Note: Descriptions are shown in the official language in which they were submitted.
MULTI-CHAMB~R AI~FOIL COOLING INSERT
FOR TURBINE ~ANE
BACKGROUND 0~ THE INVENTION
Field of the Inventi.on:
This invention pertains to the art of turbine
airfoil vanes provided with an insert, with the arrangement
as a whole providing for air cooling of the vanes.
In the turbine art, it is known that different
stages of the stator vanes require different levels of
cooling. The vane structure with which this invention is
concerned is of a character and in a stage calling for what
those knowledgeable in the art would consider to be a low
or a moderate level of cooling, which level of cooling can
be carried out by the use of impingement jets directed
against the interior walls of the vane. As is also known,
even with those vanes which do not require a high level of
cooling, the degree of cooling required at different
locations on the vane may differ, with the leading edge
region of the vane typically having a relatively higher
heat load while downstream and toward the trailing edge of
the vane the heat load may be significantly lower.
It is an aim of this invention to provide a vane
and insert structure in which a vane having a single
internal cavity is provided with a single, unitary, hollow
insert provided with a chamber arrangement and jet impinge-
ment ports all tailored to relate the impingement cooling
of the walls to the extexnal heat load.
2 ~ LS
SUMMARY OF THE INVENTION
__ __ __
In accordance with the invention, the insert is
provided with a plurality of radially extending partition
means to divide the interior thereof into a single forward
chamber in the leading edge portion of the vane, and at
least two separate, successively rearward chambers in at
least partial communication with each other, a plurality of
impingement ports in the walls of all of said chambers, one
radial end portion of all the chambers being in communica-
tion with a source of cooling air, and with means forthrottling the flow into the rearward chambers so that the
orward chamber is a relatively higher pressure than said
rearward chambers and so the impingement jets through the
ports of said forward chamber against said interior vane
walls of said leading edge portion are at a significantly
higher velocity than the impingement jets exiting the ports
of the rearward chambers~.
BRIEF DESCRIPTION OF THE DRA~lINGS
Figure 1 is a typical chordwise sectional view
through the vane and insert as would appear from a section
taken along the line I-I of Figure 2; and
Figure 2 is a view partly in elevation and partly
in section of the vane and insert, and yenerally corre-
sponding to a view taken along the line II-II of Figure l.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to Figure 1, the hollow vane having a
single internal cavity is defined by the leading edge
section generally designated 12, a concave sidewall 14, a
convex sidewall 16, the downstream portlons of these
opposite sidewalls defining a trailing edge portion gener-
ally designated 18 and provided with a slot 2~ therein.
The general direction of the hot gas past the vane is as
indicated by the dash line arrow in Figure 1.
The single, unitary, air-cooling, hollow insert
generally designated 22 has an airfoil shape in cross
section which is generally complementary to the vane
airfoil shape, and extends in a chordwise direction for
3L2~ S
substantially the entire extent of the vane cavity. While
the insert does have -the overall shape of an airoil, it
may be seen in Figure 1 that at the leading edge portion 24
the insert is bulyed somewhat, a similar bulged arrangement
being provided at the trailing edge portion 26. The
intermediate portion 28 has walls which are basically
uniformly spaced from the vane walls throughout the inter-
mediate extent between the front and rear bulges.
The unitary insert 22 has its interior divided
into a forward chamber 30 and successively rearward cham-
bers 32, 34, and 36, by the radially extending partition
means 38, 40, and 42, which also perorm a structural tying
function.
The radially inner ends of all of the chambers
are closed while the radially outer ends of the chambers
are in communication with a source of cooling air. As may
be best understood from Figure 2, the radially outer end 44
is completely open so that cooling air flows directly into
the forward chamber 30 as indicated by the arrow 46 in
Figure 2. While the rearward chambers 32, 34, and 36 are
also in communication with the source of cooling air, the
flow into these chambers is throttled by means of a radial
extension 48 of the insert comprising opposite walls 50
capped by plate 52 which prevents the direct admission of
the cooling air into the rearward chambers in the fashion
in which the forward chambers receives its air, the cooling
air being throttled into the rearward chambers by the
provision of the holes 54 in the walls 50. The throttling
results in the rearward chambers being at a lower pressure
than the forward chamber 30.
Referring to both figures, all of the chambers
are provided with impingement ports in their sidewalls.
Those ports provided in the forward chamber sidewalls are
identified by the numeral 56 as best seen in Figure 1. The
impingement ports in the convex sidewall o the insert or
the rearward chambers are designated 58 while those in the
concave wall are designated 60. As is best seen in Figure
3~
2, all of the impingement ports are in ro~"s ~Jhich eY.tend
generally radially As may be seen from ~igure 1, the rows
of ports 56 of the forward chamber are more widely spaced
from each other than the rows of ports from the rearward
chambers on the convex side, and most of the concave side
with the exception of the spacing of the rows of ports of
the concave side of the first low-pressure chamber 32. It
is also noted that the three rearward chambers are open to
each other through the provision of a series of ports 62 in
both of the partitions or ribs 40 and 42. The rearward
chambers are also in open communication ~ith each other at
the radially outer portion of the chambers by virtue of the
partitions 40 and 42 stopping short of the space 64 at the
radially outer ends of the chambers.
The insert has dimples 66 embossed outwardly in
its leading edge portion and similar dimples 68 in its
trailing edge portion to properly space the insert walls
from the vane walls.
With the arrangement as shown and described, the
forward chamber 30 is maintained at a higher pressure than
the rearward chambers 32, 34, and 36, so that the cooling
jets issuing from the forward chamber are projected at a
higher velocity than those exiting through the ports of the
rearward chambers so that the higher velocity jets are
projected at the higher heat load leading edge and forward
convex surface areas of the vane, while the jets issuing
from the lower pressure rearward chambers are projected at
a lower velocity for cooling the relatively lower heat load
regions of the airfoil vane. The relatively closer spaced
rows of ports throughout the midchord region is to obtain
more uniform cooling than would be obtained with
widely-spaced high velocity jets.
Typical pressures at which the chambers can be
maintained may be in order of, for example, 160 psig (1102
E+03PA) for the forward chamber, 155 psig (1068 E+03Pa) for
the rearward chambers, with the pressures in the spaces
q~
between the insert and the opposincJ vane walls bein~ 150
psig ( 1033 E~03Pa) .
