Transpiration cooled turbine blade made from metallic or ceramic wire

Eckert, E. R. G.

English

NASA Technical Reports Server

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TRANSPIRATION COOLED TURBINE BLADE MANUFACTURED FROM WIRES 
Filed Oct. 20, 3953 
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https://ntrs.nasa.gov/search.jsp?R=19700023915 2020-03-17T01:30:54+00:00Z
3,011,76 nited States Paten Patented Dec. 5, 1961 
1 
3,011,760 
TRANSPIRATION COOLED TURBINE BLADE 
MANUFACTURED FROM WIRES 
Erapt R G. Wed, St. Paul, MInn, assignor, by mesne 
adgumen@, to the United States of America as repre- 
sented by the AdmWxtrator of the National Aem- 
nantks and Space Adminishtion 
IMed Oct. 20,1953, Ser. No. 387,332 
4 Claims. (CL 25-9.15) 
(Granted =der Title 35, US. Code (1952), see. 266) 
The invention described herein may be manufactured 
and used by or h r  the Govement of the United States 
of America for govermental purposes without the pay- 
ment of any royalties thereon or therefor. 
This invention relates ot improvements in blades that 
in normal use are subjected to high centrifugal force 
loads and high heating conditions of operation. 
A very effective method of cooling objects which are 
subject to very severe heating conditions, such as rocket 
nodes or structural elements in gas turbines, was de- 
veloped recently and is known as transpiration, effusion 
or sweat cooling. In such cooling the wall to be cooled 
is manufactured of a porous material and the coolant 
(gas or liquid) is directed through the pores toward the 
surface of the wall which is heated, for instance, by a 
bot gas stream. The coolant leaves the wall surface 
through the pores at that surf= and builds a cooling 
film between the surface and hot gases. 
The porous wall is usually made in such a way that 
granular powder is heated to temperatures which cause 
the single particles to sinter together. In using such ma- 
terial for sweat cooled turbine blades, the following dilli- 
culty wises: the  TOW.^^ blades, the oooling of which is 
especially important, are subject to high centrifugal 
stresses. Porous material consisting of more or less 
spherical particles connected at the points where they 
touch each other is by the nature of its structure no1 
suited to give high strength against tensile stresses. Ac- 
cordingly, an object of this invention is to provide a 
blade that is capable of carrying out transpiration cool- 
ing methods but yet, is strong enough to withstand the 
stresses usually encountered in high rotational speed tur- 
bine blades. 
A more specific object of the invention is to provide 
a turbine blade with a body consisting of a plurality of 
wires made of metal, ceramic or other materials, and 
anranged with theii longitudinal axes generally and not 
necessarily precisely, parallel to the blade axis, either 
with or without a stiffener insert, whereby ample porosity 
is provided for transpiration cooling and yet, with the 
axes of the blade fibres or wires arranged as described, 
ample strength to withstand centrifugal forces is present. 
Other objects and features will become apparent in 
following the description of the illustrated forms of the 
invention. 
In the drawing: 
FIG. 1 is vertical sectional view of one form of the 
invention and taken substantially on the line 1-1 of 
FIG. 2 and in the direction of the arrows. 
FIG. 2 is a transverse sectional view of the blade of 
FIG. 1 and taken on the line 2-2 of FIG. 1. 
FIG. 3 is a fragmentary enlarged elevational view of 
a modification of the invention. 
FIG. 4 is a fragmentary enlarged elevational view of 
another modification. 
FIG. 5 is a transverse sectional view of the blade, 
showing the use of an insert for stiffening the blade, the 
use of an insert being optional with any embodiment. 
In order to carry forward the transpiration technique 
for cooling engine parts that are subjected not only to 
severe heat conditions but also high mechanical stress, 
2 
for example, turbine blades, a new concept of blade 
construction has been obtained. In the drawing several 
embodiments of this concept are illustrated. In FIGS. 1 
and 2 therh is a fragment of a turbine wheel 10 provided 
I with one of a pluraIity of pockets 12 accommodating 
blade base 14 held in place by any known means. Blade 
body 16 is made of a plurality of wires 18 extending 
generally parallel to each other and to the longitudinal 
axis of the blade. The inner ends of the wires are em- 
LO bedded or otherwise 6xed to base 14, and the wires are 
arranged to form a blade (FIG. 2) leading edge 41, trail- 
ing edge 42, and two cambered surfaces 43 connecting 
the leading with the trailing edge. The wires are spaced 
slightly from each other and are preferably connected 
For obtaining proper transpiration cooling, the cen- 
ter of the blade is hollow, as shown in FIG. 2 and has 
a main passage 44 therein in communication with the 
spaces between wires 18. Opening into the passage 44 of 
20 the blade body 16 is an aperture 22 in base 14, the aper- 
ture 22 conducting coolant supplied through turbine 
wheel 10, as by passing through passageway 26. 
In FIG. 3 another form of blade is shown, mering 
from that of FIG. 1 in that the wires 28 are in a woven 
25 pattern, while FIG. 4 illustrates a modification of the 
woven pattern in the crossing of wires 30 at right angles 
to each other. In either case and also that of FIG. 1 
the blade body 16 formed by the wires has its wires 
arranged with a number of spaces therein through which 
In some instances stiffening of the blade may be re- 
quired, making necessary the use of a stiffener 38 in the 
passage 44. The stifEener may be used with any or aIl 
of the blade body patterns as shown in FIGS. 1, 3, and 
85 5 and is preferably secured to the surfaces 43 and/or 
edges 41 and 42 of the blades. 
In operation of a turbine, the main stresses in a rotat- 
ing blade thereof are the centrifugal stresses which act 
