Research abstracts

National Advisory Committee for A



Research Abstracts
NO.62


^..ij.7f'

iautics
AIY 19 1954

/ T,


CURRENT NACA REPORTS

NACA Rept. 1131

DEFLECTION AND STRESS ANALYSIS OF THIN
SOLID WINGS OF ARBITRARY PLAN FORM WITH
PARTICULAR REFERENCE TO DELTA WINGS.
Manuel Stein, J. Edward Anderson and John M.
Hedgepeth. 1953. ii, 20p. diagrs., photo. (NACA
Rept. 1131. Formerly TN 2621)

The structural analysis of arbitrary solid cantilever
wings by small-deflection thin-plate theory is reduced
to the solution of linear ordinary differential equa-
tions by the assumption that the chordwise deflections
at any spanwise station may be expressed in the form
of a power series in which the coefficients are func-
tions of the spanwise coordinate. Experimental de-
flection and stress data for constant-thickness delta-
plate specimens of 450 and 600 sweep are presented
and are found to compare favorably with the present
theory.


NACA Rept. 1137

INITIAL RESULTS OF INSTRUMENT-FLYING
TRIALS CONDUCTED IN A SINGLE-ROTOR HELI-
COPTER. Almer D. Crim, John P. Reeder and
James B. Whitten. 1953. ii, 7p., diagrs., photos.
(NACA Rept. 1137. Formerly TN 2721.)

Instrument-flying trials were conducted in a single-
rotor helicopter, the maneuver stability of which
could be changed from satisfactory to unsatisfactory.
Results indicated that existing longitudinal flying-
qualities requirements based on contact flight were
adequate for instrument flight at speeds above that
for minimum power. Lateral-directional problems
were encountered at low speeds. The conclusion was
reached that special helicopter instruments would be
desirable under all conditions and necessary for
sustained low-speed instrument flight.



NACA Rept. 1138

STUDY OF INADVERTENT SPEED INCREASES IN
TRANSPORT OPERATION. Henry A. Pearson.
1953. ii, lip. diagrs., tab. (NACA Rept. 1138.
Formerly TN 2638)

Factors relating to inadvertent speed and Mach num-
ber increases in transport operation are discussed
with the object of indicating the manner in which they
might vary with different qualities of the airplane and


the minimum margins required to guard against
reaching unsafe values. Speed increments and the
margins required under several assumed conditions
are investigated. Results indicate that smaller
margins should be required of high-speed airplanes
than of low-speed airplanes to prevent overspeeding
in inadvertent maneuvers. The possibility of ex-
ceeding placard speed in prolonged descents is illus-
trated by computations for typical transport airplanes
Equations.are suggested that allow estimaLes-to-be- -- -



NACA Rept. 1147

THE SIMILARITY LAW FOI HYPERSONIC FLOW
AND REQUIREMENTS FOR pYtAMlC SIMILARITY ,
OF RELATED BODIES IN FPEE LIGH ._.ankM-----
Hamaker, Stanford E. Neice an Thomas J. Wong,
1953. li, llp. diagrs. INACA Rept. 1147. For-
merly TN 2443; TN 2631)

The similarity law for nonsteady, inviscid, hyper-
sonic flow about slender three-dimensional shapes is
derived. Conclusions drawn are shown to be valid
for rotational flow. Requirements for dynamic
similarity of related shapes in free flight are ob-
tained. The law is examined for steady flow about
related three-dimensional shapes. Results of an ex-
perimental investigation of the pressures acting on
two inclined cones are found to check the law as it
applies to bodies of revolution.


NACA RM E53L31a

INVESTIGATION OF EFFECT OF NOTCHES ON
ELEVATED-TEMPERATURE FATIGUE STRENGTH
OF N-155 ALLOY. C. A. Hoffman. April 1954. 8p.
diagrs., tab. INACA RM E53L31a)

An investigation of the effect of notches on the fatigue
strength of N-155 alloy at elevated temperatures was
conducted by the NACA in cooperation with the Gas
Turbine Panel of the joint A.S.T.M.-A.S.M.E. Com-
mittee on Effects of Temperature on the Properties
of Metals. Studies were made at 13500 and 15000 F
in completely reversed bending. The results on
relatively few specimens indicated that: (a) Notches
reduced fatigue strength at 13500 F by approximately
34 to 40 percent and at 15000 F by approximately 30
to 37 percent over the range of 3 to 150 hours, and
(b) the notch sensitivity in fatigue under conditions of
completely reversed bending at 13500 and 15000 F
was considerably less than that predicted for static
bending under elastic conditions.


