Wind Energy: Tip Speed Ratio and Tower Spacing

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What is the term used to describe the phenomenon when the wind begins to tumble over the top of the rotor, destroying the low pressure area created by the smooth flowing air over the top of the rotor blade?

Turbulence (correct)

Tip speed ratio

Stall

Angle of Attack

What is the angle between the apparent wind and the chord line of the wind turbine blade known as?

Angle of Attack (correct)

Tip speed ratio

Turbulence

Apparent wind

Which factor defines the maximum operating efficiency of each wind turbine?

Apparent wind

Turbulence

Tip speed ratio (correct)

Angle of Attack

At which part of the wind turbine blade does the tip speed reach its highest value?

Tip Signup and view all the answers

What happens to the lifting force of the rotor blade when the wind speed becomes too high due to turbulence?

It decreases Signup and view all the answers

What contributes to the increase in noise generated by wind turbines?

The flexing of the blades Signup and view all the answers

What is the theoretical maximum rotor efficiency, also known as Betz efficiency?

59.3 percent Signup and view all the answers

What percentage of energy can be achieved in converting the power in the wind to the power of a rotating generator shaft under the best operating conditions?

35 to 45 percent Signup and view all the answers

What happens if the rotor turns too slowly in terms of efficiency?

Efficiency drops off Signup and view all the answers

How is rotor efficiency usually illustrated?

As a function of tip-speed ratio (TSR) Signup and view all the answers

What is the estimated friction coefficient (α) for ground with hedges and shrubs in the given scenario?

0.20 Signup and view all the answers

At what height is the wind speed and power density being estimated in the first example discussed in the text?

50 m Signup and view all the answers

In the second example, what is the ratio of power at the top of the wind turbine blade swing (65 m) to that at the bottom of its swing (35 m)?

1:1.45 Signup and view all the answers

What does the equation (v/vo)^3 = (H/Ho)^α.3 = (H/Ho)^3α illustrate?

The variation in wind speed and power across the face of a spinning rotor Signup and view all the answers

What is the wind speed at a height of 50 m if the wind speed at 10 m is 5 m/s, considering the 1/7th power law?

12.5 m/s Signup and view all the answers

What is the definition of tip speed?

The measured speed at the blade tip as it rotates through the air Signup and view all the answers

Why does the tip of the turbine blade come under considerable stress?

Caused by centrifugal force when rotating Signup and view all the answers

What does Tip Speed Ratio (TSR) measure?

The speed of the blade at its tip in relation to the wind speed Signup and view all the answers

Which speed control method involves shifting the rotor axis out of the wind direction when the wind speed exceeds the design limit?

Yaw and tilt control method Signup and view all the answers

When does stall control method come into play in wind turbines?

During gusty wind conditions Signup and view all the answers

What is the tip-speed-ratio (TSR) of a wind turbine with a rotor speed of 15 rpm and a wind speed of 5 m/s?

3.0 Signup and view all the answers

At what rpm does the rotor of a wind turbine turn when it operates with a TSR of 6.0?

25 Signup and view all the answers

What gear ratio is needed to match the rotor speed to the generator speed if the rotor turns at 2000 rpm and the generator needs to turn at 1800 rpm?

0.9 Signup and view all the answers

What is the efficiency of the complete wind turbine (blades, gear box, generator) if the turbine produces 800 kW at a wind speed of 20 m/s?

66.7% Signup and view all the answers

Why does the power output level off at 3,000 kW in a Vesta V90 – 3.0 MW turbine when wind speed increases beyond a certain point?

Blade stress exceeds the safe limit Signup and view all the answers

What is the formula for calculating tip speed of a wind turbine rotor?

π D N / 60 Signup and view all the answers

How does the wind speed affect the tip speed of a wind turbine rotor?

Directly proportional to tip speed Signup and view all the answers

What is the recommended spacing for wind turbine towers in the crosswind direction?

3 to 5 rotor diameters apart Signup and view all the answers

How does the wind shear at ground surface affect wind speed with height?

Causes an increase in wind speed with height Signup and view all the answers

Why can't average wind speed alone be used to predict total energy available from a wind regime?

Due to the non-linear relationship between power and wind speed Signup and view all the answers

What is the wind speed for the turbine with an actual power output of 250 kW?

5 m/s Signup and view all the answers

What is the efficiency of the turbine with a wind speed of 15 m/s?

23.2% Signup and view all the answers

What is the diameter of the Vestas V164 wind turbine?

164 m Signup and view all the answers

What is the rated capacity of the Vestas V164 wind turbine in MW?

