How Wind Tunnels Work

        Science | Devices

Wind Tunnels Prove Their Worth
Vertical wind tunnels, like this one in China, let skydivers practice their techniques indoors.
Vertical wind tunnels, like this one in China, let skydivers practice their techniques indoors.
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Engineers and manufacturing specialists use wind tunnels to improve not just airplanes and spacecraft, but an entire assortment of industrial and consumer products. Automobile makers, in particular, rely heavily on wind tunnels.

General Motors' Aerodynamics Laboratory has the biggest wind tunnel for studying car aerodynamics. Since building the tunnel three decades ago, the company's engineers have reduced the coefficient of drag of their vehicles by around 25 percent. That kind of improvement boosts fuel economy by two to three miles per gallon.

Race-car makers use the tunnels to improve car aerodynamics, particularly speed and efficiency, to help them get a competitive edge. AeroDyn Wind Tunnel, for example, is located in North Carolina and specializes in testing full-size NASCAR stock cars and other racing cars and trucks. Another company, called Windshear, also operates in North Carolina and owns an advanced closed-circuit tunnel with a built-in rolling road, which is basically a huge treadmill for cars.

Electronics engineers use small wind tunnels to see how airflow affects heat buildup in components. Then they can design cooler computer chips and motherboards that last longer. Utilities managers use wind tunnels to test wind turbines used to generate electricity. Wind tunnels help make the turbines and their blades more efficient, effective and durable, so they can withstand constant, powerful gusts. But wind tunnels also help engineers determine wind farm layouts and turbine spacing, so as to maximize efficiency while minimizing power-sucking turbulence.

Wind tunnels and test models aren't cheap to build. That's why more and more organizations are deactivating their wind tunnels and shifting to computer modeling (also called computational fluid dynamics), which is now often used in place of physical models and tunnels. What's more, computers let engineers adjust infinite variables of the model and the test section without time-consuming (and expensive) manual labor. Physical tunnels are sometimes used only to retest the results of computer modeling.

Construction engineers use computer modeling for wind engineering testing to help them design and build skyscrapers, bridges and other structures. They investigate the interplay of building shapes and materials and wind to make them safer and stronger.

For now, though, wind tunnels are still in active use all around the world, helping scientists make safer and more efficient products and vehicles of all types. And even if newer virtual technologies do eventually replace physical wind tunnels, these marvels of engineering will always have a place in the history of humankind's development.