*AVAILABLE ON LOAN ONLY
ADDRESS REQUESTS FOR DOCUMENTS TO NACA, 1724 F ST, NW
THE REPORT TITLE AND AUTHOR.
29.13 0812.


WASHINGTON 25 D C CITING CODE NUMBER ABOVE EACH TITLE;







2

NACA TN 3076

LIFT AND MOMENT COEFFICIENTS EXPANDED
TO THE SEVENTH POWER OF FREQUENCY FOR
OSCILLATING RECTANGULAR WINGS IN SUPER-
SONIC FLOW AND APPLIED TO A SPECIFIC
FLUTTER PROBLEM. Herbert C. Nelson, Ruby A.
Rainey and Charles E. Watkins. April 1954. 53p.
diagrs. (NACA TN 3076)

Linearized theory for compressible unsteady flow is
used to derive the velocity potential and lift and
moment coefficients in the form of power series in
terms of the frequency of oscillation for a harmoni-
cally oscillating rectangular wing moving at a con-
stant supersonic speed. Closed expressions for the
velocity potential and lift and moment coefficients
associated with pitching and translation are given to
the seventh power of the frequency. These expres-
sions extend the range of usefulness of NACA Report
1028 in which similar expressions were derived to
the third power of the frequency of oscillation. The
section and total lift and moment coefficients are
discussed with the aid of several figures. In addi-
tion, flutter speeds obtained in the Mach number
range from 10 9 to 10/6 for a rectangular wing of
aspect ratio 4.53 by using section coefficients de-
rived on the basis of three-dimensional flow are
compared with flutter speeds for this wing obtained
by using coefficients derived on the basis of two-
dimensional flow.



NACA TN 3078

TRANSIENT TEMPERATURES IN HEAT EXCHANG-
ERS FOR SUPERSONIC BLOWDOWN TUNNELS.
Joseph H. Judd. April 1954. 35p. diagrs., 2 tabs.
(NACA TN 3078)

A method has been presented for the computation of
tube and fluid temperatures for fluid flowing through
heat exchangers of the heat-accumulator type in which
the temperatures are low enough so that radiation
may be neglected. Three entrance air conditions
were considered, constant temperature, exponentially
decreasing temperature, and linearly decreasing
temperature. Agreement was found between experi-
mental and computed tube and air temperatures for
inlet air at constant temperature and at atmospheric
pressure.




NACA TN 3084

A METHOD FOR MEASURING THE PRODUCT OF
INERTIA AND THE INCLINATION OF THE PRINCI-
PAL LONGITUDINAL AXIS OF INERTIA OF AN AIR-
PLANE. Robert W. Boucher, Drexel A. Rich, Harold
L. Crane and Cloyee E. Matheny. April 1954. 39p.
diagrs., photos., 6 tabs. (NACA TN 3084)

An analysis has been made of a method for experi-
mentally determining the moments of inertia and the
product of inertia about the body reference axes, the
moments of inertia about the principal axes, and the
inclination of the principal longitudinal axis. The re-
sults of the application of this method and the asso-
ciated equipment and techniques are discussed for
both a simple model and a conventional airplane.


NACA
RESEARCH ABSTRACTS NO.62

NACA TN 3085

AN EXPERIMENTAL STUDY OF POROSITY CHAR-
ACTERISTICS OF PERFORATED MATERIALS IN
NORMAL AND PARALLEL FLOW. George M.
Stokes, Don D. Davis, Jr. and Thomas B. Sellers.
April 1954. 24p. diagrs., photos. I(NACA'V 3085.
Formerly RM L53H07) -'

Experimental data have been obtained to show some
of the flow characteristics of perforated materials
when subjected to airstreams directed normal and
parallel to the surface of the material. The results
of these tests showed that the effective porosity of
the material dropped markedly as the stream veloc-
ity increased. The most important parameter for
determining the discharge coefficients of the perfo-
rated material was the ratio of the stream velocity
to the free jet velocity.


