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National Advisory Committee for Aec art
D.7 SEPTEMBER 1 __
CURRENT NACA REPORTS
NACA Rept. 1001
FUNDAMENTAL EFFECTS OF AGING ON CREEP
PROPERTIES OF SOLUTION-TREATED LOW-
CARBON N-155 ALLOY. D. N. Frey, 3. W.
Freeman and A. E. White, University of Michigan.
1950. ii, 30p. diagrs., photos., 5 tabs. (NACA
R aipt. 1001. Formerly TN 1940)
,An experimental procedure is described which is
believed suitable for establishing the fundamental
mechanisms by which processing, heat treatment,
ad chemical composition control the properties of
'alloys at high temperature. The method relates
amierostructures and X-ray diffraction characteris-
tics after various prior treatments to creep and
r re test properties. Results are given of ap-
liteation of the method to solution-treated and aged
hiw-carbon N-155 alloy and correlation with short-
time creep and rupture characteristics at 1200 F.
NACA Rept. 1004
A LIFT-CANCELLATION TECHNIQUE IN LINEAR-
IZED SUPERSONIC-WING THEORY. Harold Mirels.
11-S ii, lip. diagrs. (NACA Rept. 1004. Former-
1 TiN 2145)
A lift cancellation technique is presented for deter-
mining load distributions on thin wings at supersonic
speeds. A general expression is derived for the
load distribution over a cancellation wing. This ex-
pression permits the determination of lift distribu-
tions on wings that cannot be solved by cancellation
techniques based on the superposition of conical
flows. The boundary conditions for either a sub-
sonic leading edge or a subsonic trailing edge can
be satisfied. Applications to swept wings having
curvilinear plan forms and to wings having reen-
trant side edges are indicated.
NACA TN 2404
AN ANALYTICAL INVESTIGATION OF EFFECT OF
HIGH-LIFT FLAPS ON TAKE-OFF OF LIGHT
AIRPLANES. Fred E. Weick, L. E. Flanagan, Jr.,
and H. H. Cherry, Agricultural and Mechanical
; College of Texas. September 1951. 101p. diagrs.,
S tabs. (NACA TN 2404)
7.;4ic. An analytical study was made to determine the ef-
:t :ii,,, es of high-lift devices on the take-off character-
160:c& eof light airplanes. Three phases of the prob-
lem of improving take-off performance by the use of
flaps were considered. The optimum lift coefficient
for take-off was determined for airplanes having
loadings representative of light aircraft and flying
from field surfaces encountered in personal-aircraft
operation. Existing high-lift and control-device data
were studied and compared to determine which com-
binations of such devices appeared to offer the most
suitable arrangements for light aircraft.
Computations were made to verify that suitable
stability, control, and performance can be obtained
when the optimum devices selected are applied to a
NACA TN 2432
TRANSFORMATIONS OF THE HODOGRAPH FLOW
EQUATION AND THE INTRODUCTION OF TWO
GENERALIZED POTENTIAL FUNCTIONS. Luigi
Crocco. August 1951. 81p. diagrs. (NACA TN
It is shown that the hodograph equations of motion can
be written in symmetrical form. The equations are
further transformed so that two new generalized po-
tential functions that satisfy very compact equations
can be introduced. All the quantities concerned with
representation of the motion can then be derived from
formulas independent of the gas law adopted. An
approximate transonic method has also been
NACA TN 2436
HEAT DELIVERY IN A COMPRESSIBLE FLOW AND
APPLICATIONS TO HOT-WIRE ANEMOMETRY.
Chan-Mou Tchen, National Bureau of Standards.
