Pressure distribution over an NACA 23012 airfoil with a slotted and a plain flap

38 Pages·2015·4.02 MB·English

https://ntrs.nasa.gov/search.jsp?R=19930091708 2019-03-27T07:20:42+00:00Z
REPRODUCED BY
NATIONAL TECHNICAL
INFORMATION SERVICE
U. S. DEPARTMENT OF COMMERCE
SPRINGFIELD, VA. 22161

REPORT No. 633
PRESSURE DISTRIBUTION OVER AN N. A. C. A. 23012
AIRFOIL WITH A SLOTTED AND A PLAIN FLAP
By CARL J. WENZINGER and JAMES B. DELANO
Langley Memorial Aeronautical Laboratory
74939--38--1
NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS
HEADQUARTERS, NAVY BUILDING, WASHINGTON, D. C°
LABORATORIES, LANGLEY FIELD, VA.
Created by act of Congress approved March 3, 1915, for the supervision and direction of the scientific
study of the problems of flight (U. S. Code, Title 50, Sec. 151). Its membership was increased to 15 by
act approved March 2, 1929. The members are appointed by the President, and serve as such without
compensation.
JOSEPH S. AMES, Ph.D., Chairman, SYDNEY M. KRAUS, Captain, United States Navy,
Baltimore, Md. Bureau of Aeronautics, Navy Department.
DAVID W. TAYLOR, D. Eng., Vice Chairman, CHARLES A. LINDBERGH, LL. D.,
Washington, D. C. New York City.
WILLIS RAY GREGG, Sc. D., Chairman, Executive Committee, DENIS MULLIGAN, J. S. D.,
Chief, United States Weather Bureau. Director of Air Commerce, Department of Commerce.
WILLIAM P. MACCRACKEN, J. D., Vice Chairman, Executive AUGUSTINE W. ROBINS, Brigadier General, United States
Committee, Army,
Washington, D. C. Chief Matdriel Division, Air Corps, Wright Field,
CHARLES G. ABBOT, Sc. D., Dayton, Ohio.
Secretary, Smithsonian Institution. EDWARD P. WARNER, Sc. D.,
LYMAN J. BRIGGS, Ph.D., Greenwich, Conn.
Director, National Bureau of Standards. OSCAR WESTOVER, Major General,United StatesArmy,
ARTHUR B. COOK, Rear Admiral, United States Navy, ChiefofAir Corps,War Department.
Chief, Bureau of Aeronautics, Navy Department. ORVILLE WRIGHT, Sc. D.,
HARRY F. GUGGENHEIM, M. A., Dayton, Ohio.
Port Washington, Long Island,N. Y.
GEORGE W. LEWIS, Director of Aeronautical Research
JOHN f. VICTORY, Secretary
HENRY J. E. REID, Engineer-in-Charge, Langley Memorial Aeronautical Laboratory, Langley Field, Va.
JOHN J. IDE, Technical Assistant in Europe, Paris, France
TECHNICAL COMMITTEES
AERODYNAMICS AIRCRAFT STRUCTURES
POWER PLANTS FORAIRCRAFT AIRCRAFT ACCIDENTS
AIRCRAFT MATERIALS INVENTIONS AND DESIGNS
Coordination of Research Needs of Military and Civil Aviation
Preparation of Research Programs
Allocation of Problems
Prevention of Duplication
Consideration of Inventions
LANGLEY MEMORIAL AERONAUTICAL LABORATORY OFFICE OF AERONAUTICAL INTELLIGENCE
LANGLEY FIELD, VA. WASHINGTON, D. C.
Unified conduct, for all agencies, of Collection, classification, compilation,
scientific research on the fundamental and dissemination of scientific and tech-
nical information on aeronautics.
problems of flight.
|I
REPORT No. 633
PRESSURE DISTRIBUTION OVER AN N. A. C. A. 23012 AIRFOIL WITH A SLOTTED
AND A PLAIN FLAP
By CARL J. WEN'ZIN'GER and JAMES B. DELAI_O
SUMMARY (references 2 and 3) are available but, as the reported
Pressure-distribution tests of an N. A. C. A. 23012 tests were not very comprehensive, the present investi-
airfoil equipped with a slotted flap and with a plain flap gation was undertaken to supply information applicable
were made in the 7- by lO-foot wind tunnel. A test instal- to the structural design of slotted flaps. Similar data
lation was used in which the 7-foot-span airfoil was are already available for the design of split, external-
mounted vertically between the upper and lower sides of airfoil, and Fowler flaps (references 4, 5, and 6).
