U.S. patent application number 11/447463 was filed with the patent office on 2010-09-30 for microcircuit cooling for blades.
This patent application is currently assigned to UNITED TECHNOLOGIES CORPORATION. Invention is credited to Francisco J. Cunha.
Application Number | 20100247328 11/447463 |
Document ID | / |
Family ID | 38521344 |
Filed Date | 2010-09-30 |
United States Patent
Application |
20100247328 |
Kind Code |
A1 |
Cunha; Francisco J. |
September 30, 2010 |
Microcircuit cooling for blades
Abstract
A turbine engine component, such as a turbine blade, includes at
least one cooling circuit having a plurality of legs through which
a cooling fluid flows, and a plurality of cooling devices in at
least one of the legs. Each of the cooling devices has a heat
transfer multiplier in the range of from 1.8 to 2.4 and a
reattachment length in the range of from 1.9 to 2.5.
Inventors: |
Cunha; Francisco J.; (Avon,
CT) |
Correspondence
Address: |
BACHMAN & LAPOINTE, P.C. (P&W)
900 CHAPEL STREET, SUITE 1201
NEW HAVEN
CT
06510-2802
US
|
Assignee: |
UNITED TECHNOLOGIES
CORPORATION
|
Family ID: |
38521344 |
Appl. No.: |
11/447463 |
Filed: |
June 6, 2006 |
Current U.S.
Class: |
416/97R ;
416/223R |
Current CPC
Class: |
Y02T 50/60 20130101;
F05D 2260/204 20130101; F05D 2260/2212 20130101; F05D 2250/11
20130101; Y02T 50/676 20130101; F01D 5/186 20130101; F05D 2250/121
20130101 |
Class at
Publication: |
416/97.R ;
416/223.R |
International
Class: |
F01D 5/18 20060101
F01D005/18 |
Claims
1. A turbine engine component comprising: at least one cooling
circuit having a plurality of legs through which a cooling fluid
flows; and a plurality of cooling devices in at least one of said
legs, each of said cooling devices having a heat transfer
multiplier in the range of from 1.8 to 2.4 and a reattachment
length in the range of from 1.9 to 2.5.
2. The turbine engine component according to claim 1, further
comprising an airfoil portion having a pressure side and suction
side and said at least one cooling circuit being imbedded between
said pressure and suction sides.
3. The turbine engine component according to claim 1, further
comprising said turbine engine component having a root portion and
an inlet for said cooling fluid located within said root
portion.
4. The turbine engine component according to claim 3, wherein said
plurality of legs includes a first leg, a second leg in fluid
communication with said first leg, and a third leg in fluid
communication with said second leg.
5. The turbine engine component according to claim 4, further
comprising a refresher inlet within said root portion for
introducing said cooling fluid into said third leg.
6. The turbine engine component according to claim 4, further
comprising a plurality of cooling fluid outlets communicating with
said first and third legs.
7. The turbine engine component according to claim 1, wherein said
cooling devices have a heat transfer multiplier in the range of
from 2.2 to 2.4.
8. The turbine engine component according to claim 1, wherein each
of said cooling devices has a cylindrical shape.
9. The turbine engine component according to claim 1, wherein each
of said cooling devices has a cube shape.
10. The turbine engine component according to claim 9, wherein each
said cube shaped cooling device has one sidewall oriented
substantially normal to a flow direction of said cooling fluid.
11. The turbine engine component according to claim 1, wherein each
of said cooling devices has a diamond shape.
12. The turbine engine component according to claim 11, wherein
each diamond shaped cooling device has a tip and said tip is
aligned with a flow direction of said cooling fluid.
13. The turbine engine component according to claim 1, wherein said
component comprises a turbine blade.
14. A cooling microcircuit for use in a turbine engine component
comprising: a first leg for receiving a cooling fluid; a second leg
for receiving said cooling fluid from said first leg; a third leg
for receiving said cooling fluid from said second leg; at least one
of said first and second legs containing a plurality of cooling
devices; and each of said cooling devices having a heat transfer
multiplier in the range of from 1.8 to 2.4 and a reattachment
length in the range of from 1.9 to 2.5.
15. The cooling microcircuit according to claim 14, wherein said
cooling microcircuit has a serpentine shape.