August 1951. 63p. diagrs. (NACA TN 2436)
In a two-dimensional field a generalized potential
theory applicable to nonadiabatic and rotational flow
is developed. Three partial differential equations
are first obtained determining the three variables
which are: Distribution of additional temperature a,
velocity perturbation ft and an auxiliary function K
characterizing the rotationality of the flow. With the
use of this theory the action of heat sources on the
flow is studied, and the heat delivery in a compressi-
ble flow at subsonic and supersonic speeds is
NACA TN 2444
EFFECT OF STRESS-SOLVENT CRAZING ON TEN-
SILE STRENGTH OF POLYMETHYL METHA-
CRYLATE. B. M. Axilrod and Martha A. Sherman,
National Bureau of Standards. August 1951. 19p.
photos., 4 tabs. (NACA TN 2444)
A" "..ILE t LDOAN ONLY.
L F 4DDESS REOUEST$kR DOCUMENTS TO NACA, 1724 F ST., NW.,
WASHINGTON u5, D.C., CITING CODE NUMBER. TITLE AND AUTHOR.
RESEARCH ABSTRACTS NO. 7
Loss of strength of tensile specimens of polymethyl
methacrylate by stress-solvent crazing at 23 C and
50-percent relative humidity was investigated.
Sheet-to-sheet variability of crazed and control
specimens, effect of masking paper on crazing, and
relative effect of a few large crazing cracks as com-
pared with more numerous fine cracks were studied.
Because it was impossible to predict tensile strength
of crazed specimens from their appearance, it is
suggested that aircraft enclosures with crazing of
the type described in this work should be removed
if, in service, tensile stress occurs normal to the
NACA TN 2447
STATISTICAL FLUCTUATION OF INTENSITY IN
DEBYE-SCHERRER LINES DUE TO RANDOM ORI-
ENTATION OF CRYSTAL GRAINS. Hans Ekstein,
Armour Research Foundation. August 1951. 20p.
diagrs., tab. (NACA TN 2447)
Fluctuations of intensity are discussed for the case
of line width caused by only the natural spectral
width of the primary radiation and the finite size of
the grains (that is, pure Fraunhofer diffraction).
Mean deviation of the centroid of the intensity curve
from the Bragg angle for the strongest wave length
is considered as the error in measuring the line and
is theoretically estimated. For a typical case
(grains of 2 x 10-4 cm length and 1-sq-mm irradi-
ated area), the error was found to be about 10 times
smaller than that previously reported.
NACA TN 2450
METHOD OF MATCHING COMPONENTS AND
PREDICTING PERFORMANCE OF A TURBINE-
PROPELLER ENGINE. Alois T. Sutor and
Morris A. Zipkin. September 1951. 75p. diagrs.
(NACA TN 2450)
Analytical expressions are derived to show the geo-
metric, thermodynamic, and aerodynamic relations
among compressor, turbine, and exhaust nozzle for a
gas-turbine engine. For a known compressor per-
formance map, a matching method is described to
show some of the design compromises that must be
made when the components are to be combined into a
turbine-propeller engine. A method of predicting
engine performance for a range of operating condi-
tions from known component maps is presented. An
illustrative example of the matching method and the
performance analysis is presented, showing some of
the practical limitations of engine operation.
NACA TN 2454
JET-BOUNDARY CORRECTIONS FOR COMPLETE
AND SEMISPAN SWEPT WINGS IN CLOSED CIRCU-
LAR WIND TUNNELS. James C. Sivells and
Rachel M. Salmi. September 1951. 64p. diagrs.,
13 tabs. (NACA TN 2454)
Tables and curves are presented which give values
of the jet-boundary-induced upwash velocities at the
horizontal center plane of a closed circular wind
tunnel and at that of a closed bipolar wind tunnel
which is formed when a reflection plane is installed
in a circular tunnel for testing semispan wings. The
application of these induced upwash velocities to the
determination of the jet-boundary corrections is also
discussed. In order to facilitate the computations,
simplified computing forms are presented for evalu-
ating the corrections to the angle of attack and to the
drag, pitching-moment, rolling-moment, and yawing-
NACA TN 2455
A METHOD OF DESIGNING TURBOMACHINE
BLADES WITH A DESIRABLE THICKNESS DIS-
TRIBUTION FOR COMPRESSIBLE FLOW ALONG
AN ARBITRARY STREAM FILAMENT OF REVO-
LUTION. Chung-Hua Wu and Curtis A. Brown.
