Modeling Smoke Transport in Aircraft Cargo Compartments

Jill Suo-Anttila‡, Stefan Domino†, Walt Gill‡, Paul DesJardin‡, and Lou Gritzo‡

‡Fire Science and Technology Department†Thermal/Fluids Computational Engineering Sciences Group

Sandia National LaboratoriesAlbuquerque, NM

David BlakeFire Safety Section

FAA Technical Center

International Aircraft Systems Fire Protection Working Group MeetingMarch 13, 2002

Modeling Smoke Transport in Aircraft Cargo Compartments

Goal: Develop a CFD-based simulation tool to predict smoke transport in cargo compartments

• Improve the certification process– Identify optimum smoke detector locations– Specify sensor alarm levels – Identify worst case fire locations– Reduce the number of flight tests

• Fast running • Suitable for non-expert users • Experimental data for source term

characterization from FAA experiments• Validated using FAA full-scale experiments

Built on firm FAA knowledge base

Validated using FAA experiments

Airlines, Air-Framers, Certifiers

Robust and fast running

Insight into Physical Processes

• FAA experiments helped identify four classes of cargo FAA experiments helped identify four classes of cargo compartment fire scenarioscompartment fire scenarios

• Model capable of assessing these scenarios (curvature Model capable of assessing these scenarios (curvature and packing issues addressed)and packing issues addressed)

Buoyant Plume Attached Flow

Diffuse Source Containerized

Smoke Transport Code Features• Curvature of compartment is resolved on

grid

• Arbitrary ventilation inlets and outlets can be specified

• Location and type of fire can be selected

• HRR, MLR are time varying inputs (as measured in FAA experiments)

• Species tracking: presently soot, CO, and CO2 but addition of more or different species possible

• Simulation time on the order of hours

• Validated using FAA full-scale experiments

computational computational grid cell on wallgrid cell on wall

cellmass VMS /

cellener VQS /

180 240120600

12

10

8

6

4

2

0

Con

cent

ratio

n C

O 2, C

O, H

Cl,

H2O

(p

arts

per

thou

sand

)

Time (seconds)

Concentration A

ll Other G

ases (parts per m

illion)120

100

80

60

40

20

0

CO2

CO

H20

HCl

HCNNOethylene

acteylenemethane

HCl

Smoke Transport Code Demonstration Calculations

Insert most recent movie of temperature distribution

• Buoyant Plume

– 300 sec flaming fire in the center of sealed compartment

– 300 sec flaming fire in sealed compartment with 45o offset gravity

– 300 sec flaming fire with ventilation

• Attached Flow

– 120 sec flaming fire near wall of sealed compartment

gravityinlet

outlet

Flaming Source Characterization

Insert most recent movie of temperature distributionFlaming Source - Mass Loss Rate

0.00E+00

5.00E-05

1.00E-04

1.50E-04

2.00E-04

2.50E-04

0 60 120 180 240 300

Time from Ignition (sec)

MLR

(kg/

sec)

Flaming Source - Heat Release Rate

0

1000

2000

3000

4000

5000

6000

0 60 120 180 240 300

Time from Ignition (sec)

HRR

(J/s

ec)

Flaming Source - Species

0

0.2

0.4

0.6

0.8

1

0 60 120 180 240 300

Time from Ignition (sec)

Mas

s Fr

actio

n (k

g/kg

)

Soot (kg/kg)

CO2 (kg/kg)

CO (kg/kg)

Smoke Transport Code Demonstration CalculationBuoyant Plume

• Flaming fire in the center

• 300 second simulation

• No specified ventilation

• Species concentrations (CO, CO2, soot) - aids in sensor selection and placement

gravity

Smoke Transport Code Demonstration CalculationBuoyant Plume with Varied Orientation

• Flaming fire in center

• Orientation of cargo bay 45o (y, +x gravity)

• 300 second simulation

• No specified ventilation

45o gravity

Smoke Transport Code Demonstration CalculationBuoyant Plume with Ventilation

• Flaming fire in center

• 0.5 m/s inlet in lower forward corner, outlet in upper aft

• 300 second simulation

gravityinlet

outlet

Smoke Transport Code Demonstration CalculationsBuoyant Plume Comparisons

Buoyant Plume

Ventilation Gravity

Smoke Transport Code Demonstration Calculation

• 120 second simulation (~9 hours of compute time for 10K grid points; Sun Ultra2).

• No specified ventilation

• HRR, MLR are time varying as measured in FAA experiments

• Species concentrations (CO, CO2, soot) - aids in sensor selection and placement

Soot Concentration

Temperature CO/CO2

• Plan developed by the FAA and SNL to verify and validate the smoke transport code

• Verification and validation of the code using:– Method of manufactured solutions– FAA full-scale experiments

• Verification using method of manufactured solutions complete• Baseline validation experiments to begin shortly

Model Verification and Validation

Following validation of the smoke transport code:

• Release of alpha version• Selection of approach for user interface • Develop and implement user interface• Documentation and release of code to small user community• Revisions and final release of code

Potential Future Activities