| REUK Shop | REUK Blog | Directory | About Us  |  | RSS Web Feed for Renewable Energy UK 

Wind Turbine Tip Speed Ratio



Wind Turbine Tip Speed Ratio

Learn about how the importance of the Tip Speed Ratio (TSR) in wind turbine design

wind | education
  Printer Friendly Version Print Article     

The Tip Speed Ratio (often known as the TSR) is of vital importance in the design of wind turbine generators. If the rotor of the wind turbine turns too slowly, most of the wind will pass undisturbed through the gap between the rotor blades. Alternatively if the rotor turns too quickly, the blurring blades will appear like a solid wall to the wind. Therefore, wind turbines are designed with optimal tip speed ratios to extract as much power out of the wind as possible.

When a rotor blade passes through the air it leaves turbulence in its wake. If the next blade on the spinning rotor arrives at this point while the air is still turbulent, it will not be able to extract power efficiently from the wind. However if the rotor span a little more slowly the air hitting each turbine blade would no longer be turbulent. Therefore the tip speed ratio is chosen so that the blades do not pass through turbulent air.

Tip Speed Ratio Calculations

The tip speed ratio is given by dividing the speed of the tips of the turbine blades by the speed of the wind - for example if a 20 mph wind is blowing on a wind turbine and the tips of its blades are rotating at 80 mph, then the tip speed ration is 80/20 = 4.

Optimum Tip Speed Ratio

The optimum tip speed ratio depends on the number of blades in the wind turbine rotor. The fewer the number of blades, the faster the wind turbine rotor needs to turn to extract maximum power from the wind. A two-bladed rotor has an optimum tip speed ratio of around 6, a three-bladed rotor around 5, and a four-bladed rotor around 3.

Highly efficient aerofoil rotor blade design can increase these optimum values by as much as 25-30% increasing the speed at which the rotor turns and therefore generating more power. A well designed typical three-bladed rotor would have a tip speed ratio of around 6 to 7.

If the tip speed ratio is too low - for example if poorly designed rotor blades are used - the wind turbine will tend to slow and/or stall. If the tip speed ratio is too high the turbine will spin very fast through turbulent air, power will not be optimally extracted from the wind, and the wind turbine will be highly stressed and at risk of structural failure.

Wind turbine tip speed ratio

Pictured above is a graph showing the power coefficient for different values of tip speed ratio for a two-bladed rotor. The theoretical maximum efficiency of a wind turbine generator is given by the Betz Limit of around 59%. With a tip speed ratio (TSR) of just under 6, the power coefficient for this example turbine is 0.45.



Article Last Modified: 10:11, 6th Mar 2007

Comment on this Article

If you have any comments on this article, please email them to neil@reuk.co.uk.


Recommended Related Articles

People who read this article also enjoyed the following articles:

Betz Limit
Understand the Betz Limit and how it affects wind turbines
Article Last Modified: 15:40, 26th Jan 2007
wind | education

Savonius Wind Turbines
What is a savonius wind turbine - savonius (VAWT)
Article Last Modified: 12:31, 23rd Jul 2008
wind | education

What is Wind Turbine Furling
Understand how Furling works to protect a wind turbine from high winds
Article Last Modified: 16:22, 19th Dec 2006
wind | education

Darrieus Wind Turbines
What is a Darrieus wind turbine - Darrieus (VAWT)
Article Last Modified: 16:27, 30th Jan 2007
wind | education

Giromill Darrieus Wind Turbines
What is a Giromill wind turbine - Darrieus (VAWT)
Article Last Modified: 16:27, 30th Jan 2007
wind | education

Interconnecting Batteries for Battery Bank
Find out how best to connect batteries together into a battery bank
Article Last Modified: 13:53, 23rd Feb 2007
storage

Power Inverters
Find out about the uses of power inverters in renewable energy generation
Article Last Modified: 16:41, 21st Jul 2008
storage | general | electronics

Make a Simple Battery Status Monitor
Monitor battery status with this easy electric circuit project - no skill required!
Article Last Modified: 12:33, 16th Mar 2007
storage | electric circuit

