Hydraulisches Verhalten von Treppengerinnen mit eingetieften Stufen : selbstinduzierte Abflussinstationaritäten und Energiedissipation

This PhD thesis addresses the hydraulic behaviour of pooled stepped chutes; a geometry frequently utilized by dams to spill floodwater defined by the existence of endsills or weirs perpendicular to the flow at the end of each step. Weirs increase the energy dissipation and can cause the formation of unsteady flow, therefore the steady inflow of the flat stepped chutes was observed. Weirs are also used in steep mountain rivers to control the bed load transport. Based on hydraulic model tests with chute angles of 8.9°, 14.6° and 18.6°, and dimensionless weir heights between 0 and 1.0 (weir height w and step height s), the flow resistance, flow patterns, and the energy dissipation was investigated at high discharges in skimming flow regime. To quantify the properties of air-water flow, a double-tip conductivity probe was developed to measure the vertical profiles of air concentration and flow velocities. A video based water level measurement technique was used to investigate the unstable flow regions. This measurement method allowed for automatic water level detection and the qualitative analysis of the flow patterns by monitoring the movement of air bubbles. The work makes a significant contribution to understanding the hydraulics of pooled stepped chutes. The energy dissipation is now quantifiable if the geometry parameters of the steps are given. Furthermore the mechanism of how the self induced unsteady flow develops is described in detail. Hints of how to calculate the parameters of this unstable flow region (occurrence, wave height and wave frequencies) are also provided. Finally, design guidelines for engineers are presented.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2008

Author dc:creator

• Thorwarth, Jens

Contributors dc:contributor

• Köngeter, Jürgen

• info:eu-repo/classification/ddc/620
• Strömungswiderstand
• Kaskade
• Offenes Gerinne
• Ingenieurwissenschaften
• Treppengerinne
• Energiedissipation
• Abflusswiderstand
• Wellen
• Abflussinstationariäten
• pooled stepped chutes
• flow resistance
• energy dissipation
• instable flow
• self induced

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-112902%22

OAI record oai:identifier

https://publications.rwth-aachen.de/oai2d?verb=GetRecord&metadataPrefix=oai_dc&identifier=oai%3Apublications.rwth-aachen.de%3A50353