U.S. patent application number 13/897766 was filed with the patent office on 2014-02-13 for blade for a rotary machine.
This patent application is currently assigned to NEW WORLD ENERGY ENTERPRISES LTD. The applicant listed for this patent is NEW WORLD ENERGY ENTERPRISES LTD. Invention is credited to Andrew SMYTH, David SMYTH, Gerard SMYTH, James SMYTH, Peter SMYTH.
Application Number | 20140044552 13/897766 |
Document ID | / |
Family ID | 47901525 |
Filed Date | 2014-02-13 |
United States Patent
Application |
20140044552 |
Kind Code |
A1 |
SMYTH; James ; et
al. |
February 13, 2014 |
BLADE FOR A ROTARY MACHINE
Abstract
A blade for use in rotary machines such as a wind turbine blade
has a plurality of dimples distributed over an area of a low
pressure or suction surface of the blade which preferably extends
from immediately adjacent to a leading edge of the blade at least
partially towards a rear or trailing edge of the blade.
Inventors: |
SMYTH; James; (County Cavan,
IE) ; SMYTH; Peter; (County Longford, IE) ;
SMYTH; David; (County Longford, IE) ; SMYTH;
Gerard; (County Longford, IE) ; SMYTH; Andrew;
(County Armagh, IE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NEW WORLD ENERGY ENTERPRISES LTD |
Longford |
|
IE |
|
|
Assignee: |
NEW WORLD ENERGY ENTERPRISES
LTD
Longford
IE
|
Family ID: |
47901525 |
Appl. No.: |
13/897766 |
Filed: |
May 20, 2013 |
Current U.S.
Class: |
416/228 |
Current CPC
Class: |
F05B 2250/60 20130101;
Y02E 10/72 20130101; F03D 1/0633 20130101; F04D 29/681 20130101;
F05B 2250/28 20130101; F01D 5/145 20130101; F05B 2240/32 20130101;
F05B 2260/96 20130101; Y02E 10/721 20130101 |
Class at
Publication: |
416/228 |
International
Class: |
F01D 5/14 20060101
F01D005/14 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 9, 2012 |
IE |
S2012/0347 |
Claims
1. A blade having a plurality of dimples distributed over an area
of at least one surface of the blade which extends from at or
adjacent a leading edge of the blade at least partially towards a
rear edge of the blade.
2. A blade according to claim 1, comprising an aerofoil blade.
3. A blade as claimed in claim 1, comprising a low pressure or
suction surface and an opposed high pressure or pressure surface,
and the dimples are distributed over at least an area of the low
pressure surface.
4. A blade as claimed in claim 2, in which the aerofoil is
asymmetric.
5. A blade as claimed in claim 1, in which the leading edge is
rounded and the trailing edge is sharp.
6. A blade as claimed in claim 1, wherein the area of dimples
extends along at least a major part of the length of the blade.
7. A blade as claimed in claim 1, wherein the dimples are generally
teardrop-shaped with a wider end facing towards the leading edge of
the blade.
8. A blade as claimed in claim 1, wherein the dimples vary in
distribution density.
9. A blade as claimed in claim 1, wherein the dimples vary in
depth.
10. A blade as claimed in claim 1, wherein the dimples vary in
cross section with depth.
11. A blade as claimed in claim 1, wherein the plurality of dimples
comprises dimples of different size.
12. A blade as claimed in claim 1, wherein the trailing edge of the
blade has a localised rearward or downstream extension.
13. A blade as claimed in claim 12, wherein the localised rearward
extension is at a free end of the blade.
14. A blade as claimed in claim 1, wherein the blade is a rotary
machine blade.
15. A blade as claimed in claim 1, wherein the blade is a wind
turbine blade.
16. A blade as claimed in claim 3, wherein dimples are also
provided on the pressure surface of the blade.
17. A wind turbine comprising at least one blade according to claim
1.
18. An air displacement system comprising at least one blade
according to claim 1.
19. An air displacement system according to claim 18 comprising a
fan comprising the at least one blade.
