Because of my early postings (December 30, 2008) about the Honeywell Windtronics turbine, other observers have been sending me their comments on the product.
Chris Pollard, a mechanical engineer and an expert in fans for cooling computers, brought to my attention Windtronics’ claim that the turbine was tested in a wind tunnel. This may be an exaggeration.
Windtronics posts on its home page a youtube video titled “Windgate Video July 1 2009“. The video asserts that it is “A look inside our wind testing tunnel (note the velocity at 7.5 mph (12 km/h), when most Turbines are just starting-up). The noise heard in the background is the wind tunnel fan, the wind turbine itself is virtually silent.”
Pollard notes that this is not a “wind tunnel” in the sense of an aeronautical laboratory. It is, suggests Pollard, a shipping container or a trailer modified to test the Windtronics turbine in front of a fan.
Testing of wind turbines in wind tunnels-whether real or fabricated ones-has always been problematic since the 1970s. In the 1970s, for example, McDonnell Aircraft claimed exceptional performance of their Giromill based on wind tunnel tests. Only later was it learned that the tests by sophisticated engineers at an aerospace company failed to account for a fundamental aspect of wind tunnels, the wall effect. Of course, this result only surfaced after the turbine failed to perform as well in the field as it did in a wind tunnel.
Testing in a wind tunnel is useful in designing the wind turbine or tweaking the design. It should never be used as a form of performance testing and no performance standard accepts wind tunnel “testing” as a measure of performance.
Further, the video claims only that the turbine is spinning at 7.5 mph, not that it is actually generating any electricity. Of course, we’re only interested in generating electricity, not watching something spin in the wind.
In fact, Pollard says, the video only shows that a fan is drawing wind through the Windtronics rotor and by doing so it is accelerating the flow. In other words, the “test” is meaningless-but it makes a good video for those who don’t know any better.
While I am not an aeronautical engineer, or an engineer of any kind, I did test anemometers in a real wind tunnel at Pennsylvania State University in 1980. My tests three decades ago were more sophisticated than those depicted in the Windtronics video. In my tests the anemometer occupied a very small percentage of the wind tunnel’s cross section. This avoided any interference with the wall.