Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels
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The document discusses the use of computational fluid dynamics (CFD) simulations for assessing fire risks in road tunnels, analyzing case histories, fire dynamics, normative aspects, and numerical modeling. It highlights the importance of compliance with European and Italian fire safety regulations while emphasizing the need for detailed fire risk assessments and the utility of advanced numerical methods in safety engineering. The findings from the CFD simulations aim to enhance understanding of smoke development and heat release in tunnel scenarios, ultimately leading to improved safety measures and regulatory compliance.
Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels
- 1. “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” School of Civil and Industrial Engineering Department of Structural and Geotechnical Engineering Candidate: Tiziano Baroncelli A.Y. 2013/2014 Advisor: Prof. Eng. Franco Bontempi Co-advisor: Eng. Alessandra Lo Cane Rome, 21 May 2014
- 2. CONCEPTUAL MAP “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” Candidate: Tiziano Baroncelli A.Y.: 2013 -2014 1 4) Results 3) Specific aspects 2) General framework 1) Problem TUNNEL FIRE SAFETY COMPREHENSION OF FIRE DYNAMICS CASE HISTORY 140 EVENTS STATISTICS SPECIFIC EVENT (FREJUSFIRE) FLOW CHART OF THE EVENT NORMATIVE ASPECTS EUROPEAN NORMS: Directive 2004/54/EC ITALIAN NORMS: D.Lgs 264/2006, ANAS 2009 NUMERICAL ASPECTS TUNNEL CFDMODELS EXPLICIT HGVFIRE quantitativeRISK ANALYSIS BENCHMARK OF THE CODE
- 3. COMPREHENSION OF FIRE DYNAMICS “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” Candidate: Tiziano Baroncelli A.Y.: 2013 - 2014 2 2A) FIRE DYNAMICS UNDERSTANDING FIRE DYNAMICS CLASSIFICATION OF THE CASE HISTORY SPECIFIC EVENT: FREJUS FIRE – 06/04 a1) Typology of tunnel a2) Length of the tunnel a3) Cause of ignition a4) Number of victims a5) Number of wounded persons a6) Relevant structural damages N° 0) EVENT 1) TYPOLOGY 2) FATALITIES 3) WOUNDED 4) STRUCTURAL D. 5) LENGHT 6) CAUSE 7) COUNTRY 1 S. Martino 10/09/2007 R 2 137 YES A 4.8 km HF Collision ITA 2 Burnley 23/03/2007 R 3 3 NO A 3.5 km HF Collision AUS 3 Eidsvoll 26/10/2006 R 1 1 NO B 1.2 km HF Collision NOR 4 Viamala 16/09/2006 R 9 9 NO C 0.7 km HF Collision SWI 5 Mauernried 25/12/2005 R 5 5 NO D 0.3 km HF Collision GER
- 4. Directive 2004/54/EC NORMATIVE ASPECTS NORMATIVE ASPECTS “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” Candidate: Tiziano Baroncelli A.Y.: 2013 -2014 3 2B) NORMS 1)DIRECTIVE2004/54/ECabout‘minimumrequirementsforallthetunnelsoftheTrans-EuropeanRoadNetwork’:givesawholenewapproachinthetunnelfiresafety,forasregardsbothnewandexistingtunnels. -DefinitionofMINIMUMREQUIREMENTSFORROADTUNNELSLONGERTHAN500m; -IntroductionoftheRISKANALYSISasaninstrumentforRISKASSESSEMENTandDECISIONMAKING;RISKANALYSISisexplicitlyrequiredintunnelprojecting; -DefinitionoftheSAFETYPARAMETERSofroadtunnelsthatSHALLBETAKENINTOCOUNTEXPLICITLYINTHERISKANALYSIS(lengthofthetunnels,crosssection,lanes,trafficetc). 2)D.Lgs.264/2006:EXECUTIVENORMforItalyofthepreviousDirective2004/54. executive D. Lgs. 264/2006 «on MinimunRequirementsfor allthe Tunnel of the Trans-EuropeanRoad Network (TERN)» CASE HISTORY OF MAJOR TUNNEL FIRES