September 1951. 45p. diagrs., 6 tabs. (NACA
A rapid method for designing turbomachine blades of
a given turning and a desirable blade-thickness dis-
tribution for a compressible nonviscous fluid flow
along an arbitrary stream filament of revolution is
presented. The method is illustrated with the design
of several turbine cascades of highly cambered thick
blades. The determination of the shape of the blades
and the compressible flow past the blades was car-
ried out by hand computation in 16 hours. Because
the surface of revolution, on which the blades are
located, is completely arbitrary, the method
can be applied to axial-flow, radial-flow, and mixed-
flow turbomachines. The variation in the normal
distance between the stream surfaces of revolution
can be taken into account, thus incorporating into
the design the principal effect of three-dimensional
flow. The method is readily applied to the design
of channels on a plane and on a general surface of
NACA TN 2456
ANALYTICAL METHOD FOR DETERMINING PER-
FORMANCE OF TURBOJET-ENGINE TAIL-PIPE
HEAT EXCHANGERS. Michael Behun and Harrison
C. Chandler, Jr. September 1951. 42p. diagrs.
(NACA TN 2456)
A method of analysis is developed for computing the
performance of parallel-flow-type unfinned tail-pipe
heat exchangers installed on nonafterburning turbo-
jet engines. The results of this analysis, based on
assumed characteristics of a hypothetical engine,
are presented in the form of working charts.
Pressure drop through the heat exchanger and
effect on engine performance are discussed. The
performances of finned and unfinned heat exchangers
NACA TN 2458
AN INSTRUMENT EMPLOYING A CORONAL DIS-
CHARGE FOR THE DETERMINATION OF
DROPLET-SIZE DISTRIBUTION IN CLOUDS.
Rinaldo J. Brun, Joseph Levine, and Kenneth S.
Kleinknecht. September 1951. 53p. diagrs.,
photos., 4 tabs. (NACA TN 2458)
RESEARCH ABSTRACTS NO. 7
A flight instrument that uses electric means for
obtaining a measure of the droplet-size distribution
In above-freezing clouds has been devised and given
preliminary evaluation in flight. An electric charge
is placed on the droplets and they are separated
aerodynamically according to their mass. The de-
sirable features of an instrument based on the
method described are: (1) the instrument can be
used in clouds with temperatures above freezing,
(2) the size and the shape of the cylinders do not
change during the exposure time, (3) the error
caused by bounce-off is low, (4) the readings
are Instantaneous and continuous, and (5) the fast
instrument response permits the study of variations
in cloud structure.
NACA TN 2460
FORMATION OF SULFIDE FILMS ON STEEL AND
EFFECT OF SUCH FILMS ON STATIC FRICTION.
Erva C. Levine and Marshall B. Peterson.
September 1951. 26p. diagrs., photos. (NACA
Experimental studies were conducted to evaluate the
formation of sulfide films on heated steel specimens
Immersed in solutions of free sulfur in cetane and
to establish the necessary film thickness for effec-
tive lubrication under static friction conditions.
NACA TN 2461
ANALYSIS OF PURE-BENDING FLUTTER OF A
CANTILEVER SWEPT WING AND ITS RELATION
TO BENDING-TORSION FLUTTER. H. J.
Cunningham. September 1951. 24p. diagrs.
(NACA TN 2461)
An analytical investigation of flutter in bending alone
of a cantilever swept wing and the relation of such
bending-alcne flutter to coupled flutter is reported.
The analysis is made on the basis of certain simpli-
fying assumptions, including that each wing section
is affected aerodynamically as if it is in a two-
dimensional flow, for both compressible and incom-
pressible flow. Some quantitative effects of-wing
mass-density ratio and sweep parameter, required
to enable single-degree bending flutter, are pre-
sented, as are results of speed and frequency of
single-degree and related coupled flutter. The
effect of compressibility on characteristics
of single-degree and related coupled flutter is pre-
dicted to be marked for a normal-component Mach
number of 0.7.
