U.S. patent application number 13/617695 was filed with the patent office on 2013-07-25 for fluid turbine lightning protection system.
This patent application is currently assigned to FLODESIGN WIND TURBINE CORP.. The applicant listed for this patent is Soren Hjort, Rasmus Peter Jensen. Invention is credited to Soren Hjort, Rasmus Peter Jensen.
Application Number | 20130189099 13/617695 |
Document ID | / |
Family ID | 47430030 |
Filed Date | 2013-07-25 |
United States Patent
Application |
20130189099 |
Kind Code |
A1 |
Jensen; Rasmus Peter ; et
al. |
July 25, 2013 |
Fluid Turbine Lightning Protection System
Abstract
A fluid turbine lightning protection system includes at least
one air termination device, formed at least in part of an
electrically conductive material, that can be positioned on a
shroud of a fluid turbine and placed in electrical communication
with a down conduction system. The down conduction system is in
electrical communication with an earth-termination system
configured to dissipate electricity transferred thereto to the
ground. The at least one air termination device is configured to
intercept a lightning strike and direct it through the down
conduction system, the earth-termination system, and into the
ground. The at least one air termination device may be positioned
on a turbine shroud based on a "Rolling Sphere" derivation wherein
the "Rolling Sphere" derivation is derived from the equation
r=10I.sup.0.65, where I is the peak current in kiloamperes and r is
the rolling sphere radius in meters.
Inventors: |
Jensen; Rasmus Peter;
(Gjern, DK) ; Hjort; Soren; (Silkeborg,
DK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Jensen; Rasmus Peter
Hjort; Soren |
Gjern
Silkeborg |
|
DK
DK |
|
|
Assignee: |
FLODESIGN WIND TURBINE
CORP.
Waltham
MA
|
Family ID: |
47430030 |
Appl. No.: |
13/617695 |
Filed: |
September 14, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61534467 |
Sep 14, 2011 |
|
|
|
Current U.S.
Class: |
416/1 ;
416/244R |
Current CPC
Class: |
F01D 25/00 20130101;
F03D 1/04 20130101; F03D 80/30 20160501; Y02E 10/72 20130101; Y02E
10/726 20130101; Y02E 10/722 20130101 |
Class at
Publication: |
416/1 ;
416/244.R |
International
Class: |
F01D 25/00 20060101
F01D025/00 |
Claims
1. A fluid turbine lightning protection system, comprising: at
least one air termination device positionable on a shroud of a
fluid turbine, the air termination device formed at least in part
of an electrically conductive material; a down conduction system in
electrical communication with the at least one air termination
device; and an earth-termination system in electrical communication
with the down conduction system, the earth-termination system
configured to dissipate electricity to the ground, wherein the at
least one air termination device is configured to intercept a
lightning strike.
2. The fluid turbine lightning protection system of claim 1,
wherein the at least one air termination device comprises a
plurality of air termination devices positioned on the shroud of
the fluid turbine and configured to intercept a lightning strike
based on a "Rolling Sphere" derivation.
3. The fluid turbine lightning protection system of claim 2,
wherein the "Rolling Sphere" derivation is derived from the
equation r=10I.sup.0.65, where I is defined as the peak current in
kiloamperes and r is defined as the rolling sphere radius in
meters.
4. The fluid turbine lightning protection system of claim 1,
wherein the fluid turbine includes an ejector shroud and at least
one air termination device is positionable on the ejector
shroud.
5. The fluid turbine lightning protection system of claim 1,
wherein the shroud of the fluid turbine further includes: an
external electrically conductive material; and an internal
electrically conductive material, wherein the external electrically
conductive material is conductively engaged with the internal
electrically conductive material, and the internal electrically
conductive material is electrically engaged with the down
conduction system.
6. The fluid turbine lightning protection system of claim 5,
wherein the internal electrically conductive material is in
electrical communication with the down conductive system through a
electrical wiper system.
7. The fluid turbine lightning protection system of claim 5,
wherein the external electrically conductive material is positioned
at a leading edge of the turbine shroud.
8. The fluid turbine lightning protection system of claim 5,
wherein the internal electrically conductive material is integrated
with the surface of the turbine shroud.