NACA TN 3110

TRENDS OF ROLLING-CONTACT BEARINGS AS
APPLIED TO AIRCRAFT GAS-TURBINE ENGINES.
(Papers presented at the SAE Summer Meeting,
Atlantic City, N.J., 1952). Panel on High-Speed
Rolling-Contact Bearings. Appendix A. PROBLEMS
PERTAINING TO HIGH-SPEED ROLLING-CONTACT
AIRCRAFT BEARINGS OF CONCERN TO THE BEAR-
ING INDUSTRY. Danie! Gurney, Marlin-Rockwell
Corp. Appendix B. PROBLEMS PERTAINING TO
HIGH-SPEED ROLLING-CONTACT BEARINGS IN
AIRCRAFT TURBINE ENGINES OF CONCERN TO
THE MILITARY. C. M. Michaels, Wright Air Devel-
opment Center. Appendix C. ROLLING-CONTACT
BEARINGS AS APPLIED TO AIRCRAFT GAS TUR-
BINES FROM THE ENGINE MANUFACTURER'S
POINT OF VIEW. Stephen Drabek, General Electric
Co. Appendix D. NEW DEVELOPMENTS IN HIGH-
SPEED ROLLING-CONTACT BEARINGS. Frank W.
Wellons, SKF Industries, Inc. Appendix E. BASIC
FRICTION AND WEAR STUDIES OF ROLLING-
CONTACT-BEARING CAGE MATERIALS. Robert L.
Johnson, Max A. Swikert and Edmond E. Bisson.
Appendix F. PRESENT STATUS OF RESEARCH
KNOWLEDGE IN THE FIELD OF HIGH-SPEED
ROLLING-CONTACT BEARINGS. E. F. Macks.
April 1954. (ii), 62p. diagrs., photos. (NACA
TN 3110)

Requirements for rolling contact bearings for future
aircraft gas-turbine engines are severe. Operating
temperatures to 7500 F. thrust loads to 50,000
pounds, and DN values to 3.5 x 106 are desired.
Cage material compatibility, bearing endurance life,
high-temperature lubricants, and lubricant cooling
are expected to be the major problems. These and
related problems are discussed from the viewpoints
of the bearing industry, engine manufacturers, and
the military. Some recent research results are
given, and the need for further research on an ex-
panded scale is emphasized.


NACA TN 3128

COMPARISON BETWEEN THEORY AND EXPERI-
MENT FOR INTERFERENCE PRESSURE FIELD BE-
TWEEN WING AND BODY AT SUPERSONIC SPEEDS.
William C. Pitts, Jack N. Nielsen and Maurice P.
Gionfriddo. April 1954. 64p. diagrs., 2 tabs.
(NACA TN 3128)






NACA
RESEARCH ABSTRACTS NO.62

Pressure-distribution data were obtained for a wing-
body combination at Mach numbers 1.48 and 2.00 and
at Reynolds numbers 0.6, 1.2, and 1.5 x 106. The
model was a single-wedge, rectangular wing mounted
on a cylindrical body with an ogival nose. The body
angle of attack ranged between +60 and -60 and the
wing-incidence angle ranged from 00 to -5.70. The
experimental pressure-distribution and span-loading
results are compared with the Linear, wing-body
interference theory of NACA TN 2677.



NACA TN 3146

NOTE ON THE AERODYNAMIC HEATING OF AN
OSCILLATING SURFACE Simon Ostrach. April
1954. Z12p. (NACATN3146)

An analysis of the temperature distributions in a fluid
over an oscillating surface with heat transfer is
made and associated heat-transfer parameters are
compared with those for the case of conduction at a
stationary surface with the same initial temperature
potential. It is found that the heat transfer for the
oscillating surface can be considerably different from
that for conduction alone. The effect of the surface
oscillations on the thermal state of the fluid is studied
by means of average static- or total-temperature
defects, and it is demonstrated that the oscillations
could alter the fluid temperature appreciably.