NACA TN 2471
UNSTEADY LAMINAR BOUNDARY-LAYER FLOW.
Franklin K. Moore. September 1951. 33p. diagrs.,
2 tabs. (NACA TN 2471)
Laminar compressible boundary layer over an insu-
lated flat plate moving with a time-dependent veloci-
ty is analyzed. A group of parameters arise which,
if large, provide that the classical "starting from
rest" solUtion applies, and, if small, that the motion
is quasi-steady. These parameters relate to the
time required for temporal changes to diffuse through
the boundary layer. Deviations from quasi-steady
velocity and temperature profiles are computed.
Unsteady laminar flows with pressure gradient and,
probably, unsteady turbulent boundary layers are
governed by similar parameters, which may be
estimated in order to provide a criterion as to
whether quasi-steadiness may be assumed for a
given problem. The case of fluctuating velocity
field passing over a flat plate is discussed from this
point of view.
NACA TN 2476
AN EMPIRICAL METHOD PERMITTING RAPID
DETERMINATION OF THE AREA, RATE, AND
DISTRIBUTION OF WATER-DROP IMPINGEMENT
ON AN AIRFOIL OF ARBITRARY SECTION AT
SUBSONIC SPEEDS. Norman R. Bergrun.
September 1951. 151ip. diagrs., 11 tabs. (NACA
A method is developed which permits the determina-
tion of area, rate, and distribution of water-drop
impingement on airfoils of arbitrary section at sub-
sonic speeds. The method, which is based on the
results of extensive water-drop-trajectory calcula-
tions for five airfoil cases, requires only a few
simple numerical computations once the velocity
distribution over the airfoil has been determined.
NACA TN 2491
KINETICS OF SINTERING CHROMIUM CARBIDE.
W. G. Lidman and H. 3. Hamjian. August 1951.
16p. diagrs., photos., tab. (NACA TN 2491)
The sintering of chromium carbide under pressure
was investigated in order to study the kinetics of
grain growth and densification during this process.
Grain growth followed the empirical equation Dn = Kt
where D is grain diameter, K is a rate constant, and
t Is sintering time. A change in n was associated
with the location, size, and shape of the pores in the
compact. Densification was accompanied by grain
growth, and density and grain size seem to be inter-
dependent during this stage. Grain growth continued
after densification was complete, and for this stage
an activation energy for grain growth was obtained.
NACA RM E51G09
CHARACTERISTICS OF A WEDGE WITH VARIOUS
HOLDER CONFIGURATIONS FOR STATIC-
PRESSURE MEASUREMENTS IN SUBSONIC GAS
STREAMS. Clarence C. Gettelman and Lloyd N.
Krause. September 1951. 13p. diagrs. (NACA
The characteristics of a wedge static-pressure
sensing element with various holder configurations
were determined and compared with the character-
istics of the conventional tube. The probes were
tested over a range of Mach number from 0.3 to 0.95
and at various pitch and yaw angles. The investiga-
tion showed that the spike-mounted wedge sensing
element has a pressure coefficient comparable with
RESEARCH ABSTRACTS NO.7
the conventional subsonic static-pressure probe and
the pressure coefficient of the wedge varied less
than that of the conventional probe for corresponding
change of yaw angle.
NACA RM E51G12
A SPECIALLY CONSTRUCTED METALLOGRAPH
FOR USE AT ELEVATED TEMPERATURES. Joe E.
Jenkins, Donald R. Buchele and Roger A. Long.
September 1951. 21p. diagrs., photos. (NACA RM
A metallographic microscope v ts developed with
provision for heating a specimen to 1800 F in pro-
tective atmospheres, that is, vacuum or gas. A
special objective was constructed of reflecting
elements with an unusually long working distance
(7/16 in.) and a high numerical aperture (0.5).