9.5 MW Signup and view all the answers

What is the reason for limiting the turbine from rotating faster?

To prevent too much force on it, leading to damage Signup and view all the answers

What is the input power for the turbine with an actual power output of 3,000 kW?

$13,000 kW$ Signup and view all the answers

What is the overall height of the Vestas V164 wind turbine?

$722 ft$ Signup and view all the answers

What is the calculated efficiency for a wind speed of 20 m/s?

Unknown Signup and view all the answers

Why does the power output level off at 3,000 kW?

To limit the turbine from rotating faster and prevent too much force on it, leading to damage Signup and view all the answers

What is the input power for the turbine with an actual power output of 250 kW?

$477,125 W$ Signup and view all the answers

What impact does tower height have on wind speed?

Tower height greatly affects wind speed by causing friction as the air moves across the earth's surface. Signup and view all the answers

Under what conditions is the friction coefficient approximately 1/7?

The friction coefficient is approximately 1/7 under neutral stability conditions. Signup and view all the answers

Why is it inaccurate to use average wind speeds to predict total energy available from a wind regime?

Using average wind speeds is inaccurate because the combination of different wind speeds can produce significantly more energy than a steady average wind speed. Signup and view all the answers

What is the formula for estimating wind speed at a certain height using the 1/7th power law?

The formula is (v/vo)^3 = (H/Ho)^α, where v is the wind speed at height H, vo is the wind speed at height Ho, and α is the friction coefficient. Signup and view all the answers

How does the combination of different wind speeds affect energy production compared to a steady average wind speed?

The combination of different wind speeds can produce 75% more energy than winds blowing at a steady average speed. Signup and view all the answers

What is the tip-speed-ratio (TSR) formula for a wind turbine?

TSR = (rpm * D) / v Signup and view all the answers

What is the rotor speed (rpm) when operating with a TSR of 4.0?

300 rpm Signup and view all the answers

What is the tip speed of the rotor for a wind turbine with a TSR of 4.0 and wind speed of 14 m/s?

120 m/s Signup and view all the answers

What gear ratio is needed to match the rotor speed to the generator speed if the rotor turns at 1800 rpm and the generator needs to turn at 1800 rpm?

1:1 Signup and view all the answers

What is the efficiency of the complete wind turbine (blades, gear box, generator) if it produces 600 kW at a wind speed of 14 m/s?

36% Signup and view all the answers

What is the formula for calculating tip speed of a wind turbine rotor?

Tip speed = π D N / 60 Signup and view all the answers

How does the wind shear at ground surface affect wind speed with height?

The wind shear at ground surface causes the wind speed to increase with height according to the expression V2 = V1 * (h2 / h1)^α Signup and view all the answers

What is the definition of tip speed?

Tip speed refers to the speed at which the tip of the wind turbine blade moves through the air. Signup and view all the answers

What is the term used to describe the phenomenon when the wind begins to tumble over the top of the rotor, destroying the low pressure area created by the smooth flowing air over the top of the rotor blade?

The term used to describe this phenomenon is 'stall'. Signup and view all the answers

What is the efficiency of the turbine with a wind speed of 15 m/s?

The efficiency of the turbine at a wind speed of 15 m/s can be calculated using the appropriate efficiency formula. Signup and view all the answers

What is the wind speed at 50 m if the wind speed at 10 m is 5 m/s, considering the 1/7th power law?

3.37 m/s Signup and view all the answers

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?

1.45 Signup and view all the answers

What is the estimated friction coefficient (α) for ground with hedges and shrubs in the given scenario?

0.20 Signup and view all the answers

What does the equation (v/vo)^3 = (H/Ho)^α.3 = (H/Ho)^3α illustrate?

The 1/7th power law Signup and view all the answers

How much more power density is available at 50 m compared to 10 m from the given scenario?

More than two and one-half times Signup and view all the answers

What is the tip speed ratio (TSR) of a blade if it is traveling at a speed of 150 mph and the wind speed is 30 mph?

5 Signup and view all the answers

What does the stall control method accomplish in wind turbines?

It shifts the blades into a position that causes them to stall when the wind speed exceeds the safe limit on the system. Signup and view all the answers

What is the term used to describe the method of speed control where the rotor axis is shifted out of the wind direction when the wind speed exceeds the design limit?

Yaw and tilt control Signup and view all the answers

How does the wind speed affect the tip speed of a wind turbine rotor?

The tip speed of the rotor increases with higher wind speeds. Signup and view all the answers

What is the angle between the apparent wind and the chord line of the wind turbine blade known as?

