Fire re Suppre ression ssion Simulation lation Stu Study - - PowerPoint PPT Presentation

Fire re Suppre ression ssion Simulation lation Stu Study

Kshitij (KD) D) Deshm hmukh, Ph.D.

Au Automa matic tic Fire re Extingu inguish ishing g Systems ms (AFES FES) Pro rotec ect against st fuel el fi fires res ins nsid ide e milita litary y and nd commer mercial cial ve vehicles hicles (air, land, nd, and nd sea)

– Occupant areas – Cargo areas – Engine compartments – Landing gear bays

Background und

Design igning ing the e system m is difficul icult

– Nozzle type, placement, suppressant concentration – Especially in a cluttered volume

Simul mulation tion is a cost-sa savin ving g tool to evalua aluate e and nd optimi imize ze the design sign before re test st & build uild STAR AR-CC CCM+ + is uni niquel uely y suit ited d for this s simul mulation: tion:

– Complicated geometries – Complex multiphase physics – Fuel combustion – Suppression chemistry – Generation and transport of toxic gases – Other crew survivability criteria

Why y model l Fire Suppressio ession n Sys ystems ms?

Effective fire suppression agents are mostly HFC HFC materials have high Global Warming Potential (GWP) & Ozone depletion potential (ODP) - thousands of times that of carbon dioxide Fire Suppression Simulation study

– To test out concept agents without expensive testing and experiments – To optimize agent bottle location to maximize suppression efficacy – To minimize delivery dosage of agent concentration for suppression to keep adverse effects below lowest acceptable level – To simulate actual vehicle and tactical scenarios using exploratory test box simulation setup and experimental test data

Fire Suppress ession ion Simulatio lation n Stu Study

5 supp ppression ression agen ents ts simul mulated d over ver 4 year ars Only y FM20 200+ 0+SBC BC disc scuss ussed ed here re FM200 200 = C3HF HF7 (liq iqui uid) d) & SBC = NaHCO CO3 (soli lid) d)

Geometr try: : Explorat rator

• ry

y test box

Mesh 158K Cells, Walls @ 130 F

• Ref. Fire Extinguishing Agents for Protection of Occupied Spaces in Military Ground Vehicles,

Steven E. Hodges, Steven J. McCormick, Fire Technology, Volume 49, Issue 2 , pp 379-394

Phys ysic ics s Models ls

• St

Start at fir fire det etect ction

• n
• Model

el fir fireball ll buil ild up

• Model

el for small ll tim ime past dis ischar harge ge

Tra rans nsient ient Ana nalys lysis is

• K-epsil

silon

• n
• Reali

lizable ble wall ll funct ctions

• ns
• Segregat

gated ed solver lver

Turb rbulence lence Mo Mode del

• Two

wo-way y coupli pling ng

• Evaporati

ation n for li liquid id dro roplets plets

• Devola

lati tili liza zati tion & combu bustion stion of solids lids

Lag agra rangian ngian Physics ysics

• Liq

iquid d spray y usin ing g dro rople plet t dis istr tributi ution

• n
• Aut

Auto

• fla

flash sh

• Cont

ntinuous nuous in inje ject ction

• n

Liq iquid id Fuel el Inj njec ectio tion

Phys ysic ics s Models ls

• Mim

imic ic rele lease se from rom pressur suriz ized ed bot

• ttle

tle

• Bot
• th

h li liquid id and vapor phase

• Di

Dischar harge e tap apers s wit ith fal alli ling ng pressure sure

Su Suppre pressant ssant Di Disc scharge arge

• Hybrid

id EBU w/ fin finite e rate e kin inetics etics

• 14

14 species s & 12 reacti tions

• ns reduce

ced set et

• Soot as trans

nspor ported ed scalar lar

Combu mbustion stion Mo Mode del

• Catalyt

lytic c & non

• n-cata

catalyti ytic c effe fect cts

• Succes

ess s crit iteria eria = thermal rmal + chemical mical

• Ac

Acid id gases s monit nitored

• red

Su Suppre pression ssion Me Mecha hanisms nisms

• Partic

ticipati ating g media ia DOM S4

• User-code

coded d absor

• rpti

ption

• n coeffic

icie ient

• WSGG model for CO2, H2O & Soot

Rad adiation iation Mo Model del

Fire Suppress ession ion animation ation # 1 1

Fire Suppress ession ion animation ation # 2 2

Crew ew Surviv ivability bility Criter eria ia

Pa Parame rameter er Require ireme ment nt Consi side dere red d in in CFD? D? Fire suppression Extinguish all flames w/o reflash  Skin burns < 2nd degree burns over 10 sec  Overpressure < 11.6 psi  Agent concentration Below adverse effect level  Acid gases (HF + HBr + 2 COF2) < 746 ppm over 5 minutes  Oxygen level > 16%  Discharge noise Below hearing protection limit × Discharge forces Not to exceed 8g ×

Explor

• rat

atory y test box results lts comparis ison

• n

Set etup tailor

• red

ed to capture success essful ful suppression ession rather than suppression ession failu lure re

Crit iter eria Above ve Design n conc. c. Belo low w design gn conc. c. Experiment CFD Experiment CFD Overall PASS SS PASS SS FAIL IL FAIL IL Extinguish all flames YES YES YES NO HF acid (PPM) < 20 47 3975 N/A COF2 acid (PPM) <20 97 1550 N/A O2 levels 17.4% 18.0% 16.5% N/A

Applic lication ation to Nozz zzle le design ign

Nozzle zzle conf nfig iguratio ations I II I II Discharge harge pattern erns: s: Fire re Ball l (red) ed), SBC (yello ellow), ), FM200 200 (Blue) Blue)

Challenge:

– Fire suppression system design is challenging due to demanding requirements, cluttered environments, and complex physics. – Development efforts include many design / test / fail / repeat cycles.

Solution:

– CFD-based simulation of the fire suppression event predicts whether the design will meet suppression success criteria. – STAR-CCM+ is unique in having this capability in a general-purpose CFD tool.

Impact:

– Reduction in time and cost by evaluating and optimizing on virtual designs prior to test. – Minimal development effort due to commercial, off-the-shelf CFD tool. – Improved occupant survivability in case of a fire.

Summar ary

Fire Suppre pressi sion n Modeling ng using ng Comput utational ational Fluid d Dynamic amics, s, Vamshi M. Korivi, Bradley A. Williams, Steven J. McCormick, Kshitij Deshmukh, 2014 NDIA Ground Vehicle Systems Engineering & Technology (GVSETS) Symposium, Novi, MI, 14th August 2014, http:/ p://ww /ww2. 2.esd.or esd.org/ g/gvse gvsets/