Water-table flow tests were conducted for proposed heat-transfer tunnels which were designed to provide uniform flow into their respective test sections of a single core engine turbine vane and a full annular ring of helicopter turbine vanes. Water-table tests were also performed for the single-vane test section of the core engine tunnel. The flow in the heat-transfer tunnels was shown to be acceptable

Meitner, P. L.

English

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NASA TECHNICAL
MEMORANDUM
CO
!•>.
CO
NASA TM X-3073
WATER-TABLE TESTS OF
PROPOSED HEAT-TRANSFER TUNNELS
FOR SMALL TURBINE VANES
by Peter L. Meitner
Lewis Research Center
and
U.S. Army Air Mobility R&D Laboratory
Cleveland, Ohio 44135
\
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION • WASHINGTON, D. C. • JUNE 1974
https://ntrs.nasa.gov/search.jsp?R=19740017423 2020-03-23T08:35:48+00:00Z
1. Report No.
NASA TM X-3073
2. Government Accession No. 3. Recipient's Catalog No.
4. Title and Subtitle
WATER-TABLE TESTS OF PROPOSED HEAT-TRANSFER
TUNNELS FOR SMALL TURBINE VANES
5. Report Date
June 197!*
6. Performing Organization Code
7. Author(s)
Peter L. Meither
8. Performing Organization Report No.
E-7870
9. Performing Organization Name and Address
NASA Lewis Research Center and
U. S. Army Air. Mobility R&D Laboratory
Cleveland, Ohio 44135
10. Work Unit No.
501-24
11. Contract or Grant No.
12. Sponsoring Agency Name and Address
National Aeronautics and Space Administration
Washington, D, C. 20546
13. Type of Report and Period Covered
Technical Memorandum
14. Sponsoring Agency Code
15. Supplementary Notes
16. Abstract
Water-table flow tests were conducted for proposed heat-transfer tunnels which were designed to
provide uniform flow into their respective test sections of a single core engine turbine vane and
a full annular ring of helicopter turbine vanes. Water-table tests were also performed for the
single-vane test section of the core engine tunnel. The flow in the heat-transfer tunnels was
shown to be acceptable.
17. Key Words (Suggested by Author(sl)
Water table
18. Distribution Statement
Unclassified - unlimited
Category - 01
19. Security Classif. (of this report)
Unclassified
20. Security Classif. (of this page)
Unclassified
21. No. of Pages
15
22. Price*
$3.00
*For sale by the National Technical Information Service, Springfield, Virginia 22151
Page Intentionally Left Blank
WATER-TABLE TESTS OF PROPOSED HEAT-TRANSFER TUNNELS ' ,
FOR SMALL TURBINE VANES
by Peter L. Meitner
Lewis Research Center and
U. S. Army Air Mobility R&D Laboratory
SUMMARY
Water-table flow tests were conducted for proposed heat-transfer tunnels which
were designed to provide uniform flow to their respective test sections of a single core
engine turbine vane and a full annular ring of turbine vanes for an Army helicopter en-
gine. Water-table tests were also performed for the single-vane test section of the core
engine tunnel.
The three-dimensional flow through the tunnel configurations was simulated two di-
mensionally and at twice full size by modeling a slice through the cylindrical tunnel cross
sections. The tunnels were simulated from the burner outlet to the inlet of the corre-
sponding test sections. The single-vane test section of the core engine tunnel was mod-
eled full scale. The flow in the heat-transfer tunnel configurations was shown to be ac-
ceptable for use in planned heat-transfer tests.
INTRODUCTION
Water-table flow tests were conducted for proposed heat-transfer tunnels which were
designed to accommodate a core engine single-vane test section and a test section con-
sisting of an annular ring of turbine vanes for an Army helicopter engine. Water-table
tests were also performed for the single-vane test section of the core engine tunnel. The
overall tunnel configurations were designed to give good flow paths into their respective
test sections.
The heat-transfer tunnels,will be used for high-temperature and high-pressure tests
of core engine and helicopter vanes incorporating advanced cooling schemes. To obtain
meaningful test results, it is important that the flow patterns into the test sections be as
similar as possible to those experienced in actual engine operation. Large variations or
discrepancies in the test-section flow patterns could give heat-transfer test results
which, if incorporated into final engine designs, could seriously impair the performance
of those designs.
