Experimental investigation of air-flow uniformity and pressure level on wire cloth for transpiration-cooling applications

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Title:
Experimental investigation of air-flow uniformity and pressure level on wire cloth for transpiration-cooling applications
Series Title:
NACA RM
Physical Description:
28 p. : ill. ; 28 cm.
Language:
English
Creator:
Donoughe, Patrick L
McKinnon, Roy A
Lewis Research Center
United States -- National Advisory Committee for Aeronautics
Publisher:
NACA
Place of Publication:
Washington, D.C
Publication Date:

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Subjects / Keywords:
Airplanes -- Motors -- Cooling   ( lcsh )
Aerodynamics -- Research   ( lcsh )
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federal government publication   ( marcgt )
bibliography   ( marcgt )
technical report   ( marcgt )
non-fiction   ( marcgt )

Notes

Abstract:
Abstract: An experimental investigation was conducted to obtain information on air-flow uniformity and pressure-level effects for various meshes of stainless-steel corduroy wire cloth, and permeability and strength data for a 20- by 20-mesh stainless-steel wire cloth. It was found that close control of the wire cloth thickness yielded sufficiently uniform air flow and that available methods may be used to predict the effect of pressure level. Permeability and strengths of the 20- by 20-mesh wire cloth were similar to those already available from other meshes. The reduced tensile strength of the 20- by 20-mesh wire cloth in the direction of the primary stresses is one and a half to three times as great as the strength of the best porous sintered materials presently available.
Bibliography:
Includes bibliographic references (p. 12-13).
Statement of Responsibility:
by Patrick L. Donoughe and Roy A. McKinnon.
General Note:
"Report date July 22, 1952."
General Note:
"Classification changed to unclassified Authority: Mr. J.W. Crowley Change #2997 May 16, 1955 W.H.L.."--stamped on cover

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University of Florida
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All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 003810536
oclc - 133466406
sobekcm - AA00006186_00001
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AA00006186:00001

Full Text
IL LEADON
SECURITY INFORMInATION
51-I
RM E52E16










RESEARCH MEMORANDUM




EXPERIMENTAL INVESTIGATION OF AIR-FLOW UNIFORMITY

AND PRESSURE LEVEL ON WIRE CLOTH FOR

TRANSPIRATION-COOLING APPLICATIONS
SBy Patrick L. Donoughe and Roy A. McKinnon

Lewis Flight Propulsion Laboratory
Cleveland, Ohio
*C.&a Scqation changed to UMIa, OF FL
Uncl.sified May lo", u ME ::
1ESAREDEPARTMEND T
)Mo 0MAITON SIENCN UBMET y
Authority Mr. J, W, Crowley P.O. BOX 117011iSARY
Change # H2997
UnLcSaiidaD DOCUMEn )-T DEP T N
2 y a997 rZKrrrj ;iGyToj P .O.FL 0 17011-7011 US
Tnis material contains Informan on abiectin the r lorial Defie~e~ of ue Untal. L5; wtlhin tbe mialrg
of the esplonage laws, Title 18, U.S.C.. 3eca "93 aza ?tl, mte trana-misjion or rmvlauon af iahich n 3my
manner to an InautI~rized person L prohibited by L6.

NATIONAL ADVISORY COMMITTEE
FOR AERONAUTICS
WASHINGTON
July 22, 1952


7 TIAL












NACA RM E52E16 CONFIDENTIAL


NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS

RESEARCH MEMORANDUM

EXPERIMENTAL INVESTIGATION OF AIR-FLOW UNIFORMITY AND PRESSURE

LEVEL ON WIRE CLOTH FOR TRANSPIRATION-COOLING APPLICATIONS

By Patrick L. Donoughe and Roy A. McKinnon


SUMMARY

The problem of producing uniform air flow through a calendered or
cold-rolled sheet of brazed stainless-steel corduroy wire cloth was
investigated on 20x250 mesh cloth in regions of low permeability. The
effect of exit pressure level was determined at various exit pressures
on 20X200, 20X250, and 28X500 mesh wire cloth. In addition, permea-
bility and strength data were obtained for 20X200 mesh wire cloth to
supplement results previously published on other meshes.