Permanent Magnet Generator
Build a wind or water power system with around a PM Generator
Article Last Modified: 16:43, 6th Apr 2010
wind | hydro

Worlds Largest Wind Turbine Generator
Read about the world's biggest wind turbines - 5MW
Article Last Modified: 14:24, 6th Jan 2007
wind

© 2006-2013 REUK - All Rights Reserved
Page Last Updated on 23rd May 2013 at 05:09:53pm

Recent
Blog Posts


1.Low Voltage Disconnect with Display and Datalogger

2.Saudi Solar Power Boom About to Begin

3.Compressed Air for Storage of Renewable Energy

4.Offer of the Day – 80W Monocrystalline Solar Panel £71.98

5.Project of the Day – Wind Turbine Dynamic Blade Pitch Controller

6.Morocco Starts Vast Solar Energy Project

7.Follow Up to RC Helicopter Lighting Controller

8.Low Voltage Disconnect – User Programmable Set Points in Binary

9.UK Home Energy Smart Meter Project Delayed

10.EU to Impose High Import Duties on Chinese Made Solar Panels


Latest
Articles


New Simple Hen House Door Controller
Details of our new 2013 simple design for an automatic hen house door controller
electric circuit
11:45, 20th Apr 2013

Automatic Hen House Door Closer Opener
Find out how to put together a DIY automatic hen house door opener and closer
electric circuit
11:40, 20th Apr 2013

Butanol vs Ethanol Fuel of the Future
A brief introduction to Butanol/Biobutanol as an alternative to Ethanol
biomass
11:55, 19th Apr 2013

Cheap Pyroelectric Infrared PIR Detector
Details of a very affordable and flexible PIR motion detector
electronics
20:33, 16th Jan 2013

Heat Pump Tumble Dryer
Reduce power consumption with the latest heat pump tumble dryer technology
energy efficiency
20:16, 3rd Jan 2013

LED Spotlights
Find out about Energy Efficient LED spotlights
lighting
15:17, 3rd Jan 2013

Dimmable Energy Saving Lightbulbs
Find out more about low energy light bulbs which can be used with standard dimmer switches
lighting
14:36, 3rd Jan 2013

Review of Megaman Energy Saving Lightbulbs
Find out more about the Megaman range of CFL energy saving lightbulbs
lighting
14:08, 3rd Jan 2013



REUK Shop

Popular Items


REUK SUPER LDR DUSK DAWN RELAY CONTROLLER
Multi-function light detector triggered light/dark dawn/dusk relay controller
£19.95 each.
Complete Circuits



KARASOULI SCC 20 CHARGE CONTROLLER
20A rated wind turbine charge controller and dump load controller with blocking diode and heatsink
£43.95 each.
Renewable Energy System Parts



2013 SOLAR PUMP CONTROLLER WITH RELAY
New solar water heating pump controller with fitted 10A relay
£25.99 each.
Complete Circuits



REUK SUPER POULTRY LIGHTING CONTROLLER
Control up to 8 Watts of LED spotlights to stimulate egg production in birds
£29.99 each.
Complete Circuits



REUK SUPER TIMER 2
User programmable 12VDC powered 16A rated repeating relay timer. 1 second to 99 hours ON and OFF times
£23.99 each.
Complete Circuits



300 WATT POWER INVERTER
Convert 12V DC battery power into 230 AC to power portable televisions, computers, video recorders etc. 300 Watt power rating - peak power 600 Watts
£29.99 each.
Renewable Energy System Parts



CONVERTED PROGRAMMABLE DIGITAL TIMER RELAY
Mains powered programmable timer converted to low voltage with relay board
£21.99 each.
Renewable Energy System Parts



12 VOLT REGULATOR
Supply a fixed 12.0 Volt DC to your devices (up to 0.7 Amp output)
£4.79 each.
Complete Circuits



MR16 CERAMIC BULB HOLDER
Bulb holder for 12 Volt LED spotlight bulbs
£1.39 each.
Energy Efficient Lighting