9. The fluid turbine lightning protection system of claim 4,
wherein the ejector shroud further comprises: an external
electrically conductive material; and an internal electrically
conductive material, wherein the external electrically conductive
material is conductively engaged with the internal electrically
conductive material, and the internal electrically conductive
material is electrically engaged with the down conduction
system.
10. The fluid turbine lightning protection system of claim 9,
wherein the internal electrically conductive material is in
electrical communication with the down conductive system through an
electrical wiper system.
11. The fluid turbine lightning protection system of claim 9,
wherein the external electrically conductive material is positioned
at a trailing edge of the ejector shroud.
12. The fluid turbine lightning protection system of claim 9,
wherein the internal electrically conductive material is integrated
with the surface of the ejector shroud.
13. A lightning protected fluid turbine, comprising: a fluid
turbine including a shroud; at least one air termination device
positioned on the shroud of the fluid turbine, the air termination
system formed at least in part of an electrically conductive
material; a down conduction system in electrical communication with
the at least one air termination device; and an earth-termination
system in electrical communication with the down conduction system,
the earth-termination system configured to dissipate electricity to
the ground, wherein the at least one air termination device is
configured to intercept a lightning strike so as to prevent the
lightning from striking the fluid turbine.
14. The lightning protected fluid turbine of claim 13, wherein the
at least one air termination device comprises a plurality of air
termination devices positioned on the shroud of the fluid turbine
and configured to intercept a lightning strike based on a "Rolling
Sphere" derivation.
15. The lightning protected fluid turbine of claim 14, wherein the
"Rolling Sphere" derivation is derived from the equation
r=10I.sup.0.65, where I is defined as the peak current in
kiloamperes and r is defined as the rolling sphere radius in
meters.
16. The lightning protected fluid turbine of claim 13, wherein the
fluid turbine includes an ejector shroud and at least one air
termination device is positionable on the ejector shroud.
17. The lightning protected fluid turbine of claim 13, wherein the
shroud of the fluid turbine further includes: an external
electrically conductive material; and an internal electrically
conductive material, wherein the electrically conductive material
is conductively engaged with the internal electrically conductive
material, and the internal electrically conductive material is
electrically engaged with the down conduction system.
18. The lightning protected fluid turbine of claim 17, wherein the
internal electrically conductive material is in electrical
communication with the down conductive system through an electrical
wiper system.
19. The lightning protected fluid turbine of claim 17, wherein the
external electrically conductive material is positioned at a
leading edge of the shroud of the fluid turbine.
20. The lightning protected fluid turbine of claim 17, wherein the
internal electrically conductive material is integrated with the
surface of the shroud of the fluid turbine.
21. The lightning protected fluid turbine of claim 16, wherein the
ejector shroud further includes: an external electrically
conductive material; and an internal electrically conductive
material, wherein the electrically conductive material is
conductively engaged with the internal electrically conductive
material, and the internal electrically conductive material is
electrically engaged with the down conduction system.
22. The lightning protected fluid turbine of claim 21, wherein the
internal electrically conductive material is in electrical
communication with the down conductive system through an electrical
wiper system.
23. The lightning protected fluid turbine of claim 21, wherein the
external electrically conductive material is positioned at a
trailing edge of the ejector shroud.
24. The lightning protected fluid turbine of claim 21, wherein the
internal electrically conductive material is integrated with the
surface of the ejector shroud.
25. A method of protecting a fluid turbine from a lightning strike,
comprising: providing a fluid turbine including a shroud;
determining a peak lightning strike current; calculating a "Rolling
Sphere" circumference or radius based on the equation:
r=10I.sup.0.65, where I is defined as the peak lightning strike
current in kiloamperes and r is defined as the rolling sphere
radius in meters; and positioning one or more air termination
devices on the shroud that are in electrical communication with a
down conduction system that is in electrical communication with a
earth-termination system, wherein the one or more air termination
devices are positioned on the shroud such that the calculated
"Rolling Sphere" contacts the one or more air termination devices
before contacting the shroud when the "Rolling Sphere" is rolled
along an exterior of the shroud.
26. The method of protecting a fluid turbine from a lightning
strike of claim 25, wherein the fluid turbine is provided with an
ejector shroud and one or more air termination devices are
positioned on the ejector shroud.
27. The method of protecting a fluid turbine from a lightning
strike of claim 25, wherein the shroud includes an electrically
conductive material integrated therein and in electrical
communication with the down conduction system.