It was found that for permeability coefficients of the order of
10-9 inch2 control of the calendering process to 0.0002 inch should
yield air flow uniform within 5 percent. Results showed that available
methods may be used to predict, within experimental accuracy, the effect
of exit pressure level. The values of permeability and strength of the
20(200 mesh wire cloth were close to those already available for the
other meshes. The reduced tensile strength of 2C0200 and 20X250 mesh
1
wire cloth, in the direction of the primary stresses, was 1- to 3 times
2
as great as the strength of the best porous sintered materials presently
available.


INTRODUCTION

The superior cooling effectiveness attainable by the transpiration
cooling of a structure in a high-temperature, high-velocity gas stream
is discussed in reference 1. In this method of cooling, the part to be
cooled is made of a porous material having a predetermined permeability;
the coolant is forced through the porous wall, cooling the wall as it
passes through and forming a protective insulating layer on the surface
exposed to the hot gas stream. One material, investigated in refer-
ence 2, that could possibly be used for transpiration-cooled walls is
stainless-steel corduroy wire cloth.

It is shown in reference 2 that the rigidity of the wire cloth can
be increased by a silver-alloy brazing process and the permeability can


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2 CONFIDENTIAL NACA RM E52E16


be controlled by calendering or cold rolling. Permeability and
strength characteristics were also obtained for three different meshes,
20X250, 20X350, and 28X500. Comparison with available results on
porous sintered materials revealed that these stainless-steel wire
cloths offer a much wider range of permeability and possess ultimate
tensile strengths, in the direction of primary stresses (coinciding
with the direction of the larger number of wires), two to three times
the ultimate tensile strength of the porous sintered materials.

In the application of transpiration cooling to turbine blades, the
blade contours will probably be formed from a sheet of brazed stainless-
steel wire cloth which has been calendered to obtain desired permea-
bilities. For porous turbine blades, the required permeability coeffi-
cient is expected to be of the order of 10-9 inch2. In this range of
low permeability, small changes in thickness reduction by calendering
produced large changes in permeability (reference 2). Consequently,
the problem of producing a sheet of cloth with a uniform desired
permeability requires further study because of the close tolerances
necessary in calendering.

At altitude, the pressure level and distribution around turbine
blades are much different from those at sea-level conditions. Calcula-
tions also indicate that the maintenance of the required coolant flow
at altitude requires special study. Permeability measurements on
porous materials are usually obtained at ambient exit conditions and
extrapolated to other conditions by the use of some theoretical rela-
tion such as Darcy's law. Air-flow measurements on the wire cloth
made at different exit pressures and pressure levels give a check as
to the validity of such extrapolations.

The pressure drop for a given flow is shown in reference 2 to be
roughly proportional to the thickness of the wire cloth. For a given
pressure drop, a cloth with large wires requires less thickness reduc-
tion than one with small wires and because of the lesser reduction
uniform permeability is more easily obtained. In addition, a structure
formed with a thicker cloth should be stiffer and require less rein-
forcement. A commercially available 20X200 mesh wire cloth is thicker
than the cloth investigated in reference 2; information about this mesh,
similar to that presented for the other meshes, is desirable.

An experimental investigation was carried out at the NACA Lewis
laboratory in order to obtain information on the points previously-
specified. Results are presented herein regarding (1) uniformity of
air flow in the region of low permeability coefficient (10-9 in.2) for
20X250 mesh, (2) effect of pressure levels for pressure-square differ-
ences up to 1450 pounds2 per inch4 on air flow through 20X200, 20X250,
and 28x500 mesh, and (3) permeability and strength data for a 20X200
mesh stainless-steel wire cloth.


