Application of CFD Tools in Building Engineering and Fire Simulation

Transcription

1 Application of CFD Tools in Building Engineering and Fire Simulation Daniel Barrero, Juan Abanto, Marcelo Reggio, J-P. Hardy, Benoît Ozell SimBuild 2004 Boulder, Colorado, USA, 4-6/8/2004

2 Presentation Index Introduction Indoor ventilation Indoor fire simulation Wind engineering application 2

3 Introduction: A family of Problems Energy consumption in buildings, better indoor air quality and the evaluation of fire scenarios, can be treated via a common strategy: Computational Fluid Dynamics: CFD The strategy ask for the integration of Energy Simulation, Flow Prediction and Fire Dynamics calculations using a common CAD data.. This is not always a straightforward task. 3

4 Introduction: A family of Problems For the analysis, results are presented in ways that frequently do not convey valuable information in a clear manner to users that are not CFD experts 4

5 Introduction: A Solution using CFD To make CFD a useful tool on building design and on fire protection requires the combination of various factors: Utilization of the CAD geometry for different kinds of simulations and analysis. The original geometric model needs to respond to restrictions imposed by the CFD analysis: All objects are closed (volumetric) A CAD model with irrelevant details excluded for CFD 5

6 Introduction: A Solution using CFD To make CFD a useful tool on building design and on fire protection requires the combination of various factors: Visualization should display simulation results in a realistic way close as possible to the actual phenomena. Use of experimental data available, when possible, for the validation and the fine-tuning of the simulation results. 6

7 Workflow Geometry Generation Meshing CFD Simulation Visualization TGrid Mesh AutoCAD Catia Rhino Acis/Step Acis/Step Acis/Step V A L I D A T I O N Acis Step Multiple Meshes GAMBIT.Obj Mesh Fluent Fluent Postprocessor Vu.Obj Dice & Merge Cartesian Mesh FDS SmokeView 7

8 Indoor Ventilation Case Study: Airflow in a kitchen room Given the design of modern kitchens, the kitchen hood plays the main role on the evacuation of the effluents of cooking and on the general performance of the kitchen s ventilation system. Kitchen Hood 8

9 Indoor Ventilation Case Study: Airflow in a kitchen room Airflow simulation of the hood A Multiple Reference Frame was used for the rotating parts 0.93 million hybrid cells 0.41 million vertices Skin Mesh Detailed airflow around the extractor fins 9

10 Indoor Ventilation Case Study: Airflow in a kitchen room Using an stand alone SGI-400 Mhz 1.5 Gb RAM 70 hours CPU Numerical Error <= 10-4 The simulation results are very close to the experimental data Numerical and experimental results comparison 10

11 Indoor Ventilation Case Study: Airflow in a kitchen room Airflow on the whole kitchen Fan speed: 1540 RPM Stove Heat Flux: W/m 2 Hood System 3 Million Cells, 4 CPUs, 1Gb/CPU 11

12 Indoor Fire Simulation Case Study: Kitchen Fire The Fire Dynamics Simulator (FDS) from NIST requires a Cartesian description of the geometry. A dice and merge algorithm was developed to achieve the conversion automatically. Simulation Physical Parameters: Inlets, outlets, fire sources, etc. Skin Mesh Model Cartesian Model FDS Simulation Output for visualization and analysis 12

13 Indoor Fire Simulation Case Study: Kitchen Fire Backdraft Simulation Results Kitchen before opening the door at 404 sec Fire ball produced 12 seconds later 13

14 Indoor Fire Simulation Case Study: Kitchen Fire Backdraft Simulation Results Backdraft Video 14

15 Building Aerodynamics: Campus of the University of Montréal CFD valid CAD Model 15

16 The Campus of the University of Montréal Project 50m hill height 1000 m 35 buildings Initial CFD-CAD model using topographic data 16

17 Building Aerodynamics: Campus of the University of Montréal CFD Mesh used for the simulation 5 Million Cells Steady state solution: k-e turbulence model Species (CO,H 2 O,NOx) Computational Resources: 8 CPUs (SGI Origin 2000) 1Gb/CPU 80 CPU Hours 17

18 Building Aerodynamics: Campus of the University of Montréal Setting the wind direction Y Main Tower X 30 0 Wind = 5m/s 18

19 Building Aerodynamics: Campus of the University of Montréal Pressure field on the façade 19

20 Building Aerodynamics: Campus of the University of Montréal Path lines showing the wind flow around the building complex 20

21 Building Aerodynamics: Campus of the University of Montréal Detailed view of the wind field at different heights. 21

22 Building Aerodynamics: Campus of the University of Montréal Grond level wind field 22

23 Concluding Remarks An efficient methodology for the simulation of indoor ventilation,fire simulation and external building aerodynamics has been developed. Although not completely automatic, it allows for the integration of distinct software (CAD, CFD, FDS, Visualization). Different case scenarios (e.g. ventilation, fire simulation) have been studied using a common base of geometric models. Current advances on computer technology allows for the accomplishment of macro-projects like wind simulation over the University of Montréal campus. The use of the latest (realistic) visualization techniques allows for a better understanding of the simulation results not only to the scientific community, but to a larger audience. 23

24 The End 24

25 CFD Questions? PLEASE CONTACT JUAN ABANTO FOR ANY QUESTIONS REGARDING CFD SIMULATIONS 25