28. The method of protecting a fluid turbine from a lightning
strike of claim 27, wherein the electrically conductive material is
positioned at a leading edge of the shroud.
29. The method of protecting a fluid turbine from a lightning
strike of claim 27, wherein the electrically conductive material is
integrated with a surface of the shroud.
Description
RELATED APPLICATIONS
[0001] This application claims priority under 35 U.S.C.
.sctn.119(e) to U.S. Provisional patent application No. 61/534,467
filed on Sep. 14, 2011, the contents of which is hereby
incorporated by reference in their entirety.
BACKGROUND
[0002] The present disclosure relates to the field of wind turbines
and more particularly to the protection of shrouded turbines from
lightning strikes. Utility scale wind turbines used for power
generation may have one to five open blades comprising a rotor. The
rotor transforms wind energy into a rotational torque that drives
at least one generator rotationally coupled to the rotor, either
directly or through a transmission assembly, to convert mechanical
energy to electrical energy. Such turbines typically have long
blades that are the most susceptible component of the wind turbine
to lightning strikes. Wind turbines are required to be equipped
with lightning protection systems in order to conduct large
currents from lightning strikes to the ground without damaging the
components of the turbine. Lightning strikes pose a threat to the
blades, metallic rotational equipment, and electronic components.
Increased density in wind farms poses additional threats from
lightning strikes.
[0003] Blades comprised of weakly conductive material such as
carbon fiber or other fiber reinforced polymers, experience high
currents and therefore excessive heat when struck by lightning.
External protective conductors, such as lightning rods, are
impractical on a fast moving aerodynamic structure such as a blade.
Alternatively, a protective mesh allows for a conductive layer
without external conductors, however, the point of contact of a
lightning strike will often damage the composite surface and
provide a stress point where a crack can form.
[0004] Conventional wind turbine blades are typically engaged with
bearing systems between the blades and a hub, a shaft and a
nacelle, and between the nacelle and a tower. The blades are
typically engaged with a bearing system at the root, and rotate
about their long axis to alter the chord angle with respect to the
wind direction for control of the rotor rotational speed with
respect to the wind speed. In addition to this bearing system, the
set of blades are further engaged with a hub that is connected to a
shaft engaged with a bearing system within the generator. The shaft
is rotationally engaged with the bearing system within the
generator and drives the generator. The nacelle rotates about the
support structure to yaw the turbine with respect to the wind
direction and, for this reason, is engaged with a yaw bearing
system between the nacelle and the tower. The bearing systems of
the wind turbine as described above may provide a spark gap and can
be damaged by high current passage. In this described example wind
turbine, lightning striking the tip of a blade needs to be
conducted through three bearing systems before reaching a direct
connection to the ground.
[0005] Additionally, wind turbines may be equipped with
meteorological equipment and sensitive electronic equipment that
can be damaged by minor lightning strikes.
[0006] As the density of turbines in a wind farm increases, the
potential for a single lightning strike to damage more than one
turbine increases. Electrical installations, such as overhead
lines, may provide protective conductors arranged around or above
the installation. However, horizontal axis wind turbines having
open blades present an obstacle to such protective conductors.
SUMMARY
[0007] The present disclosure relates to a shrouded fluid turbine
lightning protection system, a shrouded fluid turbine system
comprising a lightning protection system, and a method of
protecting a shrouded fluid turbine from a lightning strike.
[0008] An example embodiment of a shrouded fluid turbine lightning
protection system includes at least one air termination device that
can be positioned on a shroud of a fluid turbine. The at least one
air termination device is formed at least in part of an
electrically conductive material and in electrical communication
with a down conduction system. The down conduction system is in
electrical communication with an earth-termination system that is
configured to dissipate electricity transferred thereto to the
ground. The at least one air termination device is configured to
intercept a lightning strike and direct it through the down
conduction system, the earth-termination system, and into the
ground. The at least one air termination device may be positioned
on a turbine shroud based on a "Rolling Sphere" method wherein the
"Rolling Sphere" method is derived from the equation
r=10I.sup.0.65, where I is the peak current in kiloamperes and r is
the rolling sphere radius in meters. The shrouded fluid turbine may
include a turbine shroud, and the at least one air termination
device may also be positionable on the turbine shroud. The shrouded
fluid turbine may include an ejector shroud, and the at least one
air termination device may also be positionable on the ejector
shroud. An electrically conductive material may be integrated with
the turbine shroud and/or the ejector shroud and electrically
engaged with the down conductive system. The electrically
conductive material may be positioned on a leading or trailing edge
of the turbine shroud, a leading or trailing edge of the ejector
shroud, or integrated with the surface of either the turbine shroud
or the ejector shroud.