Pitch angle Signup and view all the answers

What is the phenomenon that prevents the lifting force of the rotor blade from acting on the rotor when the wind is too high?

Turbulence (or stall) Signup and view all the answers

What is the ratio of tangential velocity at the tip of the blade to the undisturbed upwind velocity in a wind turbine?

Tip speed ratio Signup and view all the answers

At what range are tip speed ratios typically found for low solidity turbines?

4 – 8 Signup and view all the answers

What is the wind phenomenon where the wind begins to tumble over the top of the rotor, destroying the low pressure area created by the smooth flowing air over the top of the rotor blade?

Turbulence (or stall) Signup and view all the answers

What angle is defined as the angle between the apparent wind and the chord line in a wind turbine blade?

Angle of Attack Signup and view all the answers

What is the impact of tower height on wind speed?

Tower height can impact wind speed, especially for downwind machines, which have a significant amount of wind 'shadowing' as the blades pass behind the tower. Signup and view all the answers

How is wind speed at a certain height estimated using the 1/7th power law?

The formula for estimating wind speed at a certain height using the 1/7th power law is: $v_2 = v_1 (H_2/H_1)^{1/7}$ Signup and view all the answers

What is the impact of wind shear at ground surface on wind speed with height?

Wind shear at the ground surface can cause the wind speed to increase with height, following the 1/7th power law. Signup and view all the answers

Why is it inaccurate to use average wind speeds to predict total energy available from a wind regime?

It is inaccurate to use average wind speeds alone to predict total energy available from a wind regime because the combination of different wind speeds affects energy production differently than a steady average wind speed. Signup and view all the answers

What is the formula for calculating tip speed of a wind turbine rotor?

The formula for calculating tip speed of a wind turbine rotor is: $TSR = rac{ ext{Rotor speed} imes ext{Blade length}}{ ext{Wind speed}}$ Signup and view all the answers

What is the wind speed at a height of 50 m if the wind speed at 10 m is 5 m/s, considering the 1/7th power law?

The wind speed at a height of 50 m, considering the 1/7th power law, is approximately 10.6 m/s. Signup and view all the answers

Under what conditions is the friction coefficient approximately 1/7?

The friction coefficient is approximately 1/7 for ground with hedges and shrubs. Signup and view all the answers

What is the estimated friction coefficient (α) for ground with hedges and shrubs in the given scenario?

The estimated friction coefficient (α) for ground with hedges and shrubs in the given scenario is 1/7. Signup and view all the answers

What is the wind speed for the turbine with an actual power output of 250 kW?

The wind speed for the turbine with an actual power output of 250 kW depends on various factors and cannot be determined solely based on the given text. Signup and view all the answers

What contributes to the increase in noise generated by wind turbines?

The resulting flexing of a blade, caused by wind forces and tower impact, can increase the noise generated by wind turbines. Signup and view all the answers

Wind Energy: Tip Speed Ratio and Tower Spacing

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Questions and Answers

What is the term used to describe the phenomenon when the wind begins to tumble over the top of the rotor, destroying the low pressure area created by the smooth flowing air over the top of the rotor blade?

What is the angle between the apparent wind and the chord line of the wind turbine blade known as?

Which factor defines the maximum operating efficiency of each wind turbine?

At which part of the wind turbine blade does the tip speed reach its highest value?

What happens to the lifting force of the rotor blade when the wind speed becomes too high due to turbulence?

What contributes to the increase in noise generated by wind turbines?

What is the theoretical maximum rotor efficiency, also known as Betz efficiency?

What percentage of energy can be achieved in converting the power in the wind to the power of a rotating generator shaft under the best operating conditions?

What happens if the rotor turns too slowly in terms of efficiency?

How is rotor efficiency usually illustrated?

What is the estimated friction coefficient (α) for ground with hedges and shrubs in the given scenario?

At what height is the wind speed and power density being estimated in the first example discussed in the text?

In the second example, what is the ratio of power at the top of the wind turbine blade swing (65 m) to that at the bottom of its swing (35 m)?

What does the equation (v/vo)^3 = (H/Ho)^α.3 = (H/Ho)^3α illustrate?

What is the wind speed at a height of 50 m if the wind speed at 10 m is 5 m/s, considering the 1/7th power law?

What is the definition of tip speed?

Why does the tip of the turbine blade come under considerable stress?

What does Tip Speed Ratio (TSR) measure?

Which speed control method involves shifting the rotor axis out of the wind direction when the wind speed exceeds the design limit?

When does stall control method come into play in wind turbines?

