WIND ENERGY

Power available in the wind spectra _____________________

• $P=\frac{1}{2}\ \rho_a\ A_T\ V^3$

• $P=\frac{1}{2}\ \rho_a\ A_T\ V^2$

• $P=\frac{1}{2}\ \rho_a\ A_T^3\ V^{ }$

• $P=\frac{1}{2}\ \rho_a\ A_T\ V^{ }$

Equation for power coefficient Cp = ____________

•  $C_P=\ \ \frac{2P_T}{\rho_a\ A_{T\ }V^{ }}$  

•  $C_P=\ \ \frac{2P_T}{\rho_a\ A_{T\ }V^2}$  

•  $C_P=\ \ \frac{2P_T}{\rho_a\ A_{T\ }V^3}$  

•  $C_P=\ \ \frac{2P_T}{\rho_a\ A_{T\ }^3V^{ }}$  

Coefficient of power can be calculated with  $C_{P\ }=\frac{2\ T_T\ \Omega}{\rho_a\ A_TV^3}$  

• TRUE

• FALSE

What is tip speed ratio ?

• The tip speed ratio is given by the ratio between the velocity and power coefficient of the rotor.

• The tip speed ratio is given by the ratio between the torque coefficient and power coefficient of the rotor.

• The tip speed ratio is given by the ratio between the power coefficient and torque coefficient of the rotor.

• The tip speed ratio is given by the ratio between the torque coefficient and velocity of the rotor.

Tip speed ratio is denoted using :

• $\delta$

• $\sigma$

• $\rho$

• $\lambda$

Select the correct equations that can be used for calculating Tip speed Ratio (More than One Option) :

• $\frac{C_P}{C_T}$

• $\frac{C_T}{C_P}$

• $\frac{R\ V}{\Omega}$

• $\frac{R\ \Omega}{V}$

Check whether the sentence is True or False

Horizontal axis wind turbines (HAWT) have their axis of rotation horizontal to the ground and almost parallel to the wind stream

• TRUE

• FALSE

Select the statements true for Horizontal Axis Wind Turbines (More than One Option)

• Their axis of rotation vertical to the ground.

• The generator and gearbox of these turbines are placed in ground.

• Need for the tail or yaw drive to orient the turbine towards wind.

• Relatively high power coefficient.

Select the correct statement applicable for single bladed HAWT

• The drag losses are maximum for single bladed turbines.

• Single bladed designs are very popular due to visual acceptability.

• Single bladed turbines are cheaper due to savings on blade materials.

• They have high Solidity

Which Statement is TRUE for an Upwind Turbine ?

• They may be uneven loading on the blades.

• In Upwind turbines the rotors are placed at the lee side of the tower.

• No need of yaw mechanism.

• They do not have the problem of tower shadow.