NACA TN 3165

PRELIMINARY INVESTIGATION OF THE EFFECTS
OF HEAT TRANSFER ON BOUNDARY-LAYER
TRANSITION ON A PARABOLIC BODY OF REVOLU-
TION (NACA RM-10) AT A MACH NUMBER OF 1.61.
K. R. Czarnecki and Archibald R. Sinclair. April
1954. 23p. diagrs., photos., tab. (NACA TN 3165.
Formerly RM L52E29a)

This paper presents the results of a preliminary in-
vestigation of the effects of heat transfer on bound-
ary layer transition on a parabolic body of revolution
(NACA RM-10) at Mach number of 1.61. This paper
includes also a study of the effectiveness of cooling
on boundary-Layer transition with model surface
roughened and a comparison of the results obtained in
this investigation with other available theoretical and
experimental data.



NACA TN 3166

AN EXTENSION OF THE INVESTIGATION OF THE
EFFECTS OF HEAT TRANSFER ON BOUNDARY-
LAYER TRANSITION ON A PARABOLIC BODY OF
REVOLUTION (NACA RM-10) AT A MACH NUMBER
OF 1.61. K. R. Czarnecki and Archibald R. Sinclair.
April 1954. 21p. diagrs., photo. (NACA TN 3166.
Formerly NACA RM L53B25)

This paper covers the extension of a previous inves-
tigation of the effects of heat transfer on boundary-
layer transition to higher Reynolds numbers, to
greater amounts of healing, and to a more extensive
study of the effects of surface roughness and wind-
tunnel flow disturbances. The tests were made at a
Mach number of 1.6 and over a Reynolds number
range from 2.5 x 106 to 35 x 106. A comparison is
made between the experimental results and theory.


3

NACA TN 3170

AN EXPERIMENTAL INVESTIGATION AT LOW
SPEEDS OF THE EFFECTS OF LIP SHAPE ON THE
DRAG AND PRESSURE RECOVERY OF A NOSE IN-
LET IN A BODY OF REVOLUTION. James R.
Blackaby and Earl C. Watson. April 1954. 48p.
diagrs., photos. (NACA TN 3170)

A low-speed investigation, for an angle of attack and
angle of yaw of 00, was made of the effects of inlet
lip bluntness and profile on the performance of a
ducted body of revolution. A sharp inlet lip profile
was tested in addition to five circular-arc profiles
having contraction ratios (ratio of area at inlet
leading edge to minimum inlet area) of about 1.04.
1.08, 1.16, 1.24, and 1.33, and two lips with elliptical
internal profiles and approximately elliptical external
profiles having contraction ratios of about 1.08 and
1.18.



NACA TN 3172

EFFECTS OF LEADING-EDGE RADIUS AND MAXI-
MUM THICKNESS-CHORD RATIO ON THE VARIA-
TION WITH MACH NUMBER OF THE AERODYNAMIC
CHARACTERISTICS OF SEVERAL THIN NACA AIR-
FOIL SECTIONS. Robert E. Berggren and Donald J.
Graham. April 1954. 65p. diagrs.. 7 tabs. (NACA
TN 3172. Formerly RM A50D04)

The results of a wind-tunnel investigation at Mach
numbers to approximately 0.9 and Reynolds numbers
from 1 x 106 to 2 x 106 indicate no significant effects
of leading-edge-radius variation on the variation with
Mach number of the aerodynamic characteristics of
4- and 6-percent-chord-thick NACA 4-digit-series
airfoil sections. The results indicate beneficial ef-
fects of maximum thickness reduction on Lilt and
drag characteristics and no important effects on
moment characteristics.





BRITISH REPORTS


N-28442*

SURFACE DEFECTS IN VENEERING. R. J.
Newall, Forest Products Laboratory. (Reprint
from Wood. v. 18, December 1953, p. 462-465)

Examination of defective veneering shows that there
are two main types of defect: (1) checking or crack-
ing of the veneered surface and (2) shallow furrows
in the surface. These defects are discussed in de-
tail and suggestions are made for their elimination.
It is indicated that the cause of the defects is that
the moisture content of the base material might be
too high when the veneer is applied.


N-30304*

National Gas Turbine Establishment (Gt. Brit.)
A CORRELATION OF THE PERFORMANCE OF TWO
AIR BLAST ATOMISERS WITH MIXING SECTIONS
OF DIFFERENT SIZE. A. Radcliffe and H. Clare.
October 1953. 39p. diagrs., tab. (NGTE R. 144)










The work on the N.G.T.E. air blast atomizer has
been extended and the effect of increasing the orifice
diameter has been examined. It is shown that the
main factor controlling atomization is the air:fuel
ratio and that when this is 0.1 the Sauter mean diam-
eter is about 100 microns. This is for fuel of vis-
cosity 20 to 40 centistokes. The droplet size in-
creases approximately as the square root of the
linear dimensions of the orifice and mixing section.