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NACA RM E52E16 CONFIDENTIAL


APPARATUS AND PROCEDURE

Description and Preparation of Wire Cloth

Various meshes of stainless-steel wire cloth were utilized to
obtain uniformity of air-flow and pressure-level effects. The specifi-
cations and the preparati n of the 20X250 and the 28X500 mesh cloths
are discussed in reference 2. The same material, AIST type 304 stain-
less steel, was used for the 20X200 mesh wire cloth. This mesh has
20 wires per inch (0.011 in. diam) in the crosswise, or warp, direction
and 200 wires per inch (0.010 in. diam) in the lengthwise, or shoot,
direction. Front and side views of the 20X200 mesh wire cloth, as woven
and after calendering, are shown in figures l(a) and l(b). The average
thickness of this mesh as-woven was measured as 0.0307 inch, which is
15 percent greater than the thickest mesh reported in reference 2; this
thickness was increased to an average of 0.0312 inch by brazing. In
the brazing process, the cloth as-woven was sprayed with a silver
brazing alloy (12600 F melting point) and dipped into a salt bath at
14000 F until the sprayed alloy was brazed to the surface of the wires
(about 30 sec). Views of the cloth after brazing and after calendering
are shown in figures l(c) and l(d). This preparation was the same as
that described in reference 2. The cloth containing no brazing material
is herein referred to as "unbrazed wire cloth", and the sprayed and
heated cloth as "brazed wire cloth".


Thickness and Air-Flow Measurements

Uniformity of thickness and air flow were checked on the 20X250 mesh
wire cloth with disks 1- inches in diameter stamped from sheets which
2
1
had been calendered to a nominal thickness. The llinch diameter was
2
used only to facilitate stamping of the disks. The diameter of that
portion of the disk exposed to air flow in the test section was
1.31 inches. The thicknesses of the disks were measured with microme-
ters. Five thickness measurements were made on each disk, one in the
center and the others 1/4 inch from the disk edge spaced at 90. Prior
to stamping, orientation marks were made so that the thickness measure-
ments for each disk would be in the same relative position with respect
to the calendered sheet.

The method of sealing the test specimens was different from that
described in reference 2 and is shown in figure 2. In place of metal
gaskets, paper gaskets (0.004 in. thick) were placed above and below
the rim of the disk which lies in a groove of a pipe flange. A rubber
0-ring, 2 inches in diameter, was located in another groove outside the
disk. When a mating pipe flange was drawn tightly, the paper gaskets


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NACA RM E52E16


and the rubber 0-ring were compressed and formed an effective seal.
Only one disk, or one layer of wire cloth, was used in the current
experiments because it was found in reference 2 that the number of
layers used as the test specimen produces a negligible effect on the
permeability coefficient.

The equipment used to obtain air-flow data for the 20X200 mesh
cloth was similar to that described in reference 2 but some modifica-
tions were necessary for the pressure-level investigations. The appa-
ratus is schematically shown in figure 2. Air at room temperature and
a pressure of 120 pounds per inch2 gage was filtered, passed through
a pressure regulator, controlled by a hand valve, and measured by a
rotameter prior to entering the wire cloth. (It was noted that with
a standard commercial-type filter, no noticeable clogging of the wire
cloth occurred.)

In the pressure-level experiments on the 20X200, 20X250, and
28X500 mesh cloths, it was necessary to control the exit pressure, or
the pressure of the air leaving the specimen. To this end, hand valves
were placed in the exit line which was connected to the altitude exhaust
system to provide exit pressures below atmospheric. Exit pressures
above atmospheric were obtained by using the hand valves as throttles
and exhausting the air into the room. During the tests, pressures on
both sides of the specimens and weight flow through them were measured.
Exit pressures of 36.8, 29.4, 11.76, and 8.82 pounds per inch2 abso-
lute were maintained during the pressure-level experiments. In the
flow uniformity and 20X200 mesh studies, the exit pressure was atmos-
pheric.