16. The cooling microcircuit according to claim 14, further
comprising an inlet for introducing a first flow of said cooling
fluid into said first leg and a refresher inlet for introducing a
second flow of said cooling fluid into said third leg.
17. The cooling microcircuit according to claim 14, further
comprising a plurality of outlets communicating with at least one
of said first and third legs of said cooling microcircuit.
18. The cooling microcircuit according to claim 14, wherein each of
said cooling devices has a cylindrical shape.
19. The cooling microcircuit according to claim 14, wherein each of
said cooling devices has a cube shape.
20. The cooling microcircuit according to claim 14, wherein each of
said cooling devices has a diamond shape.
21. The cooling microcircuit according to claim 14, further
comprising a plurality of cooling devices arranged in at least one
of said legs and said plurality of cooling devices being arranged
in a staggered configuration.
Description
BACKGROUND OF THE INVENTION
[0001] (1) Field of the Invention
[0002] The present invention relates to a turbine engine component,
such as a turbine blade, having a cooling microcircuit which is
easy to fabricate and which has a plurality of cooling devices for
effecting heat pick-up.
[0003] (2) Prior Art
[0004] For an existing cooling microcircuit blade design
configuration, such as that illustrated in the two-dimensional span
of FIG. 1, each blade internal cavity feeds a microcircuit located
on a side of the airfoil, either on a pressure side or on a suction
side. Even though this design is desirable to de-sensitize the
cooling design from rotational effects and sink pressure
interferences in microcircuit supply flows, it makes the assembly
of the numerous microcircuit cores complex.
[0005] Thus, there is a need for an improved cooling microcircuit
which can be used in turbine engine components such as turbine
blades.
SUMMARY OF THE INVENTION
[0006] In accordance with the present invention, there is provided
a turbine engine component, such as a turbine blade, having a
cooling microcircuit whose assembly is not complex.
[0007] Further, in accordance with the present invention, there is
provided a turbine engine component which broadly comprises at
least one cooling circuit having a plurality of legs through which
a cooling fluid flows, and a plurality of cooling devices in at
least one of the legs. Each of the cooling devices has a heat
transfer multiplier in the range of from 1.8 to 2.4 and a
reattachment length in the range of from 1.9 to 2.5.
[0008] Also, there is provided in accordance with the present
invention, a cooling microcircuit for use in a turbine engine
component which broadly comprises a first leg for receiving a
cooling fluid, a second leg for receiving the cooling fluid from
the first leg, and a third leg for receiving the cooling fluid from
the second leg. At least one of the first and second legs contains
a plurality of cooling devices. Each of the cooling devices has a
heat transfer multiplier in the range of from'1.8 to 2.4 and a
reattachment length in the range of from 1.9 to 2.5.
[0009] Other details of the microcircuit cooling for blades of the
present invention, as well as other objects and advantages
attendant thereto, are set forth in the following detailed
description and the accompanying drawings wherein like reference
numerals depict like elements.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 illustrates the two dimensional span of a prior art
blade;
[0011] FIG. 2 illustrates the heat transfer characteristics of a
cylinder shaped cooling device;
[0012] FIG. 3 illustrates the heat transfer characteristics of a
cube shaped cooling device;
[0013] FIG. 4 illustrates the heat transfer characteristics of a
diamond shaped cooling device; and
[0014] FIG. 5 is a schematic representation of a turbine blade
having a cooling microcircuit in accordance with the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0015] One way to compensate for the assembly difficulties in the
prior art is to combine different cores together. In this context,
it is also desirable to increase the size of the combined
microcircuits without losing thermal characteristics. In general,
cooling microcircuits have banks of pedestals as cooling devices to
enhance heat pick-up. While employing these cooling devices in the
cooling microcircuits, it is also desirable to minimize their
number for the same heat pick-up capability.
[0016] In general, at the pedestal to wall junction, there are flow
horseshoe vortices due to protrusion-endwall interaction, which
contribute to the heat transfer. Also, as the flow passes these
pedestals, flow circuits reattach downstream from a shear layer
separation. These effects are common to pedestals of different
cross-sectional areas, namely cylinder, cube, and diamond-shaped
pedestals. As the cross sectional shape of the pedestal changes,
the flow can become more complex. For instance, the flow in the
cube vicinity is highly three dimensional and dominated by a number
of vortices far more complex than those around a cylinder. FIGS.
