Bottom-Pressure Development Due to an Abrupt Slope Reduction at Stepped Spillways

Water

Jorge Matos¹  Michael Pfister²  Mohammad J. Ostad Mirza Tehrani³  Anton J. Schleiss³ 

[1] CERIS, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisbon, Portugal;Civil Engineering Department, Haute Ecole d’Ingénierie et d’Architecture de Fribourg (HEIA-FR, HES-SO), CH-1705 Fribourg, Switzerland;Laboratory of Hydraulic Constructions (LCH), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland;

关键词: air–water flow;    bottom-pressure;    skimming flow;    slope reduction;    stepped spillway;   

DOI  :  10.3390/w14010041

来源: DOAJ

【 摘 要 】

Fluctuating bottom-pressures on stepped chutes are relevant for the spillway design. An abrupt slope reduction causes a local alteration of the bottom-pressure development. Little information is available regarding the air–water flow properties near an abrupt slope reduction on stepped chutes, particularly on the local pressure evolution. Nevertheless, the option of providing a chute slope reduction may be of interest in spillway layout. The experiments presented herein include pressure distributions on both vertical and horizontal step faces, subsequent to an abrupt slope reduction on stepped chutes. A relatively large-scale physical model including abrupt slope reductions from 50° to 18.6° and from 50° to 30° was used, operated with skimming flow. The data indicate a substantial influence of the tested slope reductions on the bottom-pressure development. In the vicinity of the slope reduction, the mean pressure head near the edge of the horizontal step face reached 0.4 to 0.6 times the velocity head upstream of the slope reduction, for critical flow depths normalized by the step height ranging between 2.6 and 4.6.

【 授权许可】

Unknown