- 5. BENCHMARK OF THE CALCULATION CODE “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” Candidate: Tiziano Baroncelli A.Y.: 2013 -2014 4 2C) NUMERICAL ASPECTS NUMERICAL ADVANCED METHODS for the assessmentof the consequence of road tunnel fires BENCHMARK OF THE CODE: Fire Dynamics Simulator (FDS), vers. 6.0 ISO13887(‘AssessmentandverificationofMathematicalFireModels’) NUREG1824(‘ValidationofFireModelsfornuclearpowerplantapplications CRITERIA REFERENCES PHYSICALACCURACY(representativenessofthephenomenon) MATHEMATICALACCURACY(absenceoflargenumericalerrors) PHYSICALACCURACY MATHEMATICALACCURACY ANALYTICALTESTS(submodels) SENSITIVITYTOPHISICALPARAMETERS CODECHECKING INFLUENCEOFTHEMESH(‘sensitivityanalysis’) NUMERICALTESTS(DNSsimulations) 퓧 퓧 퓧
- 6. BENCHMARK OF THE CALCULATION CODE “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” Candidate: Tiziano Baroncelli A.Y.: 2013 -2014 5 2C) NUMERICAL ASPECTS IGNITION BENCHMARK OF THE CODE: Fire Dynamics Simulator (FDS), vers. 6.0 1) MODEL # 1 a) GLOBAL LEVEL c) LOCAL LEVEL b) INTERMEDIATE LEVEL 2) MODEL # 2 3) MODEL # 2* Meshtransformations 4) MODEL # 3 5) MODEL # 4 MAINASPECTSOFTHEBENCHMARK: 1)Afinegrid(namelyabout25cm)shouldbeusedtorepresentadequatelythefiresource; 2)Theuseofafinegridincreasessignificantlycalculationtimes; 3)Possibilitytorepresentthefollowingphenomena: IGNITION(surface,object)FLASHOVERPROPAGATIONINFLUENCEOFOXYGEN
- 7. ADVANCED NUMERICAL METHODS: Application to a REAL TUNNEL TUNNEL MODELLING “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” Candidate: Tiziano Baroncelli A.Y.: 2013 -2014 GEOMETRY SAFETY EQUIPMENTS Cross section ST. DEMETRIO ROAD TUNNEL (SICILY) GEOGRAPHY CATANIA -SYRACUSE Parameters Mechanical ventilation Safety infrastructures Illumination Safety/control systems Systems for users’ information Eng. Luigi Carrarini ANAS Risk Analysis Tunnel schedule Quantitative Risk Analysis (QRA) Qualitative Risk Analysis (Risk Matrix) 2C) REAL TUNNEL ST. DEMETRIO 6
- 8. ADVANCED NUMERICAL METHODS: Application to a REAL TUNNEL TUNNEL MODELLING “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” Candidate: Tiziano Baroncelli A.Y.: 2013 -2014 ST. DEMETRIO ROAD TUNNEL (SICILY) Eng. Luigi Carrarini ANAS Risk Analysis Tunnel schedule 2C) REAL TUNNEL ST. DEMETRIO 7
- 9. ADVANCED NUMERICAL METHODS: Application to a REAL TUNNEL CREATING A SCENARIO “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” Candidate: Tiziano Baroncelli A.Y.: 2013 -2014 SCENARIO VENTILATION VEHICLE MODEL 2C) REAL TUNNEL HGV MODEL LARGE SCALE FIRE TESTS –RUNEHAMAR TESTS (2003) CONE CALORIMETER VALIDATED MODELS LARGE SCALE TESTS 5.5 ton 81% wood 19% plastic 8