Strength Measurements

Room-temperature strength measurements of the 20X250, 20X350, and
28X500 mesh cloths are described in reference 2. The strength of the
20X200 mesh cloth was determined in a similar manner. The specimens,
0.6 inch wide and 12 inches long, were tinned at the ends to obtain
better gripping in the jaws of the testing machine. A constant rate
of loading was used rather than the 100-pound increments used in ref-
erence 2.


METHODS OF CORRELATION AND CALCULATION

Reduction of Air-Flow Data to Standard Conditions

The examination of the air-flow data for pressure-level effects,
uniformity, and permeability was based on the following relation, given
in reference 3, for the flow of a gas through the plane wall of a
porous material:


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NACA RM E52E16


p12- 2 2 T''T G + 2
T = a (RTi) G + ( G)


where a is termed the viscous resistance coefficient and 0 the
inertial resistance coefficient. (Symbols are defined in appendix.)
It is noted in reference 4 that equation (1) when solved for G may be
written
G/p2 2
G/g = CI2 + C2 P 2 C1 (2)
V 2TT


C1 = ag/2p, and


C2 = g/2PR being constant for each specimen so


/1 = t 2)
G/9 = fl [ 12
\ 2TT


Equation (3) can be used to reduce the data to standard conditions by
introduction of ,o and Lo'2To, where the subscript o signifies IACA
standard temperature of 5180 R. Thus, equation (3) becomes


G -o = f
P.


l -P22 0o To
T 12T


Equation (4) is utilized as the correlation equation for the air-flow
P2 -P 2 2"1
data in this report by plotting pI-P22 o 2 against G C for a
T 2T

P12-P92 oT 2
porous specimen. The logarithm of --- is herein referred
T' p2T
to as the "pressure-drop parameter" for discussion purposes. The vis-

4o 0o To
cosity i and the temperature correction factors and

are given in table I as functions of temperature.


Calculation of Permeability, Porosity, and Strength

Comparison of results from tests on different porous materials is
usually made on the basis of permeability. A permeability coefficient
K based on Darcy's law is given by


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with
that


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6 CONFIDENTIAL NACA RM E52E16



pl 2P22 1
T--!=R (2RTi) G (5)


A linear relation between the pressure-square difference per unit thick-
ness and the mass rate of flow is assumed in this law. Actually the
relation is not quite linear; the use of equation (1) is therefore
recommended in reference 3. In reference 2 equations (1) and (5) were
equated and solved for K with the result that


K=- (6)
1 + 0 G
Capg


The permeability values given in this report and in reference 2 were
obtained in the following way: The method of least squares (refer-
ence 5) was applied to equation (1) and a and P were calculated
for a series of mass flows and pressure-square differences for a given
reduction in the original thickness of the wire cloth. In order to
make a comparison with results obtained in previous investigations,
equation (6) with G = 0 was used and K is therefore the reciprocal
of a. Both a and [ were calculated because the air-flow data for
the wire cloth fit equation (1) and not equation (5). Such an evalua-
tion method eliminates the variation in permeability coefficient with
pressure level reported in reference 6 for a given specimen. Values
of [/a were of the order of 7X10-4 inch for the 20X200 mesh wire
cloth.

The porosity of a porous specimen is defined as the ratio of the
volume of voids to the total volume. The equation used for obtaining
the porosity of brazed stainless-steel corduroy wire cloth, derived in
reference 2, is


f = 1 1 b (7)
T \s A 1b A/

The porosities of the wire cloths with different reductions in original
thickness were calculated by use of equation (7). The weight per unit
surface area of the unbrazed material is Ws/A and the difference in
weight per unit surface area between the brazed and unbrazed material
is Wt/A. (For the 18-8 stainless steel, y', was taken as
0.285 lb/in.3 and for the brazing alloy, yb was taken as 0.544 Ib/in.3.)