In the investigation described in this report, the three-dimensional flow through the
tunnel configurations was modeled twice full size by simulating a slice through the cy-
lindrical tunnel cross sections. Dye was injected at the tunnel entrances and just up-
stream of the single-vane test section of the core engine tunnel. Photographs of the re-
sulting flow patterns were obtained and analyzed qualitatively. Design modifications
were made as the tests progressed to provide straight flow into both test sections and to
ensure that the streamlines around the core engine stator vane were acceptable for the
planned heat-transfer tests.
APPARATUS
Water-Table Description
An overall view of the water table which was used to determine the flow patterns in
the heat-transfer tunnel configurations is shown in figure l(a). The rake and hypoder-
mic needles that were used to inject dye into the water stream are shown in figure l(b).
The water table measures 226 by 122 centimeters (89 by 48 in.) and is illuminated
from below through a glass plate which forms the bottom of the table. A camera is
mounted from a truss network above and records the streamline patterns in the flow
model. An electric motor continually recirculates filtered water. The depth of the
water can be set from 0 to 11. 4 centimeters (0 to 4. 5 in.), and the flow rate can be
varied from 13. 2X103 to 114X103 cubic centimeters per minute (3. 5 to 30 gal/min).
Basic Tunnel Configuration
The starting-point configuration for both tunnels is shown schematically in figure 2
by the solid lines. The labeled components of this configuration are those items which
were known to be needed. They are the burner outlet, bluff body, settling chamber, and
test-section inlet. The purpose of the settling chamber is to allow thorough mixing of
the gas stream and thus give a uniform flow temperature profile into the test section.
The bluff body is used to prevent direct radiation from the burner to the test vane or
ring of vanes. This allows accurate heat-transfer measurements to be made without
recourse to large radiation corrections. The dashed lines show the helicopter engine
test section inlet and the triangular ring which, in the course of the flow tests, was
found to be necessary to properly direct the flow to the test-section inlet.
PROCEDURES
The heat-transfer tunnel configurations were developed to provide thorough gas mix-
ing and to eliminate combustor radiation at the test sections. It was also desired to de-
velop configurations which would guide the flow into the inlet of the corresponding test
sections without undue scrubbing of the side walls. The actual tunnel configurations up-
stream of the test section are cylindrical in shape, but the geometries were developed by
taking a two-dimensional slice through the cross sections. Also, these portions of the
tunnels were modeled twice full size. The heat-transfer tunnel models were fabricated
from sections of urethane foam and clear plastic. A full-scale single-vane test section
of the core engine tunnel, including the inlet section, was fabricated from clear plastic.
The flows through the tunnels and the single-vane test section were visualized by inject-
ing dye upstream (through hypodermic needles and a rake, respectively) and photograph-
ing the streaks that formed as the water flowed through the models.
RESULTS AND DISCUSSION
Water-table flow tests are often used to model two-dimensional, isentropic, com-
pressible flow of air in which no body forces, friction, or turbulence is assumed to be
present. For a complete analogy, geometric similarity and equivalence in specific-heat
ratio y and Mach number must exist between the real case and the modeled flow. Not
all these equivalences can be satisfied in flow modeling using water-table tests.
The specific-heat ratios of air and water are not equal (y - 2. 0 for water, y < 1. 4
for air at elevated temperatures), but the error introduced by this discrepancy is small
and unavoidable when modeling an air phenomena in water. Most importantly, however,
the flow Mach number M through the heat-transfer tunnel test rig is so low (M = 0. 05
at the burner outlet, 0. 014 over the bluff body, and 0. 21 at the core engine test-section
inlet) that the flow can be considered incompressible. This negates the Mach number
equivalence in favor of geometric similarity. The main thrust of this investigation was
thus directed at correctly modeling the sudden area changes (and thus the resulting
decelerations and accelerations) which the gas stream experiences in traversing the
tunnel test rig from the burner outlet to the test-section inlet.
Core Engine Single-Vane Tunnel
The tunnel configuration for the core engine single-vane test section was developed
first. The tunnel components are the same as those assumed for the basic tunnel con-
figuration, except that it was necessary to add a triangular ring around the periphery of
the settling chamber. This ring directs the flow towards the test-section inlet and keeps
the flow from attaching to the side walls. If the triangular ring cross section was too
small, the flow impinged on the back wall, just to the side of the test-section inlet, and
in extreme cases the flow reattached itself to the side walls.
