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Chapter 6 > 6.6 > Flashcards

6.6 Flashcards

1
Q

is air moving from an area of high pressure
to an area of low pressure and results
chiefly from natural convection driven by
uneven heating of the earth’s surface and
to a certain extent from the rotation of the
earth.

A

Wind

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2
Q

*is the velocity of the wind in relation to the
ground

A

Wind Speed

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3
Q

was expressed using the direction of a 32-
point compass

A

Wind Direction

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4
Q

is a bearing from true north in degrees
clockwise in the direction from which the
wind is blowing

A

*Wind azimuth

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5
Q

is the direction from which the
wind blows

A

*windward

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6
Q

is the direction in which the wind
is blowing

A

*leeward

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7
Q

is
used to detect wind direction

A

*wind vane, windsock, or wind sensor

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8
Q

A ____________ has a vertical axis and
three cups that catch the wind and cause it
to rotate about its axis

A

cup anemometer

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9
Q

is measured with an
anemometer or wind sensor

A

Wind speed

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10
Q

detect wind speed and
direction

A

*Ultrasonic sensors

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11
Q

t or f
Wind speed and direction are always
fluctuating

A

t

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12
Q

t or f
wind tends to change direction more
frequently and be more turbulent during
the nightime hour

A

f ( daytime hour)

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13
Q

is a polar bar graph that
illustrates the distribution of winds at a
specific location

A

wind rose

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14
Q

t or f
The roughness of the surface over which
the wind blows affects its speed

A

t

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15
Q

most familiar wind energy system

A

Dutch windmill

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16
Q

collects kinetic energy from the wind and
converts it to electricity with its sleek
aerodynamic blades and tall tower

A

Wind turbine

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17
Q

*has a rotor with an axis of rotation that is
horizontal with respect to the ground and
parallel to the wind stream
*designed to operate in an upwind mode,
with the blades upwind of the tower

A

Horizontal-Axis Wind Turbines (HAWT)

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18
Q

is usually used to keep the blades
facing into the wind

A

*tail vane

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19
Q

*has blades with an axis of rotation that is
vertical with respect to the ground and
roughly perpendicular to the wind stream
*basic VAWT designs are the Darrieus,
Giromill, and Savonius

A

Vertical-Axis Wind Turbines(VAWT)

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20
Q

has a rotor section that has
multiple curved blades that look like an
eggbeater.

A

Darrieus VAWT

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21
Q

is similar to the Darrieus VAWT
except that it has straight vertical axis
blades

A

Giromill

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22
Q

has a rotor section that is
S-shaped when viewed from above. A welldesigned Savonius turbine can have a tip
speed ratio of slightly greater than 1

A

Savonius VAWT

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23
Q

converts the energy in the
wind to rotational shaft energy

A

blade or rotor

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24
Q

usually including a gearbox and a
generator

A

drive train

25
Q

*collects energy from the wind

A

Rotor

26
Q

blades are attached to the rotor hub,
which in turn is attached to the ___________
which includes the gearbox, low- and highspeed shafts, generator, controller, and
brake

A

nacelle,

27
Q

*In ______ design, the wind pushes the rotor
blades out of the way

A

drag

28
Q

The ______design is aeronautically designed as
an airfoil or wing that makes use of the
principle that enables airplanes, kites, and
birds to fly

A

lift

29
Q

is the minimum wind speed at
which the blades will turn and generate
useable power

A

*Cut-in speed

30
Q

is the minimum wind
speed at which the wind turbine will
generate its designated rated power

A

rated speed

31
Q

identify wind turbine output
versus wind speed.

A

power curves

32
Q

is the wind speed at which
shutdown occur

A

cut-out speed

33
Q

is the relationship between
rotational speed of the tips of the rotor
blade to the wind speed

A

speed ratio

34
Q

is an
electromechanical device that converts
mechanical energy into electrical energy

A

Generator

35
Q

A ________ transmission is used to step up
rotational speed of the wind turbine to
speeds required for operation of the
generator

A

gearbox

36
Q

a structure that elevates the wind turbine
so it can reach stronger winds at higher
elevations and to provide blade-to-ground
clearance.

A

Tower

37
Q

is built on a stable
and substantial foundation and stands in
place without the use of guy wires

A

freestanding tower

38
Q

is held in place with guy
wires anchored to the ground on three or
four sides of the tower

A

guyed tower

39
Q

Most stand-alone systems fall into one of 3
categories:
*_______ systems (100 W or less)
*_____ systems (100 W to 10 kW)
*_____ systems ( 10 kW to 50 kW)

A

*Micro systems (100 W or less)
*Mini systems (100 W to 10 kW)
*Small systems ( 10 kW to 50 kW)

40
Q

refers to the practice of selecting ideal sites or locations
for wind turbines.

A

Siting

41
Q
  • The main criterion for a good wind power site is ______________.
A

average
speed

42
Q

__________ on the site may limit the allowable
tower height, requiring of a conditional permit from your
city planning department

A

Zoning restrictions

43
Q

– Produces power independently of the utility grid.
– This system can be more cost-effective than extending a
power lone to the electricity grid.
– They are especially appropriate for remote,
environmentally sensitive areas, such as national parks,
cabins, and remote homes.

A

Stand-Alone Systems

44
Q

need no electrical storage because
they operate only during daylight hours.

A

Direct-coupled systems

45
Q

can supply the owner with reserve power
whenever energy demand exceeds delivered by the WECS

A

Battery systems

46
Q

interface with the utility grid.
– It supplies surplus power back through the grid to the
utility and obtain power from the utility grid when the
buildings system’s power supply is low.
– These systems eliminate the for battery storage.

A
  • Grid-connected systems–
47
Q

Some utilities only use a __________ where it turns
backwards when the system is producing more power than
it is consuming. This measuring technique is called ____________

A

single meter, net
metering

48
Q

*is a measure of the energy available in the
wind over a period of time

A

Theoretical Wind Power

49
Q

*is the unit power (W/m2
) in moving air at a
specific speed (v), in mph or m/s

A

Wind Power Density

50
Q

if wind speed is doubled, power in the
wind increases by a factor of 8 (2
3=8); if
wind speed is tripled, wind power
increases by a factor of 27 (3
3=27)

A

Law of the Cube

51
Q

*the maximum aerodynamic efficiency of a
wind turbine rotor is 0.593 (or 59.3%)

A

Betz Limit

52
Q

Able to
maintain
high
efficiency

A

Flat Curve

53
Q

Experiences
a drastic
efficiency
drop

A

Sharp Curve

54
Q

*A complete wind energy system will
produce between__and ___% of the energy
available in the wind

A

5 and 30%

55
Q

*The power available in the wind is related
to the speed of the wind and the density of
the air

A

Wind Turbine Power

56
Q

is a useful way to assess the wind
energy available at a potential wind turbine site.

A

Wind power density

57
Q

The _________ capacity of a wind turbine for a particular
installation depends on the maximum overall load and on the
wind conditions at the site

A

generating

58
Q
A

Chapter 6 (8 decks)

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