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8 August, 2001August 8, 2001 CRREL. It sounds like the name of an alien race from Star Trek. And a lot of very unusual activities take place at CRREL, to be sure. But it’s on Planet Earth, in rural central New Hampshire. A few minutes past Dartmouth University, amidst placid cows and just down the road from the Slurpee machine at the crossroads Quickie Mart, is one of the coldest places in the United States. And the cold is all indoors. CRREL, the Cold Regions Research and Engineering Laboratory, is a place where scientists and engineers make everyday things like bridges and roads very, very cold. Then they do very, very bad things to them. They stress them and push them and try their best to make sense of the pieces. The goal: to make bridges and roads and transportation systems perform better under the harsh winter conditions of the Arctic & Antarctic. A plaque on a piece of lab equipment insists :”One test is worth a thousand expert opinions.” Our group of 12 pole-bound teachers wandered through CRREL on one of the hottest days of the year. The scale of the facilities is enormous. In one of the largest sheds waited an immense blue “heavy vehicle simulator”, capable of simulating 600 fully loaded trucks per hour over a stretch of frozen asphalt. We stood astride deep grooves squished into the pavement during a previous test, watching some very hot and tired workers dig up a gravel sub-pavement and pull up sensor wires. Ultimately, a new piece of pavement will be laid down here, on top of a test piece of synthetic “carpet” which may help the frozen asphalt to hold together. While we watched, the sun came out from behind a cloud, and the metal rooftop crackled like bacon as it expanded. It was hard to imagine freezing this roadway. We hurried on, cheered by the promise of a visit to a room 24 degrees below zero. Up the stairs and into the air conditioned library provided some relief, and we admired the mammoth tusk and the large collection of hydrology, geology, military, engineering, and scientific journals. As an Army Corps of Engineers research facility, CRREL’s collection reflects its broad civilian and military missions, solving defense specific problems and fixing ice-related flooding throughout the northern US. The cold room met every expectation. Marge from Connecticut noticed ice crystals forming on my shirt within moments after she closed the door behind us. Being a big guy, and with long pants on, I wasn’t bothered, but the teachers dressed for hot weather, the sandals and shorts group, began to hop around a little. Ice cores from Greenland sat in round metal cases, stacked to the ceiling like firewood. Near where I stood, a shelf held about five hundred of those blue ice freezer packs. I have one of those in my freezer at home. We got a tour through the main test facility from smiling engineer Len Zabilinski. We were handed off to Len at the entrance of a large garage, where Maria, the public relations officer, bowed out because she’d developed some sensitivity to the strong ammonia smell permeating the building. Ammonia is used as a refrigerant for this huge building, where Len supervises the scale modeling of locks, barges, bridges, rivers, and, above all, ice. Animated, Len spoke of successes at locks and bridges. Using small scale locks a person could jump over, CRREL developed a bubblejet to clear ice from in front of barges, allowing locks to work quickly year round. Dams installed to control turbulence prevent ice from forming when supercooled water, ready and waiting to turn to ice, is mixed when it passes over rapids and a kind of Slurpee ice rapidly solidifies. This troublesome ice, called frazil ice, is ready and willing to stick to other ice and bridges, and forms ice dams, sometimes within hours. Len showed us a swimming pool sized river model which can be lined with sediment, filled with supercooled water, and tilted to create river flow. Len also spoke about less successful experiments. One trial involved placing pylons joined by a common base in the model river. The camera crew had some technical difficulties, and by the time they were ready to shoot, the ice had frozen to the pylons. When the water began to flow downstream, the pylons suddenly created a dam. Water piled up behind the ice dam until the base was lifted up and the entire apparatus was overturned. Oops. “That’s how we knew to make a really solid base,” Len explained. By modeling, and scaling up, CRREL researchers gradually develop solutions by understanding the sensitivity between the variables in their systems. “The measurements sometimes are completely different from what everyone thought was happening,” said Len. “But if the model starts to look right, then we’re on the right track.” CRREL does unique work.“It’s seat of the pants engineering : 1, 2, 3, give it a whirl. We’re really out there by ourselves.” ===== Eric Muhs Physics Instructor Seattle Academy of Arts & Sciences www.invisiblemoose.net __________________________________________________ Do You Yahoo!? Make international calls for as low as $.04/minute with Yahoo! Messenger http://phonecard.yahoo.com/
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