2-4 illustrate the heat transfer characteristics of different
shaped pedestals. FIG. 2 illustrates the heat transfer
characteristics for a cylinder shaped pedestal. FIG. 3 illustrates
the heat transfer characteristics for a cube shaped pedestal. FIG.
4 illustrates the heat transfer characteristics for a
diamond-shaped pedestal configuration.
[0017] From FIGS. 2-4, it can be seen that the spanwise domain of
influence for a cylinder type pedestal is on the lowest of all
three configurations, with the diamond-shaped pedestal being the
greatest. The spanwise domain of influence of the diamond-shaped
pedestal is about 32% greater than a cylinder shaped pedestal. With
this zone of influence, the preferred inter-element spacing for the
diamond shaped pedestal would be two-fold greater than that for the
cylinder type of pedestal with even higher heat transfer
enhancement. It can be concluded that for a given surface size, the
number of elements needed to achieve effective heat transfer
enhancement can be minimized using a diamond geometry.
[0018] For a diamond type pedestal, the value of the heat transfer
multiplier recovers downstream to reach a maximum of about 2.4 heat
transfer enhancement (reference being the flat plate heat transfer)
at an x/d of 2.5. Not only is this the farthest location of
reattachment induced enhancement downstream to the obstacle, but
also it has the highest value of maximum heat transfer multiplier.
The key factor responsible for this effect is the special flow
characteristics related to diamond shaped pedestals. It is
dominated by highly turbulent delta-wing vortices as opposed to the
commonly observed, recirculating bubble. These vortices
substantially elevate the surface heat transfer underneath their
tracks. It is expected that such influence persists further
downstream as the shear layer reattached to the endwall.
[0019] In accordance with the present invention, it is desirable to
use a cooling device having a reattachment length in the range of
1.9 to 2.5 and a heat transfer multiplier relative to flat plate
heat transfer in the range of from 1.8 to 2.2, preferably from 2.2
to 2.4.
[0020] The diamond shaped pedestal has the strongest
reattachment-induced enhancement with the widest spread in the wake
region. In addition, its reattachment length is also the
longest.
[0021] Referring now to FIG. 5, there is shown an embodiment of a
turbine engine component 10 in accordance with the present
invention. The turbine engine component 10, such as a turbine
blade, has an airfoil portion 12, a platform 14, and a root portion
16. The airfoil portion 12 has a tip 18. A cooling microcircuit 20
is imbedded within the airfoil portion 12. The imbedded cooling
microcircuit 20 receives a coolant flow stream from an inlet 24
formed within the root portion 16. The inlet 24 is preferably
positioned adjacent a leading edge of the root portion 16. The
inlet 24 may communicate with any suitable source of cooling fluid
such as engine bleed air. The coolant flow stream is allowed to
flow radially upward (in a direction away from the platform 14)
through a first leg 26 of the cooling microcircuit 20 so as to take
advantage of the natural pumping force. As can be seen from FIG. 5,
the cooling microcircuit 20 may have a serpentine configuration.
Thus, as the coolant flow stream reaches the vicinity of the tip 18
of the airfoil portion 12, the coolant flow bends and proceeds to a
second leg 28. Within the second leg 28, the coolant flows radially
downward (in a direction toward the platform 14). In this
arrangement, some bypass coolant flow may be used to cool the tip
18 via tip cooling circuits 30 and 32. As shown in FIG. 5, the tip
cooling circuit 30 comprises a plurality of spaced apart flow
passages 70. Each flow passage 70 has an inlet which may
communicate with and receive coolant from the first leg 26 as well
as from a U-shaped flow turn portion 34 connecting the legs 26 and
28.
[0022] As can be seen from FIG. 5, each of the legs 26 and 28 has a
plurality of cooling devices 80. The cooling devices 80 may have
any desired shape. While it is preferred that the cooling devices
be diamond shaped, they may also be cylindrical or cubed shaped. If
a diamond shaped cooling device is used, it is preferred that the
tip 86 of the diamond shape be aligned with the direction of the
cooling fluid flowing through the respective one of the legs 24 and
26. The angle between the surfaces forming the tip 86 is important
and should preferably be in the range of from 30 to 60 degrees.
