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Questions and Answers
What is the theoretical maximum rotor efficiency, also known as Betz efficiency or Betz’s law?
What is the theoretical maximum rotor efficiency, also known as Betz efficiency or Betz’s law?
- 100%
- 59.3% (correct)
- 35-45%
- 75%
How does the efficiency of the rotor change if the rotor turns too slowly?
How does the efficiency of the rotor change if the rotor turns too slowly?
- The efficiency drops off (correct)
- The efficiency remains constant
- The efficiency increases
- The efficiency reaches 100%
What impact does the tower have on wind speed for downwind machines?
What impact does the tower have on wind speed for downwind machines?
- Decreases wind speed significantly
- Increases wind speed significantly
- Causes wind 'shadowing' (correct)
- No impact on wind speed
What effect does the flexing of a blade have on wind turbine noise?
What effect does the flexing of a blade have on wind turbine noise?
How much energy can be extracted from the wind under the best operating conditions?
How much energy can be extracted from the wind under the best operating conditions?
What is the primary cause of turbulence (stall) in a wind turbine?
What is the primary cause of turbulence (stall) in a wind turbine?
How does the angle of attack affect the efficiency of a wind turbine rotor?
How does the angle of attack affect the efficiency of a wind turbine rotor?
What is the significance of tip speed ratio in determining the efficiency of a wind turbine rotor?
What is the significance of tip speed ratio in determining the efficiency of a wind turbine rotor?
Why does the tip of the turbine blade travel at the highest speed when it is rotating?
Why does the tip of the turbine blade travel at the highest speed when it is rotating?
How does apparent wind relate to the efficiency of wind turbine blades?
How does apparent wind relate to the efficiency of wind turbine blades?
What is the tip-speed-ratio (TSR) of a wind turbine with a rotor diameter of 40m and a rotor speed of 1800 rpm?
What is the tip-speed-ratio (TSR) of a wind turbine with a rotor diameter of 40m and a rotor speed of 1800 rpm?
What is the efficiency of the complete wind turbine (blades, gearbox, generator) when it operates with a TSR of 4.0?
What is the efficiency of the complete wind turbine (blades, gearbox, generator) when it operates with a TSR of 4.0?
At what wind speed does the turbine produce its maximum power output for a Vesta V90 – 3.0 MW turbine with a 90m diameter?
At what wind speed does the turbine produce its maximum power output for a Vesta V90 – 3.0 MW turbine with a 90m diameter?
Why does the power output level off at 3,000 kW for the Vesta V90 – 3.0 MW turbine?
Why does the power output level off at 3,000 kW for the Vesta V90 – 3.0 MW turbine?
What gear ratio is needed to match the rotor speed (TSR = 4.0) to the generator speed (1800 rpm) for a wind turbine with a rotor diameter of 40m?
What gear ratio is needed to match the rotor speed (TSR = 4.0) to the generator speed (1800 rpm) for a wind turbine with a rotor diameter of 40m?
What is the formula for tip speed in terms of rotor speed (N), rotor diameter (D), and wind speed (v)?
What is the formula for tip speed in terms of rotor speed (N), rotor diameter (D), and wind speed (v)?
How does the optimum spacing of wind turbine towers vary with wind direction?
How does the optimum spacing of wind turbine towers vary with wind direction?
How does the wind speed vary with height according to the given expression?
How does the wind speed vary with height according to the given expression?
Why can't average wind speed be used to predict total energy available?
Why can't average wind speed be used to predict total energy available?
Calculate the energy at 6 m/s using the given formula: Energy (6 m/s) = 1/2 ρAv^3t. What is the result?
Calculate the energy at 6 m/s using the given formula: Energy (6 m/s) = 1/2 ρAv^3t. What is the result?
What is the definition of tip speed?
What is the definition of tip speed?
What causes considerable stress on the tip of the turbine blade when it is rotating?
What causes considerable stress on the tip of the turbine blade when it is rotating?
What does the Tip Speed Ratio (TSR) measure?
What does the Tip Speed Ratio (TSR) measure?
Which method of speed control involves shifting the rotor axis out of the wind direction when wind speed exceeds the design limit?
Which method of speed control involves shifting the rotor axis out of the wind direction when wind speed exceeds the design limit?
What does 'stall control' involve in terms of speed regulation?
What does 'stall control' involve in terms of speed regulation?