- 10. ADVANCED NUMERICAL METHODS: Application to a REAL TUNNEL TUNNEL MODELLING “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” Candidate: Tiziano Baroncelli A.Y.: 2013 -2014 ST. DEMETRIO ROAD TUNNEL (SICILY) 2C) REAL TUNNEL HGV MODEL VALIDATED MODELSFOR VEHICLES –BUILDING A SIMPLE MODEL To model the real geometry of the pallets, a mesh of about 1 cm or less would be required: this is pratically impossible SIMPLIFIED APPROACH: materials are organized in layers 9 VENTILATION VEHICLE MODEL CONE CALORIMETER VALIDATED MODELS LARGE SCALE TESTS
- 11. ADVANCED NUMERICAL METHODS: Application to a REAL TUNNEL TUNNEL MODELLING “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” Candidate: Tiziano Baroncelli A.Y.: 2013 -2014 ST. DEMETRIO ROAD TUNNEL (SICILY) 2C) REAL TUNNEL HGV MODEL VALIDATED MODELSFOR VEHICLES –BUILDING A SIMPLE MODEL To model the real geometry of the pallets, a mesh of about 1 cm or less would be required: this is pratically impossible SIMPLIFIED APPROACH: materials are organized in layers 10 VENTILATION VEHICLE MODEL CONE CALORIMETER VALIDATED MODELS LARGE SCALE TESTS
- 12. ADVANCED NUMERICAL METHODS: Application to a REAL TUNNEL TUNNEL MODELLING “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” Candidate: Tiziano Baroncelli A.Y.: 2013 -2014 ST. DEMETRIO ROAD TUNNEL (SICILY) 2C) REAL TUNNEL HGV MODEL 11 VENTILATION VEHICLE MODEL CONE CALORIMETER VALIDATED MODELS LARGE SCALE TESTS IGNITION SOURCE OTHER MATERIALS
- 13. ADVANCED NUMERICAL METHODS: Application to a REAL TUNNEL TUNNEL MODELLING “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” Candidate: Tiziano Baroncelli A.Y.: 2013 -2014 ST. DEMETRIO ROAD TUNNEL (SICILY) 2C) REAL TUNNEL HGV MODEL OTHER MATERIALS 12 VENTILATION VEHICLE MODEL CONE CALORIMETER VALIDATED MODELS LARGE SCALE TESTS IGNITION SOURCE
- 14. ADVANCED NUMERICAL METHODS: Application to a REAL TUNNEL TUNNEL MODELLING “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” Candidate: Tiziano Baroncelli A.Y.: 2013 -2014 ST. DEMETRIO ROAD TUNNEL (SICILY) 2C) REAL TUNNEL VENTILATION MECHANICAL VENTILATION NATURAL VENTILATION ONLY FOR TUNNELS NO LOGER THAN 500 m TRANSVERSE: often in BIDIRECTIONAL TUNNELS (ONE TUBE) LONGITUDINAL: in MONODIRECTIONAL TUNNELS (TWO TUBES) –«JET FANS SYSTEMS» 13 MECHANICAL VENTILATION NATURAL VENTILATION VENTILATION VEHICLE MODEL
- 15. ADVANCED NUMERICAL METHODS: Application to a REAL TUNNEL TUNNEL MODELLING “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” Candidate: Tiziano Baroncelli A.Y.: 2013 -2014 ST. DEMETRIO ROAD TUNNEL (SICILY) 2C) REAL TUNNEL VENTILATION MECHANICAL VENTILATION NATURAL VENTILATION MECHANICAL VENTILATION NATURAL VENTILATION ONLY FOR TUNNELS NO LOGER THAN 500 m TRANSVERSE: often in BIDIRECTIONAL TUNNELS (ONE TUBE) LONGITUDINAL: in MONODIRECTIONAL TUNNELS (TWO TUBES) –«JET FANS SYSTEMS» 퓧 13 VENTILATION VEHICLE MODEL