Description
REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to Irish Patent Application
No. S2012/0347, filed Aug. 9, 2012, the disclosure of which is
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention is concerned with a blade for a rotary
machine, which in use undergoes driven or driving rotation, and is
particularly but not exclusively concerned with such blades when
used in air or gas driven applications such as a wind turbines, or
air or gas driving or displacing applications such as fans,
compressors, and blowers, and in particular blades having improved
flow characteristics, for example reduced boundary layer
separation, reduced turbulence, etc.
BACKGROUND OF THE INVENTION
[0003] Rotating blades are used in a large number of applications
and in particular rotary machines as described above, and in many
of those applications it is desirable to improve the efficiency
and/or performance of the blade through various means. In one
application aerofoil blades are utilised in augmented wind turbine
systems, for example comprising a shroud surrounding a set of
aerofoil blades such as to take advantage of the higher velocity
profile. By improving the performance and/or efficiency of such
blades a greater power output can be achieved and/or the turbines
can be located in a more diverse range of locations. It will also
be appreciated that the invention can be used in conventional wind
turbine systems or other rotational blade applications or
machines.
[0004] As a further example, blades of various size, shape and
design are used in air displacers such as fans, compressors, blower
based applications, for example HVAC applications, refrigeration
applications, or any other applications requiring air or other
fluid such as gas to be displaced. Such blades may have a full or
partial aerofoil section, or may define a simple paddle/vane style
blade design
[0005] It is therefore an object of the present invention to
provide a blade or set of blades for a rotary machine having
improved performance and/or efficiency.
SUMMARY OF THE INVENTION
[0006] According to the present invention there is provided a blade
having a plurality of dimples distributed over an area of at least
one surface of the blade which extends from at or adjacent a
leading edge of the blade at least partially towards a rear edge of
the blade
[0007] Preferably, the blade comprises an aerofoil blade.
[0008] Preferably, the aerofoil comprises a low pressure or suction
surface and an opposed high pressure or pressure surface, and the
dimples are distributed over at least an area of the low pressure
surface.
[0009] Preferably, the aerofoil is asymmetric.
[0010] Preferably, the leading edge is rounded and the trailing
edge is sharp.
[0011] Preferably, the area of dimples extends along at least a
major part of the length of the blade.
[0012] Preferably, the dimples are generally teardrop-shaped with a
wider end facing towards the leading edge of the blade.
[0013] Preferably, the dimples vary in distribution density.
[0014] Preferably, the dimples vary in depth.
[0015] Preferably, the dimples vary in cross section with
depth.
[0016] Preferably, the plurality of dimples comprises dimples of
different size.
[0017] Preferably, the trailing edge of the blade has a localised
rearward or downstream extension.
[0018] Preferably, the localised rearward extension is at a free
end of the blade.
[0019] Preferably, the blade is a wind turbine blade.
[0020] Preferably, dimples are also provided on the pressure
surface of the blade.
[0021] As used herein, the term "dimple" is intended to mean a
localised depression in a surface, and which may vary in cross
section with depth, and may be of any suitable shape and
orientation.
[0022] Various other objects, advantages and features of the
present invention will become readily apparent to those of ordinary
skill in the art, and the novel features will be particularly
pointed out in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Embodiments of the invention will now be described, by way
of example, with reference to the accompanying drawings, in
which;
[0024] FIG. 1 is a perspective view of an embodiment of aerofoil
blade according to the invention, having particular application in
a wind turbine;
[0025] FIG. 2 is a schematic partial cross section through the
blade of FIG. 1;
[0026] FIG. 3 is a partial top view of the blade of FIG. 1; and
[0027] FIG. 4 is a perspective view of a modification of the
aerofoil blade of FIG. 1.