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NACA RM E52E16 CONFIDENTIAL 7


The ultimate tensile strength of a material is defined as the
force required to break or rupture the specimen divided by the cross-
sectional area of the specimen,

a = F/a (8)

In reference 2, it is pointed out that for aircraft structural elements
where weight is an important factor, a better strength criterion is a
reduced tensile strength given by


= F 1.ys (9)


Both the ultimate tensile strength and the reduced tensile strength
were calculated for the 20X200 mesh wire cloth by use of equations (8)
and (9) with the substitution of the measured values of breaking force,
area, weight, and length for the different reductions in original
thickness.

It is shown in reference 2 that for porous sintered materials the
relation between the reduced tensile strength and ultimate tensile
strength is

o' = (10)
1-f

Where strengths of these materials are given herein, this relation,
which credits the porous material with its lighter weight, is used.


RESULTS AND DISCUSSION

Air-Flow Uniformity for Calendered Wire Cloth

The air-flow uniformity tests were made on two sheets of 20X250 mesh
S^ stainless-steel wire cloth calendered tcr nominal reductions of 36 per-
cent and 49 percent of the original thickness, respectively. Because
any nonuniformity in thickness will probably result in a nonuniform air
flow, detailed thickness measurements were made as noted in the
"APPARATUS AND PROCEDURE" section. The measured thicknesses of the
20X250 mesh wire-cloth disks are shown in figures 3(a) and 3(b) for
specimens reduced in the calendering process 36 and 40 percent, respec-
tively. Sketches that show the disk location on the sheet are included
in these figures. The average thicknesses of the disks from the right
sides of the sheets were less than those of the other disks. The
thinner disks were expected to pass less air flow for a given pressure
S drop because of the decreased permeability.


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NACA RM E52E16


Air-flow data are presented in figure 4(a) for the sheet of
20X250 mesh wire cloth that was reduced 56 percent in thickness by
calendering; the pressure-drop parameter is plotted against the correc-
ted mass flow through the disks. Rather than show the data for all
15 disks on one ordinate scale, five plots are presented; each plot is
for three disks at the same y position. A curve representing the
average of all the data points is drawn through each set of data. The
36-percent reduction in the original thickness of this piece of wire
cloth corresponds to a permeability coefficient of about 6X10-9 inch2
(range for turbine blades); the air flow may be considered uniform
within ,5 percent. For lesser thickness reductions, the air flow should
be more uniform because of the permeability-thickness reduction charac-
teristics of the wire cloth.

The air-flow data for the sheet reduced 40 percent in thickness
are shown in figure 4(b); again, the same curve is drawn for both plots.
Disks 1 and 4, which showed greater thickness reductions (fig. 3(b)),
passed about 50 percent less mass flow for a given value of the pressure-
drop parameter. The 40-percent reduction, which corresponds to a permea-
bility coefficient of about 10-10 inch2, requires closer control of the
final thickness of the wire cloth than is required for the 56-percent
reduction for the same uniformity in air flow. Such control may be
possible by improved calendering techniques.


Effect of Exit Pressure or Pressure Level on Air Flow

Three different meshes, having various thickness reductions, were
used to determine any effects on air flow due to different exit pres-
sures or pressure levels. The results in the form of the pressure-drop
parameter against mass flow are shown in figure 5(a) for the 20X200 mesh,
in figure 5(b) for the 20X250 mesh, and in figure 5(c) for the
28X500 mesh. Although the exit pressures ranged from 0.6 to 2.5 atmos-
pheres and the pressure-square differences ranged up to 1450 pounds2
per inch4, the resulting variations in air flow were small and are repre-
sented with good accuracy by equations (1) and (6) in the range in which
Vo
0< G -L <0.004.