[0009] An example embodiment relates in general, to a shrouded
fluid turbine comprising a ringed turbine shroud that surrounds a
rotor, and at least one air termination device positioned on the
shroud of the fluid turbine. The at least one air termination
device is formed at least in part of an electrically conductive
material and in electrical communication with a down conduction
system. The down conduction system is in electrical communication
with an earth-termination system that is configured to dissipate
electricity transferred thereto to the ground. The at least one air
termination device is configured to intercept a lightning strike
and direct it through the down conduction system, the
earth-termination system, and into the ground. The at least one air
termination device may be positioned on a turbine shroud based on a
"Rolling Sphere" method wherein the "Rolling Sphere" method is
derived from the equation r=10I.sup.0.65, where I is the peak
current in kiloamperes and r is the rolling sphere radius in
meters. This embodiment may further comprise an ejector shroud that
surrounds the exit of the turbine shroud.
[0010] In one embodiment, the turbine shroud may comprise a set of
mixing lobes along the trailing edge.
[0011] In one embodiment, the set of mixing lobes along the
trailing edge are in fluid communication with the inlet of the
ejector shroud. Together, the mixer lobes and the ejector shroud
form a mixer-ejector pump that provides increased fluid velocity
near the inlet of the turbine shroud, at the cross sectional area
of the rotor plane. The mixer-ejector pump further provides a means
of energizing the wake behind the rotor plane. The combination of
the effects of the mixing lobes and the energized wake provide a
rapidly-mixed, short wake when compared to non-shrouded horizontal
axis wind turbines. The at least one air termination device may
also be positionable on the ejector shroud. An electrically
conductive material may be integrated with the turbine shroud
and/or the ejector shroud and electrically engaged with the down
conductive system.
[0012] The electrically conductive material may be positioned on a
leading or trailing edge of the turbine shroud, a leading or
trailing edge of the ejector shroud, or integrated with the surface
of either the turbine shroud or the ejector shroud.
[0013] An example embodiment relates to a method of protecting a
shrouded fluid turbine from a lightning strike. In the example
method, a shrouded fluid turbine is provided and a peak lightning
strike current is determined for the shrouded fluid turbine. A
"Rolling Sphere" circumference is calculated based on the equation
r=10I.sup.0.65, where I is the peak current in kiloamperes and r is
the rolling sphere radius in meters. One or more air termination
devices are positioned on the shroud such that the calculated
"Rolling Sphere" will contact the one or more air termination
devices before contacting the shroud when the "Rolling Sphere" is
rolled along an exterior of the shroud.
[0014] The present embodiment discloses a Primary Lightning
Protection system (LPS) and a Secondary Lightning Protection System
(LPS2). The LPS is intended to intercept and conduct lightning
strikes of a range from approximately .gtoreq.25 kA to .ltoreq.200
kA, safely from the air-termination system through the down
conduction system to the earth-termination system. The
corresponding rolling sphere system includes a range of radii from
.gtoreq.81 m to .ltoreq.313 m. A secondary lightning protection
system (LPS2) is comprised of materials integral to the shroud
surfaces in combination with a down conduction system to the
earth-termination system. The LPS2 is intended to intercept and
conduct lightning strikes of a range from approximately .gtoreq.3
kA to .ltoreq.10 kA usually in the form of static electricity.
These charges correspond to a rolling sphere radius of 20 m.
[0015] The turbine shroud and/or the ejector shroud provide a
platform for an integrated lightning protection system resulting in
a system with reduced complexity when compared to the lightning
protection systems of horizontal axis wind turbines. The turbine
shroud and/or the ejector shroud include few to no electrical
components or mechanical moving parts, thus further reducing the
risk of critical damage to the shrouded turbine.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The following is a brief description of the drawings, which
are presented for the purposes of illustrating the disclosure set
forth herein and not for the purposes of limiting the same.
