Hot Topic

JETS' Pre-Engineering Times Hot Topics column highlights current research related to the featured engineering discipline each month. JETS wants you to know the new field advances being made through exciting research discoveries.

This month's research focuses on computational fluid dynamics (CFD), which is a growing area of research at many universities.

One new tool in the HVAC&R designer's toolkit is CFD. With today's high speed computers, users can make three-dimensional models of spaces and keep track of temperature, pressure, and airflow at each point in the space.

By using the CFD technique on domed stadiums, engineers can now adjust the airflow so that both the players on the field and fans in the stands are comfortable, but there is a donut of stagnant air hovering high around the perimeter of the field (where there are no people). When they want to do laser shows for rock concerts, they inject smoke into this donut, turn down the lights, and have some fun.

Lang Park Stadium - Brisbane, Queensland:
Project Services, HOK Architects

The Lang Park football stadium was recently redeveloped for increased capacity. As it is being designed to be capable of incorporating a retractable pitch roof in the future, CFD modeling was used to determine the natural ventilation openings necessary to provide acceptable spectator comfort conditions. Several scenarios were simulated for the different environmental conditions in the case of both an open stadium and with a pitch roof.

Occupancy issues in newly developed sports arenas and stadiums are becoming increasingly important, particularly with regard to comfort, health, and safety. Cost effective and innovative, CFD techniques are now commonly used in the engineering design process to inform and help achieve desired outcomes. These may relate to the natural or mechanical (HVAC) ventilation of the arena, the threat to life safety due to fire and smoke spread, and specialized assessment of topics unique to sports complexes such as pitch ventilation.

Occupant comfort in naturally ventilated environments is affected by the air temperature, the air movement, and solar radiation. The air temperature in the stadium is dependent primarily on environmental conditions, but is also affected by direct solar radiation warming building elements, including the roof. The extent of natural ventilation also affects the air temperatures, as greater air exchange reduces the effect of localized heat sources, such as spectator body heat. If the natural ventilation is reduced, for example by closing the roof of a stadium with a retractable roof, this will reduce air movement within the arena, which can adversely affect spectator comfort.

Author: Eric Jal
Excerpts take from his paper presented during PHOENICS 2004 User Conference held in Melbourne, Australia, in May 2004. For additional information: www.airah.org.au/downloads/2004-10-01.pdf

Penn College of Technology will be adding CFD to their programs very soon. They are interested in CFD for modeling air distribution in commercial HVAC applications, and they hope to employ CFD for refrigeration and heat exchanger design as well. CFD will compliment the FEA analysis used for heat transfer analysis at Penn College of Technology. Students will use CFD in the commercial HVAC design course as well as for senior design projects.

Other universities currently utilizing CFD techniques include Carnegie Mellon University, Georgia Institute of Technology, Penn State University–University Park, Purdue University, Rensselaer Polytechnic Institute, University of Georgia, and University of Tennessee– Chattanooga.