Changes in specimen microstructure were observed
and recorded on 35-millimeter motion-picture film.
The resulting pictures were projected as motion
pictures and individual frames were cut and enlarge-
ments made for close observation. Structural
changes upon heating a 0.35-percent annealed carbon
steel and a 5-percent tin phosphor bronze
specimen were observed and recorded. Newly
formed mnicrostructures were revealed by selective
vacuum etching and specimen relief resulting from
recrystallization and varying grain orientation.
NACA RM L51H07
A RELATION OF WIND SHEAR AND INSOLATION
TO THE TURBULENCE ENCOUNTERED BY AN
AIRPLANE IN CLEAR-AIR FLIGHT AT LOW
ALTITUDES. James K. Thompson. September
1951. 12p. diagrs., tab. (NACA RM L51H07)
The observed gust experience of an airplane and
information on the associated meteorological con-
ditions are utilized to obtain a simple empirical re-
lation for estimating the intensity of turbulence in
the earth's friction layer. The data were obtained
from 23 flights by an airplane operating in clear air
at 1500 feet altitude above the average elevation of
a given course near Wilmington, Ohio. Coefficients
of correlation between a meteorological quantity and
effective gust velocities which were equalled or ex-
ceeded on the average of once in distances of 1 and
10 miles for each flight were 0.88 and 0.84,
NACA TM 1303
RESISTANCE E OF CASCADE OF AIRFOILS IN GAS
STREAM AT SUBSONIC VELOCITY. (Soprotivlenie
Reshetki Profilei v Gazovom Potoke s
Dokriticheskimi Skorostiami). L. G. Loitsianskii.
September 1951. 30p. diagrs. (NACA TM 1303.
Trans. from Prikladnaya Matematika i Mekhanika,
v.13, no.2, 1949).
A method of computing the resistance of an airfoil in
cascade in a viscous compressiblfe gas stream with
subsonic velocity is presented. An essential as-
sumption of the method is that there is only a small
degree of nonhomogeneity in the flow at the section
downstream of the cascade where the trailing wakes
from the individual airfoils merge. The resistance
is expressed in terms of the boundary-layer proper-
ties at the trailing edge of the airfoil in cascade;
these properties can be computed by any compressi-
ble boundary-layer theory or canrt be measured.
NACA TM 1304
GENERALIZATION OF JOUKOWSKI FORMULA TO
AN AIRFOIL OF A CASCADE IN COMPRESSIBLE
GAS STREAM WITH SUBSONIC VELOCITIES.
(Obobshchenie Formuly Zhukovskogo na Sluchai
Profilia v Reshetke Obtekaemoi Szhimaemym Gazom
pri Dozvukovykh Skorostiakh). L. G. Loitsianskii.
September 1951. 16p. diagrs. (NACA TM 1304.
Trans. from Prikladnaya Matematika i Mekhanika,
v.13, no.2, 1949, p.209-216).
It is shown that the ordinary Joukowski formula for
lift force of cascade blades in incompressible flow
can be applied to the case of subsonic compressible
flow with sufficient accuracy, provided that the
density in the formula is taken as the arithmetic
mean of the densities far ahead of and behind the
TTACA TM 1313
ON THE RECORDING OF TURBULENT LONGITUDI-
NAL AND TRANSVERSE FLUCTUATIONS. (trber
das Messen turbulenter IAngs- und Querschwank-
ungen). H. Reichardt. August 1951. lOp. diagrs.
(NACA TM 1313. Trans. from Zeitschrift fiur
angewandte Mathematik und Mechanik, v. 18, no. 6,
December 1938, p.358-361).
A three-wire arrangement of a hot-wire probe to be
used in the measurement of nonisotropic turbulence,
such as in a turbulent boundary layer, is described.
A mathematical analysis of the probe's behavior is
given. A typical example of the application and the
results obtained with this probe are presented.