- 16. Scenario Fire source Distance from the portal Ventilation Jet fans 1 2 CARS 200 m Yes (~ 3 m/s) Yes 2 BUS 200 m Yes (~ 3 m/s) Yes RESULTS OF THE ANALYSIS “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” Candidate: Tiziano Baroncelli A.Y.: 2013 - 2014 RESULTS OF THE ANALYSIS HGV SIMULATIONS RISK ANALYSIS Scenario Fire source Distance from the portal Ventilation Jet fans 1 HGV 200 m No No 2 HGV 200 m Yes (1 m/s) No 3 HGV 200 m Yes (2 m/s) No 4 HGV 200 m Yes (3 m/s) No 5 HGV 200 m Yes (~ 2 m/s) Yes The vehicles are not modelled explicitly, but using a specific ramp (forced combustion at a specific rate). RESULTS RESULTS Global level: SMOKE and FLAME DEVELOPMENT (qualitative); FIELDS OF TEMPERATURES Intermediate level: HRR and BURNING RATE Local level: THERMOCOUPLES Global level: SMOKE DEVELOPMENT (qualitative); FIELDS OF TEMPERATURES Local level: TEMPERATURES, CO, SOOT and OXYGEN CONCENTRATIONS, VISIBILITY, FED 14
- 17. RESULTS OF THE ANALYSIS “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” Candidate: Tiziano Baroncelli A.Y.: 2013 -2014 t = 1min t = 2 min t = 3 min t = 4 min t = 5 min GLOBAL LEVEL RESULTS: 1) SMOKE DEVELOPMENT BACKLAYERING after 95 s TUNNEL FULFILLMENT after 239 s REACHED BY SMOKE after 54 s REACHED BY SMOKE after 208 s 2895 m + z + y 2295 m 2595 m 2695 m BY-PASS BY-PASS HGV EXIT PORTAL (Syracuse) ENTRANCE PORTAL (Catania) TRAFFIC FLOW 105 m 195 m 300 m + Φ + z 9.5 Φ 36.8 Φ 45.9 Φ 27.3 Φ 9.5 Φ 17.7 Φ v = 2 m / s (uniform) 66.7 Φ 15
- 18. RESULTS OF THE ANALYSIS “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” Candidate: Tiziano Baroncelli A.Y.: 2013 -2014 2190 m LOCAL LEVEL RESULTS: 1) THERMOCOUPLES Front FIRE SOURCE Mid1 Mid2 Back 2895 m + z + y 2295 m 2595 m 2695 m BY-PASS BY-PASS HGV EXIT PORTAL (Syracuse) ENTRANCE PORTAL (Catania) TRAFFIC FLOW 105 m 195 m 300 m + Φ + z 9.5 Φ 36.8 Φ 45.9 Φ 27.3 Φ 9.5 Φ 17.7 Φ v = 2 m / s (uniform) 66.7 Φ HGV/ #3 PRESCRIPTIVEFIRE BASED DESIGN PERFORMANCEFIRE BASED DESIGN 16 NO DECAY
- 19. “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” Candidate: Tiziano Baroncelli A.Y.: 2013 -2014 COMPARISON «FUEL –CONTROLLED» FIRES UNLESSSEVERALVEHICLESAREINVOLVEDINTHEFIRE,THEQUANTITYOFAIRISMUCHENOUGHTOALLOWTHECOMPLETECOMBUSTIONOFTHEMATERIAL:THEVEHICLEBURNSASINOUTDOORFIRES,WHERETHEVENTILATIONDOESN’TINFLUENCETHEHEATRELEASE. CFD comparisontest* Scenario #2 –v = 1 m/s Scenario #1 –v = 0 m/s Scenario #3 –v = 2 m/s TIME SHIFT FOR THE HRR CURVE INTERMEDIATE LEVEL RESULTS: 1) SMOKE DEVELOPMENT 17
- 20. “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” Candidate: Tiziano Baroncelli A.Y.: 2013 -2014 COMPARISON «FUEL –CONTROLLED» FIRES THE TIME SHIFTIS ASSOCIATED TO THE DIFFERENT ORIENTATION OF THE IGNITION SOURCE IN THE COMPARED SIMULATIONS. CFD comparisontest* Scenario #2 –v = 1 m/s Scenario #1 –v = 0 m/s Scenario #3 –v = 2 m/s TIME SHIFT FOR THE HRR CURVE + z -x -y ≠ Scenario #1 –v = 0 m/s CFD comparisontest* INTERMEDIATE LEVEL RESULTS: 1) SMOKE DEVELOPMENT 17
- 21. SIMPLIFIED APPROACH FOR QUANTITATIVE RISK ASSESSMENT TUNNEL MODELLING “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” Candidate: Tiziano Baroncelli A.Y.: 2013 -2014 BURNING SURFACES ON THE BASIS OF THE EUREKA TESTS 2C) REAL TUNNEL VENTILATION 18 CRITERIA FOR QUANTITATIVE RISK ASSESSMENT 2 CARS FIRE BUS FIRE WHICH ASPECTS OF THE FIRE THREAT TO USER’S LIFE? HEAT SMOKE RADIATION SIMPLIFIED APPROACHES: basedon simplecriteriaaboutthe mentionedaspects COMPLETE APPROCHES: basedon toxicitycriteriawith allthe concentrationsof toxicgasesand oxygen. Carbon monoxide Oxygen Carbon dioxide