the closed test section so that two-dimenslonal flow was Pressure-distribution tests were made in the 7- by
approximated. The pressures were measured on the 10-foot wind tunnel of an N. A. C. A. 23012 airfoil in
upper and lower surfaces at one chord section both on the combination with a slotted flap. The optimum flap
main airfoil and on the flaps for several different flap path previously developed for this flap (reference 1)
deflections and at several angles of attack. was used in these tests. Pressure-distribution tests
were also made over the same airfoil in combination
The data are presented in the form o] pressure-distribu-
tion diagrams and as graphs of calculated section coe_- with a plain flap for purposes of comparison and also to
obtain additional information for the detailed structural
cients ]or the airfoil-and-flap combinations and also for
design of both flaps and ailerons.
the flaps alone. The results are useful ]or application to
rib and flap structural design; in addition, the plain-flap
APPARATUS AND TESTS
data furnish considerable information applicable to the
MODELS
structural design of plain ailerons.
The models used in the present tests are the ones
INTRODUCTION previously used in the force tests reported in reference
1. The main airfoil, made of laminated pine to the
Up to the present time, many high-lift devices have
N. A. C. A. 23012 profile, has a uniform chord of 3
been developed and investigated, but each appears to
feet and a span of 7 feet. A removable full-span
have some disadvantages. One of the most promising
trailing-edge section permits the testing of different
high-lift devices thus far developed is the combination
full-span flaps in combination with the same main
of a slotted flap with a main airfoil. Investigations of
airfoil. Both a slotted flap and a plain flap made of
this arrangement (reference 1) have shown that it is
laminated pine were tested; each was supported on the
capable of developing high lifts and that it gives lower
main airfoil by three metal fittings, one located at mid--
drags at these high lifts than do external-airfoil, plain,
span and one inboard of each flap tip.
or split flaps.
The slotted flap tested (fig. 1) is the one previously
The force tests of reference 1, in which several com- developed by the N. A. C. A. and designated 2-h in
binations of an N. A. C. A. 23012 airfoil with flaps of reference 1; it has a chord of 9.238 inches (25.66 per-
different sections and with slots of several different
cent of the over-all airfoil chord). A full-span fixed
shapes were investigated, indicated that the best ar- lip made of strip brass is located on the upper surface
rangement thus far obtained is a combination of an of the main airfoil over the flap-slot exit to seal the slot
airfoil and a slotted flap, the flap having an airfoilshape when the flap is neutral and to direct the passage of
and the slot an easy entrance; this combination is des- air downward over the flap when the flap is defleete(h
ignated flap 2-h in reference 1. A survey of flap loca- The path of the nose point of the flap chosen (fig. 1) is
tion with respect to the main airfoil was made to obtain the optimum one reported in the tests described in
the best aerodynamic characteristics. It was also reference 1. The nose point of the flap is defined as
found that some particular flap path would give opti- the point of tangency of a line drawn normal to the
mum aerodynamic characteristics; the flap path airfoil chord and tangent to the leading-edge arc of the
developed is reported in reference 1.
flap when neutral. The flap is arranged for locking at
Very few data are available for application to the downward flap deflections between 0° and 60° in
structural design of slotted flaps. Some recent data increments of 10%
1
2 REPORT NO. 633--NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS
The plain flap (fig. 1) has a chord of 7.20 inches outside the tunnel by rotating the torque tubes with a
calibrated electric drive. Approximately two-dimen-
(20.0 percent of the over-all airfoil chord). The flap
sional flow is obtained with this type of installation,
gap was sealed for all flap deflections by interchange-
and the section characteristics of the model under test
able full-span brass lips on the upper and lower sur-
faces of the airfoil to prevent a flow of air through the may be determined. TESTS
gap. The flap is arranged for locking at flap deflec-
All the tests were made at a dynamic pressure of
tions between 45° up and 75° down in increments of
16.37 pounds per square foot, corresponding to an air
15°.
A single row of pressure orifices was built into the
upper and lower surfaces of both the main airfoil and
!i!
the flaps at a chord section 21 inches from one end of
the models (fig. 2). The orifices were located on the
models as listed in table I, the tubes from the orifices
being brought through the models and out at one end.
