Rotary kinetic fluid motors or pumps – With diversely oriented inlet or additional inlet for...
Reexamination Certificate
2000-07-27
2002-03-12
Lopez, F. Daniel (Department: 3745)
Rotary kinetic fluid motors or pumps
With diversely oriented inlet or additional inlet for...
C415S116000, C415S170100
Reexamination Certificate
active
06354795
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to a turbine engine cooling component such as a shroud cooling segment useful in turbine engines such as high pressure turbines. The present further relates to a turbine cooling subassembly that uses a pair of such turbine components in combination with at least one spline seal.
To increase the efficiency of gas turbine engines, a known approach is to raise the turbine operating temperature. As operating temperatures are increased, the thermal limits of certain engine components can be exceeded, resulting in material failure or, at the very least, reduced service life. In addition, the increased thermal expansion and contraction of these components adversely affects clearances and their interfitting relationships with other components of different thermal coefficients of expansion. Consequently, these components should be cooled to avoid potentially damaging consequences at elevated operating temperatures.
It is common practice then to extract from the main airstream a portion of the compressed air at the output of the compressor for cooling purposes. So as not to unduly compromise the gain in engine operating efficiency achieved through higher operating temperatures, the amount of extracted cooling air should be held to a small percentage of the total main airstream. This requires that the cooling air be utilized with the utmost efficiency in maintaining the temperatures of these components within safe limits.
A particularly important component subjected to extremely high temperatures is the shroud located immediately downstream of the high pressure turbine nozzle from the combustor. The shroud closely surrounds the rotor of the high pressure turbine and thus defines the outer boundary of the extremely high temperature, energized gas stream flowing through the high pressure turbine. To prevent material failure and to maintain proper clearance with the rotor blades of the high pressure turbine, adequate shroud cooling is an important concern.
Shroud cooling is typically achieved by impingement cooling of the back surface of the shroud, as well as by drilling cooling holes that extend from the back surface of the base of the shroud and through to the forward or leading shroud, the bottom or inner surface of the base in contact with the main (hot) gas stream and the side panels or rails of the shroud to provide both convection cooling inside the holes, as well as impingement and film cooling. See, for example, commonly assigned U.S. Pat. No. 5,169,287 (Proctor et al), issued Dec. 8, 1992, which shows an embodiment of shroud cooling of the high pressure turbine section of one type of gas turbine. This cooling minimizes local oxidation and burning of the shrouds near the hot main or core (hot) gas stream in the high pressure turbine. Indeed, the cooling holes that exit through the side panels of the shroud of commonly assigned U.S. Pat. No. 5,169,287 can provide important impingement cooling to the side panel of the adjacent shroud.
While impingement cooling of the entire length of the side panel of the adjacent shroud is desirable, it has been found to be particularly important to provide impingement cooling to the side panels from about the midsection of thereof forward to the leading edge of the shroud, and especially in the region of the midsection of this side panel. It has been discovered that, for some high pressure turbines, the hottest point of the main gas stream tends to localize in the region around this midsection. This means that the greatest opportunity for undesired oxidation and burning of the shroud can occur at this point.
One approach to shroud cooling is disclosed in commonly assigned U.S. Pat. No. 5,169,287. See, in particular, FIG. 2 of U.S. Pat. No. 5,169,287 which shows a pattern of three rows cooling holes or passages 82, 84 and 86 that are formed in shroud segment 22 and extend from back surface 44a of base 44 and exit through the inner surface 44b of base 44, the forward or leading edge or end 45 and one side panel or rail 50. As also shown in FIG. 2 of U.S. Pat. No. 5,169,287, a majority of these cooling passages are skewed in a direction such that the exit holes are opposed to the direction of the main gas stream to minimize the ingestion of the hot gases from this stream into the passages of rows 82, 84 and 86. The set of three passages, indicated by 88, that exit through the one side panel 50 provide a flow of cooling air that impinges against the side panel of the adjacent shroud segment. However, because the cooling passages exit through only one of the side panels, impingement cooling is provided to only one of the side panels of each adjacent pair of shrouds in the shroud assembly of U.S. Pat. No. 5,169,287.
Another prior approach to shroud cooling is shown in
FIG. 1
of the present application. The prior shroud of
FIG. 1
has a pattern of three rows of cooling holes or passages
182
,
184
and
186
that are formed in shroud segment
122
that again exit from the inner surface of base
144
, the forward or leading edge or end
145
and one side panel or rail
150
. A set of five passages, indicated by
188
, exit through one of the side panels
150
but in direction perpendicular to this side panel and also perpendicular to the main gas stream. As a result, there is a tendency for these passages
188
in the prior shroud of
FIG. 1
to ingest hot gases from this stream, thus increasing the chance of undesired oxidation and burning of the shroud. Also, and like the shroud disclosed in U.S. Pat. No. 5,169,287, the cooling passages
188
again exit through only one of the side panels of the prior shroud of
FIG. 1
, so that impingement cooling is provided to only one of the side panels of each adjacent pair of shrouds in the shroud assembly.
As shown in
FIG. 2
of the present application, the side panels
150
of the prior shroud of
FIG. 1
has three spline seal slots formed therein hereinafter referred to as bottom spline seal slot
192
, top spline seal slot
194
and back spline seal slot
196
. Each of these slots
192
,
194
and
196
receive one edge, respectively, of the bottom, top and back spline seals (not shown) that are positioned in the gap between each adjacent pairs of shrouds. These spline seals generally conform to or assume the same shape as the respective slots
192
,
194
and
196
and extend generally the length each of the respective side panels
150
from the forward or leading edge or end
145
to the aft or trailing edge or end
148
of the shroud. As also shown in
FIG. 2
, bottom slot
192
has a plateau shaped or “humped” section
198
that curves upwardly in the forward section of the shroud before reaching exit holes
188
, extends across and above holes
188
, and then curves downwardly once past holes
188
in the aft section of the shroud. The bottom spline seal received by slot
192
also generally conforms to the shape of section
198
and thus has a “humped” or “hooded” section. As a result, the cooling air exiting holes
188
tends to be localized in the region of this humped section
198
of the bottom spline seal.
Yet another prior approach to shroud cooling is shown in
FIG. 3
of the present application. The prior shroud of
FIG. 3
has a pattern of three rows of cooling holes or passages
282
,
284
and
286
that are formed in shroud segment
222
and again exit through the inner surface of base
244
, the forward or leading edge or end
245
and one side panel or rail
250
. A set of three passages, indicated by
288
, extend through one of the side panels
250
, the one closest to the leading edge
245
being skewed in a direction opposed to the main gas stream, the next passage being perpendicular to this side section and also perpendicular to the main gas stream and the last passage closest to the aft or trailing edge or end
248
being skewed in a direction that generally follows the main gas stream. Another set of two passages, indicated by
289
, extend through the other side panel
250
, both passages being perpendicular
Lee Ching-Pang
White Gregory Alan
Ande William Scott
General Electric Company
Hess Andrew C.
Lopez F. Daniel
McCoy Kimya N
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