Star Global Conference 2013 Emergency Ventilation System Modeling Michael Carl Rowan Williams Davis & Irwin Inc. Page 1 Cover image courtesy of Pelli Clarke Pelli Architects Canada | USA | UK | India | China www.rwdi.com Reputation Resources Results
Star Global Conference 2013 Consulting in the Science of Buildings, Structures & Environment Cover image courtesy of Pelli Clarke Pelli Architects Page 2 Canada | USA | UK | India | China www.rwdi.com Reputation Resources Results
Star Global Conference 2013 Outline 1. Project Background 2. Sectional Model 3. Boundary Conditions 4. Performance Criteria 5. Transient Simulations Cover image courtesy of Pelli Clarke Pelli Architects Page 3 Canada | USA | UK | India | China www.rwdi.com Reputation Resources Results
Star Global Conference 2013 Project Background • Transbay Transit Center by Pelli Clarke Pelli Architects (Design Architect) and Transbay Joint Powers Authority (Ownership) • Mixed use complex including Bus Deck (3 rd level) • Location: San Francisco California • Dimensions: 439 by 55 by 23 m (1440 by 180 by 75 ft.) • Buses: 44 parking spots • Challenge: fire event on bus deck with natural ventilation system (close to 20% open) and sprinklers Page 4 Canada | USA | UK | India | China www.rwdi.com Reputation Resources Results
Star Global Conference 2013 Project Background- Multi-Study Analysis Objective: Evaluate egress tenability on bus deck in case of bus fire. Approach: CFD (STAR-CCM+) was used because of the size and complexity of the geometry, the boundary conditions related to determining a worst case wind condition and fire location, and the physics of modeling the sprinkler system. Page 5 Canada | USA | UK | India | China www.rwdi.com Reputation Resources Results
Star Global Conference 2013 Sectional Model • 200 m Four fire locations (modeled separately) • Each model approx. 200 m (660 ft. long) • 22 buses parked, none in transit • Cross wind run for all fire locations • Steady and transient runs • Steady state to evaluate: • Wind speed • Turbulence model • Mesh refinement • Transient runs to evaluate tenability Page 6 Canada | USA | UK | India | China www.rwdi.com Reputation Resources Results
Star Global Conference 2013 Sectional Model- Meshing • 2-3 million Cells, Polyhedral • 0.1 m near fire increasing to 0.5 m max • 0.2 m refinement in sprinkler spray paths • 0.1 m for important features (buses, ceiling etc.) • Refinement simulation: • Sprinkler spray paths reduced from 0.2 m to 0.1 m • Cells adjacent to fire bus reduced from 0.2 m to 0.1 m Page 7 Canada | USA | UK | India | China www.rwdi.com Reputation Resources Results
Star Global Conference 2013 Boundary Conditions- Fire Representation • Peak Heat release = 35 MW (at ~9 min), soot production = 0.142 kg/s • Volumetric Heat source with density of 1 MW/m 3 • 70% convective • Soot released as scalar • Fire grown and monitored using field functions and macros developed by RWDI Page 8 Canada | USA | UK | India | China www.rwdi.com Reputation Resources Results
Star Global Conference 2013 Boundary Conditions- Fire Location Page 9 Canada | USA | UK | India | China www.rwdi.com Reputation Resources Results
Star Global Conference 2013 Boundary Conditions- Sprinkler System • Sprinkler flow rate: 1.62 l/s (26 gpm) • Active size: 3.7 m (12 ft) by 4.3 m (14 ft) grid • Max coverage: 139 m 2 (1,500 ft) • Quick response (activated 90s into event) • Lagrangian multiphase used with multi- component gas physics • No reduction in fire size • Only evaporative cooling and momentum effects of sprinkler water spray on the smoke plume was modeled • Injection at sprinkler heads • Inner and outer spray circle • Rosin-Rammler size distribution Page 10 Canada | USA | UK | India | China www.rwdi.com Reputation Resources Results
Star Global Conference 2013 Boundary Conditions- Model Page 11 Canada | USA | UK | India | China www.rwdi.com Reputation Resources Results
Star Global Conference 2013 Performance Criteria Results were evaluated based on the following criteria: 1. Smoke obscuration levels (Visibility) 2. Radiant heat exposure 3. Convective heat exposure For all these criteria tenability is assessed at 2.5 m (8 ft.) above the occupied floor level (as required in NFPA 130). Page 12 Canada | USA | UK | India | China www.rwdi.com Reputation Resources Results
Star Global Conference 2013 Performance Criteria- Visibility Calculated based on the soot properties and concentration as well as the object being viewed. View object Constant Visibility C S K m Y s Mass Mass fraction soot extinction Local gas density Page 13 Canada | USA | UK | India | China www.rwdi.com Reputation Resources Results
Star Global Conference 2013 Transient Simulations • Unsteady, Reynolds Averaged Navier Stokes (RANS), Lagrangian multiphase, ideal multi-component gas with gravity and passive scalar (represent soot) • Heat and soot production increase with time (sprinklers 90s) • Studied four fire locations • NW wind direction with a wind speed above the bus deck of 4 – 6 m/s • Intent is to assess tenability during initial growth stages of the fire including the impact of sprinklers on the smoke plume Page 14 Canada | USA | UK | India | China www.rwdi.com Reputation Resources Results
Star Global Conference 2013 Transient Simulations- Results • Results are presented as instantaneous snap shots at 4 min (240 s) • On floor plans, temperature and visibility are presented at 2.5 m (8 ft.) above the bus deck floor • Exits are located by red & green dots (red = blocked, green = open) • Section views are through the fire bus Page 15 Canada | USA | UK | India | China www.rwdi.com Reputation Resources Results
Star Global Conference 2013 Clear areas Transient Results – Fire Location 2 criterion met Visibility contours at 2.5 m (8 ft) above the Bus Deck Floor Temperature contours at 2.5 m (8 ft) above the Bus Deck Floor Page 16 Canada | USA | UK | India | China www.rwdi.com Reputation Resources Results
Star Global Conference 2013 Transient Results – Fire Location 2 Visibility contours through the fire Temperature contours through the fire Page 17 Canada | USA | UK | India | China www.rwdi.com Reputation Resources Results
Star Global Conference 2013 Transient Results – Fire Location 4 Visibility contours at 2.5 m (8 ft) above the Bus Deck Floor Temperature contours at 2.5 m (8 ft) above the Bus Deck Floor Page 18 Canada | USA | UK | India | China www.rwdi.com Reputation Resources Results
Star Global Conference 2013 Transient Results – Fire Location 4 Visibility contours through the fire Temperature contours through the fire Page 19 Canada | USA | UK | India | China www.rwdi.com Reputation Resources Results
Star Global Conference 2013 Transient Results – Plume Animation Page 20 Canada | USA | UK | India | China www.rwdi.com Reputation Resources Results
Star Global Conference 2013 Questions? Page 21 Canada | USA | UK | India | China www.rwdi.com Reputation Resources Results
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