Permeability and Strength of 20X200 Mesh Wire Cloth

The results of the permeability tests on the 20x200 mesh wire
cloth are plotted as the pressure-drop parameter against the corrected
mass flow in figure 6(a) for the unbrazed wire cloth and in figure 6(b)
for the brazed wire cloth. Each of the figures contains the results of
various reductions in thickness by calendering. The effect of brazing


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NACA RM E52E16


the cloth is evidently more apparent for the larger reductions in thick-
ness. This effect is shown by a comparison of the specimens reduced 42
and 23 percent (figs. 6(a) and 6(b)). At a given value of the pressure-
drop parameter, the brazed specimen that was reduced about 42 percent in
thickness passed only about 1/5 as much mass flow as did the unbrazed
specimen. The mass flow through the specimens that were reduced about
23 percent in thickness was nearly the same whether brazed or unbrazed.

This same effect is also illustrated in figure 7 where the calcu-
lated permeability coefficients are given as a function of the reduction
of thickness produced by calendering. Also included are curves showing
results from reference 2 for the three meshes investigated therein.
The reason for the discrepancy between the previous results and those
obtained with the 20X200 mesh wire cloth is not readily apparent. The
scatter of the data in reference 2 made the curves difficult to estab-
lish; and the lack of data scatter for the results on the 20X200 mesh
is perhaps attributable to refinements in sealing made in the test appa-
ratus.

The porosities of the 20X200 mesh cloth were calculated by use of
equation (7). Because both porosity and permeability are functions of
the reduction in thickness, it is possible to show the porosity as a
function of the permeability coefficient. This relation is shown in
figure 8 where porosity is plotted against permeability coefficient for
the 20X200 mesh wire cloth, brazed and unbrazed. Also included are
results from reference 2 for different meshes and some values for the
porous sintered materials recently reported in references 6 and 7. The
20X200 mesh wire cloth shows the same trends as the meshes previously
investigated and the permeability range is much greater than that of
the porous sintered materials (fig. 8).

In figures 9(a) and 9(b), the ultimate tensile strengths and
reduced tensile strengths, obtained by use of equations (8) and (9),
are given as functions of the reduction in thickness of the unbrazed
and brazed wire cloth. Also included as a dashed line are some results
from reference 2 for the 20X250 mesh cloth. Strength data obtained in
the present investigation for the brazed 20X250 mesh are also shown in
figure 9(b). The reduced strengths of the 20X200 mesh cloth are not
very different from those of the 20X250 mesh.

Finally, the reduced tensile strength of the 20X200 mesh wire
cloth was plotted against the permeability coefficient in figure 10
along with results from reference 2 for other meshes and from refer-
ences 6 and 7 for porous sintered materials. Average strength results
from reference 7, calculated by use of equation (10) are represented
by curve 8. The strength range of the 20X200 mesh wire cloth is similar
to that obtained for the 20X250 mesh. Much higher strengths than pre-
viously reported are shown for the porous sintered materials because
of the additional process of coining and resintering. The reduced


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NACA RM E52E16


tensile strengths of the 20X200 and 20X250 mesh wire cloth, in the
1
direction of the primary stresses, however, are still 1- to 3 times
2
the strengths of the porous sintered materials.


SUMMARY OF RESULTS

An experimental investigation was conducted with stainless-steel
corduroy wire cloth to determine: uniformity of air flow in the region
of low permeability coefficient (10-9 in.2) for brazed and calendered
20X250 mesh; effect of pressure level on air flow for brazed and calen-
dered 20X200, 20X250, and 28X500 meshes; and permeability and strength
data for brazed and unbrazed 20X200 mesh with different amounts of
calendering. The following results were obtained:

1. For a reduction of 36 percent in the original thickness of the
wire cloth, control of the calendering to 0.0002 inch yielded uniform
air flow within k5 percent. Reduction of 40 percent would require
closer control of calendering for the same air flow uniformity.

