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| New wind tunnel will make airplanes quieter  A newly completed wind tunnel at the University of Florida may help reduce the noise of commercial airplanes as they fly over homes and neighborhoods. Engineers will use the $400,000 tunnel to learn how to reduce the noise caused by the flow of air over wings, flaps and landing gear – the primary sources of the annoying sound that reaches people on the ground when planes are landing. The wind tunnel, completed this spring after two years, is timely. Also, engineers have reduced jet engine noise to an extent that it now makes sense to focus attention on the noise from other aircraft components.UF’s tunnel is housed in a soundproof room in one of UF’s mechanical and aerospace engineering buildings. The room’s walls and ceiling and even the door are covered with 3-foot-long fiberglass wedges designed to absorb 99 percent of the sound the engineers are concerned with. Anyone inside the tunnel must speak loudly to be heard by someone just a few feet away. The tunnel itself is composed of a reinforced fiberglass inlet separated by an open 6-foot-long test section from an acoustically lined outlet that collects and diffuses the wind. The chamber is not large enough to accommodate full-scale aircraft parts, so engineers plan to use scale models. They will place the models, expected to be one-tenth to one-fifth the size of the real thing, in the chamber, then measure the flow and noise they create – a noise intended to be untarnished either by unrelated noise from outside or echo effects inside. A 300-horsepower fan pulls air through the tunnel. It is located outside the building on its own concrete pad and foundation, which ensures its noise and vibration don’t contaminate experiments. The fan is capable of moving air at speeds of up to 170 mph, the typical speed of most commercial jets as they approach an airport for landing. Mechanical and aerospace engineering doctoral students Jose Mathew and Chris Bahr said the toughest challenge was crafting 60 airfoils that turn the air flow 90 degrees as it leaves the building. The team needed to make that turn to fit the tunnel into the available space, and the fiberglass and rubber-filled vanes make the process as streamlined and quiet as possible. write your comments about the article :: © 2005 Construction News :: home page |