N-30305*

National Gas Turbine Establishment (Gt. Brit.)
CALCULATED PRESSURE, AREA AND IMPULSE
RATIOS FOR SUPER-CRITICAL EXPANSION OF
COMBUSTION GASES. A. B. P. Beeton. November
1953. 31p. diagrs., 3 tabs. (NGTE R. 145)

Expansion conditions beyond the throat of convergent-
divergent exit nozzles are studied. Assuming isen-
tropic flow, theoretical values have been calculated
relating the flow area, impulse and pressure for com-
bustion gases expanded down to supercritical pres-
sure ratios. The results are expressed in the form
of two master curves which apply to 20:1 air/fuel
ratio, 4500 K initial air temperature and 1 atmosphere
total pressure. Additional curves are given to de-
rive an additive correction for any air/fuel ratio be-
tween 10:1 and 50:1. The range covered is from the
throat down to about 12:1 pressure ratio.



N-30307*

National Gas Turbine Establishment (Gt. Brit.)
THE FATIGUE PROPERTIES OF INVESTMENT-
CAST 0.2 PER CENT CARBON, 18 PER CENT
CHROMIUM, 2 PER CENT NICKEL STAINLESS
STEEL AND THEIR IMPROVEMENT BY NITRIDING
AND SHOT-PEENING. T. Fitzgerald and J. E.
Northwood. October 1953. 46p. diagrs., photos.,
6 tabs. (NGTE Memo. M. 162)

Low fatigue properties have been obtained with the
0.2-percent carbon, 18-percent chromium, 2-percent
nickel stainless steel in the investment cast and heat
treated condition. Attempts have been made to im-
prove its fatigue strength by processes which in-
crease the endurance ratio, without any serious ef-
fect on tensile properties and ductility. Fatigue
tests have shown that nitriding or shot-peening can
be used to increase the fatigue strength of invest-
ment cast blades to a level on a par with that of the
wrought material. The increase in fatigue strength
brought about by either of these processes was
partly controlled by the condition of the metal sur-
face prior to treatment, increases in fatigue
strength of up to 40 percent above that of the "as
cast" surface condition being obtained by nitriding or
peening the surfaces of buffed or electrolytically
polished blades and test pieces.


N-30309*

Aeronautical Research Council (Gt. Brit.)
LIQUID MANOMETERS WITH HIGH SENSITIVITY
AND SMALL TIME-LAG. F. A. MacMillan.
August 14, 1953. 14p. diagrs., photos. 'ARC
16,091; TP 404; FM 1941)


NACA
RESEARCH ABSTRACTS NO. 62

For some purposes a sensitive manometer is re-
quired having a small time lag when connected to a
small bore tube or orifice. The time lag which can
be tolerated is limited by the rate of change of the
zero reading. Some problems in the design of a
manometer with small time lag and small rate of
change of zero reading are discussed, and sore
general principles of design are derived. Ii is
shown that with a null-reading inclined-tube manom-
eter, changes of zero reading due to variation of
temperature can be eliminated by correct choice of
the manometer dimensions. A manometer designed
according to the principles derived is described; this
has a small time lag, a range of 2.5 cm of liquid,
and a sensitivity of 0.0005 cm of liquid.




UNPUBLISHED PAPERS


N-19795*

THE CURRENT FORCE FOR PARALLEL AND CON-
CENTRIC CONDUCTORS. (Die Stromkraft bei
parallelen und konzentrischen Leitern). Wilhelm
Beetz. April 1954. lOp. diagrs. (Trans. Irom
Elektrotechnik und Maschinenbau, v. 48, no.33,
August 1930, p.761-763)

The repellent force for parallel and concentric con -
ductors is calculated by substitution of an "effective
distance" instead of the actual distance into the
formula valid for dimensionless conductors. The
influence of the current displacement in case of
technical frequencies is discussed.

