleration and take place when the foil has reached the null inclination. The collapses in these three modes were compared to the cloud shedding in the stationary regime, and a relation between the stationary shedding and the hydrofoil motion collapse was established. We have compared the velocity profiles around the hydrofoil for the non-cavitating case, and the cavitating cases with stationary and moving hydrofoil. Results show that the cavitation collapse has a significantimpact on the fluid velocity field.
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Dates et versions

hal-04064721 , version 1 (11-04-2023)

Identifiants

  • HAL Id : hal-04064721 , version 1

Citer

Luis A Morocho, Henda Djeridi, Fivel Marc, Giovanni Gigliotti. Experimental Study of Cavitation Unsteadiness and Erosion on a Plane Convex Hydrofoil.. 19th U.S. National Congress on Theoretical and Applied Mechanics, Jun 2022, Austin, Texas, United States. ⟨hal-04064721⟩
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