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Author:Stening, Mikael
Title:Pressure Losses in Flow through Manholes and Cross-ducts in Ship
Virtauksen energiahäviöt alusten miesaukoissa ja krossikanavissa
Publication type:Master's thesis
Publication year:2010
Pages:76      Language:   eng
Department/School:Insinööritieteiden ja arkkitehtuurin tiedekunta
Main subject:Vesitalous ja vesirakennus   (Yhd-12)
Supervisor:Koivusalo, Harri
Instructor:Järvelä, Juha
OEVS:
Electronic archive copy is available via Aalto Thesis Database.
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Location:P1 Ark Aalto     | Archive
Keywords:discharge coefficient
manhole
cross-duct
girder
laboratory experiments
purkautumiskerroin
miesaukko
krossikanava
jäykkääjä
laboratoriokokeet
Abstract (eng): The survivability of passenger ships in damaged condition is assessed with flooding simulation tools.
The reliability of these tools depends on the availability of proper discharge coefficients for various flow obstacles.
The purpose of this study was to improve knowledge about the discharge coefficients of typical openings in ships.
Laboratory experiments were carried out in order to examine the discharge coefficients of manholes and cross-ducts in various flow conditions.
The tested objects were a full-scale manhole, a scale model manhole, a scale model cross-duct and a scale model girder with two manholes.
The influence of cross-duct length, structural stiffeners, a web frame and inclination was examined.
The discharge and the level of submergence were varied in the tests.

The discharge coefficient for the full-scale manhole was lower than for the scale model manholes when the jet discharged into air.
The relationship was opposite when the jet discharged into water.
The discharge coefficients of the test objects were higher in submerged flow than in free flow.
Structural stiffeners were found to increase the value of the discharge coefficient.
The influence of flow velocity and the web-frame was small.

Experimentally obtained discharge coefficients for cross-ducts were compared to estimates obtained with the standard computational methods of the International Maritime Organization (IMO).
The computational methods slightly overestimated the discharge coefficients.
The results suggested that the geometry of the girders and the influence of stiffeners should be taken into account when determining a discharge coefficient for a cross-duct.
Abstract (fin): Matkustaja-alusten selviytymismahdollisuuksia vaurioituneessa tilassa arvioidaan vuotosimulointiohjelmistoilla.
Arvioiden tarkkuus riippuu luotettavien purkautumiskertoimien saatavuudesta erilaisille aukoille.
Tämän tutkimuksen tavoitteena oli lisätä tietoa laivoissa yleisesti esiintyvien aukkojen purkautumiskertoimista.
Miesaukkojen ja krossikanavien purkautumiskertoimia selvitettiin laboratoriokokeilla.
Testikappaleina olivat täysimittainen miesaukko, miesaukon pienoismalli, krossikanavan pienoismalli ja kaksi miesaukkoa käsittävän krossikanavan jäykkääjän pienoismalli.
Kokeissa tutkittiin krossikanavan pituuden, krossikanavarakenteen jäykistäjien, kehyskaaren ja kallistuksen vaikutusta purkautumiskertoimeen.
Virtaamaa ja alajuoksun vedenpinnan korkeutta vaihdeltiin.

Vapaassa virtauksessa täysimittaisen miesaukon purkautumiskertoimen arvo oli pienempi kuin pienoismallien vastaavat arvot, mutta veteen purkautuessa purkautumiskertoimien välinen suhde oli päinvastainen.
Kaikkien testikappaleiden purkautumiskertoimet olivat korkeammat veteen purkautuessa kuin vapaassa virtauksessa.
Rakenteen jäykistäjien todettiin nostavan purkautumiskertoimen arvoa.
Virtausnopeuden ja kehyskaaren vaikutus purkautumiskertoimeen todettiin pieneksi.

Kokeellisesti määritettyjä krossikanavan purkautumiskertoimen arvoja verrattiin Kansainvälisen merenkulkujärjestön (IMO) standardin laskentamenetelmän mukaisiin laskennallisiin arvioihin.
Laskentamenetelmien todettiin hieman yliarvioivan purkautumiskertoimia.
Koetulosten perusteella on suositeltavaa ottaa huomioon jäykkääjien geometria ja jäykistäjien vaikutus krossikanavan purkautumiskerrointa määritettäessä.
ED:2010-05-19
INSSI record number: 39670
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