[0023] As noted above, each cooling device 80 could have a cube
shape. When using a cube shaped cooling device, one of the sides of
the cube should be oriented substantially normal to the direction
of flow of the cooling fluid in the leg in which the cooling device
80 is located.
[0024] As can be seen from FIG. 5, a plurality of cooling devices
80 may be positioned within each of the legs 24 and 26. Preferably,
the cooling devices 80 in each leg are arranged in a staggered
configuration.
[0025] The cooling microcircuit 20 may be provided with a third leg
36 in which the coolant flows radially upward. The tip circuit 32
also may comprise a plurality of spaced apart flow passages 72.
Each flow passage 72 may have an inlet which communicates with the
third leg 36 of the cooling microcircuit 20 so as to receive
coolant therefrom. Each cooling circuit passage 70 and 72 has a
fluid outlet or exit 33 which allows cooling fluid to flow over a
surface of the airfoil portion 12. Preferably, the exits 33 are
configured to allow the coolant to exit on the pressure side 35 of
the airfoil portion 12. The tip cooling exits 33 from the circuits
30 and 32 may extend from a point near the leading edge 44 to a
point near the trailing edge 50 of the airfoil portion 12. By
providing the cooling microcircuit arrangement described herein,
three separate circuits make up one unit and thus facilitate the
assembly process.
[0026] A root inlet refresher leg 38 may be fabricated within the
root portion 16. The root inlet refresher leg 38 is in fluid
communication with the third leg 36 and may be used to insure
adequate cooling flow in the third leg 36. The root inlet refresher
leg 38 may communicate with any suitable source (not shown) of
cooling fluid such as engine bleed air.
[0027] As can be seen from the foregoing description, an integral
main body and tip microcircuit arrangement 20 has been provided.
The turbine engine component 10 is cooled convectively in this
way.
[0028] If desired, exit tabs 40 forming film slots 42 may be
provided in the legs 26 and/or 28. The exit tabs 40 and film slots
42 allow coolant fluid to flow from the legs 26 and/or 28 onto a
surface of the airfoil portion. The surface may be the pressure
side surface 35 or the suction side surface 37. Fluid exiting the
slots 42 helps form a cooling film over one or more of the exterior
surfaces of the turbine engine component 10. Such film slots 42 may
be useful in an open-cooling system.
[0029] If desired, the leading edge 44 of the airfoil portion 12
may be provided with a plurality of fluid outlets or exits 46 which
allow a film of coolant to flow over the leading edge portions of
the pressure side 35 and the suction side 37 of the airfoil portion
12. The outlets or exits 46 may be supplied with coolant from a
supply cavity 48. The supply cavity 48 may communicate directly
with a source (not shown) of cooling fluid, such as engine bleed
air, or alternatively, the supply cavity 48 may be in fluid
communication with the first leg 26.
[0030] The cooling microcircuit of the present invention may also
be used in a closed loop system without film cooling for industrial
gas turbine applications where the external thermal load is not as
high as that for aircraft engine applications.
[0031] The cooling microcircuit arrangement of the present
invention may be formed using any suitable technique known in the
art. In a preferred method of forming the cooling microcircuit, one
or more sheets formed from a refractory metal material may be
configured in the shape of the cooling microcircuit arrangement 20
including the inlet 24 and the root inlet refresher leg 38, the
legs 26, 28, and 36, the tip cooling microcircuits 30 and 32, the
exits 33, the tabs 40, and the film slots 42. The refractory metal
material sheets may be placed or positioned within a mold cavity.
Thereafter, the turbine engine component 10 including the airfoil
portion 12, the platform 14, and the root portion 16 may be cast
from any suitable metal known in the art such as a nickel based
superalloy, a titanium based superalloy, or an iron based
superalloy. After the turbine engine component has been cast, the
refractory metal material sheets may be removed using any suitable
means known in the art, leaving the cooling microcircuit
arrangement 20 of the present invention.
[0032] It is apparent that there has been provided in accordance
with the present invention microcircuit cooling for blades which
fully satisfies the objects, means, and advantages set forth
hereinbefore. While the present invention has been described in the
context of specific embodiments thereof, other unforeseeable
alternatives, modifications, and variations may become apparent to
those skilled in the art having read the foregoing description.
Accordingly, it is intended to embrace those alternatives,
modifications, and variations as fall within the broad scope of the
appended claims.
* * * * *