IAHR Document Library

« Back to Library Homepage « Proceedings of the 2nd IAHR Europe Congress (Munich, 2012)

Pressure Drop and Recovery Across Sharp-Edged Multi-Hole Orifices

Author(s): Umberto Fratino; Alessandro Pagano; Stefano Malavasi; Gianandrea Vittorio Messa

Linked Author(s): Alessandro Pagano, Umberto Fratino

Keywords: No Keywords

Abstract: Multi-hole orifices are largely used in hydraulic pressurized systems either as flow conditioner or, placed side by side a control device, to attenuate the onset and the development of cavitation. The hydraulics of single and multi-hole orifices have been widely discussed in literature, with the main aim of identifying the most important parameters affecting their performances. In particular, it has been found by many Authors that the dissipation and cavitation characteristics of such devices are significantly affected by geometrical features, such as the contraction ratioβ, the dimensionless plate thickness t/d h and the number n h and disposition of the holes. In order to further clarify the role played by these parameters, with particular attention for the case of multihole orifices, the results of two experimental campaigns, carried out by research groups of Polytechnic School of Bari and Polytechnic School of Milan in two different pilot plants, are reported and discussed. Several devices, characterized by different geometries, were tested in variable flow conditions. In particular, the equivalent diameter ratio varied between 0. 2 and 0. 72, the dimensionless thickness between 0. 2 and 1. 44 and the number of holes between 1 and 52. The result of the two campaigns appear consistent, and confirm the remarkable dependency of the dissipation characteristics of the devices, expressed in terms of pressure loss coefficient K and discharge coefficient C d, upon the above mentioned geometrical parameters. A comparison to different literature models is provided. At last, the problem of estimating the pressure recovery length is also considered.


Year: 2012

Copyright © 2024 International Association for Hydro-Environment Engineering and Research. All rights reserved. | Terms and Conditions