1. 1 of 26 Advances in Water-Based Fire Suppression Modeling: Evaluating Sprinkler Discharge Characteristics June 24, 2008 7 th International Fire Sprinkler Conference and Exhibition Copenhagen, Denmark Students: Ning Ren, Andrew Blum, Di Wu, and Chi Do Faculty Advisor: Andre Marshall Sponsors: NFSA, FM Global, NSF

2. 2 of 26 Overview  Introduction  Motivation  Project History  Previous Work  Global Objective  Evaluate Discharge Characteristics  Advanced Measurements  SAM Development  Approach  Experimental  Modeling (SAM)  Results  Sheet Formation (Deflector)  Sheet Breakup  Drop Formation  Dispersion  Summary  Plans  Experimental  Modeling

3. 3 of 26 Motivation Gain New Knowledge  Physical models characterizing the break-up process and the associated initial spray in fire suppression devices have yet to be developed. Develop Injector Technology  The absence of this analytical capability impedes the development of fire suppression injectors/systems. Understanding the relationship between atomization physics and injector control parameters would facilitate a transition away from ‘cut and try’ injector development.

4. 4 of 26 Motivation D D D L L  D   def boss space tine boss o inlet jet inlet AA Section A-A t arm ‘Cut and Try’ ‘Characterization’

5. 5 of 26 Motivation Advance Fire Protection Engineering Practices  CFD modeling tools of fire phenomena are becoming increasingly popular for fire protection analysis and performance based design.  The absence of physical models describing atomization in sprinklers and water mist injectors results in uncertainties in CFD simulation of suppressed fires.  Errors in the specification of the initial spray will be propagated and amplified during dispersion calculations. The atomization model represents a critical missing link in the modeling of suppressed fires.

6. 6 of 26 Project History NFSA Betatti - U. Modena Sprinkler Atomization Modeling and FDS Integration DuPont Surfactant Effects on Fire Suppression FY2005FY2006FY2007FY2008FY2009 FM Global Scaling Laws and Models for Fire Suppression Devices HP Mist Modeling UM Fire Suppression Spray Research FY2010FY2011 FY2012 NSF CAREER Award Exploring Atomization and Jet Fragmentation in Combustion and Fire Suppression Systems

7. 7 of 26 Previous Work Dundas, 1974 K = 7.2 (0.5) K = 27.4 (1.9) K = 62.0 (4.3) K = 110 (7.6) K = 245 (17.0) K = 435 (30.2) Yu, 1986 K = 179 (12.4) Widmann, 2001 43 < K < 81 Sheppard, 2002 40 < K < 363 Putorti, 2003 11 < K < 49 1 3 Previous Research FDFD FF

8. 8 of 26 Global Objective Evaluate discharge characteristics from fire suppression devices using measurements and models. Parameter Space  based on varied injector geometry and injection conditions. Experiments  based on state-of-the art diagnostics focused on the initial spray. Analysis  based on physics based models using semi-empirical approaches (e.g. scaling laws and wave dispersion analysis).

9. 9 of 26 Approach HP Nozzle 100 bar ~ 60  m Growth of Waves Ligament  Drop Sheet Formation Jet Deflector Sheet  Ligament Injected Flow LP Nozzle 2 bar ~ 700  m TYCO TY4211 MP Nozzle 15 bar ~ 225  m TYCO AM4 Injectors

10. 10 of 26 Approach Geometric parameter space w/n LP injector (sprinkler) configuration ‘Basis’ Nozzle ‘Tined’ Nozzle (Tyco D3 Nozzle) ‘Standard’ Nozzle (Tyco D3 Nozzle) Sprinkler 38 mm 3.2, 6.7, 9.7 mm

11. 11 of 26 Trajectory Measurements (PLIF) Camera FOV t exp = 900  s Cooke 16-bit cooled 2.0Mpixel High-Speed Digital Video Camera. Approach (12.7 mm) (22.7 mm) (62.7 mm)

12. 12 of 26 Approach Sheet Break-up Measurements Canon 12-bit 3.4 Mpixel Digital SLR Camera

