Show simple item record

dc.contributor.advisorBjerketvedt, Dagnb_NO
dc.contributor.authorKristoffersen, Kjetilnb_NO
dc.date.accessioned2014-12-19T11:24:40Z
dc.date.available2014-12-19T11:24:40Z
dc.date.created2004-09-03nb_NO
dc.date.issued2004nb_NO
dc.identifier124813nb_NO
dc.identifier.isbn82-471-6371-3nb_NO
dc.identifier.urihttp://hdl.handle.net/11250/231186
dc.description.abstractIn this thesis, gas explosions inside pipes are considered. Laboratory experiments and numerical simulations are the basis of the thesis. The target of the work was to develop numerical models that could predict accidental gas explosions inside pipes. Experiments were performed in circular steel pipes, with an inner diameter of 22.3 mm, and a plexiglass pipe, with an inner diameter of 40 mm. Propane, acetylene and hydrogen at various equivalence ratios in air were used. Pressure was recorded by Kistler pressure transducers and flame propagation was captured by photodiodes, a SLR camera and a high-speed camera. The experiments showed that acoustic oscillations would occur in the pipes, and that the frequencies of these oscillations are determined by the pipe length. Several inversions of the flame front can occur during the flame propagation in a pipe. These inversions are appearing due to quenching of the flame front at the pipe wall and due to interactions of the flame front with the longitudinal pressure waves in the pipe. Transition to detonation was achieved in acetylene-air mixtures in a 5 m steel pipe with 4 small obstructions. Simulations of the flame propagation in smooth pipes were performed with an 1D MATLAB version of the Random Choice Method (RCMLAB). Methods for estimation of quasi 1D burning velocities and of pipe outlet conditions from experimental pressure data were implemented into this code. The simulated pressure waves and flame propagation were compared to the experimental results and there are good agreements between the results. Simulations were also performed with the commercial CFD code FLACS. They indicated that to properly handle the longitudinal pressure oscillations in pipes, at least 7 grid cells in each direction of the pipe cross-section and a Courant number of maximum 1 should be used. It was shown that the current combustion model in FLACS gave too high flame speeds initially for gas explosions in a pipe with an inner width of 40 mm.nb_NO
dc.languageengnb_NO
dc.publisherFakultet for ingeniørvitenskap og teknologinb_NO
dc.relation.ispartofseriesDoktoravhandlinger ved NTNU, 1503-8181; 2004:79nb_NO
dc.subjectgas explosionsen_GB
dc.subjectrandom choice methoden_GB
dc.subjectcombustion modelingen_GB
dc.subjectdeflagration to detonation transitionen_GB
dc.subjectacoustic oscillations in pipesen_GB
dc.titleGas explosions in process pipesnb_NO
dc.typeDoctoral thesisnb_NO
dc.source.pagenumber156nb_NO
dc.contributor.departmentNorges teknisk-naturvitenskapelige universitet, Fakultet for ingeniørvitenskap og teknologinb_NO
dc.description.degreedr.ing.nb_NO
dc.description.degreedr.ing.en_GB


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record