What is the power density in the wind at a height of 50 m, assuming the wind speed at 10 m is 5 m/s?
What is the power density in the wind at a height of 50 m, assuming the wind speed at 10 m is 5 m/s?
According to the 1/7th power law, how does the power in the wind at the top tip of the rotor compare to that at the lowest point that it falls to?
According to the 1/7th power law, how does the power in the wind at the top tip of the rotor compare to that at the lowest point that it falls to?
What is the estimated friction coefficient α for ground with hedges and shrubs?
What is the estimated friction coefficient α for ground with hedges and shrubs?
Using the 1/7th power law, what is the relationship between wind speed and height (v/vo)3?
Using the 1/7th power law, what is the relationship between wind speed and height (v/vo)3?
What is the ratio of specific power in the wind at the highest point that a rotor blade tip reaches to the lowest point that it falls to, for a wind turbine with a 30-m rotor diameter?
What is the ratio of specific power in the wind at the highest point that a rotor blade tip reaches to the lowest point that it falls to, for a wind turbine with a 30-m rotor diameter?
What is the theoretical maximum rotor efficiency, also known as Betz efficiency or Betz’s law?
What is the theoretical maximum rotor efficiency, also known as Betz efficiency or Betz’s law?
If the wind speed is increased from 5 m/s to 15 m/s, what will be the expected increase in power output of the wind turbine (in percentage)?
If the wind speed is increased from 5 m/s to 15 m/s, what will be the expected increase in power output of the wind turbine (in percentage)?
What is the efficiency of the wind turbine when the wind speed is 15 m/s and the actual power output is 3,000 kW?
What is the efficiency of the wind turbine when the wind speed is 15 m/s and the actual power output is 3,000 kW?
Why does the power output level off at 3,000 kW according to the provided text?
Why does the power output level off at 3,000 kW according to the provided text?
What is the rated capacity of the Vestas V164, the world's biggest wind turbine?
What is the rated capacity of the Vestas V164, the world's biggest wind turbine?
What impact does the tower have on wind speed for downwind machines as mentioned in the text?
What impact does the tower have on wind speed for downwind machines as mentioned in the text?
How much energy can be extracted from the wind under the best operating conditions according to the text?
How much energy can be extracted from the wind under the best operating conditions according to the text?
What is the diameter of the Vestas V164, the world's biggest wind turbine?
What is the diameter of the Vestas V164, the world's biggest wind turbine?
What is the overall height of the Vestas V164, the world's biggest wind turbine?
What is the overall height of the Vestas V164, the world's biggest wind turbine?
What is the theoretical maximum rotor efficiency, also known as Betz efficiency or Betz’s law?
What is the theoretical maximum rotor efficiency, also known as Betz efficiency or Betz’s law?
What is the usual way to illustrate rotor efficiency?
What is the usual way to illustrate rotor efficiency?
What is the significance of the tip speed ratio in determining the efficiency of a wind turbine rotor?
What is the significance of the tip speed ratio in determining the efficiency of a wind turbine rotor?
How much energy can be extracted from the wind under the best operating conditions?
How much energy can be extracted from the wind under the best operating conditions?
What is the impact of the tower on wind speed for downwind machines?
What is the impact of the tower on wind speed for downwind machines?
What is the relationship between wind speed and height according to the 1/7th power law?
What is the relationship between wind speed and height according to the 1/7th power law?
What is the primary cause of turbulence (stall) in a wind turbine?
What is the primary cause of turbulence (stall) in a wind turbine?
What is the definition of tip speed?
What is the definition of tip speed?
What is the impact of tower height on wind speed?
What is the impact of tower height on wind speed?
Under what conditions does the 1/7th power law provide an approximate value for the friction coefficient?
Under what conditions does the 1/7th power law provide an approximate value for the friction coefficient?
What is the significance of using average wind speed to predict energy in the wind?
What is the significance of using average wind speed to predict energy in the wind?
How does the efficiency of wind turbine blades change based on wind speed probability distributions?
How does the efficiency of wind turbine blades change based on wind speed probability distributions?
What is the relationship between wind speed at different heights and the roughness of the earth’s surface?
What is the relationship between wind speed at different heights and the roughness of the earth’s surface?
How does the energy output of wind regimes with different wind speeds compare?
How does the energy output of wind regimes with different wind speeds compare?