in a direction normal to the axis of rotation. This direc- 
40 tion coincides usually with the direction of the blade 
axis (span) and therefore, it is suilicient for the material 
fnnn which the blade body is made to have high tensile 
strength in one direction. A porous material of such 
Characteristic can be obtained when it is composed of 
wires or threads of metal. glass quartz or other ceramics 
arranged in the way described hereinbefore. Thus, 
where the term "wire" is used, this term is not to be lim- 
ited in interpretation to metal wires, but means also wire 
made of any material suitable to carry out the inven- 
60 tion. The porous material used for transpiration cooling 
heretofore consists more or less of spherical particles 
connected at the points where they touch each other and 
therefore, by nature, is not strong enough in tension to 
withstand the centrifugal loads imposed upon turbine 
blades. 
If centrifugal stresses alone were present it would be 
sufficient to have the wires Nnning parallel to each other 
as shown in FIG. 1 and even the interconnections at 20 
would be unnecessary. There are bending forces to con- 
e' tend with, but even under severe turbine operating condi- 
tions, the bending forces, which are caused by the deflec- 
tion of the gas stream passing the blades, are only about 
one tenth of the centrifugal forces. A slight inclination 
of the wires from the radial direction and/or connection 
of the wires will compensate for these forces. In reality, 
the gas flow along the outside of the blade causes pressure 
differences around the blade cross-section. These pressure 
merences would deform such a blade. Thus, some 
interconnection of the wires of the blades is desirable for 
Ex- 
amples of such interconnection are shown in FIGS. 3 
16 together, as by welding 20 or other suitable means. 
30 coolant fluid may pass. 
'O producing a more satisfactorily operative blade. 
-1 d 
8,011,760 
3 4 
and 4. Moreover, to have the desired coolant flow dis- tions the shell of said turbine blade, said 6rst plurality of 
tribution the blades may be built up of several layers of wires having spaces therebetween, a second plurality of 
wire. wires interconnected with said 6rst plurality of wires and 
It is understood that known practices and techniques extending generally transverse thereto, means to conduct 
may be used to produce the described invention, and that 6 cooling fluid through said base and into said blade whereby 
various modifications and variations as fall within the said cooling fluid is supplied to said spaces to provide 
scope of the claims may bc made without departing from transpiration cooling of said blade, and a stiffener disposed 
the protection thereof. within and connected to said shell of said turbine blade. 
What is claimed is: 4. A turbomachine blade consisting of: a hollow porous 
1. A hollow turbine blade comprising a base adapted to 10 shell structure having aerofoil profile; said hollow shell 
be co~ec ted  to a turbine wheel, a plurality of wires con- structure having opposed faces and formed of a first plu- 
nected to said base and having their axes extending gen- rality juxtapositioned wires having their axes extending 
erally parallel to each other and away from said base, generally parallel to each other and having spaces there- 
said wires defining by their relative positions the upper and between, a second plurality of juxtapositioned wirea gen- 
lower cambers and leading and trailing edges of said hol- 16 erally parallel to each other and having spaces therebe- 
low turbine blade, said wires having spaces therebetween tween, and in contact with and interconnected with said 
to provide for transpiration cooling of the blade, and said first plurality of wires and extending in angular relation 
base having an aperture therethrough to conduct cooling thereto, whereby cooling fluid supplied to the interior of 
fluid through said base and into said hollow blade where- said hollow shell structure will pass through said spaces for 
by said cooling fluid is supplied to said spaces and flows &o transpiration cooling of said blade. 
therethrough to the exterior of said blade. 
2. A turbine blade comprising a base adapted to be References Cited in the fie of thii patent 
UNITED STATES PATENTS connected to a turbine wheel, a first plurality of wires connected to said base and having their axes extending 
generally parallel to each other and away from said base, 25 
said first plurality of wires defining by their relative posi- 
tions the shell of said turbine blade, said first plurality 
of wires having spaces therebetween, a second plurality 
of wires interconnected with said first plurality of wires 
and extending generally transverse thereto. and means to 30 
2309,376 
2,509,377 
2,529,946 
2;699,598 
2,720,356 
2,774,566 
conduct cooing fluid-through said base-and into said 
blade whereby said cooling fluid is supplied to said spaces 
to provide transpiration cooling of said blade. 
3. A turbine blade comprising a base adapted to be 
connected to a turbine wheel, a 6rst plurality of wires con- 36 
nected to said base. and having their axes extending gen- 
erally parallel to each other and away from said base, 
said first plurality of wires defining by their relative posi- 
235,304 
619,634 
619,722 
715,421 
924,012 
1,OQ7,303 
Trask ____________  --_- May 30, 1950 
Trask ..__-________ ----_ May 30, 1950 
Imbert _________________  Nov. 14,1950 
Daugherty _________-___ Jan. 18, 1955 
Erwin _______-____-_-_ Oct. 11, 1955 
Richardson _____________  Dec. 18, 1956 
FOREIGN PATENTS 
Great Britain -------___ June '12, 1925 
Great Britain _-_--_- --__ Mar. 11,1949 
Great Britain ____-_____ Mar. 14, 1949 
Germany ____- - ______-_ Dec. 20, 1941 
France _________________ Mar. 3, 1947 
France ________________ Feb. 6, 11952 
, 


Transpiration cooled turbine blade manufactured from wires Patent

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