Computational fluid dynamics (CFD), in recent years, has played an increasingly important role in contributing to the study and identification of the various phenomena involved in the development of a tunnel fire. In particular, in the following work, thanks to the software modeling Fire Dynamics Simulator (FDS), we were able to study the various dynamics, as well as interactions that occur following the development of a fire between the phenomenon of backlayering and the activation of a system of fire suppression. Firstly, we worked on a model of a tunnel in scale, going to model the aforementioned tunnel with FDS, in order to validate the results obtained experimentally by Zhao et al. (2017 with regard to temperature profiles along the tunnel axis.) Experimental cases were chosen with lower ventilation speed (Test 12) and higher (Test 16), two simulations were performed for each test, using different sized cells, both simulations returned results in accordance with the experimental tests, showing only a slight difference in the temperature values measured in the tunnel part in which the backlayering develops, as the cell size varies. we proceeded to the study of a full scale tunnel, proceeding initially to the validation of the experimental tests carried out by Ko et al. (2013), comparing the temperature profiles obtained experimentally with those obtained from the simulations. cases related to two different tunnel geometries, one of 37,5 m and one of 53 m with constant fire power, ventilation cost doors and sprinkler system not active. After that, validation was carried out with an active sprinkler system, using three different discharged water flow rates. Finally, we moved to a parametric analysis, going to perform different simulations with different fire powers, different air intake flow rates and different discharge water flow rates, analyzing how the speed of the backlayering varied in relation to the variation of the previous three parameters.
La fluidodinamica computazionale (CFD), negli ultimi anni, ha avuto un ruolo sempre più di primaria importanza nel contribuire allo studio ed all’identificazione dei vari fenomeni coinvolti nello sviluppo di un incendio in galleria. In particolare, nel seguente lavoro, grazie al software di modellazione Fire Dynamics Simulator (FDS), si sono potute studiare le varie dinamiche, nonché interazioni che avvengono in seguito allo sviluppo di un incendio tra il fenomeno del backlayering e l’attivazione di un impianto di soppressione incendi. Dapprima si è lavorato su un modello di tunnel in scala, andando a modellare il suddetto tunnel con FDS, al fine di convalidare i risultati ottenuti sperimentalmente da Zhao et al. (2017), per ciò che riguarda i profili di temperatura lungo l’asse del tunnel. Si sono scelti i casi sperimentali con velocità di ventilazione più bassa (Test 12) e più alta (Test 16), si sono effettuate due simulazioni per ciascun test, utilizzando celle di differenti dimensioni. Entrambe le simulazioni hanno restituito dei risultati in accordo con le prove sperimentali, evidenziando solo una lieve differenza nei valori di temperatura misurati nella parte di tunnel in cui si sviluppa il backlayering, al variare della dimensione delle celle. Successivamente, si è passati allo studio di un tunnel in scala reale, procedendo inizialmente alla convalida delle prove sperimentali effettuate da Ko et al. (2013), confrontando i profili di temperatura ottenuti sperimentalmente con quelli ottenuti dalle simulazioni. In un primo momento si sono analizzati i casi relativi a due differenti geometrie di tunnel, una di 37,5 m ed una di 53 m con potenza costante dell’incendio, ventilazione costante ed impianto sprinkler non attivo. Dopodiché, si è proceduto alla convalida con impianto sprinkler attivo, utilizzando tre differenti portate d’acqua scaricata. Infine, si è passati ad un’analisi parametrica, andando ad effettuare diverse simulazioni con diverse potenze dell’incendio, diverse portate d’aspirazione dell’aria e diverse portate d’acqua scaricata, analizzando come variava la velocità del backlayering in relazione alla variazione dei precedenti tre parametri.
Analisi dell'influenza di un impianto sprinkler sulle conseguenze d'incendi in galleria
MARUELLI, DAVIDE;BARBIERO, DAVIDE
2017/2018
Abstract
Computational fluid dynamics (CFD), in recent years, has played an increasingly important role in contributing to the study and identification of the various phenomena involved in the development of a tunnel fire. In particular, in the following work, thanks to the software modeling Fire Dynamics Simulator (FDS), we were able to study the various dynamics, as well as interactions that occur following the development of a fire between the phenomenon of backlayering and the activation of a system of fire suppression. Firstly, we worked on a model of a tunnel in scale, going to model the aforementioned tunnel with FDS, in order to validate the results obtained experimentally by Zhao et al. (2017 with regard to temperature profiles along the tunnel axis.) Experimental cases were chosen with lower ventilation speed (Test 12) and higher (Test 16), two simulations were performed for each test, using different sized cells, both simulations returned results in accordance with the experimental tests, showing only a slight difference in the temperature values measured in the tunnel part in which the backlayering develops, as the cell size varies. we proceeded to the study of a full scale tunnel, proceeding initially to the validation of the experimental tests carried out by Ko et al. (2013), comparing the temperature profiles obtained experimentally with those obtained from the simulations. cases related to two different tunnel geometries, one of 37,5 m and one of 53 m with constant fire power, ventilation cost doors and sprinkler system not active. After that, validation was carried out with an active sprinkler system, using three different discharged water flow rates. Finally, we moved to a parametric analysis, going to perform different simulations with different fire powers, different air intake flow rates and different discharge water flow rates, analyzing how the speed of the backlayering varied in relation to the variation of the previous three parameters.File | Dimensione | Formato | |
---|---|---|---|
2018_07_Barbiero_Maruelli.pdf
accessibile in internet solo dagli utenti autorizzati
Dimensione
3.11 MB
Formato
Adobe PDF
|
3.11 MB | Adobe PDF | Visualizza/Apri |
I documenti in POLITesi sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
https://hdl.handle.net/10589/141288