DETAILED DESCRIPTION OF THE DRAWINGS
[0028] Referring to FIGS. 1 to 3, an aerofoil blade for use with a
wind turbine is illustrated, and comprises an outwardly tapered
blade 10 with a rounded leading edge 12, and a sharp or narrow
trailing edge 14 and an outer free end or tip 16. It will however
be appreciated that the size, shape and profile of the blade 10 may
be varied as required, depending on the particular application with
which the blade 10 is to be employed. A large number or array of
dimples 18 are distributed over a lower pressure or "suction"
surface 20 of the blade 10, and as will be described in detail
hereinafter, are arranged to augment the flow of air around the
blade 10 in order to improve the performance and/or efficiency of
the blade 10
[0029] In this particular embodiment the dimples 18 extend fully
from the leading edge 12 of the blade to the trailing edge 14 and
from the root to the tip of the blade 10, i.e. they cover
substantially the entire suction surface 20. In general, however,
the dimpled area of the upper or suction surface 12 may extend
rearwardly from immediately adjacent to the leading edge 12 of the
blade 10 only partially to the trailing edge 14, preferably at
least one quarter the way to the trailing edge. In addition the
dimples may not extend all the way to the root or the tip, and
further alternatively the suction surface 12 may have one or more
regions devoid of dimples
[0030] Also, the dimpled area does not necessarily need to extend
along the full length of the leading edge 12 of the blade 10,
although it preferably extends along at least a major part of the
length of the leading edge
[0031] In this embodiment the dimples 18 are generally concave
teardrop-shaped depressions aligned with their wider ends facing
upstream towards the leading edge 12 of the blade, as shown in FIG.
3, and the narrow or tapered ends facing downstream towards the
trailing edge 14. The dimples 18 are preferably closely spaced, but
their distribution density may vary over the dimpled area. The
dimples may also vary in depth, and may vary in cross section with
depth. It will also be appreciated that the dimples 18 may be of
any other suitable shape or size in order to generate a desired
augmentation of the air flowing around the blade 10. In addition
dimples 18 of different size, shape and/or depth may be used on the
same blade 10.
[0032] The dimples 18 can be created directly in the upper or
suction surface 20 of the blade, or by using blade protection tape
22 (FIG. 2) or any other suitable carrier (not shown) which is
embossed with the teardrop or other shaped dimples 18 and applied
to the upper surface 20. This allows the array of dimples 18 to be
quickly and easily retrofitted to an existing blade.
[0033] In the embodiment shown in FIGS. 1 to 3 the length of the
blade 10 was 2.45 m with an average chord of 300 mm. The dimples
are 15 mm long by 9 mm wide at their widest part, with a maximum
depth of 0.33 mm. These particular dimensions are suited to wind
turbine blades, and may of course be varied to suit the intended
application. For example in HVAC or refrigeration applications, the
blade 10 may be employed with refrigeration fans, blowers and/or
compressors (not shown) and will therefore be dimensioned
accordingly, with the profile of the blade 10 being altered to suit
the velocity profile of the gas being displaced.
[0034] The above turbine blade design serves to accelerate airflow,
increase lift, reduce the wake created and/or increase the air
displaced by the blade 10. The dimples 18 serve to create a
micro-turbulent layer across the blade 10 which in turn causes the
wind-force acting on the blade to be greater. The dimples delay
boundary layer separation thereby reducing the wake of the blade
10. The dimples 18, when in an inverted teardrop shape, may also
act as mini-augmenters and give the air direction. The depth, size,
shape and distribution density of the dimples 18 may vary with
blade characteristics or other system parameters.
[0035] In a modification of the above embodiment, FIG. 4, the
trailing edge 14 of the blade 10 has a localised rearward or
downstream paddle-like extension 24, preferably at its free end or
tip 16. The extended paddle-like tip 24 of the blade 10 serves to
increase the surface area. However the dimples 18 can still work
effectively on a conventional aerofoil blade which does not have
the projection, i.e. as shown in FIG. 1.
[0036] If desired, similar dimples may be provided on the "high
pressure" surface of the blade (not shown), again extending
rearwardly from the leading edge.
[0037] The present invention is not limited to the embodiment(s)
described herein, which may be amended or modified without
departing from the scope of the present invention.
[0038] Therefore, it is intended that the appended claims be
interpreted as including the embodiments described herein, the
alternatives mentioned above, and all equivalents thereto.
* * * * *