13. 13 of 26 Approach Drop Size Measurements Malvern Spraytec Analyzer (Light Diffraction Technique) P = 2.07 bar r/R = 0.45 Local Local MeasurementsLocal Drop Size Distribution

14. 14 of 26 Approach Volume Flux Measurements 1.0 m 3.0 m 1.0 m Patternator 30º 15º Nozzle 3.0 m5.0 m 1.0 m 2.0 m 4.0 m 8.6 m 7.2 m 0º Basis D o = 9.7 mm P = 2.07 bar Basis D o = 9.7 mm P = 2.07 bar d v50 = 780 μm

15. 15 of 26 Approach Transport equations for mass and momentum provide the sheet trajectory. Annular Sheets (Ibrahim, 2004) Sheet Angle Curvilinear Coordinate Along Sheet Gas-liquid Interfacial Friction  P Across Sheet Velocity Surface Tension Thick Radial Location Vertical Location Mass r-mom z-mom Jet Radius Radius where Wall Effects Reach Free Surface Jet Flow Rate Kinematic Viscosity Arbitrary Length Scale Determined from Matching Deflector Radius Impinging Jet (Watson, 1964) Viscous interactions with deflector important for initial thickness and velocity of unstable free liquid sheet.

16. 16 of 26 Approach Viscous Inviscid Most Unstable Wavelength Fastest Growing Wave Dimensionless Wave Growth Rate Viscous Wave Growth (Sterling and Sleicher, 1975; Weber, 1931) The most unstable wave is determined, which breaks up the sheet at r bu,lig into a fragment having characteristic length bu,lig. The most unstable wave is determined, which breaks up the sheet at r bu,sh into a fragment having characteristic length bu,sh /2. Wave Growth (Dombrowski, 1963) p-p- p+p+ p+p+ p-p- p-p- U Gas V jet p+p+ p-p- r Sinusoidal Waves r z

17. 17 of 26 Results Governing Equations Dimensionless Solution The thickness and velocity of the sheet is reduced by viscous effects depending on the nozzle geometry (not yet accounting for spaces). Sheet Formation 

18. 18 of 26 Results Two distinct streams are formed: the jet is deflected radially outward along the tines and the jet is forced downward through the spaces The flow split between these streams governs the sheet thickness and the resulting drop size. Sheet Formation

19. 19 of 26 Results Sheet Breakup Sheet breakup locations occur several jet diameters away from the sprinkler. Data collapses well with appropriate theory Standard Nozzle, D o = 6.35 mm, p = 2 bar

20. 20 of 26 Results Drop Formation Drop size in the space stream are siginificantly smaller than tine stream, but follow Rosin-Rammler Testing scaling law for drop size Dimensionless Drop Size, d v50 /D o p = 2 bar

21. 21 of 26 Results The radial coordinate has been normalized with the maximum theoretical radial value for each condition. K = 7.2 (0.5)K = 25.9 (1.8)K = 54.7 (3.4) Dispersion Spatial Drop Size Distributions Spatial Volume Flux Distributions

22. 22 of 26 Summary  Viscous effects along the deflector can be important (for small K-factors).  Two well characterized sheets (radially expanding and orthogonal fan) are formed through the tines and the spaces.  SAM successfully models the tine stream. Space stream submodel in SAM currently under development.  Sheet breakup locations are predicted well by SAM with We -1/3.  ‘Ligament’ break-up (high We) modes and ‘rim’ break-up modes (low We) are observed. The We transition depends on nozzle geometry.  Drop size predicted well by SAM when nozzle operates in ‘ligament’ breakup mode with We -1/3.

23. 23 of 26 Experimental Plans Space Stream Tine Stream QUANTITATIVE SHADOWGRAPH / PTV BREAKUP IMAGING DROP SIZE / VELOCITY

24. 24 of 26 Experimental Plans

25. 25 of 26 SAM Modeling Plans Basis Nozzle Standard Nozzle (Tyco D3 Nozzle) Fundamental Models To Inner To Outer Splitter Space Stream Submodel CFD Integration Device Characterization Expanding Validated Parameter Space

26. 26 of 26 Questions?