Knowing the Fire Sprinkler Spray

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1 Knowing the Fire Sprinkler Spray November 9, 2011 The Science of Suppression FireSEAT Edinburgh, Scotland UK Ning Ren, Chi Do, and Andre Marshall Sponsors: FM Global, NSF 1 of 28

2 Overview Introduction How do we quantify sprinkler sprays? Objective Evaluate discharge characteristics through measurements Measurements and Results Stream Formation Stream Breakup Initial Spray Dispersed Spray Summary 2 of 28

3 Introduction Sprinkler Spray Example d > 2 mm Flux, mm/min 1 mm < d < 2 mm d < 1 mm Tyco D3 K = 81 lpm bar -1/2 P = 1.4 bar 3 of 28

4 Introduction Sprinkler Spray Characteristics How do we quantify sprinkler sprays? Deflector Center z " r Droplet Spray Discharge Drop by Drop x y d v50 (mm) Discharge Properties 2.1 r (m) (deg) " (deg) d (mm) u (m/s) u inj (m/s) inj (deg) q (mm/min) r cov (m) ,000, of 28

and fire suppression product development (nozzle and system)

5 Objective Evaluate discharge characteristics from fire suppression devices from measurements to support CFD model and fire suppression product development (nozzle and system) Mastery of sprinkler spray physics CFD Model Improved Product 5 of 28

6 Measurements Overall Methodology 6 of 28

7 Approach Stream Formation Planar Laser Induced Fluorescence (PLIF) Qualitative view of sheet topology. Difficulty measuring exact sheet thickness due to deflector surface reflections. High speed camera would provide breakup visualization. 7 of 28

8 Results Stream Formation Tine Stream Slot Stream Two distinct streams are formed. Flow split between these streams governs the sheet thickness and the resulting drop size 8 of 28

9 Approach / Results Stream Formation Short Time Exposure Photography Frame Arm Slot Tine Qualitative view of sheet topology 9 of 28

10 Approach Stream Breakup Short Time Exposure Photography Canon 12-bit 3.4 Mpixel Digital SLR Camera 10 of 28

11 Results Stream Breakup Ambient Condition X sheet = (" a /" l ) 2 f o 2 (We /# 3 $) Injector Disturbances Modified Weber Number 1 3 (Slot) 11 of 28

12 Approach Initial Spray Shadowgraph/PTV (Drop Size/Velocity) Measurements Sprinkler Splash Guards 40 mm Camera Field of View 170 X 170 mm Depth of Field 25 mm Laser Background (Fresnal Lens) 12 of 28

13 Approach Initial Spray Area used: 150X150 mm 150 mm Image size: 170X170 mm Minimum drop resolved: ~0.2mm 13 of 28

14 Std Nozzles (D3): D o = 6.2 mm - tine, D o = 11.0 mm tine, D o = 6.2 mm - slot, D o = 11.0 mm - slot; Basis Nozzles: D o = 3.2 mm, D o = 6.2 mm, D o = 9.5 mm Results Initial Spray Drop Formation Rim Breakup Basis Nozzle Ligament Breakup Standard Nozzle (Space) Orthogonal Fan Sheet Actual Sprinkler Standard Nozzle X drop = (" a /" l ) 1/ 2 f o (We /# 3 $) 14 of 28

15 z Deflector " r Center x y Tine Slot Tyco D3 K = 81 lpm bar-1/2 P = 1.4 bar Droplet Results Initial Spray Description Reference Droplet ~ 2 mm Gaussian Function Legendre Polynomials (θ Distribution) Legendre Polynomials (θ Distribution) Fourier Series (ψ Distribution) Measurements Basis Functions Ren, N., Baum, H., & Marshall, A., A comprehensive methodology for characterizing sprinkler sprays, Proceedings of the Combustion Institute, 2010, pp of 28

16 Results Initial Spray Tyco D3 K = 81 lpm bar -1/2 P = 1.4 bar Peak (Gaussian) Sprinkler Discharge Physically rational compact description of spray. Volume Probability Density (for location) d f V ( " t,s ) v50 / D o D o =18 =11 mm Drop Size (distribution width) Velocity u /U U =15 m/s Provides a framework for spray evaluation and insight. 48 coefficients describe (and can generate) the 3D stochastic spray. 15 first order coefficients describe primary spray characteristics. Table (Legendre) Avg. Shape L * 0.46 * F ( o ) " ( o ) t s t s t s t s N/A L 1 /L L 2 /L L 3 /L L 4 /L L 5 /L of 28

17 Results Initial Spray Tyco D3 K = 81 lpm bar -1/2 P = 1.4 bar Fourier Coefficients Volume Probability Density (for location) f V ( t,s ) t s a Shape a a Shape f v ( s ) / f v ( t ) = of 28

18 Approach Dispersed Spray Malvern Drop Size Measurements Malvern Spraytec Analyzer (Light Diffraction Technique) Local Measurements Local Drop Size Distribution P = 2.07 bar r/r = 0.45 Drop size limit (~ 0.8 mm) 18 of 28

19 Tyco D3 K = 81 lpm bar -1/2 Results Drop Size Comparison P = 0.7 bar P = 1.4 bar 19 of 28

20 Approach Dispersed Spray Volume Flux Measurements 3.0 m 1.0 m 1.0 m 30º Patternator 15º Nozzle 7.2 m 0º 2.0 m 4.0 m 1.0 m 3.0 m 5.0 m 8.6 m 20 of 28

21 Tyco D3 K = 81 lpm bar-1/2 P = 1.4 bar 2.9 mm/min Results Dispersed Spray Initiation Sphere Measurement Patternation (z= -1 m) Prediction 21 of 28

22 Summary Focused measurements provide insight into the discharge characteristics of sprinkler sprays. Qualitative and quantitative measurement methods are available to explore sprinkler spray behavior from stream formation to the dispersed spray. These measurements provide insight into basic features of the spray (images/ comprehensive framework), relationship with nozzle geometry (scaling laws), CFD modeling input (detailed measurements), and suppression performance (volume flux measurements). 22 of 28

23 Future Work - Measurements Tyco D3 K = 81 lpm bar -1/2 P = 0.7 bar Near Field Patternation Measurements 350 mm Initiation Sphere 50 mm 23 of 28

24 Acknowledgements FM Global Sponsors Dr. Bert Yu Dr. Sergey Dorofeev UM Fire Suppression Spray Group Current Dr. Howard Baum Dr. Ning Ren Dr. Paolo Santangelo Ms. Yinghui Zheng Mr. Giovonni Bendetto Graduates Mr. Ning Ren Mr. Paolo Santangelo Mr. Chi Do Mr. Andrew Blum Ms. Di Wu Ms. Delphine Guillemin 24 of 28

Unraveling Fire Suppression Sprays

Unraveling Fire Suppression Sprays ANDRE W. MARSHALL Department of Fire Protection Engineering University of Maryland College Park, Maryland 20742 USA ABSTRACT Spray generation represents a tremendously