N-29585*

FATIGUE TESTS ON MULTIPLE-RIVETED JOINTS
OF 75 S-T ALUMINUM ALLOY. (Utmattnzngsprov
Pa Flerradigt Nitf6rband Av Material 75 S). Gunnar
Wallgren. March 1954. 15p. diagrs., 2 tabs.
(Trans. from Flygtekniska Forsoksanstallen,
Stockholm, February 21, 1947, Rept. HU-220)

W6hler curves were determined for two types of
riveted joints of 75-ST aluminum alloy under pulsating
tension load. The static breaking limit of the joints
was also determined.


N-29811*

PRESSURE ERRORS IN PNEUMATIC MEASURING
INSTALLATIONS IN FLIGHT TESTS AND IN THE
WIND TUNNEL. (Druckfalschung in pneumatischen
Messanlagen im Flugversuch und im Windkanal).
Helmut Danielzig. April 1954. 65p. diagrs., 9 tabs.
(Trans. from ZWB, Berlin, FB 1907, December 8,
1943)

A theoretical method is developed which makes it
possible for the engineer working in flight measure-
ments to estimate pneumatically measured quantities
like dynamic pressure, static pressure, angle of
attack, or angle of sideslip with respect to the error
caused by tube friction which is inherent in the
measuring method. The theoretical results given in
this report have been compared to examples from
flight-measurement operation and from wind tunnels.







NACA
RESEARCH ABSTRACTS NO. 62

MISCELLANEOUS

NACA Rept. 1147

Errata No. 1 on "THE SIMILARITY LAW FOR
HYPERSONIC FLOW AND REQUIREMENTS FOR
DYNAMIC SIMILARITY OF RELATED BODIES IN
FREE FLIGHT." Frank M. Hamaker, Stanford E.
Neice and Thomas J. Wong. 1953.


NACA RM L53E07b

Errata No. I on "ANALYTICAL STUDY OF
CLOCKAGE- AND LIFT-INTERFERENCE CORREC-
TIONS FOR SLOTTED TUNNELS OBTAINED BY
THE SUBSTITUTION OF AN EQUIVALENT HOMO-
GENEOUS BOUNDARY FOR THE DISCRETE SLOTS."
Don D. Davis, Jr. and Dewey Moore. June 29, 1953.




DECLASSIFIED NACA REPORTS


NACA RM LBJO6

NACA TRANSONIC WIND-TUNNEL TEST SECTIONS.
Ray H. Wright and Vernon G. Ward. October 25,
1948. 93p. diagrs., photos., 3 tabs. (NACA
RM L8J06) (Declassified from Confidential,
3/10 54)

An approximate subsonic theory has been developed
for the solid blockage in a circular wind tunnel with
walls slotted in the direction of flow. In tests of a
tunnel based on this theory, a prediction of the theory
regarding the possibility of practical elimination of
the interference due to solid blockage has been real-
ized. Choking limitations did not occur in the
slotted tunnel, and it could be operated with continu-
ous Mach number variation up to low supersonic
Mach numbers merely by varying the power.
Pressure distributions over the surface of a non-
lifting model in the slotted tunnel were compared
with those obtained over the same model in a much
larger tunnel where the interference was negligible.



NACA RM L9D18

PRELIMINARY INVESTIGATION OF 3-INCH
SLOTTED TRANSONIC WIND-TUNNEL TEST SEC-
TIONS. George P. Bates. September 9, 1949. 18p.
diagrs. (NACA RM L9D18) (Declassified from
Confidential, 3/10/54)

An investigation has been made on two slotted test
sections in a 3-inch circular blowdown apparatus to
determine the characteristics of slotted throats for
transonic and supersonic operation. One of the sec-
tions investigated had 20 slots, with 1/5-open wall
area, while the other section had 8 slots and was
1/8 open.


5

NACA RM L9D29a

PRELIMINARY INVESTIGATION OF A VARIABLE
MACH NUMBER TWO-DIMENSIONAL SUPERSONIC
TUNNEL OF FIXED GEOMETRY. William J. Nelson
and Frederick Bloetscher. June 9, 1949. 54p.
diagrs., photos. (NACA RM L9D29a) (Declassified
from Confidential, 3/10/54)

Variable Mach number supersonic flows have been
generated in a 2-1/4 by 4-1/2 inch fixed-geometry
rectangular channel by removal of air through longi-
tudinal slots of several profiles and proportions.
The nature of the flow over a range of Mach numbers
up to 1.45 is shown in schlieren photographs and
pressure distributions along the channel. The most
uniform flow was produced by removal of air through
a single slot in a flat surface.