Various shapes of bluff bodies were investigated (see fig. 3). The curvature on the
front of the bluff body had no significant effect on the flow downstream. The depth of the
bluff body in the axial direction was dictated by the need to get the internal cooling con-
figuration into the bluff body. Figure 4 shows the final geometry of the core engine vane
tunnel. The tunnel is 31. 8 centimeters (12. 4 in.) in length and has a diameter of
30. 5 centimeters (12. 0 in.). The back face of the triangular ring is located 21. 6 centi-
meters (8. 5 in.) from the burner outlet face, and its height is 4. 45 centimeters
(1. 75 in.). The bluff body has an outside diameter of 17. 8 centimeters (7. 0 in.), and
its back is cut off perpendicular to the axial flow direction. The bluff body is supported
by two radial struts. These struts were not modeled in the two-dimensional water-
table tests. They are indicated by dashed lines in figure 4. The struts serve the dual
purpose of supporting the bluff body and carrying the cooling water for the internal cool-
ing passages to and from the bluff body.
Typical test streak patterns for the final tunnel configuration are shown in figure 5.
Note that the extraneous dark lines and spots in these photographs are caused by the
rubber suction cups and supporting braces upon which the water table rests, as well as
by the overhead truss structure for the camera. It can be seen from these photographs
that the final tunnel configuration should provide the flow uniformity required at the inlet
to the single-vane test section.
The core engine single-vane test section was developed separately from the heat-
transfer tunnel geometry. The development model was full size and is shown in figure 6.
The flow tests for the single-vane test section were performed with the whole test sec-
tion submerged in the water. As such, these tests were performed in a "water tunnel"
rather than a "water table" configuration. The vane is designed for the first stage of a
core engine high-pressure turbine. The core turbine is expected to operate at tempera-
. /-» fi
uires and pressures up to 2480 K (4000 j?1) ana '6. 10X10 newtons per square meter
(450 psia), respectively. The turbine has an outside diameter of 25. 4 centimeters
(10. 0 in.) and uses 36 vanes in the first stage stator ring. The first stage vane, which
is modeled in this test section, has a span of 3. 81 centimeters (1. 50 in.) and a chord of
5. 552 centimeter (2. 186 in.) and has no twist or taper. A cross section of its profile is
shown in figure 7.
The geometry of the test section was derived by considering the flow path between
two adjacent vanes, separated by a distance of the mean pitch. A sketch of the test-
section configuration is shown in figure 8. The side walls represent the suction and
pressure sides of the adjacent vanes. The vane was placed approximately two chord
lengths behind the bellmouth inlet. This was considered sufficient distance to give
4
straight flow at the vane leading edge. Photographs of typical streamlines (fig. 9) show
good flow characteristics into the inlet and over the vane. For each of these pictures,
the rake was positioned so that the dye streaks were at roughly the half way point on the
vane span. The grid pattern observable in these pictures was achieved by placing a
plastic sheet with grid lines below the test section. This allowed easy determination of
the relative straightness of the inlet streamlines.
The approximate nature of the water-table flow tests prompted a more detailed
examination of the flow behavior in the single-vane test section. The flow over the vane
was tested at ambient conditions in air. The results of the investigation are reported
in reference 1. The investigation confirmed the findings of the water-table tests. That
is, the flow behavior over the test vane is acceptable and adequate for use in the planned
heat-transfer tests.
Helicopter Engine Stator Ring Tunnel
The heat-transfer tunnel for the full stator ring test section was developed in a man-
ner analogous to, and starting with, the single-vane cascade heat-transfer tunnel config-
uration. The overall tunnel dimensions are the same: length, 31.8 centimeters
(12. 5 in.); diameter, 30. 5 centimeters (12. 0 in.). The major change was the relocation
and reduction in size of the triangular ring. The back face of the triangular ring is lo-
cated 22. 23 centimeters (8. 75 in.) from the burner outlet face, and its height is
1. 91 centimeters (0. 75 in.). The bluff body for the full stator ring test section is sup-
ported by three radial struts, as well as by a rear extension which extends to the plane
of the test-section inlet. As for the core engine single-vane tunnel, the radial struts
were not modeled in the water-table tests. They are indicated by dashed lines in fig-
ure 10, which shows the final tunnel and bluff body configuration. Typical test streak
patterns for this tunnel geometry are shown in figure 11. From these photographs it ap-
pears that the final tunnel geometry will be adequate to provide uniform flow into the full
stator ring test section.
