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Towards the Enhancement of Aircraft Cargo CompartmentFire Detection System Certification using
Smoke Transport Modeling
Walt Gill and Jill Suo-Anttila
Fire Science and Technology Department
Sandia National LaboratoriesAlbuquerque, NM
David BlakeFire Safety Section
FAA Technical Center
International Fire and Cabin Safety Research ConferenceNovember 2004
Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL85000.
Sandia National Laboratories Team Members
• Experimental – David Blake, Walt Gill, and Jill Suo-Anttila
• Model Development – Jim Nelsen and Stefan Domino
• Graphical User Interface and Code Development– Carlos Gallegos
• Technical Support– Louis Gritzo, manager of the Fire Science and
Technology Department
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 most challenging 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
Pre-Processor Overview
• Provide models for different aircraft
• Boeing 707, 727, 747, etc.
• User defined
• Capabilities
• Refine mesh
• Enter fire(s) location and type
• Enter ventilation velocities and locations
• Enter compartment temperature and pressure
• Add obstacles and recessed areas
• Instantaneous visual feedback
Running a Simulation Compartment and Mesh Specification
• Execute the Pre-Processor
• Select the type of compartment
– 707
– DC-10
– User Defined
• Input the dimensions
• Enter the mesh size - # of nodes
FAA_PreProcessor.lnk
custom
707 or DC-10
Running a Simulation Created 707 and DC-10 Meshes
• Automatically generated 707 mesh
• Curvature captured by mesh
• Right side of screen shows selected plane
• Automatically generated DC-10 mesh
• Internal view of compartment
Running a Simulation Recessed Area Specification
1. Advance to selected Y-plane
2. Select desired cells
3. Perform operation using buttons
1
2
3
Running a Simulation Ventilation and Fire Specification
1. Select cells
2. Enter type of cell (inlet, outlet, fire) – cell colored to denote type
3. Use table to enter ventilation properties
4. Fire properties in file
31
2
Fire
Inlet
Outlet
Running a Simulation Mesh Refinement Specification
1. Select the plane for refinement
2. Use refinement tool
3. Enter level of refinement
12
3
Resulting Grid
Running a Simulation Running the Analysis Code
• Analysis - - - Run Analysis
• Status monitored on screen
Smoke Transport Analysis Code
• Curvature of compartment is resolved on grid
• 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 = 1 hour per minute of real time
• 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
Co
nce
ntr
atio
n C
O2,
CO
, HC
l, H
2O
(pa
rts
pe
r th
ou
san
d)
Time (seconds)
Co
nce
ntra
tion
All O
the
r Ga
ses
(pa
rts pe
r millio
n)
120
100
80
60
40
20
0
CO2
CO
H20
HCl
HCN
NO
ethylene
acteylene
methane
HCl
Temp (K)
Post-Processor
Allow users to manipulate data in a variety of ways • contour plots
• time history of field variables
• 3D smoke visualization in time
Code Validation Metrics
Insert most recent movie of temperature distribution
• Thermocouple temperature rise
– 0 - 60 seconds
– 0 -120 seconds
– 0 -180 seconds
• Light transmission– 30 and 45 sec (ceiling and vertical)
– 60 sec (vertical - high, mid, low)
– 120 sec (vertical - mid and low)
– 180 sec (vertical - mid and low)
• Gas species concentration rises– 0 - 60 seconds
– 0 -120 seconds
– 0 -180 seconds
Experimental ceiling temperature distribution at 60 sec
Computational temperature distribution at 60 sec
Status of FAA Full-Scale Validation Experiments
Insert most recent movie of temperature distribution
• 707 experiments completed– Baseline – center fire
– Attached – sidewall fire
– Corner – corner fire
– Determined leakage ventilation had no impact on data
– All 707 experiments were conducted without ventilation
• DC-10 experiments– Ventilation validation
707 Validation Simulations
Insert most recent movie of temperature distribution
• Interface described used to create mesh and run simulation
• Results and comparisons follow
Internal view (showing fire and recessed areas) of 707 computational domain
707 Baseline computational mesh
Preliminary Validation – Temperature
Insert most recent movie of temperature distribution
• Baseline 707 experiments– center fire– 40 thermocouples– Model including heat transfer to
the ceiling and walls – h=7 W/m2K in model
• Comparison– Trends captured– Magnitudes predicted away
from fire – Magnitudes agree above fire
better at early times
Phase 2 - Temperatures at 60 sec
290
295
300
305
310
315
320
0 10 20 30 40
Thermocouple Number
Tem
per
atu
re (
K)
Exp_60s (K)
Model
Phase 2 - Temperatures at 120 sec
290
295
300
305
310
315
320
325
330
335
0 10 20 30 40
Thermocouple Number
Tem
per
atu
re (
K)
Exp_120s (K)
Model
Preliminary Validation – Light Transmission
Insert most recent movie of temperature distribution
Phase 2 - Smokemeters at 30 sec
70
75
80
85
90
95
100
0 1 2 3 4 5 6 7
Smokemeter (Fwd, Mid, Aft, High, Mid, Low)
% L
igh
t T
ran
smis
sio
n
EXP_30s
Model
Phase 2 - Smokemeters at 45 sec
70
75
80
85
90
95
100
0 1 2 3 4 5 6 7
Smokemeter (Fwd, Mid, Aft, High, Mid, Low)
% L
igh
t T
ran
smis
sio
n
EXP_45s
Model
Phase 2 - Smokemeters at 60 sec
70
75
80
85
90
95
100
0 1 2 3 4 5 6 7
Smokemeter (Fwd, Mid, Aft, High, Mid, Low)
% L
igh
t T
ran
smis
sio
n
EXP_60s
Model
• Baseline 707 experiments– center fire– 6 smoke meters
• Comparison– Good agreement in trends and
magnitudes
• Continue validation of the smoke transport code– Finish code modifications– 707 validation comparisons– DC-10 validation comparison
• Release of code to small user community– Includes theory and users manual– Tutorial at FCS conference
• Revisions and final release of code (Summer ’05)
Future Activities