Introduction: Vertical Axis Wind Turbine
Wind Turbines are an effective way of harnessing energy from a natural source. Many companies are looking into 'green' energy alternatives as the price and cost to the environment of fossil fuels rise.
We are a team of second year Product Design Engineering students from Glasgow School of Art and Glasgow University.
Our aim was to produce the most efficient wind turbine out of the time and resources we had at our disposal. We researched many different designs and developed them until we reached our final solution.
Our design is based around a purpose built wind tunnel that we used to test our concepts and final design. The dimensions given could be scaled up or down depending on the application.
The following step-by-step guide will show you how you too can produce a cost-effective wind turbine.
medium-density fibreboard (MDF)
extruded polystyrene foam
two bought-in gears
hot glue sticks
hot glue gun
Step 1: Fan Base
The fan is one of the most important components in this design.
The MDF base is made of two 300mm diameter discs, with a 260mm diameter disc in between - all 18mm thick. These were roughly cut to shape using a bandsaw and then accurately sized using a belt sander. A hot glue gun and 30 x 1.6mm panel pins were used to attach the discs together.
The lower-most disc was cut to size the same way as the other discs. This disc had a 155mm outer diameter channel cut out using a router. The channel is for the ball bearings to run and its width was 6mm (chosen due to the ball bearings purchased).
Through all four discs is the hardwood dowel axle - 22mm in diameter - cut to 240mm in length using a bandsaw. A hole of the same diameter as the axle was cut through all the discs using a pillar drill. The axle was forced through and required no glue due to the accurate fit.
Step 2: Blades
The blades were cut to shape, using a band saw, out of a 1mm thick sheet of aluminium. The rough edges were filed and holes of 4mm diameter were punched. The two straight edges were bent using a sheet bender. Tin snips were used to cut out the folds where the screws would go through and the triangle sections - this was done so that the blade could be curved. The whole blade was curved by hand and a rubber hammer. They stand 186mm tall after bending.
Holes through the base of diameter 3.5mm were drilled with a power drill. The blades were screwed on in two places per blade, and an allen key was used to tighten them as much as possible. The screws were 20mm long and 4mm diameter (7mm head).
Step 3: Base
The base is simple and quick to construct, but needs to be accurately made.
The base was made out of a 415 x 340mm piece of MDF (medium density fibreboard), 18mm thick. A hole was cut into this base using a router. A disc of diameter 320mm was then sunk and glued into place.
A channel of 155mm outer diameter was cut out using a router. The channel is for the ball bearings to run and its width was 6mm (chosen due to the ball bearings purchased). This matches the one cut out of the fan base.
A hand-held jigsaw and sand paper was used to shape the hole in the middle; diameter 115mm. This was so that the generator axle could connect to the gear attached to the bottom of the fan base.
The support stands were cut to the height of 147mm using a bandsaw. This height was required so that the generator and its housing could fit underneath. The MDF stands are 15mm thick and the pieces were PVA glued and nailed together.
Step 4: Generator
A generator with quoted values of 3500rpm and 24 Volts DC was given to us to use; a different generator could be used in your design.
A housing was required to hold the generator in the correct place as well as protect the generator. Extruded polystyrene foam was cut to size using a saw and attached using a hot glue gun. The foam allows slight movement of the generator which is required for efficient running. It also acts as a good insulator as the generator heats up during use.
The MDF housing was cut to size using a bandsaw with holes at either end to allow the generator axle and connections to be reached. The outside dimensions are 67 x 70 x 68 mm.
This was glued with a hot glue gun to the stand which was designed so that the small gear was at the correct height (match up to the big gear on the fan base). An extra styrene piece was heat formed to shape to further protect the generator from the wind.
The large gear was screwed onto the centre of the fan base. Two holes were hand-drilled into the gear and the screws were drilled in. This gearing creates a gear ratio to increase the rpm the generator axle is turning (and hence decreasing the torque).
Step 5: Wind Deflector
Since our wind turbine was designed with a wind tunnel test in mind, a wind deflector was made. The blades are designed (curved) so that the fan will have more force pushing on one side than the other, which spins the fan. A deflector would decrease the opposing force and so increase the speed at which the fan will spin.
This may not be suitable for your application as the natural wind direction cannot be guaranteed and so the deflector may be ineffective.
A 1mm thick aluminium sheet was cut with a guillotine to a height of 260mm. Tin snips were used to cut out the folds and triangle sections and a sheet bender used to bend these parts to 90 degrees. The sheet was curved by hand to match the outside radius of the fan base.
Holes of 4mm were punched into the folds for the screws (same as for the blades) to go through. The base was hand drilled for the screws, which were tightened using an allen key.
Step 6: Conclusion
Due to our application we have not connected the generator to an output. However this could be simply done using electrical wires connected up to the generator at one end.
We hope you found this instructable informative and easy to understand.
Any questions or advice on design changes are welcome, please comment below.