[0017] FIG. 1 is a front, right, perspective view of an example
embodiment of the present disclosure;
[0018] FIG. 2 is a front, orthographic view of the example
embodiment of FIG. 1;
[0019] FIG. 3 is a side, orthographic view of the example
embodiment of FIG. 1;
[0020] FIG. 4 is a front, orthographic view of an example
embodiment of the present disclosure;
[0021] FIG. 5 is a side, orthographic view of the example
embodiment of FIG. 4;
[0022] FIG. 6 is a front, orthographic view of an example
embodiment of the present disclosure;
[0023] FIG. 7 is a side, orthographic view of the example
embodiment of FIG. 6;
[0024] FIG. 8 is a front, right, perspective, detail view of an
example embodiment of the present disclosure;
[0025] FIG. 9 is a right, perspective, detail view of the example
embodiment of FIG. 8;
[0026] FIG. 10 is a front, right, perspective view of an example
embodiment of the present disclosure;
[0027] FIG. 11 is a front, orthographic view of the example
embodiment of FIG. 10; and
[0028] FIG. 12 is a side, orthographic view of the example
embodiment of FIG. 10.
DETAILED DESCRIPTION
[0029] A more complete understanding of the components, processes,
and apparatuses disclosed herein can be obtained by reference to
the accompanying figures. These figures are intended to demonstrate
the present disclosure and are not intended to show relative sizes
and dimensions or to limit the scope of the exemplary
embodiments.
[0030] Although specific terms are used in the following
description, these terms are intended to refer only to particular
structures in the drawings and are not intended to limit the scope
of the present disclosure. It is to be understood that like numeric
designations refer to components of like function.
[0031] The term "about" when used with a quantity includes the
stated value and also has the meaning dictated by the context. For
example, it includes at least the degree of error associated with
the measurement of the particular quantity. When used in the
context of a range, the term "about" should also be considered as
disclosing the range defined by the absolute values of the two
endpoints. For example, the range "from about 2 to about 4" also
discloses the range "from 2 to 4."
[0032] A Mixer-Ejector Turbine (MET) provides an improved means of
generating power from fluid currents. The Mixer-Ejector Turbine
includes tandem cambered shrouds and a mixer/ejector pump. The
primary shroud contains a rotor, which extracts power from a
primary fluid stream. The tandem cambered shrouds and ejector bring
more flow through the rotor allowing more energy extraction due to
higher flow rates. The mixer/ejector pump transfers energy from the
bypass flow to the rotor wake flow allowing higher energy per unit
mass flow rate through the rotor. These two effects enhance the
overall power production of the turbine system.
[0033] A shrouded turbine provides an improved means of generating
power from fluid currents. The shrouded turbine includes only a
single shroud and does not include a mixer/ejector pump. The sole
shroud contains a rotor, which extracts power from a primary fluid
stream.
[0034] The term "rotor" is used herein to refer to any assembly in
which one or more blades are attached to a shaft and able to
rotate, allowing for the extraction of power or energy from fluid
(wind or water) rotating the blades. Exemplary rotors include a
propeller-like rotor or a rotor/stator assembly. Any type of rotor
may be enclosed within the turbine shroud in the shrouded turbine
of the present disclosure.
[0035] The leading edge of a turbine shroud may be considered the
front of the fluid turbine, and the trailing edge the turbine
shroud may be considered the rear of the fluid turbine. In
embodiments with an ejector shroud, the trailing edge of the
ejector shroud may be considered the rear of the fluid turbine. A
first component of the fluid turbine located closer to the front of
the turbine may be considered "upstream" of a second component
located closer to the rear of the turbine. Put another way, the
second component is "downstream" of the first component.
[0036] In one embodiment, the present disclosure relates to a
shrouded fluid turbine that includes a turbine shroud that
surrounds a rotor and an integrated lightning protection system
that employs the structure and surfaces of the shroud. In some
embodiments, the present disclosure relates to a shrouded fluid
turbine that includes a turbine shroud that surrounds a rotor, an
ejector shroud that surrounds the exit of the turbine shroud and an
integrated lightning protection system that employs the structure
and surfaces of the shrouds.