2. The effect of pressure level for exit pressures from 0.6 to
2.5 atmospheres was predicted by known analytical relations, within
experimental accuracy, in the corrected mass flow range up to
0.004 pound per second-inch2.

3. The permeability and the porosity data for the 20X200 mesh wire
cloth were in the same range as the data for other meshes previously
investigated, but for a given pressure-square difference less thickness
reduction was necessary for the 20X200 mesh wire cloth.

4. The reduced tensile strengths of the 20X200 mesh wire cloth
were about the same as those of the 20X250 mesh. The reduced tensile
strength of the cloth, in the direction of the primary stresses, was
1
1. to 3 times as large as the strength of the best porous sintered
materials presently available.


Lewis Flight Propulsion Laboratory
National Advisory Committee for Aeronautics
Cleveland, Ohio


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NACA RM E52E16


APPENDIX SYMBOLS

The following symbols are used in this report:

A surface area, in.2

a cross-sectional area, in.2


Cl M, sec-2


C 9 (in.)(R)/sec2
C2 2PR-

F rupture force, lb

f porosity, dimensionless

flf2 functions

G mass rate of air flow, lb/(sec)(in.2)

g gravitational constant, in./sec2

K permeability coefficient, in.2

L length, in.

p static pressure of air, Ib/in.2

R gas constant for air, in./OR

T static temperature of air, OR

W weight, Ib

x direction perpendicular to calendering, or direction of cross-
wise wires

y direction parallel to calendering, or direction of lengthwise
wires

a viscous resistance coefficient, in.-2

P inertial resistance coefficient, in.-1

Y weight per unit volume of specimen, lb/in.3


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NACA RM E52E16


1 absolute viscosity of air,(lb)(sec)/in.2

a tensile strength, lb/in.2

a' reduced tensile strength, lb/in.2

T thickness of porous material, in.

Subscripts:

1 side of porous material at high pressure

2 side of porous material at low pressure

b brazed

o NACA standard temperature of 5180 R

s steel


REFERENCES

1. Eckert, E. R. G., and Esgar, Jack B.: Survey of Advantages and
Problems Associated with Transpiration Cooling and Film Cooling of
Gas Turbine Blades. NACA RM E50K15, 1951.

2. Eckert, E. R. G., Kinsler, M R., and Cochran, R. P.: Wire Cloth
as Porous Material for Transpiration-Cooled Walls. NACA RM E51H23,
1951.

3. Green, Leon, Jr.: Fluid Flow Through Porous Metals. Prog. Rep. No.
4-111, JPL, CIT Aug. 19, 1949 (Ordnance Dept. Contract No.
W-04-200-ORD-455.)

4. Bartoo, Edward R., Schafer, Louis J., Jr., and Richards, Hadley T.:
Experimental Investigation of Coolant-Flow Characteristics of a
Sintered Porous Turbine Blade. NACA RM E51K02, 1952.

5. Lipka, Joseph: Graphical and Mechanical Computations. Part II -
Experimental.Data. John Wiley & Sons, Inc., 1921, p. 124.

6. Reen, 0. W., and Lenel, F. V.: Production of Porous Metal Compacts
Bi-Monthly Prog. Rep. No. 8, Powder Metallurgy Lab., Rensselaer
Polytechnic Inst., August 6, 1951. (Navy Research Contract
Noa(s) 11022).


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NACA RM E52E16


7. Comstock, Gregory J., Mott, Lambert H., Bradbury, John D., and
Grinthal, Robert D.: Navy Project for Investigation of Porous
Material From Spherical Metal Powders. Bi-Monthly Prog. Rep. No.6,
Powder Metallurgy Laboratory, Stevens Inst. of Tech., September 30,
1951. (BuAer. Contract Noas 51-185-c).