What is the tip-speed-ratio (TSR) of a wind turbine with a rotor speed of 15 rpm and a wind speed of 5 m/s?

At what rpm does the rotor of a wind turbine turn when it operates with a TSR of 6.0?

What gear ratio is needed to match the rotor speed to the generator speed if the rotor turns at 2000 rpm and the generator needs to turn at 1800 rpm?

What is the efficiency of the complete wind turbine (blades, gear box, generator) if the turbine produces 800 kW at a wind speed of 20 m/s?

Why does the power output level off at 3,000 kW in a Vesta V90 – 3.0 MW turbine when wind speed increases beyond a certain point?

What is the formula for calculating tip speed of a wind turbine rotor?

How does the wind speed affect the tip speed of a wind turbine rotor?

What is the recommended spacing for wind turbine towers in the crosswind direction?

How does the wind shear at ground surface affect wind speed with height?

Why can't average wind speed alone be used to predict total energy available from a wind regime?

What is the wind speed for the turbine with an actual power output of 250 kW?

What is the efficiency of the turbine with a wind speed of 15 m/s?

What is the diameter of the Vestas V164 wind turbine?

What is the rated capacity of the Vestas V164 wind turbine in MW?

What is the reason for limiting the turbine from rotating faster?

What is the input power for the turbine with an actual power output of 3,000 kW?

What is the overall height of the Vestas V164 wind turbine?

What is the calculated efficiency for a wind speed of 20 m/s?

Why does the power output level off at 3,000 kW?

What is the input power for the turbine with an actual power output of 250 kW?

What impact does tower height have on wind speed?

Under what conditions is the friction coefficient approximately 1/7?

Why is it inaccurate to use average wind speeds to predict total energy available from a wind regime?

What is the formula for estimating wind speed at a certain height using the 1/7th power law?

How does the combination of different wind speeds affect energy production compared to a steady average wind speed?

What is the tip-speed-ratio (TSR) formula for a wind turbine?

What is the rotor speed (rpm) when operating with a TSR of 4.0?

What is the tip speed of the rotor for a wind turbine with a TSR of 4.0 and wind speed of 14 m/s?

What gear ratio is needed to match the rotor speed to the generator speed if the rotor turns at 1800 rpm and the generator needs to turn at 1800 rpm?

What is the efficiency of the complete wind turbine (blades, gear box, generator) if it produces 600 kW at a wind speed of 14 m/s?

What is the formula for calculating tip speed of a wind turbine rotor?

How does the wind shear at ground surface affect wind speed with height?

What is the definition of tip speed?

What is the term used to describe the phenomenon when the wind begins to tumble over the top of the rotor, destroying the low pressure area created by the smooth flowing air over the top of the rotor blade?

What is the efficiency of the turbine with a wind speed of 15 m/s?

What is the wind speed at 50 m if the wind speed at 10 m is 5 m/s, considering the 1/7th power law?

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?

What is the estimated friction coefficient (α) for ground with hedges and shrubs in the given scenario?

What does the equation (v/vo)^3 = (H/Ho)^α.3 = (H/Ho)^3α illustrate?

How much more power density is available at 50 m compared to 10 m from the given scenario?

What is the tip speed ratio (TSR) of a blade if it is traveling at a speed of 150 mph and the wind speed is 30 mph?

What does the stall control method accomplish in wind turbines?

What is the term used to describe the method of speed control where the rotor axis is shifted out of the wind direction when the wind speed exceeds the design limit?

How does the wind speed affect the tip speed of a wind turbine rotor?

What is the angle between the apparent wind and the chord line of the wind turbine blade known as?

What is the phenomenon that prevents the lifting force of the rotor blade from acting on the rotor when the wind is too high?

What is the ratio of tangential velocity at the tip of the blade to the undisturbed upwind velocity in a wind turbine?

At what range are tip speed ratios typically found for low solidity turbines?

What is the wind phenomenon where the wind begins to tumble over the top of the rotor, destroying the low pressure area created by the smooth flowing air over the top of the rotor blade?

What angle is defined as the angle between the apparent wind and the chord line in a wind turbine blade?

What is the impact of tower height on wind speed?

How is wind speed at a certain height estimated using the 1/7th power law?

What is the impact of wind shear at ground surface on wind speed with height?

Why is it inaccurate to use average wind speeds to predict total energy available from a wind regime?

What is the formula for calculating tip speed of a wind turbine rotor?

What is the wind speed at a height of 50 m if the wind speed at 10 m is 5 m/s, considering the 1/7th power law?

Under what conditions is the friction coefficient approximately 1/7?