Validity of Strapping a Wind Turbine on a Vehicle

[Jan Ben]

Aside from placing the turbine on a test site and gathering data to measure and build its power curve or testing it on a wind tunnel (which is the most ideal one), is it valid to strap a turbine on a car or trailer and drive on straight roads at pre-defined vehicle speed?

For example, what this guy is trying to do - Wind Power on a CAR #1- Is it FREE? - YouTube

But I think it would be better to drive on straight roads at 22kmph and 36kmph to get data at 6m/s and 10m/s wind speed.

[Rob Beckers]

Hi Jan,

The premise of the YouTube video (I think) is to lower gasoline use by generating wind energy to power the car, which of course will fail. The addition of the turbine will increase gas use, not lower it. TANSTAAFL as Heinlein put it! :laugh:

That aside, yes, you can use a vehicle to simulate wind and test turbines. It's been done before to get test data. I've never tried, but some thoughts: Air flow is disturbed not just behind a vehicle, but also ahead of it (though the disturbance ahead extends nowhere near as far as it does behind the vehicle). How far ahead depends on the aerodynamics. That means you have to get your test turbine far enough ahead of the vehicle to avoid this air. The other one is the effect of the ground: While the air above the ground is not disturbed in itself, the moment you start messing with the airflow using a turbine, that airflow will be affected by its proximity to the ground. So you can't go too low either.

A university department I was in many years ago was working on using a helicopter to take air data measurements, and one of the issues there too was to put probes far enough ahead of the cockpit to stay out of the rotor wash during flight, and the disturbed air of the body itself. CFD simulations were done that showed the airflow and disturbed area vs. helicopter speed to find out what the best location was. Interesting stuff!

Lastly, contrary to what you mention, wind tunnels are one of the worst ways to get wind turbine data! They make for a confined airflow, and that confinement has a profound effect on objects in that flow (unless they are very small compared to the diameter of the flow). In effect the air is forced through the turbine, making the turbine appear much more efficient and produce much more power than it would in actual real-world use!

-RoB-

[Jan Ben]

Hi,

I agree, law of conservation of energy will always prevail.

How did your testing using a vehicle in the past go?
I'm thinking of using a vehicle for rough testing and confirmation of turbine CFD and simulations.
I think using wind tunnels and/or vehicles would be the most practical way to test design concepts and confirm or compare empirical results with the CFD and simulations.

But of course the actual performance of the turbine would have to be one where it is sitting somewhere and gathering data for a few months to a year.

[Rob Beckers]

As mentioned in my previous post I never tried testing a turbine on a vehicle. I've read stories from a number of people that did, it's not a bad way if you don't have the millions to build a large enough wind tunnel to do valid testing of a turbine in that.

Wind tunnels have been abused by the less scrupulous turbine manufacturers to "prove" their turbine produces lots at low wind speeds. As mentioned, unless the tunnel diameter is very large compared to the turbine diameter the results won't be valid, since you're forcing air through the blades (if the air can't go around).

Just putting a turbine on a high enough tower with a logging anemometer works too!

-RoB-