Wind power

Question 1

Horizontal axis wind turbines

Answer 1

most common, single/double/triple, most have 3

Question 2

solidity

Answer 2

number of blades determines solidity, how much area is covered in blades, 3 blades have low solidity

Question 3

turbine parts

Answer 3

gearbox (middle), pillar, generator (middle), nacelle (back), yaw control motor (back)

Question 4

lift principle/aerofoil

Answer 4

high velocity on one side, low velocity on other, air travels faster above blade than slower air at bottom as has to move over more area and causes uplift, flow of fast moving air makes pressure difference and moves turbine

Question 5

power of wind equaton

Answer 5

1/2 x area swept by blades x air density x velocity(3)

Question 6

Kinetic energy equation

Answer 6

1/2 x mass x velocity (2)

Question 7

Mass equation

Answer 7

volume x density

Question 8

what is the power of the wind mean

Answer 8

kinetic energy and mass of the wind

Question 9

upstream and downstream wind

Answer 9

upstream goes into turbine downstream goes out, downstream is slower as energy is converted to heat

Question 10

turbine efficiency

Answer 10

40%, means turbines extract 40% energy, if all energy extracted then there would be no downstream

Question 11

Power coefficient equation

Answer 11

energy extracted by the wind, 4a (1-a)(2)

Question 12

a

Answer 12

interference factor

Question 13

a equation

Answer 13

v(o) - v(1)/v(o)

Question 14

Betz limit

Answer 14

maximum theoretical efficiency, maximum when power coefficient is maximum

Question 15

power of turbine

Answer 15

c(p) x p(w) = 1/2 x c(p) x air density x area of blades x velocity (3)

Question 16

Make sure units are always the same and base units

Answer 16

s, W, J, Kg, m/cm etc

Question 17

beufort scale

Answer 17

classifies wind speed, 0 is calm 13 is stormy, 3 moves turbines, 4 generates power, 6 full power

Question 18

cut in speed

Answer 18

minimum wind speed, not enough to turn turbines

Question 19

cut out speed

Answer 19

maximum wind speed, wind speed to high

Question 20

cut in/out speed cycle

Answer 20

wind increases past cut in speed and power output raises to rated power output (maximum power that can be produced), rated power output is constant till it reaches cut out speed

Question 21

rated wind speed

Answer 21

minimum wind speed to make rated power output

Question 22

capacity factor

Answer 22

how often power plant runs at maximum power, average power output/maximum theorical

Question 23

how to work out average power output

Answer 23

multiply by capacity factor