Q&A With Airfoil Generators

What makes your design different?    Our unique airfoil design increases the speed of the wind just before the rotor. In addition, the airfoil shields those rotor blades that are on the return trip around the axis, eliminating the drag often associated with vertical wind power generators.  This increases the net torque produced.

 Why is wind speed such a big deal?  Wind speed is the single most important factor in producing energy, because increasing the velocity of the wind exponentially increases the kinetic energy it contains. The equation for this is (V3 or V x V x V ) where V is velocity of the wind.  Every time the wind velocity doubles, you don’t just double the energy available; the potential energy is increased eight times.

This is why utilities spend so much money on choosing the right site or building taller and taller towers to put the generators on. In our case, we chose to accelerate the wind instead. In our way of thinking, it is easier and a whole lot less expensive.

How does your airfoil accelerate the wind? CFD Velocity TestThe very first thing it does is to increase the velocity of the wind before it even gets to the turbine. Have a look at this test:

Note how the wind speed approaching the nose of the airfoil is at 20 MPH, but after it contacts the airfoil, it accelerates up to 32 MPH at the location of our turbine. That provides a 160% increase in the energy available in that wind than there was before.   

It also creates a pressure differential above and below the airfoil that we use to turn the turbine as well.

We take the relative high-pressure area below the airfoil and duct it into the turbine housing, where it lessens the drag within the housing and increases the speed of the rotor. This increase in the rotor RPM pulls even more air along the top of the generator and over the turbine, increasing the velocity of the wind yet again.   

For more on this, please enjoy our 2 minute “How it Works” video here: http://airfoilgen/howitworksvideo

Why the long tail?   That “tail” is the long extension of our airfoil. It performs three important jobs for us:

  1. It points the wind power generator into the prevailing wind much like a wind vane does. Other designs require yaw motors and systems to keep the wind generator pointed the right way, which this design does not need. This means less complexity, lower costs, and higher reliability for you.
  1. Second, as the spent wind (that which has already had its energy extracted) exits along the long tail of the airfoil, it converts the turbulent air after the rotor into a smooth laminar flow, which further increases the velocity of the air over the generator, stepping up revolutions and torque of the rotor.
  1. Finally, the reduction in turbulence that the airfoil provides cleans up the wake after the generator. In this image, you can see how smooth the airflow is after the generator turbine. This is very unusual for a wind power generator whose wake is usually very turbulent and messy. Because the wake behind our generator is far less turbulent, it means that it will be much quieter and, should you want to install several of them together, they do not need to be nearly as far apart as other designs.

What are the benefits of a modular design?   Unique to our design, the Airfoil Generator is modular. The main airfoil and impeller are designed in sections that are easily transported and handled. For example, a single module of our Model 18-12 generator is 5’ wide X 4’ high X 18’ long1 and fits on a regular semi-trailer.  When all three modules are assembled onsite, the finished generator will be 5’ wide X 12’ high X 18’ long. The modular design also makes it easier to erect and maintain. All of this means more “up time” for you and lower cost of ownership.

 What do you mean by “scalable”?   This is another new innovation unique to our design. How often does it happen where a consumer selects and installs a certain wind power generator based on what they need only to find that, in their chosen location, it doesn’t quite make as much power as they’d hoped? Site variables such as buildings, trees, and topography make estimating how much power a WPG will make at a particular site very tricky. But now, should that happen to you, it can be dealt with easily. Our design is scalable. You can simply add another 4’ section to the top, and enjoy2.

Is your generator self-starting?  Yes. Computer testing has shown the Airfoil Generator to be self-starting.  This avoids starter motors and their systems, and again lowers complexity and purchase prices.  

What is blade fatigue and why should I care:  Long, unsupported blades of some wind turbine designs allow the blades to twist and bend on every rotation.  All materials that undergo repeated flexion will eventually fail. Know that those designs will require blade replacement at some interval, and that this adds a cost-of-ownership expenditure and a scheduled maintenance event to these generators. However, the Airfoil Generator’s blades are well supported and flex much less, and as a result, are not as susceptible to material fatigue, failure, and replacement.

Why are you are using a helical rotor?  We’ve opted for a helical rotor  for the following reasons:

Helical rotor demoEfficiency: Helical rotors are known for their efficiency in converting wind energy into rotational motion. Our CFD simulations confirmed this. The helical design also allows the rotor to capture wind from all directions, unlike traditional straight-bladed rotors that work optimally only when wind hits them at specific angles.

Low Wind Speed Performance: Helical rotors are effective at capturing wind even at low wind speeds. This can be advantageous in areas where wind speeds are not consistently high.

Quiet Operation: Helical rotors are typically quieter compared to traditional straight-bladed rotors. This can be beneficial, especially in residential areas where noise pollution is a concern.

Self-Starting: Helical rotors have a tendency to be self-starting, meaning they can begin rotating with less wind force compared to other rotor designs. This feature can be advantageous in areas with variable wind conditions.

Less Maintenance: Helical rotors are known for their durability and can require less maintenance compared to other rotor designs. This is a result of their improved strength as a self-supporting structure. This can result in cost savings over the lifespan of the VAWG.

What are your site recommendations?   Select a site that is away from buildings and tall trees because they disturb the wind flow. You will want to install the generator atop a tower, but because our generators are vertical, the tower may not need to be as tall as those for other designs. The height of the tower is site-specific, but for our generators a 30’ to 50’ tower should be fine. Please measure the windspeed at your proposed site with an anemometer at several heights above the ground to decide what is best.

Tower type: we like towers with a hinge or knee in them because they make access to the generator so good and at ground level. Saves from climbing the tower or renting a crane when you want to do maintenance. There are several good manufacturers and designs.

1 For our Model 18-12. See our “Model-Size-Output chart for dimensions of all our models.
2 Assuming the tower you have installed it on can safely handle the additional wind load of the increase in height.