DECLASSIFIED NACA REPORTS
NACA RM L6J30
COMPARATIVE DRAG MEASUREMENTS AT
TRANSONIC SPEEDS OF AN NACA 65-006 AIRFOIL
AND A SYMMETRICAL CIRCULAR-ARC AIRFOIL.
Jim Rogers Thompson and Bernard W. Marschner.
March 6, 1947. 16p. diagrs., photo. (NACA
RM L6J30) (Declassified from Confidential,
Measurements were made by the freely falling body
method to compare the drag of a rectangular plan-
form airfoil of aspect ratio 7.6 having an NACA
65-006 section with that of an airfoil of identical
plan form and maximum thickness having a sym-
metrical circular-arc section. These measure-
ments showed the drag for the symmetrical
6-percent-thick circular-arc airfoil to be 16 percent
greater at the speed of sound and 11 percent greater
RESEARCH ABSTRACTS NO.7 5
at a Mach number of 1.16 than the drag of the NACA
NACA RM L8A23
THE LANGLEY ANNULAR TRANSONIC TUNNEL
AND PRELIMINARY TESTS OF AN NACA 66-006
AIRFOIL. Louis W. Habel. June 23, 1948. 23p.
diagrs., photos. (NACA RM L8A23) (Declassified
from Confidential, 7/20/51)
A description is given of the Langley annular trans-
onic tunnel which was designed to obtain two dimen-
sional airfoil pressure-distribution data at any Mach
number between approximately 0.6 and approximately
1.4. Preliminary data obtained with an NACA 66-006
airfoil in the transonic tunnel are compared with re-
sults obtained in a conventional subsonic wind tunnel,
the theoretical Prandtl-Meyer expansion, and data
obtained by the freely falling body method.
NACA RM L8Fll
METHOD FOR STRESS ANALYSIS OF A SWEPT
PROPELLER. Richard T. Whitcomb. Septem-
ber 27, 1948. 29p. diagrs. (NACA RM L8FlI)
(Declassified from Confidential, 8/15/51)
The methods used to estimate and reduce the
stresses in a swept propeller to be tested in the
Langley 8-foot high-speed tunnel are presented.
NACA RM L9G19
ANALYSIS OF MEASURED PRESSURES ON AIR-
FOILS AT MACH NUMBERS NEAR 1. Louis W.
Habel and Mason F. Miller. September 19, 1949.
25p. diagrs. (NACA RM L9G19) (Declassified
from Confidential, 7/20/51)
Measured supersonic pressures over airfoils at
Mach numbers near 1 with subsonic velocities at the
front and supersonic velocities throughout the rear
portion are analyzed by comparing with the pressure
turning-angle relationship of the Prandtl-Meyer
flow and with the linear-velocity extrapolation of the
subsonic pressure distribution. The effect of
boundary-layer thickness upon the turning angle is
NACA RM L50E18
PRELIMINARY INVESTIGATION OF AIRFOIL
CHARACTERISTICS IN THE LANGLEY ANNULAR
TRANSONIC TUNNEL. Louis W. Habel and
James H. Henderson. August 11, 1950. 21p. diagrs.
(NACA RM L50E18) (Declassified from Confidential,
Data obtained in the Langley annular transonic
tunnel with a reduced entrance length are compared
with theory and with data from 'other sources. The
data are presented in the form of pressure distri-
butions for several thin airfoils.
Aeroplane and Armament Experimental Establish-
ment (Gt. Brit.) WESTLAND SIKORSKY MK. 1 A
G-ALIK. HANDLING TESTS WITH POWERED CON-
TROLS. June 14, 1951. 5p. (AAEE Rept.
To assist in deciding whether powered controls
should be fitted to the Dragonfly 1 helicopters, brief
handling trials have been made on this civil counter-
part. It was fitted with powered azimuth and collec-
tive pitch controls. The flying qualities of the heli-
copter was greatly improved and the aircraft was
easy and pleasant to fly. The pilots thought that
some form of control feel should be incorporated in
the system. Because of the improvement in the
handling qualities, it is thought that a similar system
should be fitted to the Dragonfly without awaiting the
incorporation of feel.
