Head loss coefficient through sharp-edged orifices

28th IAHR symposium on Hydraulic Machinery and Systems

Adam, Nicolas J.^1 ; De Cesare, Giovanni^1 ; Schleiss, Anton J.^1 ; Richard, Sylvain^2 ; Muench-Alligné, Cécile^2

Laboratory of Hydraulic Constructions, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland^1

Institut de Systme Civil, HES so Valais Wallis, Sion, Switzerland^2

关键词: Discharge control;    Edge angle;    Head loss coefficient;    Installed power;    Main effect;    Peak power;    Research studies;    Safety level;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/49/6/062009/pdf
DOI  :  10.1088/1755-1315/49/6/062009

来源: IOP

【 摘 要 】

Nowadays, high-head power plants could increase their installed power capacity for many reasons, e.g. dam heightening, increase of their peak power capacity or refurbishment with new turbines. Frequently, due to several considerations, e.g. topographical or economical limitations, the existing surge tank cannot be extended to keep previous safety levels and efficiency. A valuable way to adapt these surge tanks is to place a throttle at their entrance like, for example, an orifice. The main effect of this adaptation is the introduction of head losses that reduce the extreme levels in the surge tank due to the mass oscillations resulting from a closure or opening of downstream discharge control. This research studies the influence of the edge angle of a ASME-standard orifice on the head losses. This angle introduces an asymmetrical behavior and influences head losses. Different angles are tested from 0? to the 67? (biggest angle possible for this configuration). The first step of this study is to determine experimentally the steady losses produced by orifice for several discharges. In the second step, a numerical model on ANSYS CFX is performed. Combining the two approaches, it is possible to understand and quantify the effect of the edge angle.