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J. Lee 11-17-04 Simulation Methods for Fire Suppression Process inside Engine Core and APU Compartments Boeing Commercial Airplanes Group Seattle, Washington,

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Presentation on theme: "J. Lee 11-17-04 Simulation Methods for Fire Suppression Process inside Engine Core and APU Compartments Boeing Commercial Airplanes Group Seattle, Washington,"— Presentation transcript:

1 J. Lee Simulation Methods for Fire Suppression Process inside Engine Core and APU Compartments Boeing Commercial Airplanes Group Seattle, Washington, , USA Jaesoo Lee The Fourth Triennial International Aircraft Fire and Cabin Safety Research Conference Lisbon Conference Center, Portugal November 15-18, 2004

2 J. Lee FAA Tech Center: D. Ingerson: Nacelle Fire Simulator Test Data Boeing : C. Roseburg: Thermodynamic Properties of Agents A. Nazir: Hflowx Modification D. Lackas, J. Petkus: Certification Test Data M. Dunn: Engine Cooling Airflow Data D. Dummeyer: APU FireX Test Data M. Grueneis, R. Moody, B. Hsiao: Mesh Generation Acknowledgment

3 J. Lee Introduction / Background Engine Fire Suppression Process Simulation Methods:  FireX System  Agent Concentration Distribution Example Applications:  FAA Nacelle Fire Simulator  APU Compartment  Engine Core Compartment Conclusions Future Activities Outline

4 Engine Fire / Overheat Detection and Fire Extinguishing Engine Fire Switch fireX agent fireX agent Thermal Sensors Aural / Visual Warnings J. Lee,

5 J. Lee Environmental and Physical Properties (Halon 1301 and Alternate FireX Agents) Chemical Formula CF 3 Br CF 3 CHF 2 CF 3 I CH 2 CBrCF 3 Ozone Depletion Potential Molecular Weight Global Warming Potential Critical Temperature, ºF Atmospheric Lifetime, years Liquid Density at 77 ºF, lb/ft Boiling Point, ºF Heat of Vaporization, Btu/lb Vapor Pressure at 77 ºF, psia Halon HFC CF 3 I BTP Properties

6 J. Lee Certification Requirement (Engines and APUs) If Halon 1301 (CF 3 Br) is used as the fire extinguishing agent, the minimum agent concentration is 6 % by volume for a minimum of 0.5 seconds for all 12 concentration probe locations, simultaneously (FAA AC ). Range of Concentration Histories %V/V Time 6.0 ½ sec min. conc. history max. conc. history Probe Locations inside APU Compartment Injection Nozzle

7 J. Lee Technology Status and Need No Analysis Tool to Simulate the Entire Fire Suppression Process for Engines and APUs. FireX System can be Over-Designed (Heavy, Excess Discharge of Agent to Environment) or Under-Designed. Installation of Injection Nozzles:  Many Ground Tests to meet FAA Requirements.  Time-Consuming and Costly. Need an Analytical Tool for Performance Design of FireX Systems:  Engine Nacelles / APUs of Commercial, Military Airplanes, Helicopters.  Reduces Cost of Design / Certification by ~50 Percent.  Technology Ready for Halon Replacement.

8 J. Lee Simulation of Fire Extinguishing Process Complex Geometries Uncertainties in Airflow Sources Complicated Flow Physics:  Two-Phase Agent Jet Flow  Droplet Formation / Break-up  Droplet Interaction with Solid Surfaces Two-Phase CFD Problems  Coupled Transport Phenomena  Long Analysis Cycle Time Challenges: Storage Bottle FireX Agent Storage Liquid- / Gas-Phase FireX Agent / N2 Distribution Pipe Injection Nozzles Compartment Vented air Injection Nozzles Compartment air Non-Pressurized Engine Core Air/Agent Mixture Gas

9 J. Lee Elements of the Simulation Process FireX System Analysis CFD Mesh Generation Engine Core Compartment Geometry CFD Analysis for Concentration Propagation Initial Vented Airflow Distribution Post-Processing for Concentration Histories

10 J. Lee Unsteady Analysis of Agent Injection Process Agent Storage Bottle Agent Storage Bottle Distribution Pipe Multiple Injection Nozzles Agent Mass, Bottle (P, T, Vol), Distribution Pipes, Nozzle Size Hflowx Unsteady BCs at Injection Nozzles ŵ (t) liquid ŵ (t) vapor P (t) mixture T (t) mixture

11 J. Lee FLOW SPLIT 9/32”ID ORIFICE 55/8” TUBE NOZZLES STORAGE BOTTLE Halon Mass = 5.2 lbm Bottle Volume = 219 In 3 Charge Pressure = 720 psig Test Temperature = 100 ºF Agent Types: ICHEM = 1 (Halon 1301) = 2 (HFC-125) = 3 (CF3I) Validation Analysis of Hflowx

12 J. Lee Predicted Agent Discharge Characteristics FireX System Conditions Agent Mass:22 lbm Bottle Volume:800 In 3 Charge Press.:825 psia Test Temp.: 10  F Pipe Diameter:0.75 In Pipe Length:80 Ft Two-Phase Vapor / Liquid Mixture Jet Liquid-Phase AgentsVapor-Phase Agents