Royal Aircraft Establishment (Gt. Brit.)
SOME FACTORS GOVERNING THE LIFE OF STEEL
WIRE ROPE IN AIRCRAFT. W. 3. Taylor. May
1951. 4p. (RAE Tech. Note Met. 144)
Occasionally the life of a steel wire rope in aircraft
control systems is disappointing. This note dis-
cusses the effect of the size of pulley on the life-to-
fraying of the rope and gives values of the ratio of
diameter of pulley to diameter of rope for long life.
Pennsylvania State Coll. Engineering Experiment
Station. PLASTIC STRESS-STRAIN RELATIONS
UNDER CONSTANT AND VARIABLE BIAXIAL TEN-
SION STRESS RATIOS FOR A 14S-T4 ALUMINUM
ALLOY. Joseph Marin and L. W. Hu. March 1951.
78p. diagrs., photo., 6 tabs. (Pennsylvania State
Coll. Engineering Experiment Station)
Constant-stress-ratio tests of the usual type were
made on a tubular 14S-T4 aluminum alloy specimen
to provide information on the biaxial strength prop-
erties of the material and the plastic stress-strain
relation. Special- and variable-stress-ratio tests
were also made to determine which type of plastic
flow theory the deformation, slip or flow type -
agrees best with test results.
THE THEORY OF GASES AT HIGH SPEED PRINCI-
PLES AND SUGGESTIONS FOR THE DESIGN OF
TURBINES. (Str6mungen von Gasen bel hohen
Geschwindlgkelten Grundlagen mund Anregungen fur
UNIVERSITY OF FLORIDA
3 1262 09079 7415
6 RESEARCH ABSTRACTS NO.7
den Bau von Stromungsmaschinen). Albert Betz.
21p. diagrs. (Trans. from Zeitschrift des Vereines
Deutscher Ingenieure, v.92, no.9, 1950, p.201-206).
The problems in flow research, in the foreground at
present, are associated, in part, with the boundary-
layer problems and in part with the elasticity of the
gases. In this report, a few results from the flow
research of elastic gases are discussed. These
elastic phenomena appeared on turbines, then on air-
planes, and later on compressors and blowers. The
more the speed increases the more these phenomena
gain in importance. It, therefore, is appropriate to
apply the data obtained on airplanes to turbines also.
The arguments presented are advanced as basic and
AGAINST FORMALISM IN THE THEORY OF PLAS-
TICITY. (Protiv Formalizma v Teorii Plastich-
nosti). S. T. Kishkin. 18p. (Trans. from Izvestia
Akademii Nauk, SSR. February 1950, p.266-278).
Discusses the formulation of a theory of strength and
plasticity of materials based on both theory and ex-
DETERMINATION OF PURELY CIRCULATORY
FLOW ABOUT CASCADE OF AIRFOILS. -
(Opredelenie Chisto Tsirkuliatsionnogo Obtekania
Reshetki Profilei). M. I. Zhukovskii. 5p. diagrs.
(Trans. from Prikladnaya Matematika i Mekhanika,
v.13, no.4, 1949, p.457-458).
Plane potential flow is considered about an isolated
airfoil that is composed of the sum of three flows;
(1) noncirculatory, having at infinity a direction par-
allel to the x-axis; (2) noncirculatory directed at in-
finity along the y-axis; and (3) purely circulatory.
The result may be formulated: The potential of the
purely circulatory flow at a certain point on an iso-
lated airfoil or an airfoil in a cascade is equal to the
angle of attack (expressed as a fraction of 2r) of the
noncirculatory flow that determines the stagnation of
the flow at this point. This result permits finding
the circulatory flow, in particular, about a
cascade of airfoils by use of experimental values of
the noncirculatory velocity potential determined by
the method of the electrohydrodynamic analogy.
NACA-Langiey, 9-17-51 s2550
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