The pressures were photographically recorded by a
multiple-tube liquid manometer.
i
T i
I co I I /0'
082 7c_
_ ._0o788c_ lR=oO8#cj -- -d-Lzrwec,f_zo.. "_ _ ',,, , [ __...__
asos/_, -------_" F-4 °<\', 1 ,
(al 60°
Path of flop nose
Horizon/a/ _ect/on
(a) N. A. O. A'. 23012 airfoil with a 0.2566¢, slotted flap.
i-Balance frame
[
{/Mode/ support
Path of flap nose for
various flap deflec- _,]]fPressure tubes to oF/rices
tions. Dtst anees
measured from /. _//--
lower edge of lip in IWI"
3! (deg.) percent airfoil chord
c_
i i I l
r, i, i, 2/"
x y
--._t--..i.... t,--. __¢: of
i " 'Z
0 8.36 3.91 I ' I /2t-assure
10 5.41 3.63 , I I Orl'fl'ce5
20 3.83 3.45 i [ t
30 2.63 3.37
40 1.35 2.43
50 •50 1.63
60 •12 1.48 i i
I i
1"I 1
I I
I i
('" Gaps ueole(] 1 I I
i 5ZZ".r 1
"= -----<VTooos<I
32
=oo2 <',\I /
(b) '_! ,_,:75° Vertical section
':,y
t FmUR_ 2.--Model installation for two-dimensional flow tests in the 7- by 10-foot
wind tunnel.
(b) N. A. C. A. 23012 airfoil with a O.2Oc, plain flap.
Fio, unE 1.--(;ross sections of model showing airfoil-flap combinations used in pres- speed of about 80 miles per hour at standartl sea-level
sure-distribution tests.
conditions. The average test Reynolds Number,
TEST INSTALLATION based on the plain airfoil chord, was 2,190,000. This
The model was mounted in the N. A. C. A. 7- by test Reynolds Number, when converted to an effective
10-foot closed-jet wind tunnel (references 1 and 7) as Reynolds Number (reference 8) that takes account
indicated in figure 2. The main airfoil was rigidly of the turbulence in the air stream, is 3,500,000. (Ef-
attached to the balance frame by torque tubes, which fective Reynolds Number=average test Reynolds
extended through the upper and lower sides of the Number Xturbulence factor; turbulence factor for the
tunnel. The angle of attack of the model was set from tunnel is 1.6.)
PRESSURE DISTRIBUTION OVER AN N. A. C. A. 23012 AIRFOIL WITH FLAPS
The model was tested with the slotted flap set at
chf=h-_f_, hinge-moment coefficient of plain flap about
angles of 0°, 10°, 20°, 30°, 40°, 50°, and 60° down; and qvf flap hinge axis.
with the plain flap set at angles of 45°, 30°, and 15°
__ Xf
up, 0°, and 15°, 30°, 45 °, 60°, and 75° down. The ccf--_, chord-force coefficient of slotted flap alone.
angles of attack ranged from --14 ° to 20°, and the lift
coefficients included those from approximately maxi- (e. p.),o= 0.25- c_m-/_N\ 100, center-of-pressure location
of main airfoil with flap
mum negative to maximum positive. With the model
at a given angle of attack and with a given flap setting, in percent airfoil chord
tunnel conditions were allowed to become steady from leading edge.
before a record of the pressures at the orifices was 00c,oo or-o - o =o
taken.
of flap alone in percent
PRESENTATION OF DATA
flap chord from leading
PRESSURE DIAGRAMS edge of flap.
All diagrams of pressures over the upper and lower where the forces and moments per unit span are:
surfaces of the airfoil-flap combinations are given as n_, normal force on main airfoil with flap (this force is
ratios of the orifice pressure p to the dynamic pressure normal to chord of main airfoil and is equal to
q of the free air stream for the flap deflections and for n,_-[-nf cos _f, neglecting the normal component
the angles of attack investigated. Pressure diagrams of the flap chord force).
for the airfoil with the slotted flap are shown in figures n_, normal force on main portion of the airfoil without
3 to 15 and, for the airfoil with the plain flap, in figures flap (this force is normal to chord of main airfoil
16 to 24. The effect of the flaps on the pressure distri- and is equal to n,_--nf cos _s).
bution over the main airfoil is shown by a comparison nf, normal force on flap alone normal to chord of flap.
of the pressures over the plain airfoil with the pressures mr, pitching moment of main airfoil with flap about
over both the slotted-flap and the plain-flap combina- quarter-chord point of airfoil.
tions at the same total normal-force coefficient and ms. pitching moment of slotted flap about quarter-
also at the same angle of attack (figs. 25 and 26). In chord point of flap.
figures 3 to 9 and 16 to 26, the pressures over the main hf, hinge moment of plain flap.
airfoil are plotted normal to the airfoil chord and the xs, chord force on slotted flap alone.
pressures over the flaps are plotted normal to a reference and
line which is parallel to the main airfoil chord when the q, dynamic pressure of free air stream.
flap is neutral but which deflects with the flap. c_, chord of main airfoil.
Figures 10 to 15 are included to show the pressures cl, chord of flap.
parallel to the chord of the slotted flap. These pres- The coefficients for the combination were derived
sures are also given as ratios of orifice pressure to the from the normal forces alone, the chord forces of the
dynamic pressure of the air stream; however, the flaps being neglected. In the case of the slotted flap,
pressure values are plotted parallel to, instead of however, neglecting the flap chord-force component
normal to, the flap reference line and are measured in the computation of the total normal-force coefficient
from the maximum ordinates of the flap instead of of the combination reduces these coefficients by a
from its reference line. maximum of about 0.08.
COEFFICIENTS Because the model completely spanned the jet, the
integrated results, which are given in coefficient form
The pressure diagrams were mechanically integrated
in figures 27 to 42, may be taken to be section charac-
to obtain data from which section coefficients were
teristics. The normal-force coefficients of the airfoil-
computed. Where the term "flap alone" is used, refer-
flap combinations include an experimentally determined
ence is made to the characteristics of the flap in the
correction for tunnel-wall effects, which was made as
presence of the main airfoil. The section coefficients in reference 1.
are defined as follows:
PRECISION
normal-force coefficient of main airfoil with
Cnw_ qTbcww, No air-flow alinement tests were made in the wind
flap.
tunnel with the test arrangement used in this investiga-
Cn¢_ fbf , normal-force coefficient of flap alone. tion, so the absolute angle of attack may be slightly in
" qcr
error; the relative angles are correct to within _0.1 °.
mw pitching-moment coefficient of main airfoil The flaps were set to specified angles to within _-0.1 °.
Cmw----"_w 2, with flap about quarter-chord point of air- The orifice pressures, based on check tests in which
foil.
both the angle of attack and the flap setting were
pitching-moment coefficient of slotted flap independently changed, show that they agreed to
alone about quarter-chord point of flap. within ± 2 percent, with the exception of upper-surface
4 REPORT NO. 633--NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS
0o 0 o
W _o--4 O°
c,_ =-0.23
_o = 12.0 °
C_= 1.30
_o = 0.0 °
c_= O./'q
-4
p__
q
-2
q
0
I -_- _o= 16.0 °
c,,_= 1.40
Upper- 5urfoce
........... £ower
b
_o= 8.0 ° ao= 20.0 °
c._= 0.34 c,,_= 1.23
FIGURE &--Pressure distribution on the N. A. C. A. 23012airfoil with a 0.2566c_slotted flap, at various angles of attack. Flap set a_0%
PRESSURDEISTRIBUTIOONVERANN.A.C.A.23012AIRFOILWITHFLAPS 5
/0 °
7
II
_o=-4.0°
e..: 0.03
_o 120
c,_,= 1.84
h'
_o= 0"0° v
c_= 0.59
'._._-_- - _ _ _ _ao- =_ /6.0 ° ta,,
V,_,= 1.60
.°= 4.0" _"
c._= 1.06 Upper surfoce
Lowez-
q
\ 19-4-2 _._
0
,i
'--- ao= 20.0"
c._,= 1.51
,..-" _o = 8.0 _ ; --
C..= 1.48
FIGURE4.--Pressure distribution on the N. A. C. A. 23012airfoil with a0.2566c_slotted flap, at various angles ofattack. Flap set at 10%
. REPORT NO. 633---NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS
f (
_--_o°
_o =-8.0" .__ _ ez°= 8.0 °
C.== 0.10 C,_= 1..93
-°t
-6
P
q
c,.,= 0.5,.9
c._ = _2.23
i _
ao = 0.0 °
c..= /.07
"_"" " _a = 16.0" _'- ......
C._ = I. 78
UpDer surface
L0wer ,,
\
0:-;;.......-_/-:
c.,. = 1,53 J
,...... ,,,o= ao.o° ;.-.....
c_,_= L66
FIGURE5.--Pressuro distribution on the N. A. C. k. 23012airfoil with a0.2566c, slotted flap, at various angles ofattack. Flap set at 20°.