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Water Mist Spray Modeling With FDS

Water Mist Spray Modeling With FDS. Fire and Evacuation Modeling Technical Conference 2011 Simo Hostikka , Jukka Vaari, Topi Sikanen, Antti Paajanen VTT Technical Research Centre of Finland. SPRAY COMPUTATIONS IN FDS. Droplet momentum. Size distribution. DRAG REDUCTION BY WAKE EFFECT. L.

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Water Mist Spray Modeling With FDS

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  1. Water Mist Spray Modeling With FDS Fire and Evacuation Modeling Technical Conference 2011 Simo Hostikka, Jukka Vaari, Topi Sikanen, Antti PaajanenVTT Technical Research Centre of Finland

  2. SPRAY COMPUTATIONS IN FDS Droplet momentum Size distribution

  3. DRAG REDUCTION BY WAKE EFFECT L Ramírez-Mũnoz et al. (2007).

  4. INTRODUCING THE DROPLETS INTO THE COMPUTATION • Segment of a spherical surface • Here:  = 5 and  = 0 • Initial velocity: • User specifies the offset distance f

  5. EXAMPLE NOZZLES • Spraying systems LN-2 • High-pressure micro-nozzles A, B and C from Marioff. • Multi-orifice spray heads

  6. SPRAY PROFILE TESTS NFPA 750

  7. RESULTS: SPRAY PROFILES (LN-2 NOZZLE) • 0.4 m below the nozzle • 20 bar pressure

  8. RESULTS: SPRAY PROFILES (A, B, C NOZZLES) • 1 m below the nozzle • 70 bar pressure

  9. AIR ENTRAINMENT TESTS • Rectangular channel 2.0 m  0.6 m  0.6 m • Multi-orifice nozzles in the middle of the channel • Pressures 50…10 bar • Air speed measurement 0.5 m upstream (center and 6 cm from wall)

  10. RESULTS: AIR ENTRAINMENT Channel center 6 cm from wall • SH4 and SH5 have different perimeter angles • Difference in momentum transfer difficult to capture • Results were sensitive to offset value

  11. RADIATION ATTENUATION TESTS • LPG gas heater • 0.2 m  0.3 m • Temperature 950 C • Nozzles A, B and C • 50, 70 and 100 bar • Experimental uncertainty < 7 %

  12. RADIATION ATTENUATION SIMULATIONS • Two sets of simulations • Set 1 = ‘good resolution’ • Set 2 = ‘even better’

  13. RADIATION ATTENUATION RESULTS Set 1 Set 2

  14. RADIATION ATTENUATION SENSITIVITY STUDY x = 1.0 cm DROP INSERT RATE= 1105 1/s x = 2.0 cm DROP INSERT RATE = 1105 1/s

  15. ACKNOWLEDGEMENTS • Spray profile measurements were performed by Maria Putkiranta, Riina Rajala, Pentti Saarenrinne and Markus Honkanen of the Tampere University of Technology. • Co-operation with the members of the FDS development team • Funding • Finnish Funding Agency for Technology and Innovation, • Marioff Corporation Oy, • Rauta­ruukki Oyj, • YIT Kiinteistö­tekniikka Oy • Insinööri­toimisto Markku Kauriala Ltd.

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