NACA RM L50B01

PRELIMINARY INVESTIGATION OF CONSTANT-
GEOMETRY, VARIABLE MACH NUMBER, SUPER-
SONIC TUNNEL WITH POROUS WALLS. William J.
Nelson and Paul L. Klevatt. May 3, 1950. 27p.
diagrs., photos. (NACA RM L50B01) (Declassified
from Confidential, 3/10/54)

A method of generating variable Mach number super.
sonic flow in a channel of fixed geometry by the re-
moval of air through uniform porous walls is dis-
cussed. Calculated porosity distributions are pre-
sented for several minimum-length nozzles designed
to operate at Mach numbers up to 2.0. The axial
pressure gradient has been calculated for several
constant-porosity walls over a range of Mach num-
bers. The applicability of these calculations to a
two-dimensional tunnel is illustrated by comparison
of calculated and experimentally determined pres-
sure gradients in the 2-1/4 by 4-1/2 inch channel at
Mach numbers in the range covered in the present
tests, 0.99 to 1.17. Schlieren photographs of the
flow in the experimental channel are also presented.



NACA RM L50D27

PRELIMINARY INVESTIGATION OF POROUS WALLS
AS A MEANS OF REDUCING TUNNEL BOUNDARY
EFFECTS AT LOW-SUPERSONIC MACH NUMBERS.
William J. Nelson and Frederick Bloetscher.
September 13, 1950. 21p. diagrs., photos. (NACA
RM L50D27) (Declassified from Confidential,
3/10/54)

The use of porous-walled tunnels at supersonic Mach
numbers as a means of avoiding reflection of stream
disturbance extending to the walls is discussed. Cal-
culated shock-reflection characteristics of porous
materials are presented in the form of design charts
for Mach numbers up to 1.5 and incident shock devia-
tions up to 60. Shocks reflected from sintered-
bronze and bonded-screen walls at a Mach number of
1.2 are consistent with the calculated reflections.










NACA RM L50G19a

PRELIMINARY INVESTIGATION OF REFLECTIONS
OF OBLIQUE WAVES FROM A POROUS WALL. Don
D. Davis, Jr. and George P. Wood. November 9,
1950. 33p. diagrs., photos. (NACA RM L50G19a)
(Declassified from Confidential. 3/10/54)

A porous wall was used in an attempt to eliminate re-
flections of oblique waves from a tunnel wall. Calcu-
lations were made of the required resistance charac-
teristics of a wall in order that the flow through the
wall, due to the pressure difference across a shock
wave, would equal the component normal to the wall of
the flow behind the shock wave. The resistance char-
acteristic of a sintered-bronze wall was measured
and the reflections of waves impinging on the wall
were observed at a Mach number of 1.62. The inten-
sity of the reflections was greatly reduced by per-
mitting flow through the wall.



NACA RM L51F14

COMPARISON OF TRANSONIC CHARACTERISTICS
OF LIFTING WINGS FROM EXPERIMENTS IN A
SMALL SLOTTED TUNNEL AND THE LANGLEY
HIGH-SPEED 7- BY 10-FOOT TUNNEL. William
C. Sleeman, Jr., Paul L. Klevatt and Edward L.
Linsley. November 5, 1951. 44p. diagrs., photos.
(NACA RM L51F14) (Declassified from Confidential,
3/10/54)

A comparison is made of the transonic aerodynamic
characteristics of two unswept and two 450 swept-
back wings tested in a 4.5- by 6.25-inch slotted tun-
nel over a Mach number range from 0.70 to 1.30 and
the Langley high-speed 7- by 10-foot tunnel side-
wall reflection plane up to M = 1.08. Two geo-
metrically similar wings having a semispan of 4.24
and 2.55 inches for both sweep angles were tested to
investigate effects of model size in the slotted tun-
nel. Two slot areas, 1/8 and 1/5 of the horizontal
boundaries open, were used in the tests.




