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Sökning: id:"swepub:oai:DiVA.org:hig-17832" > Turbulent jets in c...

LIBRIS Formathandbok  (Information om MARC21)
FältnamnIndikatorerMetadata
00005206nam a2200445 4500
001oai:DiVA.org:hig-17832
003SwePub
008141109s1996 | |||||||||||000 ||eng|
020 a 9171706674q print
024a https://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-178322 URI
040 a (SwePub)hig
041 a engb eng
042 9 SwePub
072 7a vet2 swepub-contenttype
072 7a dok2 swepub-publicationtype
100a Karimipanah, Taghi,d 1953-u Högskolan i Gävle,Avdelningen för bygg- energi- och miljöteknik4 aut0 (Swepub:hig)tkh
2451 0a Turbulent jets in confined spaces :b application in mixing ventilation: experimental and numerical studies
264 1a Stockholm :b KTH Royal Institute of Technology,c 1996
300 a 95 s.
338 a electronic2 rdacarrier
520 a The basis of mixing ventilation is the airflow supply to the room by means of jets initiatedfrom the ventilation diffusers. To avoid the draught problem, the design of mixing ventilationmakes uses the throw term, which is defined as the distance to the supply air terminal inwhich the jet centreline mean velocity is decreased to a given value. Traditionally, the throw ismeasured by the supply air device manufacturer. The throw is applied by designers to estimatethe velocity levels in the occupied zone. A standard for determining the throw is the CENstandard CEN/TC156/WG4 N86 "Draft Standard. Air terminal Devices. AerodynamicsTesting And Rating For Mixed Flow Application".The measurement of the throw is very time consuming even with the free jets and theinfluence of the room (the effect of confinement) is not considered. The objective of thepresent study is to give a basis for modifying the existing design and testing method used topredict the velocities in the occupied zone during the design process. A new method whichmay probably be more easier than the existing methods and at the same time give a betterprecision by including the confinement effect.In this thesis two methodological systems of experiment and numerical simulations have beenused. The numerical predictions are used in comparison with the measurements. Thereasonable agreement of the above mentioned methods is implemented to numerical study ofthe other room configurations which are not experimentally studied. This examining methodallows the possibility of studying a lot of configurations and in this manner generalising of theresults. Although the experimental part was made for both model-scale and full-scale testrooms, a large amount of data was obtained for a new test room whose dimension aresystematically varied. All of studies have been made for the isothermal case and themeasurements of velocities and pressures conducted along the room perimeters. The effect ofshort and deep rooms on the properties of the jet ( velocities, pressure, integral scale, jetmomentum, the rate of spreading of jet and turbulence intensities) have been carried out.Some old and recent investigations have been examined. Specially the concept of correlationsfrom open to closed rooms is criticised. It is also shown that the flow field in a confined roomis affected by many other factors than the Reynolds number. The surface pressure on theperimeters was used to calculate the reaction forces at the corners which causes recirculatingbubbles at corners. A study of the turbulent axisymmetric jet which is the basic element inturbulent shear flows and some restrictions of the traditional measurement techniques at theregion of interest in ventilation applications are discussed. The jet momentum is measured byweighing on a balance. Also a study of jets which collide with a wall , that is impinging jet,the effect of walls and confinement on the jet momentum have experimentally andnumerically been carried out. A new momentum balance model was developed for both thefree jet and confined one. An empirical relation has been found for estimation of the room’srotation centre which is used for validation of CFD results.Finally, it is found that the jets in a ventilated room which are a combination of free jet, walljet and impinging jet differ from the traditional wall jets. The rate of spreading of the jet andthe maximum velocity decay in a ventilated room are also different depending on the roomsize and its confinement.
650 7a TEKNIK OCH TEKNOLOGIERx Annan teknik0 (SwePub)2112 hsv//swe
650 7a ENGINEERING AND TECHNOLOGYx Other Engineering and Technologies0 (SwePub)2112 hsv//eng
653 a turbulent
653 a wall jet
653 a impinging jet
653 a free jet
653 a confinement effect
653 a pressure
653 a throw
653 a experimental
653 a numerical
653 a corner
653 a momentum
653 a mixing ventilation
700a Sandberg, Mats4 ths
700a Awbi, H. A.,c Professoru University of Reading, England4 opn
710a Högskolan i Gävleb Avdelningen för bygg- energi- och miljöteknik4 org
856u https://hig.diva-portal.org/smash/get/diva2:761872/FULLTEXT01.pdfx primaryx Raw objecty fulltext
8564 8u https://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-17832

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