Vibration prevention for your wind turbine
There are of course many considerations when setting up your wind turbine at home or in your business. This could include the positioning of your turbine, the mounting height of your turbine, how many obstructions there are to the wind flow and many more! One of the most important considerations that TESUP has not mentioned much in the past is the importance of reducing the vibration of your turbine to reduce the potential for damage within your wind turbine system and keep your turbine running well for many years to come. There are many reasons why a wind turbine might vibrate and even more ways in which to stop this vibration. We will cover a few of these in today’s blog.
What about turbulence?
So why is wind turbine vibration a major issue, how does it form and why can it cause damage to your turbine? There are a few main sources of vibration in the turbines. A particularly pronounced source of vibration for bladed horizontal axis turbines (think similar to the Magnum 5) is the interaction of wind with the turbine blades. As the wind passes over the blades it is imparted with a sideways velocity and begins to spin, forming eddy currents behind the blade. This phenomenon is better known as turbulence.
As the eddy currents form, changes in the pressure of the air around the turbine blades start to develop. The pressure drops in the centre of the eddy current causing the blade to be pulled backwards slightly towards the centre of the eddy current. The eddy current then disperses, removing the pressure that was just present, allowing the blade to spring back to its original position. As the blades themselves are made from strong materials the blade bounces back (similar to a ruler held over the table and pushed down). This springing back causes small vibrations in the blade which travel throughout the turbine.
A type of bladeless turbine that converts these eddy vibrations into useful movement. (https://www.inceptivemind.com/vortex-bladeless-wind-turbines-generate-electricity-vibration/18413/)
These vibrations generally do not cause much damage at all, potentially only loosening bolts within the turbine attachment. To avoid this simply check the tightness of the bolts within your turbine at regular maintenance intervals. Another major cause of some more damaging vibrations is in the balancing of the turbine. A balanced turbine is one which has the weight of the spinning components of the turbine evenly and symmetrically distributed over the supporting components. If a turbine is not balanced properly, having the weight of spinning components not evenly distributed, the heavy side can scrape and knock against other components.
For this reason, an unbalanced turbine can usually be detected by hearing a periodic knocking sound as your turbine spins, or by spinning the turbine by hand and feeling if at any point there is resistance to the spinning. Unbalance can be caused by wind turbine blades not being identical, even if they are the same overall weight, a difference in weight distribution over the length of the blade can cause issues with balancing. The first thing to check if you are concerned your turbine is unbalanced is that none of the blades exhibit any damage, this could be in the form of large scratches or maybe something stuck to the blade.
Secure the screws
An uneven weight distribution can also be caused by the presence of something like snow settled on the wind turbine blades. Here is an excellent example from a TESUP customer. Their turbine is very clearly off balance, listing off to one side. This imbalance is clearly as a result of their turbine being unevenly covered in layers of snow, with more snow settling on one side. If this turbine were to spin with this level of imbalance the bearings and support pillar of the wind turbine would likely be damaged, especially if the wind turbine was spinning at high speeds.
You are lucky today blog reader, as a TESUP pro has popped in and given some expert advice on some of the most common mistakes with balancing and how you can easily fix them! The first is for any customers with a TESUP horizontal axis turbine, including but not limited to Master X or Magnum 5 wind turbine models. This tip regards the tail end of your turbine. If the centre of the tail shaft of the turbine is not properly aligned with the centre of the rotor shaft (the one which spins with the blades mounted to it) the turbine will be unbalanced. To remedy this, ensure the screws attaching the tail shaft are secure, without over tightening them.
Another tip from the TESUP pro is relevant for all of TESUP’s wind turbine stock. Many customers take advantage of the higher wind speeds at higher heights and place their turbines on a tall mounting pole (can be upwards of about 6m in height). As the wind pushes on the turbine, the turbine spins, generating useful rotational movement. This also pushes the wind turbine backwards with not so useful backwards and forwards motion. As the turbine is pushed backwards on a large pole, a large moment is generated on the pole, flexing it backwards like a large spring and releasing it as the wind gusts on and off. This creates some dangerous vibrations and can damage your wind turbine and mounting pole.
To remedy this your wind turbine pole should be supported by several guy wires secured to the ground, like this TESUP customer! If you are interested in using a mounting pole for your turbine, check on this official TESUP pole! TESUP hopes this blog helped you to troubleshoot some problematic vibrations in your turbine or at least informed you about some things to watch out for!