- 22. “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” Candidate: Tiziano Baroncelli A.Y.: 2013 -2014 RESULTS OF THE ANALYSIS GLOBAL LEVEL RESULTS: 1) SMOKE DEVELOPMENT –2 CARS FIRE 2895 m + z + y 2190 m 2295 m 2595 m 2695 m BY-PASS BY-PASS BUS EXIT PORTAL (Syracuse) ENTRANCE PORTAL (Catania) TRAFFIC FLOW 100 m 200 m 300 m + Φ + z 9.5 Φ 38.1 Φ 47.6 Φ 66.7 Φ 28.6 Φ 9.5 Φ 19 Φ JET FAN JET FAN JET FAN 2375 m 2525 m 2675 m 2825 m v,emergency ~3 m / s (jet fans) t = 4min t = 6min t = 8min t = 10 min t = 12 min REACHED BY SMOKE after49 s REACHED BY SMOKE after205 s 푉푚,1= 2.04 m/s 푉푚,2= 1.92 m/s t = 14 min ControlledBacklayering 19
- 23. “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” Candidate: Tiziano Baroncelli A.Y.: 2013 -2014 RESULTS OF THE ANALYSIS GLOBAL LEVEL RESULTS: 1) SMOKE DEVELOPMENT –BUS FIRE 2895 m + z + y 2190 m 2295 m 2595 m 2695 m BY-PASS BY-PASS BUS EXIT PORTAL (Syracuse) ENTRANCE PORTAL (Catania) TRAFFIC FLOW 100 m 200 m 300 m + Φ + z 9.5 Φ 38.1 Φ 47.6 Φ 66.7 Φ 28.6 Φ 9.5 Φ 19 Φ JET FAN JET FAN JET FAN 2375 m 2525 m 2675 m 2825 m v,emergency ~3 m / s (jet fans) t = 2 min t = 4 min t = 6 min t = 8min t = 10 min REACHED BY SMOKE after66 s REACHED BY SMOKE after154 s 푉푚,1= 1.51 m/s 푉푚,2= 2.59 m/s Lossof stratification 20
- 24. “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” Candidate: Tiziano Baroncelli A.Y.: 2013 -2014 CONCLUSIONI CONCLUSIONS: -NumericaladvancedmethodsareassumingacrucialroleintheFireSafetyEngineering,withanincreasinglevelofdetailingandafinereprodutionofthephenomenon;themainadvantagesarethedeterministicdescriptionoftheconsequencesofafireandthediffusionofvalidatedmodelsforvehicles,extremelyusefulbothintheFireStructuralEngineeringandintheRiskAnalysis,andthepossibilitytoassessdifferentfailurescenarios. -Theexplicitmodelofavehiclecancatchveryprecise(local)aspectsthatcan’tbereproducedwithadifferentapproach; -SomeaspectsarewellcatchedbythemodeloftheSt.DemetrioRoadtunnel(growingphase,peakofHRR,firstphaseofdecay),whileotherswouldneedafinermodel,bothforthegridandthevehicle; -Thecriteriafortheassessmentoftheriskgiveaveryprecisedescriptionofthesafetyconditionsinsideatunnelforescapingusers. 21
- 25. “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” Candidate: Tiziano Baroncelli A.Y.: 2013 - 2014 THE END 22 Fig. 6.6 – Summary of the local results (thermocouple temperatures). Fig. 6.7 – Temperatures above the fire source. The local analysis of the temperatures (fig. 6.6 and 6.7) show that the temperature above the fire source is good represented (unless the second phase of the decay mentioned
- 26. “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” Candidate: Tiziano Baroncelli A.Y.: 2013 -2014 TURBULENCE MODELLING 23
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- 30. “Computational Fluid Dynamics Simulations for Risk Analysis of Fires in Road Tunnels” Candidate: Tiziano Baroncelli A.Y.: 2013 -2014 TURBULENCE MODELLING 27