NACA RM L52C18

AN EXPERIMENTAL INVESTIGATION OF THE
ZERO-LIFT PRESSURE DISTRIBUTION OVER A
WEDGE AIRFOIL IN CLOSED, SLOTTED, AND
OPEN-THROAT TUNNELS AT TRANSONIC MACH
NUMBERS. William J. Nelson and Frederick
Bloetscher. June 16, 1952. 34p. diagrs., photos.
(NACA RM L52C18) (Declassified from
Confidential, 3/10/54)

Pressure distributions and schlieren photographs of
the flow atout a 10-percent-thick diamond airfoil at
zero lift in two-dimensional closed, slotted, and
cpen-throat tunnels are presented and discussed.
Uncorrected airfoil pressures obtained in 1/5- and
1/8-open slotted throat tunnels are compared at sub-
sonic Mach numbers with corrected results from
open and closed test sections of the same dimen-
sions. The effect of varying the slot width has been
investigated at Mach numbers up to 0.92. At Mach


NACA
RESEARCH ABSTRACTS NO. 62


numbers up to 1.18, data obtained in test sections
whose upper and lower boundaries were slotted to
provide openings the combined width of which was
equal to 1/8 of the tunnel width are shown to be con-
sistent with theory and available experiments.

'S
NACA RM L52E27

REFLECTION OF SHOCKWAVES FROM SLOTTED
WALLS AT MACH NUMBER 1.62. George P.
Wood. July 21, 1952. 16p. diagrs., photos.
(NACA RM L52E27) (Declassified from
Confidential, 3/10/54)

A brief study was made of the effect of slots in a
test-section wall on the reflection from the wall of
an incident oblique shock wave at a free stream
Mach number of 1.62. The reflection was observed
with an interferometer for various combinations of
slot width, spacing, and contour. The reflections
from the open and closed portions of the wall, being
at different angles to the wall, were not superposed
and, therefore, did not cancel each other.


NACA RM L53A26

THEORETICAL STUDY OF THE TUNNEL-
BOUNDARY LIFT INTERFERENCE DUE TO
SLOTTED WALLS IN THE PRESENCE OF THE
TRAILING-VORTEX SYSTEM OF A LIFTING
MODEL. Clarence W. Matthews. April 7, 1953.
56p. diagrs. (NACA RM L53A26) (Declassified
from Confidential, 3/10/54)

The equations which represent the interference on
the lift of uniformly loaded wings of finite span in
circular tunnels with mixed open and closed bounda-
ries are derived, with special attention to those tun-
nels containing symmetrical arrangements of the
open and closed portions. The equations are appli-
cable to tunnels with other cross-sectional shapes,
provided a transformation function can be found
which will transform the tunnel cross section into a
circle.



NACA RM L53E07b

ANALYTICAL STUDY OF BLOCKAGE- AND LIFT-
INTERFERENCE CORRECTIONS FOR SLOTTED
TUNNELS OBTAINED BY THE SUBSTITUTION OF
AN EQUIVALENT HOMOGENEOUS BOUNDARY FOR
THE DISCRETE SLOTS. Don D. Davis, Jr. and
Dewey Moore. June 29, 1953. 57p. diagrs.
(NACA RM L53E07b) (Declassified from
Confidential, 3/10 54)

Numerical results are presented for the boundary
interference on lifting wings and for the solid-
blockage interference for a doublet on the tunnel
axis in circular, rectangular, and two-dimensional
slotted tunnels. In the analysis, an equivalent ho-
mogeneous wall has been substituted for the physical
boundary of discrete slots. The results are four.d
to be consistent with those calculated for the dis-
crete slots and with available experimental results.






NACA
RESEARCH ABSTRACTS NO.62 7


NACA RM A53E29

WALL INTERFERENCE IN WIND TUNNELS WITH
SLOTTED AND POROUS BOUNDARIES AT SUB-
SONIC SPEEDS. Barrett S. Baldwin, Jr., John B.
Turner and Earl D. Knechtel. October 9, 1953.
42p. diagrs. (NACA RM A53E29) (Declassified
from Confidential, 3 10 54)

Linearized compressible-flow analysis is applied to
the study of wind-tunnel-wall interference for sub-
sonic flow in either two-dimensional or circular test
sections having slotted or porous walls. Expres-
sions are developed for evaluating blockage and lift
interference.


NACA-Langley 5-4-54 4M





UNIVERSITY OF FLORIDA


3 1262 08I53 102 1
3162851 02Uob f1





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