Numerical simulation of fire and smoke development in road tunnels

Παπαδήμα, Γεωργία; Papadima, Georgia

dc.contributor.author	Παπαδήμα, Γεωργία	el
dc.contributor.author	Papadima, Georgia	en
dc.date.accessioned	2021-07-13T11:50:55Z
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/53613
dc.identifier.uri	http://dx.doi.org/10.26240/heal.ntua.21311
dc.rights	Default License
dc.subject	Tunnel	en
dc.subject	Longitudinal ventilation	en
dc.subject	Critical velocity	en
dc.subject	CFD	en
dc.subject	FDS	en
dc.subject	Οδικές σήραγγες	el
dc.subject	Κρίσιμη ταχύτητα	el
dc.subject	Κώδικας υπολογιστικής ρευστομηχανικής	el
dc.title	Numerical simulation of fire and smoke development in road tunnels	en
dc.title	Υπολογιστική προσομοίωση φαινομένων φωτιάς και καπνού σε οδικές σήραγγες	el
heal.type	bachelorThesis
heal.classification	Fire engineering	en
heal.dateAvailable	2022-07-12T21:00:00Z
heal.language	en
heal.access	embargo
heal.recordProvider	ntua	el
heal.publicationDate	2021-03
heal.abstract	The occurrence of a fire incident in road tunnels is a particularly severe event, jeopardizing tunnel’s integrity and motorist’s safety while causing major financial losses and physical impairments or even fatalities to its users. Since the introduction of tunnel structures to the transportation network, numerous fire incidents have occurred, highlighting those severe hazards. To improve the understanding of such incidents, an extensive database has been established, consisting of the main existing fire incidents of the last 20 years, various sequences of full-scale and model-scale fire experiments and numerical simulations, along with several full-scale evacuation tests. As it regards fire protection strategies, a conventional approach for unidirectional road tunnels has been to employ longitudinal ventilation with jet fans to eliminate the hazards associated with smoke backlayering at the direction that the entrapped motorists are located or attempting to escape. Consequently, the primary design objective of this tactic is the determination of the critical ventilation velocity that prevents entirely the flow development of toxic smoke in the upstream direction of the fire. The evolution of fire and smoke characteristics in a tunnel is widely investigated with the utilization of CFD codes. Fire Dynamics Simulator (FDS), developed by NIST, is a computational model, specially designed to resolve fire-driven fluid flows. A numerical series of large-scale tunnel experiments has been conducted, via FDS, in an 854m long, non-inclined tunnel, with various exhaust volume flow rates delivered by the jet fans in order to create the required critical ventilation conditions for three different fire heat release rates (20, 50 & 100MW). It is found that critical ventilation velocity increases with increasing fire size but above a certain HRR value, it becomes independent of the fire size. The design of longitudinal ventilation systems, employing jet fans do meet the requirements at all fire sizes in managing the adverse spread of smoke, upstream of the fire site. The resulting critical velocity for a 20MW fire is 2.75m/s, while a corresponding velocity of approximately 3.10m/s can diminish the backlayering effect for both a fire of 50 and 100MW, for the particular tunnel structure. Existing empirical correlations for critical ventilation have been also proposed, depending on their appropriateness for the respective fire sizes. Before the numerical tests, a twofold validation study has been performed against actual experimental data of Test Case 502 and 615b, of the Memorial Tunnel Fire Ventilation Test Program, to verify the credibility and fidelity of the numerical findings, produced in the present thesis.	en
heal.advisorName	Διονύσης, Κολαΐτης	el
heal.committeeMemberName	Διονύσης, Κολαΐτης	el
heal.committeeMemberName	Φούντη, Μαρία	el
heal.academicPublisher	Εθνικό Μετσόβιο Πολυτεχνείο. Σχολή Μηχανολόγων Μηχανικών. Τομέας Θερμότητας	el
heal.academicPublisherID	ntua
heal.numberOfPages	182 σ.	el
heal.fullTextAvailability	false