U.S. patent application number 11/473893 was filed with the patent office on 2007-12-27 for leading edge cooling using wrapped staggered-chevron trip strips.
This patent application is currently assigned to UNITED TECHNOLOGIES CORPORATION. Invention is credited to William Abdel-Messeh, Eleanor Kaufman, Jeffrey R. Levine.
Application Number | 20070297916 11/473893 |
Document ID | / |
Family ID | 38349575 |
Filed Date | 2007-12-27 |
United States Patent
Application |
20070297916 |
Kind Code |
A1 |
Levine; Jeffrey R. ; et
al. |
December 27, 2007 |
Leading edge cooling using wrapped staggered-chevron trip
strips
Abstract
A turbine engine component has an airfoil portion having a
leading edge, a suction side, and a pressure side and a radial flow
leading edge cavity through which a cooling fluid flows for cooling
the leading edge. The turbine engine component further has a
staggered arrangement of trip strips for generating a vortex in the
leading edge cavity which impinges on a nose portion of the leading
edge cavity.
Inventors: |
Levine; Jeffrey R.; (Vernon,
CT) ; Abdel-Messeh; William; (Middletown, CT)
; Kaufman; Eleanor; (Cromwell, 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: |
38349575 |
Appl. No.: |
11/473893 |
Filed: |
June 22, 2006 |
Current U.S.
Class: |
416/96R |
Current CPC
Class: |
F05D 2260/2212 20130101;
F05D 2240/303 20130101; F05D 2260/22141 20130101; F05D 2240/12
20130101; F05D 2240/121 20130101; F01D 5/187 20130101 |
Class at
Publication: |
416/96.R |
International
Class: |
F01D 5/18 20060101
F01D005/18 |
Claims
1. A turbine engine component comprising: an airfoil portion having
a leading edge, a suction side, and a pressure side; a radial flow
leading edge cavity through which a cooling fluid flows for cooling
said leading edge; and means for generating a vortex in said
leading edge cavity which impinges on a nose portion of said
leading edge cavity.
2. The turbine engine component according to claim 1, wherein said
vortex generating means comprises a plurality of first trip strips
wrapped around said nose portion of said leading edge cavity.
3. The turbine engine component according to claim 2, wherein said
first trip strips are mounted to the suction side of said airfoil
portion.
4. The turbine engine component according to claim 2, wherein said
first trip strips are mounted to the pressure side of said airfoil
portion.
5. The turbine engine component according to claim 2, wherein said
vortex generating means further comprises a plurality of second
trip strips and a plurality of gaps between said first trip strips
and said second trip strips.
6. The turbine engine component according to claim 5, wherein said
second trip strips are mounted on said pressure side of said
airfoil portion.
7. The turbine engine component according to claim 5, wherein said
second trip strips are mounted on said suction side of said airfoil
portion.
8. The turbine engine component according to claim 5, wherein said
first trip strips and said second trip strips are staggered.
9. The turbine engine component according to claim 5, wherein said
plurality of gaps are located along a parting line of said airfoil
portion.
10. The turbine engine component according to claim 5, wherein said
first trip strips and second trip strips are positioned along a
direction of flow of said cooling fluid.
11. The turbine engine component according to claim 10, wherein the
first trip strips are oriented substantially normal to the
direction of flow so as to generate said vortex at said leading
edge.
12. The turbine engine component according to claim 10, wherein
said first and second trip strips are each oriented at an angle of
45 degrees relative to the direction of flow of said cooling
fluid.
13. The turbine engine component according to claim 10, wherein
each of said first and second trip strips has a leading edge and
said leading edge of each of said trip strips is positioned in a
region of highest heat load.
14. The turbine engine component according to claim 13, wherein
said leading edge of said first trip strips overlap said leading
edge of said second trip strips.
15. The turbine engine component according to claim 13, wherein
said leading edge of said second trip strips overlap said leading
edge of said first trip strips.
16. The turbine engine component according to claim 10, wherein
said trip strips have a P/E ratio in the range of from 3 to 25
where P is a radial pitch between trip strips and E is trip strip
height.
17. The turbine engine component according to claim 10, wherein
said trip strips have an E/H ratio between 0.15 and 1.50 where E is
trip strip height and H is height of the cavity.
18. The turbine engine component according to claim 10, wherein
said first trip strips and said second trip strips are staggered
approximately one half pitch apart.
Description
BACKGROUND
[0001] (1) Field of the Invention
[0002] The present invention relates to enhanced cooling of the
leading edge of airfoil portions of turbine engine components using
trip strips that are staggered and wrapped around the nose of the
leading edge cavity.
[0003] (2) Prior Art
[0004] Due to the extreme environment in which they are used, some
turbine engine components, such as blades and vanes, are cooled. A
variety of different cooling techniques have been employed. One
such scheme is illustrated in FIG. 1 where there is shown an
airfoil portion 10 of a turbine engine component 12. As can be seen
from the figure, a radial flow leading edge cavity 14 is used to
effect cooling of the leading edge region.
[0005] Despite the existence of such a cooling scheme, there
remains a need for improving the cooling of the leading edge of the
airfoil portions of turbine engine components.
SUMMARY OF THE INVENTION
[0006] Accordingly, it is an aim of the present invention to
provide enhanced cooling for the leading edge of airfoil portions
of turbine engine components.
[0007] In accordance with the present invention, a turbine engine
component broadly comprises an airfoil portion having a leading
edge, a suction side, and a pressure side, a radial flow leading
edge cavity through which a cooling fluid flows for cooling the
leading edge, and means for generating a vortex in the leading edge
cavity which impinges on a nose portion of the leading edge cavity.
The vortex generating means comprises a first set of trip strips
which wrap around the nose portion of the leading edge cavity and a
second set of trip strips. The first set of trip strips is
staggered relative to the second set of trip strips.
[0008] Other details of the leading edge cooling using staggered
trip strips 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
[0009] FIG. 1 illustrates a prior art turbine engine component
having a radial flow leading edge cavity;
[0010] FIG. 2 illustrates a cross-section of a leading edge portion
of an airfoil used in a turbine engine component having staggered
and wrapped trip strips;
[0011] FIG. 3 illustrates the trip strips on the suction side of
the leading edge portion;
[0012] FIG. 4 illustrates the trip strips on the pressure side of
the leading edge portion;
[0013] FIG. 5 illustrates the placement of the leading edge of the
staggered trip strips;
[0014] FIG. 6 is a three dimensional view of the leading edge trip
strips; and
[0015] FIG. 7 illustrates the vortex generated in the leading edge
cavity.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0016] Referring now to the drawings, FIG. 2 illustrates the
leading edge 30 of an airfoil portion 32 of a turbine engine
component. As can be seen from this figure, the leading edge 30 has
a leading edge cavity 34 in which a cooling fluid, such as engine
bleed air, flows in a radial direction. The leading edge 30 also
has a nose portion 36 and an external stagnation region 38.
[0017] It has been found that trip strips are desirable to provide
adequate cooling of the leading edge, especially at the nose
portion 36 of the airfoil portion 32 adjacent to the external
stagnation region 38. The trip strip arrangement which will be
discussed hereinafter provides high heat transfer to the leading
edge 30 of the airfoil portion 32.
[0018] As shown in FIGS. 2, 5 and 6, a plurality of trip strips 40
are positioned on the pressure side 42 of the airfoil portion 32,
while, as shown in FIGS. 2, 3, and 6, a plurality of trip strips 44
are placed on the suction side 46 of the airfoil portion 32.
Referring now to FIGS. 2 and 6, the trip strips 40 on the pressure
side 42 are wrapped around the leading edge nose portion 36. As the
pressure side trip strips 40 wrap around the leading edge, the
curvature of the leading edge nose portion 36 causes the trip
strips 40 to be oriented more or less normal to the direction of
flow 48 (see FIG. 6). As cooling air passes over the thus oriented
trip strips 40, the flow is tripped and generates a large vortex 49
at the leading edge (see FIG. 7). This large vortex generates very
high heat transfer coefficients at the leading edge nose 36.
[0019] Referring now to FIGS. 4 and 6, it can be seen that the trip
strips 40 and the trip strips 44 are preferably staggered
approximately one half pitch apart between the suction side 46 and
the pressure side 42 of the airfoil portion 32. As shown in FIGS. 2
and 7, there is also a gap 47 between adjacent ones of the trip
strips 40 and the trip strips 44. Each gap 47 is preferably located
along a parting line 70 of the airfoil portion 32.
[0020] The orientation of the trip strips 40 and 44 in the cavity
34 also increases heat transfer at the leading edge 30 of the
airfoil portion 32. If desired, the trip strips 40 and 44 may be
oriented at an angle .alpha. of approximately 45 degrees relative
to the flow direction 48. The leading edges 54 and 56 of the trip
strips 40 and 44 are positioned in the region of highest heat load,
in this case the leading edge nose 36. This trip strip orientation
permits the creation of a turbulent vortex 49 in the cavity 34. The
cooling fluid initially hits the leading edges 54 and 56 of the
trip strip and separates from the airfoil surface. The flow then
re-attaches downstream of the trip strip leading edges 54 and 56
and moves toward the divider rib 60 between the leading edge cavity
34 and the adjacent cavity 62. As the flow approaches the divider
rib 60, it is forced toward the opposite airfoil wall. The flow is
directed perpendicular to the pressure side and suction side walls
42 and 46, and meets at the center of the cavity 34. The flow is
now forced back towards the leading edge 30 of the airfoil portion
32. The result of this flow migration causes a large vortex 49 that
drives flow into the leading edge of the cavity, acting as an
impingement jet which also enhances heat transfer at the leading
edge nose 36.
[0021] Using the trip strip configuration of the present invention,
radial flowing leading edge cavities of turbine engine components
will see an increase in convective heat transfer at the leading
edge nose of the cavity.
[0022] The particular orientation of the trip strip configuration
allows for cooling flow to impinge on the leading edge nose 36,
further enhancing heat transfer. The leading edge of the trip
strips 40 and 44 is located near the nose 36 of the leading edge
cavity 34.
[0023] The trip strips 40, although skewed at an angle a with
respect to the direction of flow 48 along the pressure-side wall
42, become normal to the direction of flow 48 as they wrap around
the nose 36 of the leading edge cavity 34, increasing the turbulent
vortex 49 generated by the trip strips 40 and 44, and subsequently
increasing the heat transfer coefficient.
[0024] The trip strips 40 and 44 may overlap with the trip strip 40
extending underneath the trip strip 44, and vice-versa.
[0025] While the trip strips 40 have been described as being on the
pressure side wall 42 of the airfoil portion, they could instead be
mounted to the suction side wall 46 if desired. In such a
situation, the trip strips 44 would be mounted to the pressure side
wall 42.
[0026] Away from the leading edge nose 36, the staggered and 45
degree angled trip strips generate a vortex that impinges flow onto
the nose 36 of the leading edge cavity.
[0027] The trip strip configuration of the present invention
maintains a P/E ratio between 3 and 25 where P is the radial pitch
in between trip strips and E is trip strip height. Further, the
trip strip configuration described herein maintains an E/H ratio of
between 0.15 and 1.50 where E is trip strip height and H is the
height of the cavity 34.
[0028] Airflow testing has shown that the heat transfer
coefficients at the leading edge of the airfoil adjacent to the
external stagnation region when using the staggered trip strips of
the present invention are enhanced by approximately two times,
greatly increasing airfoil oxidation and thermo-mechanical fatigue
cracking life.
[0029] It is apparent that there has been provided in accordance
with the present invention leading edge cooling using
staggered-chevron trip strips that wrap around the nose of the
leading edge cavity 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 detailed description. Accordingly, it is intended to
embrace those alternatives, modifications, and variations as fall
within the broad scope of the appended claims.
* * * * *