Author(s): Gregory Guyot; Alain Cartellier; Jean Phillipe Matas

Linked Author(s): Grégory Guyot

Keywords: Plunging jet; Penetration Depth

Abstract: Whether it is to ensure the oxygenation of an ecosystem, or the efficiency and safety of a hydroelectric installation, it is necessary to understand the impact of plunging jets. Using a multi-scale approach based on two experiments (a laboratory one, and a large scale one named JetHigh), we address here, the prediction of the penetration depth of free-falling jets. We measured the penetration depth for a wide range of jet diameters, from 0.3 mm to 210 mm for a round nozzle and for a rectangular nozzle (648 mm by 32 mm). We also studied a wide range of fall heights, from 0.06 m to 9.5 m. With the addition of video analysis of the jet and in the bubble cloud and optical probe measurements in the bubble cloud, we propose a quite simple model to predict the penetration depth of a wide variety of jet structures at impact. It is based on the momentum theorem applied on the bubble cloud. This model extends the model proposed by Clanet & Lasheras (1997) and coincides with the empirical correlation explained by Mc Keogh & Ervine (1981). Based on our measurements with a rectangular nozzle, we propose a similar model for the nappe. It shows that the nappe can behave as a sheet of side-by-side round jets if the instabilities are developed enough.

DOI: https://doi.org/10.3850/IAHR-39WC25217119202246

Year: 2022