What is the impact of tower height on wind speed for downwind machines?
What is the impact of tower height on wind speed for downwind machines?
What is the relationship between energy output and wind speed at different heights?
What is the relationship between energy output and wind speed at different heights?
What is the tip-speed-ratio (TSR) of a wind turbine with a rotor diameter of 40m and a rotor speed of 1800 rpm?
What is the tip-speed-ratio (TSR) of a wind turbine with a rotor diameter of 40m and a rotor speed of 1800 rpm?
What is the formula for tip speed in terms of rotor speed (N), rotor diameter (D), and wind speed (v)?
What is the formula for tip speed in terms of rotor speed (N), rotor diameter (D), and wind speed (v)?
At what wind speed does the turbine produce its maximum power output for a Vesta V90 – 3.0 MW turbine with a 90m diameter?
At what wind speed does the turbine produce its maximum power output for a Vesta V90 – 3.0 MW turbine with a 90m diameter?
What is the estimated friction coefficient α for ground with hedges and shrubs?
What is the estimated friction coefficient α for ground with hedges and shrubs?
What is the significance of tip speed ratio in determining the efficiency of a wind turbine rotor?
What is the significance of tip speed ratio in determining the efficiency of a wind turbine rotor?
What causes considerable stress on the tip of the turbine blade when it is rotating?
What causes considerable stress on the tip of the turbine blade when it is rotating?
What gear ratio is needed to match the rotor speed (TSR = 4.0) to the generator speed (1800 rpm) for a wind turbine with a rotor diameter of 40m?
What gear ratio is needed to match the rotor speed (TSR = 4.0) to the generator speed (1800 rpm) for a wind turbine with a rotor diameter of 40m?
What is the theoretical maximum rotor efficiency, also known as Betz efficiency or Betz’s law?
What is the theoretical maximum rotor efficiency, also known as Betz efficiency or Betz’s law?
According to the 1/7th power law, how does the power in the wind at the top tip of the rotor compare to that at the lowest point that it falls to?
According to the 1/7th power law, how does the power in the wind at the top tip of the rotor compare to that at the lowest point that it falls to?
Study Notes
Wind Turbine Efficiency
- Theoretical maximum rotor efficiency, also known as Betz efficiency or Betz's law, is 59.3%.
- Efficiency of rotor decreases if it turns too slowly.
Wind Speed and Tower Impact
- Tower has a significant impact on wind speed for downwind machines.
- Wind speed varies with height according to the 1/7th power law (v/vo)³.
Turbine Blade Noise and Flexing
- Flexing of a blade affects wind turbine noise.
Energy Extraction and Power Output
- Maximum energy that can be extracted from the wind under the best operating conditions is 59.3% of the total energy.
- Power output levels off at 3,000 kW for the Vesta V90 – 3.0 MW turbine.
- Power output increases with wind speed, but levels off at maximum capacity.
Tip Speed Ratio and Rotor Efficiency
- Tip speed ratio (TSR) measures the efficiency of a wind turbine rotor.
- TSR of a wind turbine with a rotor diameter of 40m and a rotor speed of 1800 rpm is 4.0.
- Formula for tip speed is (πDN)/60, where N is the rotor speed, D is the rotor diameter, and v is the wind speed.
Wind Turbine Design and Operation
- Vestas V164 is the world's biggest wind turbine, with a diameter of 164m and a height of 220m.
- Rated capacity of the Vestas V164 is 9.5 MW.
- Tower height has a significant impact on wind speed and energy output.
Turbulence and Stall
- Primary cause of turbulence (stall) in a wind turbine is angle of attack.
- Stall control involves shifting the rotor axis out of the wind direction when wind speed exceeds the design limit.
Wind Speed Probability Distributions
- Efficiency of wind turbine blades changes based on wind speed probability distributions.
- Average wind speed cannot be used to predict energy in the wind.
Roughness of the Earth's Surface
- Wind speed at different heights is related to the roughness of the earth's surface.
- Energy output of wind regimes with different wind speeds compares using the 1/7th power law.
Gear Ratio and Generator Speed
- Gear ratio is needed to match the rotor speed (TSR = 4.0) to the generator speed (1800 rpm) for a wind turbine with a rotor diameter of 40m.
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Description
Test your knowledge about wind turbine blade tip speed and related concepts with this quiz. Explore topics like tip speed ratio and centrifugal force.