[0037] Various standards for lightning protection of wind turbines
exist, and, as such, lightning protection systems typically employ
a multi-faceted approach to the reduction of risk. An example
external lightning protection system may consist of an
air-termination system, a down conduction system, and an earth
termination system. An air-termination system also known as a
lightning rod, is a component of an external lightning protection
system intended to intercept lightning flashes. A down conduction
system is a conductor that is intended to conduct the lightning
current from the air-termination system to the earth-termination
system. An earth-termination system is a network of electrically
interconnected rods, plates, mats, piping, grids, or other
conductive components, installed below grade to establish a low
resistance contact with the earth.
[0038] One method of determining the risk of direct lightning
attachment is known as the "Rolling Sphere" method, in which an
imaginary sphere is rolled about the surfaces of a 3D digital model
of the wind turbine. The radius of the sphere is defined as:
r=10I.sup.0.65
[0039] where r is the rolling sphere radius in meters [m] and I is
the Peak Current in kiloamperes [kA]. For given rolling sphere
radius r, it can be assumed that all lightning strikes with peak
values higher than the corresponding current will be intercepted.
As the imaginary sphere is rolled about the surfaces of the 3D
digital model of the wind turbine, it is determined if the sphere
is able to come in contact with the wind turbine prior to
contacting an air termination system. There is risk of direct
lightning attachment to the turbine where the sphere is able to
come in contact with the wind turbine prior to contacting an air
termination system.
[0040] FIGS. 1 through 9 depict example embodiments of a shrouded
fluid turbine having two shrouds. FIG. 1 is a perspective view of
an exemplary embodiment of a shrouded fluid turbine of the present
disclosure. FIG. 2 is a front view of the fluid turbine of FIG. 1.
FIG. 3 is a side view of the fluid turbine of FIG. 1. Referring to
FIG. 1 through FIG. 3, the shrouded fluid turbine 100 comprises a
turbine shroud 110, an ejector shroud 120, a rotor 140, and a
nacelle body 150. The turbine shroud 110 includes a front end 112,
also known as an inlet end or a leading edge, and a rear end or
trailing edge 116, also known as an exhaust end. The trailing edge
116 includes high energy lobes 117 and low energy lobes 115. The
depiction of the recited high energy lobes 117 and low energy lobes
115 is solely for illustrative purposes. One of ordinary skill in
the art will readily recognize that the shape and orientation of
the lobes may take numerous forms and the illustrated embodiment is
not intended to be limiting in scope. The ejector shroud 120
includes a front end 122, also known as an inlet end or leading
edge, and a rear end or trailing edge 124, also known as an exhaust
end. Support members 106 connect the turbine shroud 110 to the
ejector shroud 120.
[0041] The rotor 140 surrounds the nacelle body 150 and comprises a
central hub 141 at the proximal end of the rotor blades. The
central hub 141 is rotationally engaged with the nacelle body 150.
The rotor 140, turbine shroud 110, and ejector shroud 120 are
coaxial with each other, i.e., they share a common central axis
105.
[0042] At least one air termination device 161, between 1/80 to
1/20 the diameter of the ejector in length, is engaged with the
turbine shroud 110. Additionally, at least one air termination
device 164 between 1 m and 2 m in length is also engaged with the
ejector shroud 120.
[0043] A Primary Lightning Protection system (LPS) is illustrated
in FIGS. 1 through FIG. 5. FIG. 4 is a front view of an example
embodiment, and FIG. 5 is a side view of the example embodiment of
FIG. 4.
[0044] FIG. 2 and FIG. 3 depict a rolling sphere radius in relation
to the outer surface of the fluid turbine 100. The rolling sphere
circumference is illustrated by arc 170 and the radius is
illustrated by arrow 172. The rolling sphere arcs 170 have an
approximate diameter of 313 meters, which corresponds to a
lightning current of up to 200 kA. It can be seen in FIGS. 2 and 3
that the arcs 170 do not come in contact with the body of the
turbine shroud 110 or the ejector shroud 120 before coming in
contact with at least one of the air termination devices 161/164.
It can be further seen in FIGS. 2 and 3 that the arcs 170 do not
come in contact with the rotor 140, the hub 141, or the nacelle 150
before coming in contact with at least one of the air termination
devices 161/164. The air termination devices 161/164 are in
electrical communication with a down conduction system 176 by way
of electrically coupled first and second conductors 174/175. The
down conduction system 176 transfers electricity to an
earth-termination system 178 for dispersion of the electricity.
