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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 Slide 2 2 04/12/2015 Slide 3 3 Slide 4 4 Slide 5 5 Slide 6 6 SPRAY COMPUTATIONS IN FDS Droplet momentum Size distribution Slide 7 7 04/12/2015 DRAG REDUCTION BY WAKE EFFECT L Ramrez-Mnoz et al. (2007). Slide 8 8 04/12/2015 INTRODUCING THE DROPLETS INTO THE COMPUTATION Segment of a spherical surface Here: = 5 and = 0 Initial velocity: User specifies the offset distance Slide 9 9 04/12/2015 EXAMPLE NOZZLES Spraying systems LN-2 High-pressure micro- nozzles A, B and C from Marioff. Multi-orifice spray heads Slide 10 10 04/12/2015 SPRAY PROFILE TESTS NFPA 750 Slide 11 11 04/12/2015 RESULTS: SPRAY PROFILES (LN-2 NOZZLE) 0.4 m below the nozzle 20 bar pressure Slide 12 12 04/12/2015 RESULTS: SPRAY PROFILES (A, B, C NOZZLES) 1 m below the nozzle 70 bar pressure Slide 13 13 04/12/2015 AIR ENTRAINMENT TESTS Rectangular channel 2.0 m 0.6 m 0.6 m Multi-orifice nozzles in the middle of the channel Pressures 5010 bar Air speed measurement 0.5 m upstream (center and 6 cm from wall) Slide 14 14 04/12/2015 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 Slide 15 15 04/12/2015 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 % Slide 16 16 04/12/2015 RADIATION ATTENUATION SIMULATIONS Two sets of simulations Set 1 = good resolution Set 2 = even better Slide 17 17 04/12/2015 RADIATION ATTENUATION RESULTS Set 1 Set 2 Slide 18 18 04/12/2015 RADIATION ATTENUATION SENSITIVITY STUDY x = 2.0 cm DROP INSERT RATE = 1 10 5 1/s x = 1.0 cm DROP INSERT RATE= 1 10 5 1/s Slide 19 19 04/12/2015 Slide 20 20 04/12/2015 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 Kiinteisttekniikka Oy Insinritoimisto Markku Kauriala Ltd.