The Wall of Wind: destroying buildings in the cause of science
During my week at the National Hurricane Center this October that I spent as part of their Visiting Scientist Program, I had the opportunity to visit one of the most remarkable engineering efforts used in hurricane research--the International Hurricane Research Center's "Wall of Wind" (WoW) on the campus of Florida International University. As I pulled into the parking lot next to the big metal building that houses the Wall of Wind research lab, I was met by Erik Salna, the Associate Director of the International Hurricane Research Center. He walked me over to their 2-story high "Wall of Wind", which consists of a bank of six 500 horsepower "hot-rod" auto engines with propellers attached, arranged in a box pattern. When the six engines are all fired up, they can generate Category 1 hurricane wind speeds of 80 - 85 mph (not to mention an unholy racket!) Researchers at the Wall of Wind study how full-scale buildings fare under the onslaught of these winds, and in the presence of flying debris and wind-driven rain. Fifteen peer-reviewed journal articles have resulted from WoW research, and changes to the Florida Building Code for 2010 have been recommended by the Technical Advisory Committee at the 2010 Florida Building Code meeting, based on WoW research. It was pretty cool to see how the WoW group tested different shingles, roof slopes, and roof edge and corner designs by wiring the roofs being tested with an elaborate network of pressure transducers. WoW research has shown the importance of protecting your windows with shutters--an open window in a house with a ceiling hatch increases the wind load on the windward side of a gable roof by 45%, greatly increasing the chances of complete roof failure.
Figure 1. Now if I just reach out and flip the switch to my left, my hair will get massively blow-dried! The current 6-fan version of the Wall of Wind (which became operational in 2007) can generate Category 1 hurricane winds of 80 - 85 mph. The reinsurance company Renaissance Re Holdings Ltd provided the funding for the 6-fan Wall of Wind.
Phase 2: the 12-fan Wall of Wind
Last year, Congress thought highly enough of the Wall of Wind's research results to appropriate $1 million to fund a new 12-fan Wall of Wind that will be able to generate wind speeds of 140 mph--Category 4 strength. Additional support is coming from the State of Florida. The new fans are truly massive, and it will be an impressive sight and sound when the new wall goes live. The new wall should greatly aid efforts to engineer new buildings that can withstand the winds of a major hurricane.
One other cool thing the WoW people are doing is sponsoring a Wall of Wind contest for high school students. Each year, local student compete to design a roof structure that fare the best in the Wall of Wind in some engineering category. This year, the kids had to design a roof that would minimize the amount of loose gravel that would fly off a 14x14" test roof. There were some very ingenious entries the kids designed.
Figure 2. The new 12-fan version of the Wall of Wind is currently under construction, and will be able to generate Category 4 hurricane winds of 140 mph when it is completed. Walter Conklin (left) is Laboratory Manager of the Laboratory for Wind Engineering Research, and James Erwin (right) is a research scientist studying hurricane wind damage.
The Wall of Wind website has some links to videos of the Wall in action.
I'll have a new post on Friday.