[0045] FIG. 4 and FIG. 5 depict a rolling sphere radius of
approximately 80 meters, which corresponds to a lightning current
in the range of approximately .gtoreq.25 kA to .ltoreq.50 kA. The
rolling sphere circumference is depicted by arcs 270 and the radius
is depicted by arrow 272. It can be seen in FIG. 4 and FIG. 5 that
the rolling sphere has minimal contact with the turbine shroud 210
and the ejector shroud 220. Simultaneous contact of the rolling
sphere with either of the turbine shroud 210 or the ejector shroud
220 and at least one of the air termination devices 261/264 is
possible. In such a situation, e.g., in the even of simultaneous
contact, current is safely conducted to an earth-termination 278
system through the air termination devices 261/264 that are coupled
with a down conduction system 276 by way of electrically coupled
first and second conductors 274/275. This provides for the
conduction of the current without significant damage to the turbine
shroud 210 or the ejector shroud 220, due to the current range. It
can be further seen in FIG. 4 and FIG. 5 that the arcs 270 do not
come in contact with the rotor 240, the hub 241, or the nacelle 250
before coming in contact with at least one of the air termination
devices 161/164.
[0046] A secondary lightning protection system (LPS2) is
illustrated in FIG. 6 and FIG. 7. The LPS2 comprises electrically
conductive materials integrated with the surfaces of a turbine
shroud 310 and an ejector shroud 320. The electrically conductive
materials are connected with a down conduction system 376 by way of
electrically coupled first and second conductors 374/375, the down
conduction system 376 is connected to an earth-termination system
378. FIG. 6 and FIG. 7 depict a rolling sphere radius of
approximately 20 meters, which corresponds to a lightning current
in the range of approximately .gtoreq.3 kA to .ltoreq.10 kA. The
rolling sphere circumference is depicted by arcs 370 and the radius
is depicted by arrow 372. The LPS2 is intended to intercept and
conduct lightning strikes of a range from approximately .gtoreq.3
kA to .ltoreq.10 kA usually in the form of static electricity.
Exposed hardware, for example, various metal fasteners (not shown)
on the surface of the turbine shroud 310 and the ejector shroud 320
provide a sufficient means of dissipating a static charge prior to
contact with the rotor 340, the hub 341, or the nacelle 350.
[0047] In addition to the protection provided by the air
termination devices, shroud surfaces with embedded or integrated
materials provide additional lightning protection to rotating and
electrical generation components.
[0048] FIG. 8 and FIG. 9 illustrate an air-termination system
integrated into the shroud surfaces. Referring to FIG. 8, a mixer
ejector turbine 400 comprises a turbine shroud 410 surrounding a
rotor 440, engaged with a hub 441 that is further engaged with a
nacelle 450. An ejector shroud 420 has an inner diameter greater
that the outer diameter of the trailing edge of the turbine shroud
410 and the injector shroud 420 and the turbine shroud 410 are
concentric to one another. In some embodiments the ejector shroud
420 surrounds the trailing edge of the turbine shroud 410. In some
embodiments the ejector shroud 420 is located downstream from the
trailing edge of the turbine shroud 410. A first electrically
conductive material 470 is comprised of metalized polymers, fiber
reinforced composites with electrically conductive fibers woven
into the reinforcement, or composites with metallic characteristics
such as those provided by nanoparticles made from graphite. The
first electrically conductive material 470 is engaged with the
leading edge of the turbine shroud 410 and further conductively
engaged with an internal structure 472 of the turbine shroud 410
that is both electrically conductive and insulated. The internal
structure 472 is further conductively engaged, through an
electrical wiper system, as described below, with a down-conductive
system 476 that is conductively engaged with an earth-termination
system 478. A second electrically conductive material 475 is
engaged with the trailing edge of the ejector shroud 420 and is
further conductively engaged with an internal structure 474 of the
ejector shroud 420 that is further conductively engaged with the
down-conductive system 476 that is conductively engaged with the
earth-termination system 478.