13 J. Lee CFD Modeling of Agent Injection / Conc. Propagation Process Mass Continuity Eq. Momentum Eqs. Energy Eq. Species Conservation Eq. Turbulence Model Eqs. Mass Continuity Eq. Momentum Eqs. Energy Eq. Species Conservation Eq. Turbulence Model Eqs. Mass Continuity Eq. Momentum Eqs. Energy Eq. Species Transport Eq. Turbulence Model Eqs. Air / Agent Gas Mixture Eulerian Description Liquid Agent Droplets Mass Transport Eq. (Evaporation) Momentum Transport Eqs. (Trajectories) Energy Transport Eq. (Heat Transfer) Mass Transport Eq. (Evaporation) Momentum Transport Eqs. (Trajectories) Energy Transport Eq. (Heat Transfer) Mass Transport Eq. (Evaporation) Momentum Transport Eqs. (Trajectories) Energy Transport Eq. (Heat Transfer) Lagrangian Description 2-Way Coupling 2-Way Coupling Injector nozzle

14 J. Lee CFD Input Data / Solution Control Unsteady Vented Airflows:  Pre-Cooler Air, Bleed Air  Turbine Cooling Air, Leaks Unsteady Agent Injection at Nozzles:  Vapor-Phase Flow  Liquid-Phase Flow  Droplet Size  Two-Phase Flow Velocities Droplet Break-up Model. Droplet-Solid Surface Interaction. Non-Slip / Thermal BCs on Surfaces. Thermodynamic Properties of Agent. Variable Time Steps Agent Injection Concentration Propagation yesBuoyancy Effect All Transport Eqs.Under-Relaxation Scheme Double-PrecisionCalculation Precision 2 nd –Order UpwindDiscretization Schemes SIMPLE Pressure-Velocity Coupling 30 ~60Iterations per time-step 2 nd –Order ImplicitTime-Marching Eff. ConditionsSolution Controls

15 J. Lee Volumetric Concentration  v = f h / [f h + (1 - f h ) ( M h / M a )] where, f h = Predicted Mass Fraction of Agent M h = Mol. Weight of Agent Vapor M a = Mol. Weight of Air  v = Volumetric Concentration  v, %V/V time, sec

16 J. Lee Validation Application - Case 1 (FAA Nacelle Fire Simulator) Axial View Vertical Center Plane Pool Fire Test Pan Exhaust Gas Pipe Engine Core Flanges Fuel Nozzles Injection Nozzles and Orifices airflow Exhaust gas

17 J. Lee Halon 1301 Concentration Histories Vented Airflow:  Unsteady Airflow Rate: (2.2 steady-state)  Temperature: 100 °F FireX Condition:  Halon 1301 Mass:5.2 lbm  Bottle Volume: 219 in 3  Bottle Charge: 812 psi, 100 °F  Discharge Temp.: 100 °F Predicted Measured 4 Probes (12, 3, 6, 9 o’clocks) 4 Probes (4:30, 7:30, 12, 6 o’clocks) 4 Probes (12, 3, 6, 9 o’clocks) 12 Probe Locations

18 J. Lee Validation Application - Case 2 (APU Compartment) Surface Mesh Side ViewTop View t = 0.30 sec after injection Initial Airflow Pattern

19 J. Lee Halon 1301 Concentration Histories Probe Locations Agent Injection:  Halon Mass: 14 lbm  Charge Pressure: 600 psi  Bottle Vol.: 536 In 3 Vent Air:  Initial avg. Air Temp.: 125 ºF  Transient Vented airflow Measured Predicted

20 J. Lee Validation Application - Case 3 (Engine Core Compartment) Surface Mesh Airflow Streamlines Halon 1301 Flow:  Mass (CBrF 3 ) = 22 lbm  Bottle Volume = 800 in 3  P (Charge) = 825 psia Vented Airflow:  Flow Rate = lbm/sec t = 0.13 s t = 3.70 s t = 7.10 s

21 J. Lee Analysis Types / Cycle Times ♣ : CPU time depends on: Total simulation time; Size of CFD mesh; No. of injection nozzles; No. of droplet sizes; No. of droplet starting locations per nozzle; No. of computer processors; Convergence criteria, etc. 1 Injection Nozzle ~1 Wk ORIGIN 3800 (6 cpus) 0.32 Mcells~0.5 Day ORIGIN 3800 (4 cpus) < 1 Min. SGI Octane2 400 MHz Remarks Analysis Time ♣ Computer Platform Unsteady Agent Injection / Concentration Distribution Steady- State Initial Airflow Distribution FireX System Analysis Types

22 J. Lee Key Factors for Improved Simulations Analysis Domain based on Fire Suppression Process. Advanced Flow Physics Models: - Two-Phase Agent Jet Flow - Droplet Interaction with Solid Surfaces Accurate Airflow / Agent Jet Flow Boundary Conditions. Refined CFD Mesh including Details of Important Geometry. Accurate Property Correlations of Agents.

23 J. Lee Conclusions Simulation Methods for Fire Suppression Process inside Aircraft Propulsion Systems have been Developed. The Capabilities of the Methods have been Demonstrated by Simulating the FireX Tests of Engines and APUs. Predicted Concentration Histories are well Correlated with Measured Data. The Simulation Methods need to be Improved for More Accurate Prediction of Concentration Histories.

24 J. Lee Future Activities Continuous Improvement of the Developed Methods to Enhance Applicability and Practicality. Support the Design and Installation of FireX System for Commercial, Military Airplanes, Helicopters, and for Halon Replacements. Complement of the FAA Certification Tests. 7E7 Dreamliner


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