CONCLUDING REMARKS
The water-table flow tests described in this report have shown the heat-transfer
tunnels to have acceptable flow patterns for both the core engine single-vane test sec-
tion and the full stator ring test section. Furthermore, the core engine single-vane test
section has been shown to have excellent streamlines, both at the inlet and over the test
vane itself. It must be realized, however, that water-table flow tests are not an abso-
lute measure of subsonic flow behavior. The water-table test results can thus be used
only qualitatively to point out the general flow behavior.
Lewis Research Center,
National Aeronautics and Space Administration,
and
U. S. Army Air Mobility R&D Laboratory,
Cleveland, Ohio, March 11, 1974,
501-24.
REFERENCE
1. Stabe, Roy G.; and Kline, John F.: Aerodynamic Performance of a Core-Engine
Turbine Stator Vane Tested in a Two-Dimensional Cascade of 10 Vanes and in a
Single Vane Tunnel, NASA TM X-2766, 1973.
(a) Overall view. (b) Rake and hypodermic needles used to inject dye into water
flow.
Figure 1.- Water table.
Bluff body -
Burner
outlet
Flow
Settling chamber
- Helicopter engine
test-section inlet
- Core engine vane
test-section inlet
*- Triangular ring
Figure 2. - Starting-point tunnel configuration.
(a) First con- (b) Second configuration. (c) Third configu- (d) Fourth configu-
figuration. ration. ration.
Figure 3. - Shapes of bluff bodies investigated.
?1 p Ml
" r Rad, 1 1
/ , 6 .351 1
\ U r9.531 *
\l 1 1
4 (V -0y\-^ \
\j
Rad,
1.27
30.5
Figure 4. - Final heat-transfer tunnel geometry for core engine single-vane test section.
(Dimensions in centimeters.)
Flow
direction
Flow
direction
(a) Streak pattern shortly after dye injection at burner
outlet.
(b) Streak pattern after most of dye had traversed
tunnel configuration.
Figure 5. - Streak patterns for core engine single-vane tunnel configuration.
C-71-813
Figure 6. - Core engine vane cascade test-section model.
(5.552cm)
Point
ZF
x/c
0.0915
Y/C
0.0915
Point
ZR
X/C
09840
Y/C
0.0160
Leading
edge
Rj/C
0.0915
Trailing
edge
RZ/C
0.0160
x/c
0
.023
.046
.059
.091
.114
.137
.160
.183
.206
.229
.252
.274
.320
.366
YL/C
0.091
.031
.012
.003
0
.003
.011
.022
.030
.037
.043
.048
.053
.059
.065
YU/C
0.091
.153
.181
.202
.219
.232
.242
.251
.257
.262
.264
.265
.266
.263
.258
X/C
0.412
.457
.503
.549
.595
.640
.686
.732
.777
.823
.869
.915
.961
1.000
YL/c
0.068
.069
.069
.067
.064
.059
.054
.047
.040
.032
.024
.015
.005
.016
YU/C
0.249
.238
.226
.214
.200
.186
.170
.153
.134
.115
.093
.070
.047
.016
Figure 7. - Core engine vane and coordinates.
10
Ellipse for bellmouth
Figure 8. - Core engine single-vane test section geometry. (Dimensions in centimeters.)
11
. l l . ' / i
(a) Midchannel streamlines. (b) Side wall streamlines, pressure side.
(c) Side wall streamlines, suction side. (d) Test vane streamlines, suction side.
Figure 9. - Streamline patterns for core engine one-vane test section.
12
Figure 10. - Final heat-transfer tunnel geometry for full stator ring test section.
(Dimensions in centimeters.)
13
Flow
direction
Flow
direction
(a) Streak pattern shortly after dye injection at burner
outlet.
(b) Streak pattern shortly after dye had traversed
inlet section.
Figure 11. - Streak patterns for full stator ring tunnel configuration.
14 NASA-Langley, 1974 E-7870
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Water table tests of proposed heat transfer tunnels for small turbine vanes

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