8. Keenan, Joseph H., and Kaye, Joseph: Gas Tables. John Wiley & Sons,
Inc., 1948, p. 34.


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TABLE I TEMPERATURE CORRECTION FACTORS

Static Absolute Temperature
tempera- viscosity correction
ture of of airl factors
air 2
T (lb-sec/in.2) o11 To
(R) \ ) T

400 21.6X10-10 1.210 1.8960
450 23.5 1.110 1.4183
500 25.5 1.025 1.0893
518 26.1 1.000 1.0000
550 27.2 .960 .8685
600 29.1 .896 .6936
650 30.9 .846 .5706
700 32.6 .801 .4751
750 34.1 .766 .4050
800 55.8 .729 .3440
850 37.3 .699 .2981
900 38.6 .676 .2630
1000 41.4 .630 .2057
1100 44.3 .590 .1640
1200 47.1 .555 .1330
1300 49.6 .526 .1103
1400 52.2 .500 .0925
1500 54.6 .478 .0790
1600 57.0 .458 .0680
1700 59.1 .442 .0594
1800 61.3 .426 .0522
1900 63.2 .413 .0465
2000 65.2 .401 .0416
2100 67.1 .389 .0373
2200 69.1 .378 .0337
2300 71.0 .368 .0305
2400 73.0 .358 .0277

lValues obtained from reference 8. 4


CONFIDENTIAL


CONFIDENTIAL







NACA EM E52E16


'!








it~ CA" jjtp f;


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(a) Unbrazed and uncalendered.





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i'r"U u' J C- 29729
(b) Unbrazed and calendered.
Figure 1. Photographs of 20X200 mesh stainless-steel corduroy wire cloth; X10.
CONFIDENTIAL


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L6 CONFIDENTIAL

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C-29730
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(d) Brazed and calendered.
Figure 1. Concluded. Fbot..-'.grapha of 20x200 mesh stainless-steel corduroy wire cloth; X10.
COCTFIDEITIAL









NACA RM E52E16


Air, 120 Ib/in.2
gage

Sample-
S0 Lo-ring
\ .-i.31 in.- ,





Filter
T'ermoc.:uple





Pressure
regulator


Altitude exhaust,
20 in. Hg
ta vacuum

I


valve


-Static-pressure
/ tape


Rotameter


Flow-control
valve


Figure ?. Schematic diagram of equipment used for measuring
air flow broughth specimens of wire cloth.


CONFIDENTIAL


CONFIDENTIAL










NACA RM E52E16


.0)17-
..l I o I

o 1 2 3 4 5 6
Distance in direction perpendicular to calendering, x, in.

(a) Thickness reduction, 36 percent.

Figure 3. Thickness measurements of brazed 20x250 mesh wire cloth.


CONFIDENTIAL


-
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CONFIDENTIAL










; ACA RM E52E16


CONFIDENTIAL


n NACAI i


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Averages
I I
0.0163 0.0184 0.011- 0.0163 0.0iE3 0.0156
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Distance In direction perperndcular to calenaderirn, x, In.
(.-I TMickneas reduction, 40 percent.

Figure 3. Concluded. Thicknese measurements o'f braz'oi 2,>r25: mesh hire cioth.


CONFIDENTIAL


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Figure 4. Unl 'c.rmlty o" air r ow through Drazed 20 250 mesh wire cloth.


CONFIDENTIAL












NACA RM E52E16


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NACA RM E52E16


O 20X200 mesh, brazed
S- 20CXS00 mesh, unbrazed
I 1 -- ---- Average unbrazei 20x250,
h 20x550, and 28x500 mesh
(reference 2)
--- Average brazed 20x250,
20x350, and 28x500 mesh
(reference 2)







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0 10 20 30 40 50 6
Reduction in original thickness, percent

Figure 7. Effect of calendering on permeability coefficient of brazed
and unbrazed wire cloth.


CONFIDENTIAL


CONFIDENTIAL












CONFIDENTIAL


NACA RM E52E16




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CONFIDENTIAL


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120 Il0p '
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GAINESVILU


FLORIDA .


065699. .



- FLORIDA
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