[0049] Electrical wiper systems, also known as slip rings, are
commonly used to transfer electricity between stationary and
rotating components and include conductive arms engaged with
rotating disks. The conductive arms are often formed of metal such
as brass or copper with a combination carbon and metallic substance
at the distal ends. The distal ends engage with the rotating disks
and provide rotational electrical connectivity.
[0050] Referring to FIG. 9, a mixer ejector turbine 500 comprises a
turbine shroud 510 that surrounds a rotor 540, engaged with a hub
541 that is further engaged with a nacelle 550. An ejector shroud
520 has an inner diameter greater than the outer diameter of the
trailing edge of the turbine shroud 510, and the ejector shroud 520
and the turbine shroud 510 are concentric with one another. In some
embodiments the ejector shroud 520 surrounds the trailing edge of
the turbine shroud 510. In some embodiments the ejector shroud 520
is located downstream from the trailing edge of the turbine shroud
510. A first electrically conductive material 580 is integrated
into the surface of the turbine shroud 510 and further conductively
engaged with an internal structure 572 of the turbine shroud that
is conductively engaged 510 that is electrically conductive and
insulated. The internal structure 527 is further conductively
engaged with a down-conductive system 576 that is conductively
engaged to an earth-termination system 578. A second electrically
conductive material 586 is integrated into the surface of the
ejector shroud 520 and is further conductively engaged with an
internal structure 574 of the ejector shroud 520 that is
electrically conductive and insulated. The internal structure 574
is further conductively engaged with the down-conductive system 576
that is conductively engaged to the earth-termination system
578.
[0051] FIGS. 10 through 12 depict example embodiments of a single
shroud fluid turbine. FIG. 10 is a perspective view of an exemplary
embodiment of a single shroud fluid turbine of the present
disclosure. FIG. 11 is a front view of the single shroud fluid
turbine of FIG. 10. FIG. 12 is a side view of the single shroud
fluid turbine of FIG. 10. Referring to FIG. 10 through FIG. 12, the
single shrouded fluid turbine 600 comprises a turbine shroud 610, a
rotor 640, and a nacelle body 650. The turbine shroud 610 includes
a front end 612, also known as an inlet end or a leading edge, and
a rear end or trailing edge 616, also known as an exhaust end. The
trailing edge 616 includes high energy lobes 617 and low energy
lobes 615.
[0052] The rotor 640 surrounds the nacelle body 650 and includes a
central hub 641 at the proximal end of the rotor blades. The
central hub 641 is rotationally engaged with the nacelle body 650.
The rotor 640 and turbine shroud 610 are coaxial with each other,
i.e., they share a common central axis 605.
[0053] At least one air termination device 661, between 1/80 to
1/20 the diameter of the turbine shroud 610 in length, is engaged
with the leading edge 612 of the turbine shroud 610. Additionally,
at least one air termination device 664 between 1 m and 2 m in
length is also engaged with the trailing edge 616 of the turbine
shroud 610.
[0054] A Primary Lightning Protection system (LPS) is illustrated
in FIG. 10 through FIG. 12. FIG. 11 is a front view of an example
embodiment, and FIG. 12 is a side view of the example embodiment of
FIG. 11.
[0055] FIG. 11 and FIG. 12 depict a rolling sphere radius in
relation to the outer surface of the fluid turbine 600. The rolling
sphere circumference is illustrated by arc 670 and the radius is
illustrated by arrow 672. The rolling sphere arcs 670 have an
approximate diameter of 313 meters, which corresponds to a
lightning current of up to 200 kA. It can be seen in FIGS. 11 and
12 that the arcs 670 do not come in contact with the body of the
turbine shroud 610 before coming in contact with at least one of
the air termination devices 661/664. It can be further seen in
FIGS. 11 and 12 that the arcs 670 do not come in contact with the
rotor 640, the hub 641, or the nacelle 650 before coming in contact
with at least one of the air termination devices 661/664. The air
termination devices 661/664 are in electrical communication with a
down conduction system 676 by way of an electrically coupled
conductor 675. The down conduction system 676 transfers electricity
to an earth-termination system 678 for dispersion of the
electricity.
[0056] Although a few example embodiments have been described in
detail above, those skilled in the art will readily appreciate that
many modifications are possible in the example embodiments without
materially departing from this disclosure. Accordingly, all such
modifications are intended to be included within the scope of this
disclosure as defined in the following claims.
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