Small vertical axis wind turbines (VAWT) are very attractive sources
of clean wind energy for individual residences, small communities, localized
power supplies (such as cell phone towers) and other applications. A major
problem for custom designed and production vertical axis turbines is in starting
the rotation process. This is especially true for low wind conditions . This
provides a new solution where the designer can develop working designs
directly on their personal computer and reduce both the cost of building
prototypes and development times. This results in a less expensive line of
products that will be an affordable source of clean energy for a growing
The Design Process
Wind turbines and other devices are efficiently designed using a modern
computer aided design (CAD) program such as SolidWorks or Autodesk Inventor.
However, for the engineer to know if the designs work or not, they must be
built and tested in a wind tunnel or the physical environment. This is a
time consuming and costly step.
A faster and cost effective solution is to test the design directly
on the computer (ideally the same one where the design was developed). An
aerodynamics analysis software program such as Stallion 3D can test the turbine
designs directly in their digital form (as produced by the CAD
The figure below shows a vertical axis wind turbine that was imported
into Stallion 3D using the STL format. This file format is an available export
option in most three dimensional CAD software tools.
Analyze the Turbine
The next step is to determine whether or not the design will spin
under desired wind conditions. Stallion 3D allows the engineer to enter various
wind conditions and angles to test the design. This is done by simply entering
the wind condition in a dialog box as shown in the picture below.
Of course Stallion 3D is not the only software package that can perform
an aerodynamics analysis on a CAD file. However, Stallion 3D works on an
ordinary personal computer or laptop that runs Windows XP, Vista or 7. It
also eliminates the time consuming and expensive process of grid generation
that is inherent in other computational fluid dynamics (CFD) method. Since
cost and time reduction is the goal of this new design process, using Stallion
3D with its automatic grid generation tool is the logical choice. The picture
below shows the pressure solution and a crosssection of the computational
grid that comprises 150,000 cells. The grid and solution for this case were
obtained in less than two hours.
Designed to Start
To design a starting machine, the engineer must test the design for
various wind velocity conditions (speed and direction). Stallion 3D computes
the flow field, forces and moments for any value of the wind direction. The
picture below shows separated flow on the lower blade at 45 degree wind direction
and 15 miles per hour.
The software also computes the aerodynamics moments generated by the
wind turbine and compares it to the starting torque of the power generator.
If the aerodynamic moments are greater than the starting torque, then the
generator will turn for the specified wind conditions and we will have success.
If not, the engineer can make modifications in the CAD program and repeat
the process without the expensive step of metal cutting. The picture below
shows the forces and moment that are computed by Stallion 3D to determine
the torque and structural requirements of the wind turbine tower.
Stallion 3D is a 3-dimensional aerodynamics software product developed
by Hanley Innovations. The product is intended as a tool for engineers, designers
and students that will allow them to solve problems on their personal computers
(without the need for external assistance). It is a component of their
professional toolbox and bag-of-tricks that allow them to be innovation and
productive at work and contribute to their professional advancement.
Stallion 3D Details
click here for details about Stallion 3D.
Stallion 3D requires a PC running either Windows XP, Vista or Version
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