Ändra sökning
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Analysis of load and response on large hydropower draft tube structures
KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Betongbyggnad.
KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Betongbyggnad.ORCID-id: 0000-0002-9609-4122
KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Betongbyggnad. Sweco.ORCID-id: 0000-0001-6840-9986
2019 (Engelska)Rapport (Refereegranskat)
Abstract [en]

In a reaction turbine, the runner outlet is connected to a diffuser which is called the draft tube. Large hydropower units with large effect and large discharge normally require large dimensions on the waterways. In some large-scale facilities, the total width of the draft tube is so large there is a need for a supporting centre wall in the draft tube. In the Swedish hydropower business, there are several cases where damages or cracks have been reported in the contact between the roof and the supporting centre wall. The most likely reason for cracking between wall and roof is when refilling the draft tube after it has been drained for inspection. A too quick refilling will give an upwards lifting force on the roof that can be larger than the capacity in the joint. There are still uncertainties regarding the risk for a long-term scenario where any operational pattern could give continued crack propagation.

Vattenfall Hydropower has made an installation with pressure and strain sensors in one of their facilities with a centre wall supported draft tube and a cavity between the roof and the rock cavern. The aim of the project is to get a better understanding on the behaviour of the roof and centre wall during different operational events by evaluating measurements from the draft tube and investigating possible load cases that can create continued crack propagation during operation. In this regard, in this project, the measurements are analysed to discover the different operational patterns and the corresponding effect on applied pressure on draft tube central wall and roof and structure response. A simplified finite element model of the draft tube is demonstrated and the response from the structure due to extracted load patterns is compared with the measurements.

One-year measurements of the unit operation indicated that unit operates over the whole range with many start/stops. Three major types of operation were: normal operation (working in daytime and downtime at night), continuous operation with no stop and start-stop events with sharp start/stop in the morning and afternoon. The analysis of pressure measurements indicated that the fluid motion in the straight diffuser is turbulent and possibly influenced by vortex formation under the runner. Therefore, the pressure on the right side of the central wall was higher than on the left side.

The quality of the strain measurements showed to be of insufficient quality and lack of information regarding the set-up. This has given questions on the possibility to get reliable results in the evaluation. Nevertheless, an evaluation has been performed. The evaluation of strain measurements demonstrated higher strain values at the upstream side of the central wall and roof. Moreover, the strain on underside of the roof was higher than on the central wall. Sudden fluctuation during continuous operation and sequence of start/stop were the cases that in long-term may cause damage to the structure due to fatigue problems. The results from finite element model indicated high tensile strength at the upstream side of the straight diffuser, in contact between the roof and the central wall where a crack has been detected in the real structure.

Ort, förlag, år, upplaga, sidor
Energiforsk AB , 2019. , s. 78
Nationell ämneskategori
Samhällsbyggnadsteknik
Identifikatorer
URN: urn:nbn:se:kth:diva-261088ISBN: 978-91-7673-567-1 (digital)OAI: oai:DiVA.org:kth-261088DiVA, id: diva2:1356296
Anmärkning

QC 20191002

Tillgänglig från: 2019-10-01 Skapad: 2019-10-01 Senast uppdaterad: 2019-10-02Bibliografiskt granskad

Open Access i DiVA

fulltext(7511 kB)7 nedladdningar
Filinformation
Filnamn FULLTEXT01.pdfFilstorlek 7511 kBChecksumma SHA-512
1ec803f98e1b0ae369a72c2d820aaa20f531bb94f5a75e9426696788b31c4453dd4dde25a76941e3ed0fcfc4a6462250b0c80f03db2f5428607b44b8014814f9
Typ fulltextMimetyp application/pdf

Personposter BETA

Ahmed, LamisNordström, Erik

Sök vidare i DiVA

Av författaren/redaktören
Abbasiverki, RoghayehAhmed, LamisNordström, Erik
Av organisationen
Betongbyggnad
Samhällsbyggnadsteknik

Sök vidare utanför DiVA

GoogleGoogle Scholar
Totalt: 7 nedladdningar
Antalet nedladdningar är summan av nedladdningar för alla fulltexter. Det kan inkludera t.ex tidigare versioner som nu inte längre är tillgängliga.

isbn
urn-nbn

Altmetricpoäng

isbn
urn-nbn
Totalt: 125 träffar
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf