U.S. patent application number 17/084919 was filed with the patent office on 2021-05-06 for controlled flow turbine blades.
The applicant listed for this patent is General Electric Company. Invention is credited to Brian Robert HALLER, Ivan William MCBEAN.
Application Number | 20210131287 17/084919 |
Document ID | / |
Family ID | 1000005195794 |
Filed Date | 2021-05-06 |
![](/patent/app/20210131287/US20210131287A1-20210506\US20210131287A1-2021050)
United States Patent
Application |
20210131287 |
Kind Code |
A1 |
HALLER; Brian Robert ; et
al. |
May 6, 2021 |
CONTROLLED FLOW TURBINE BLADES
Abstract
The present application provides a turbine blade. The turbine
blade includes a root section with a first curved section, a tip
section with a second curved section, and number of mean sections
positioned between the root section and the tip section. The mean
sections each include a substantially prismatic shape.
Inventors: |
HALLER; Brian Robert; (Rugby
Warwickshire, GB) ; MCBEAN; Ivan William;
(Nussbaumen, CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
General Electric Company |
Schenectady |
NY |
US |
|
|
Family ID: |
1000005195794 |
Appl. No.: |
17/084919 |
Filed: |
October 30, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F05D 2250/71 20130101;
F01D 5/141 20130101; F01D 5/225 20130101; F05D 2220/31
20130101 |
International
Class: |
F01D 5/14 20060101
F01D005/14; F01D 5/22 20060101 F01D005/22 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 31, 2019 |
EP |
19206667.8 |
Claims
1. A turbine blade, comprising: a root section; the root section
comprising a first curved section; a tip section; the tip section
comprising a second curved section; and a plurality of mean
sections positioned between the root section and the tip section;
the plurality of mean sections each comprising a substantially
prismatic shape.
2. The turbine blade of claim 1, wherein the substantially
prismatic shape comprises a ratio (K) of a throat dimension to a
pitch dimension of K.+-.0.1.
3. The turbine blade of claim 1, wherein the plurality of mean
sections comprises a reduced axial width as compared to the first
curved section and the second curved section.
4. The turbine blade of claim 1, wherein the first curved section
and the second curved section comprise an inward curve away from
the plurality of mean sections.
5. The turbine blade of claim 1, wherein the first curved section
comprises a first decreasing blade outlet angle, wherein the second
curved section comprises a second decreasing blade outlet angle,
and wherein the plurality of mean sections comprises a
substantially constant blade outlet angle.
6. The turbine blade of claim 5, wherein the first decreasing blade
outlet angle and the second decreasing blade outlet angle are less
than the substantially constant blade outlet angle.
7. The turbine blade of claim 5, wherein the first decreasing blade
outlet angle and the second decreasing blade outlet angle are
between about two and eight degrees.
8. The turbine blade of claim 1, wherein the first curved section
comprises a first ratio of a throat dimension to a pitch dimension,
wherein the second curved section comprises a second ratio, and
wherein the plurality of mean sections comprises a substantially
constant ratio.
9. The turbine blade of claim 8, wherein the first ratio and the
curved ratio are less than the substantially constant ratio.
10. The turbine blade of claim 8, wherein a first change in the
first ratio along the first curved section and a second change in
the second ratio along the second curved section are greater than a
mean change in the substantially constant ratio .+-.0.1 along the
plurality of mean sections.
11. The turbine blade of claim 1, wherein the first curved section
extends along a first height of the blade from about zero percent
to about fifty percent of a total height of the blade for an aspect
ratio of about one to two.
12. The turbine blade of claim 1, wherein the second curved section
extends along a second height of the blade from about fifty percent
to about one hundred percent of a total height of the blade for an
aspect ratio of about one to two.
13. The turbine blade of claim 1, wherein the first curved section
extends along a first height of the blade from about zero percent
to about fifteen percent of a total height of the blade for an
aspect ratio of higher than about two.
14. The turbine blade of claim 1, wherein the second curved section
extends along a second height of the blade from about eighty-five
percent to about 100 percent of a total height of the blade for an
aspect ratio of higher than about two.
15. The turbine blade of claim 1, comprising an aspect ratio of
about one to six.
16. A steam turbine blade, comprising: a root section; the root
section comprising a first curved section; a tip section; the tip
section comprising a second curved section; and a plurality of mean
sections positioned between the root section and the tip section;
the plurality of mean sections comprises a substantially prismatic
shape and a reduced axial width as compared to the first curved
section and the second curved section.
17. The steam turbine blade of claim 16, wherein the substantially
prismatic shape comprises a ratio (K) of a throat dimension to a
pitch dimension of K.+-.0.1.
18. The steam turbine blade of claim 16, wherein the first curved
section comprises a first decreasing blade outlet angle, wherein
the second curved section comprises a second decreasing blade
outlet angle, wherein the plurality of mean sections comprises a
substantially constant blade outlet angle, and wherein the first
decreasing blade outlet angle and the second decreasing blade
outlet angle are less than the substantially constant blade outlet
angle.
19. The steam turbine blade of claim 18, wherein the first
decreasing blade outlet angle (.alpha.) and the second decreasing
blade outlet angle (.alpha.) are between about two and eight
degrees.
20. The steam turbine blade of claim 16, comprising an aspect ratio
of about one to six.
Description
TECHNICAL FIELD
[0001] The present application and the resultant patent relate
generally to axial flow turbines such as steam turbines, gas
turbines, and the like and more particularly relate to controlled
flow turbine blades for use at higher aspect ratios for improved
efficiency.
BACKGROUND
[0002] Generally described, steam turbines and the like may have a
defined steam path that includes a steam inlet, a turbine section,
and a steam outlet. Steam generally may flow through a number of
turbine stages typically disposed in series, including first or
control stage blades with guides and runners (or nozzles and
buckets) and subsequent guides and runners of later stages of the
steam turbine. In this manner, the guides may direct the steam
toward the respective runners, causing the runners to rotate and
drive a load, such as an electrical generator and the like. The
steam may be contained by circumferential shrouds surrounding the
runners, which also may aid in directing the steam along the path.
In this manner, the turbine guides, runners, and shrouds may be
subjected to high temperatures resulting from the steam, which may
result in the formation of hot spots and high thermal stresses in
these components. Because the efficiency of a steam turbine is
dependent in part on its operating temperatures, there is an
ongoing demand for components positioned along the steam or hot gas
path to be capable of withstanding increasingly higher temperatures
without failure or decrease in useful life. Of significance is
improving overall operational flexibility and part-load
performance.
[0003] Certain turbine blades may be formed with an airfoil
geometry. The blades may be attached to tips and roots, where the
roots are used to couple the blade to a disc or drum. Known turbine
blades may have an airfoil cross-section of straight or "prismatic"
form extending radially between the tip and the root. Orientations
of both fixed and moving blades have been standardized for the
prismatic blade design. Depending on the design, the turbine blade
geometry and dimensions may result in certain profile losses,
secondary losses, leakage losses, mixing losses, and the like that
may affect efficiency and/or performance of the steam turbine or
other type of axial flow device.
SUMMARY
[0004] The present application and the resultant patent thus
provide a turbine blade. The turbine blade may include a root
section with a first curved section, a tip section with a second
curved section, and a number of mean sections positioned between
the root section and the tip section. The mean sections each
include a substantially prismatic shape.
[0005] The present application and the resultant patent further
provide a steam turbine blade. The steam turbine blade may include
a root section with a first curved section, a tip section with a
second curved section, and a number of mean sections positioned
between the root section and the tip section. The mean sections may
include a substantially prismatic shape and a reduced axial width
as compared to the first curved section and the second curved
section.
[0006] These and other features and improvements of this
application and the resultant patent will become apparent to one of
ordinary skill in the art upon review of the following detailed
description when taken in conjunction with the several drawings and
the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a schematic diagram of a steam turbine with a high
pressure section and an intermediate pressure section.
[0008] FIG. 2 is a schematic diagram of a portion of a steam
turbine showing a number of stages with guide blades and runner
blades.
[0009] FIG. 3 is a partial perspective view of a pair of blades
that have been conventionally used in the stages of FIG. 2.
[0010] FIG. 4 is a plan view of the pair of blades of FIG. 3.
[0011] FIG. 5 shows the blade outlet angle a of the pair of blades
of FIG. 3.
[0012] FIG. 6 is perspective view of a blade as may be described
herein.
[0013] FIG. 7 is a chart showing the change in a ratio (K) of a
throat dimension to a pitch dimension along the height of the blade
of FIG. 6.
[0014] FIG. 8 is a chart showing the change in a ratio (K) of a
throat dimension to a pitch dimension along the height of a similar
blade.
DETAILED DESCRIPTION
[0015] Referring now to the drawings, in which like numerals refer
to like elements throughout the several views, FIG. 1 shows a
schematic diagram of an example of a steam turbine 10. Generally
described, the steam turbine 10 may include a high pressure section
15 and an intermediate pressure section 20. Other pressures and
other sections also may be used herein. An outer shell or casing 25
may be divided axially into an upper half section 30 and a lower
half section 35. A central section 40 of the casing 25 may include
a high pressure steam inlet 45 and an intermediate pressure steam
inlet 50. Within the casing 25, the high pressure section 15 and
the intermediate pressure section 20 may be arranged about a rotor
or disc 55. The disc 55 may be supported by a number of bearings
60. A steam seal unit 65 may be located inboard of each of the
bearings 60. An annular section divider 70 may extend radially
inward from the central section 40 towards the disc 55. The divider
70 may include a number of packing casings 75. Other components and
other configurations may be used.
[0016] During operation, the high pressure steam inlet 45 receives
high pressure steam from a steam source. The steam may be routed
through the high pressure section 15 such that work is extracted
from the steam by rotation of the disc 55. The steam exits the high
pressure section 15 and then may be returned to the steam source
for reheating. The reheated steam then may be rerouted to the
intermediate pressure section inlet 50. The steam may be returned
to the intermediate pressure section 20 at a reduced pressure as
compared to the steam entering the high pressure section 15 but at
a temperature that is approximately equal to the temperature of the
steam entering the high pressure section 15.
[0017] FIG. 2 shows a schematic diagram of a portion of the steam
turbine 100 including a number of stages 110 positioned in a steam
or hot gas path 120. A first stage 130 may include a number of
circumferentially-spaced first-stage controlled flow guides 140 and
a number of circumferentially-spaced first-stage controlled flow
runners 150. The first stage 130 may include a first-stage shroud
160 extending circumferentially and surrounding the first-stage
controlled flow runners 150. The first-stage shroud 160 may include
a number of shroud segments positioned adjacent one another in an
annular arrangement. In a similar manner, a second stage 170 may
include a number of second-stage controlled flow guides 180, a
number of second-stage controlled flow runners 190, and a
second-stage shroud 200 surrounding the second-stage controlled
flow runners 190. The controlled flow guides and runners may have a
Reaction Technology Blading (RTB) design and the like. The
controlled flow guides and runners may be original equipment or
part of a retrofit. Any number of stages with corresponding guides
and runners may be included herein. Other embodiments may have
different configurations.
[0018] FIG. 3 shows a pair of blades 205, 210 such as the
controlled flow guide 140 shown in FIG. 2. The blades 205, 210 may
be of the known straight or prismatic orientation. In other words,
the blades 205, 210 are designed such that the notional airfoil
sections, each considered orthogonal to a radial line from the
rotor, may have the same shape from a blade root 215 to a blade tip
220 (and a mean section 225 in-between), are untwisted from the
blade root 215 to the blade tip 220, and are stacked with a leading
edge 230 and a trailing edge 240 each on a straight line. Each
blade 205, 210 also has a concave pressure surface 250 and a convex
suction surface 260.
[0019] The following parameters related to the design of the blades
205, 210 will be described in detail herein. As is shown in FIG. 5,
the "blade outlet angle .alpha." of an airfoil blade is, for
example, the angle, relative to the circumferential direction of
the rotor, that the working fluid leaves a circumferential blade
row and can be derived from the relationship:
.alpha.=sin.sup.-1K where: K=throat dimension(t)/pitch
dimension(p).
[0020] As is shown in FIG. 4, the "throat dimension (t)" is, for
example, defined as the shortest line extending from one airfoil
blade trailing edge 240 normal to a suction surface 260 of an
adjacent airfoil blade in the same row. The "pitch dimension (p)",
for example, is a circumferential distance from one airfoil blade
trailing edge 240 to the adjacent airfoil blade trailing edge 240
in the same row at a specified radial distance from the platform
region of the airfoil blade.
[0021] A "setting angle (.beta.)" is, for example, an angle through
which any particular airfoil section at a position along the height
or span of the airfoil blade is displaced in its own plane from a
predetermined zero datum. The datum, for example, can be taken at a
radial location where the airfoil section has the same "stagger
angle (.PSI.)" as a known prismatic airfoil blade in a known
turbine utilizing such airfoil blades. The stagger angle (.PSI.)
is, for example, the angle between an axis A of the turbine and a
tangent line 290 touching a trailing edge circle 270 and a leading
edge 280 of the airfoil section (as will be discussed in more
detail below), and indicates an orientation of the airfoil section
relative to the turbine axis A.
[0022] A "chord line" 285 is, for example, the shortest line
tangent to leading 230 and trailing edge 240 radii of an airfoil
section. The "chord length" is the distance between two lines
normal to the chord line and passing through the points where the
chord line touches the leading 230 and trailing edges 240
respectively. The "axial width" (W) of an airfoil blade is, for
example, an axial distance between the leading 230 and trailing
edges 240 (e.g., the distance between the leading and trailing
edges as measured along the rotational axis A of the turbine). The
"back surface deflection (BSD) angle" is, for example, a change in
angle on an uncovered surface of the airfoil blade between a throat
point and a trailing edge blend point on the suction surface. An
"aspect ratio" may define a ratio of the height to the width or the
chord of the airfoil blade.
[0023] FIG. 4 shows a radial plan view of the orientation of the
blades 205, 210 relative to the turbine axis A (the rotor 55) and a
transverse (e.g., tangential or circumferential) plane T containing
the casing 25 and to which the turbine axis A is perpendicular. The
blade airfoil section is based on the small trailing edge circle
270 and the larger leading edge 280. A tangent line 290 to these
two points defines the stagger angle .PSI. from the turbine axis A
direction. The larger leading edge 280 may have continuous
curvature. The axial width (W) of these known fixed blades 205, 210
at a given radial position is the distance between the leading and
trailing edges 230, 240 at the given radial position.
[0024] If a perpendicular line is drawn from the suction surface
260 of the blade 205 to meet the pressure surface 250 of the
adjacent blade 210, and then if the shortest such line is taken,
this is the throat dimension t, which occurs in the region of the
trailing edge 240 of the blade 210. As described above and shown in
FIG. 5, the ratio of this throat dimension (t) to the pitch
dimension (p) of the fixed blades gives the value K, which is equal
to the sine of the blade outlet angle (.alpha.), as previously
defined. It can be seen that, approximately, this angle is the
blade outlet angle from each blade relative to the transverse plane
T.
[0025] FIG. 6 shows an airfoil blade 300 as may be described
herein. The airfoil blade 300 may accommodate stages with a greater
height and, hence, a greater aspect ratio. The airfoil blade 300
may have a prismatic straight trailing edge 240 extending along the
height of the blade 300. Instead of the three sections (the root
215, the tip 220, and the mean section 225) described above, the
blade 300 may have the root section 215, the tip section 220, and
any number of mean sections 225 therebetween. Specifically, the
leading edge 230 may have a first curved controlled flow section
310 about the root section 215, a second curved controlled flow
section 320 about the tip section 220, and any number of mean
sections 225 with a straight or prismatic shape 330 in between for
a "locally blended" region.
[0026] The term "curved" describes a surface having a change in the
blade outlet angle (.alpha.) over a prescribed length, i.e., a
"monotonically decreasing" angle. The curved controlled flow
sections 310, 320 curve outward away from the mean sections 225
with the straight or prismatic shape 330 such that the mean
sections 225 have a reduced axial width for improved lift while the
wider curved controlled flow sections 310, 320 provide greater
leading edge sweep. These sections 310, 320 may be combined with a
relatively high back surface deflection angle along the pressure
side 250 with modified controlled flow stacking along the trailing
edge 240. The controlled flow section 310 may define a first
decreasing blade outlet angle, the second controlled flow section
320 may define a second decreasing outlet angle, and the mean
sections 225 may define a substantially constant blade outlet
angle.
[0027] The nature of the curved controlled flow sections 310, 320
may be shown in FIGS. 7 and 8, which plots the change in K (ratio
of throat dimension (t) to the pitch dimension (p)) along the
fractional height (ht) of the blade 300. From the root section 215
to a height ht.sub.1 along the first curved controlled flow section
310, the reduction in the blade outlet angle (.alpha.) provides an
increase in K. From the height (ht.sub.1) to a height ht.sub.2
along the mean sections 225 with the straight or prismatic shape
330, K may remain substantially stable, i.e., within a range of
about .+-.0.1. From the height (ht.sub.2) to the end of the tip
section 220 of the second curved controlled flow section 320, the
decrease in the blade outlet angle (.alpha.) provides a similar
decrease in K.
[0028] Generally speaking along the height of the blade 300 as is
shown in FIG. 7, the height (ht.sub.1) of the first curved section
310 is between about 0% and less than about 50% of the blade height
(ht) (0.ltoreq.ht.sub.1.ltoreq.0.5) and the height (ht.sub.2) of
the second curved section 320 is between more than about 50% and
100% of the blade height (ht) (0.5.ltoreq.ht.sub.2.ltoreq.1.0) for
smaller aspect ratios of about 1 to 2. In other blades as is shown
in FIG. 8, the first curved section 310 extends from about 0% to
about 15% of the blade height (0.ltoreq.ht.sub.1.ltoreq.0.15) and
the second curved section 320 extends from about 85% and about 100%
of the blade height (0.85.ltoreq.ht.sub.2.ltoreq.1.0) for higher
aspect ratios (that is aspect ratios greater than about 2). In some
blades, the aspect ratio may be from between about 1 to about 6.
The heights ht.sub.1 and ht.sub.2 of the curved control sections
310, 320 may be the same or different with the height along the
mean sections 225 varying.
[0029] Likewise, the change in the blade outlet angle (.alpha.) may
be about 2.ltoreq..DELTA..alpha..sub.1.ltoreq.8.degree., and
2.ltoreq..DELTA..alpha..sub.2.ltoreq.8.degree.. Interestingly, the
closing at the endwalls may be greater than the range of K.+-.0.1
along the straight or prismatic shape 330 of the mean sections 225,
i.e., the change in K along the first curved controlled flow
section 310 and the change in K along the second curved controlled
flow section 320 are both greater than the range of K .+-.0.1 along
the number of mean sections 225.
[0030] The airfoil blade 300 thus may accommodate aspect ratios
from about 1 to about 6 or so for use in stages of greater height
and may result in reduced profile and secondary loses.
Specifically, the use of the mean sections 225 with the straight or
prismatic shape 330 provides increased lift with lower profile
losses due to the higher opening/pitch with high back surface
deflection while the curved controlled flow sections 310, 320 with
the forward leading edge sweep reduces overall secondary flow
losses. Given such, the blade 300 has a more constant K
distribution over most of the overall height (about 15% to about
85%) with only local controlled flow closing losses towards the
endwalls. All of the sections have high aft loading to reduce
further profile and secondary loses.
[0031] The airfoil blade 300 thus may improve overall efficiency
while reducing possible component damage and/or failure.
Specifically, the improved airfoil blade 300 may improve overall
efficiency with the easy ability to retrofit.
[0032] It should be apparent that the foregoing relates only to
certain embodiments of this application and resultant patent.
Numerous changes and modifications may be made herein by one of
ordinary skill in the art without departing from the general spirit
and scope of the invention as defined by the following claims and
the equivalents thereof.
* * * * *