Michael Carl Rowan Williams Davis & Irwin Inc. Page 1 Cover - - PowerPoint PPT Presentation

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Michael Carl Rowan Williams Davis & Irwin Inc. Page 1 Cover - - PowerPoint PPT Presentation

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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

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Star Global Conference 2013

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Reputation Resources Results

Canada | USA | UK | India | China www.rwdi.com

Emergency Ventilation System Modeling

Michael Carl Rowan Williams Davis & Irwin Inc.

Cover image courtesy of Pelli Clarke Pelli Architects

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Star Global Conference 2013

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Reputation Resources Results

Canada | USA | UK | India | China www.rwdi.com

Cover image courtesy of Pelli Clarke Pelli Architects

Consulting in the Science of Buildings, Structures & Environment

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Star Global Conference 2013

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Reputation Resources Results

Canada | USA | UK | India | China www.rwdi.com

Outline

1. Project Background 2. Sectional Model 3. Boundary Conditions 4. Performance Criteria 5. Transient Simulations

Cover image courtesy of Pelli Clarke Pelli Architects

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Star Global Conference 2013

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Reputation Resources Results

Canada | USA | UK | India | China www.rwdi.com

Project Background

  • Transbay Transit Center by Pelli Clarke Pelli Architects (Design Architect) and Transbay

Joint Powers Authority (Ownership)

  • Mixed use complex including Bus Deck (3rd 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%
  • pen) and sprinklers
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Reputation Resources Results

Canada | USA | UK | India | China www.rwdi.com

Project Background- Multi-Study Analysis

Objective: Evaluate egress tenability on bus deck in case

  • f 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.

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Canada | USA | UK | India | China www.rwdi.com

Sectional Model

  • 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

200 m

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Canada | USA | UK | India | China www.rwdi.com

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
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Reputation Resources Results

Canada | USA | UK | India | China www.rwdi.com

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/m3
  • 70% convective
  • Soot released as scalar
  • Fire grown and monitored using field functions and macros developed by RWDI
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Canada | USA | UK | India | China www.rwdi.com

Boundary Conditions- Fire Location

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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 m2 (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
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Canada | USA | UK | India | China www.rwdi.com

Boundary Conditions- Model

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Reputation Resources Results

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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).

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Canada | USA | UK | India | China www.rwdi.com

Performance Criteria- Visibility

Calculated based on the soot properties and concentration as well as the object being viewed.

s m Y

K C S  

Visibility View object Constant Mass extinction Mass fraction soot Local gas density

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Canada | USA | UK | India | China www.rwdi.com

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

  • f sprinklers on the smoke plume
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Canada | USA | UK | India | China www.rwdi.com

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
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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

Transient Results– Fire Location 2

Clear areas criterion met

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Transient Results– Fire Location 2

Temperature contours through the fire Visibility contours through the fire

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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

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Transient Results– Fire Location 4

Temperature contours through the fire Visibility contours through the fire

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Transient Results– Plume Animation

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Questions?