Water tunnel visualization of the flow about bodies at high angles of attack was done. Wind tunnel tests on a series of models with non-circular cross sections are reported

Clarkson, M. H.

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tCOLLEGE UNIVERSITY OF FLORIDA^t
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AREA CODE 904 PHONE 392.0961
DEPARTMENT OF ENGINEERING SCIENCES
AEROSPACE ENGINEERING
APP',IMD MATHEMATICS Decembr 14, 1982COASTAL AND OCEANOGRAPHIC ENGINEERING
1NGINEERING MECHANICS
ENGINEERING SCIENCE
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NASA Scientific and Technical
Information Facility
F.O. Box 8757
Baltimore-Washington International Airport
Maryland	 21240
Dear Sirs:
3^	 Please find enclosed two copies of the final report of cooperative grant
NCC2-23 entitled "The Investigation of the Flow About General Fuselage Shapes
at High Angles of Attack".
Also enclosed are two copies of AIAA paper ra. 82-0056.
Sincerely,
s
M. H. Clarkson
Principal. Investigator 	 j
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	 THE INVESTIGATION OF THE
	 N83-14067
FLOW ABOUT GENERAL FUSELAGE SHAPES AT HIGH
ANGLES OF ATTACK
	 Final Report,	 1 Nov.	 1979
- 31 Oct.
	 1982	 (Florida Univ.)
	 8 p	 Unclas
HC A02/MF A01 CSCL OIA G3/02	 02168
FLORIDA'S FIRST UNIVERSTY
EQUAL EMPLOYMENT OPPORTUNITY/AFFIRMATIVE ACTION EMPLOYER
, MM
THE INVESTIGATION OF THE FLOW ABOUT
GENEPAL FUSELAGE SHAPES AT
91"M ANGLES OF ATTACK
Final Report for the Period
November 1, 1979 to October 31, 1982
by
Mark H. Clarkson, Principal Investigator
Department of Engineering Sciences
University of Florida
Gainesville, Florida 32611
NASA Technical Officer for this Cooperative Agreement is Mr. Gerald N. Malcolm,
Aerodynamic Research Branch, NASA, Ames Research Center, Moffett Field,
California 94035.
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Cooperative Agreement Number is NCC2-23
Date: December 1982
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I.	 HISTORYy.
The writer was a Senior NRC Associate at the Ames Research Center from
September, 1973 through August, 1974. It was proposed, originally, to develop
parameter identification methods for use in deducing aerodynamic data from
flight tests conducted on full-scale aircraft and on scaled instrumented
models during spin entry and the ensuing spin. However, it became apparent
early in the tenure of the associateship that the parameter identification
problem for the spinning aircraft was too unwieldy to use brute force methods
and that a better knowledge of the aerodynamics of spinning bodies at high
angles of attack was needed, not only for parameter identification work, but
for design purposes as well.
It was known *_ha*_ aircraft spin producing mouents are highly dependent on
fuselage shape and on Reynolds number for the case of the flat spin. However,
as no rotary aerodynamic data were known to exist over the wide range of
Reynolds numbers achievable in the Ames 12-foot pressure tunnel, it was
decided to conduct an exploraztor3 investigation of rotary characteristics of
some fuselage-like shapes in the 12-foot tunnel using a modified existing
rotary rig and existing TASK 6-component internal strain gage balance. These
tests were carried out during the summer of 1974 and the results were reported
at the 1975 annual Technical Meeting of the AIAA. These results were also
published in the AIAA Journal of Aircraft. l Much of the analysis was dune at
the University of Florida by the writer under a consortium agreement with the
Ames Research Center.
, Although the results of this investigation were quite informative, the
sensitivity of the balance at the lower range of Reynolds numbers was quite
low in the side force direction. For this reason, it was deeded to repeat
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portions of the rotary tests with balances designed for the pulrpose, i.e.,
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strong in the axial and normal force directions but more sensitive in the side
force direction. These tests were carried out in the summer of 1975 with the
writer serving as a co-prinicpal investigator with Mr. Gerald N. Malcolm of
ARC. A portion of the results of these tests were repot:ed on at the AIAA
Aerodynamics Testing Conference in Arlington, Texas in June 1976. In addition
to the rotary tests, Lorce measurements were made in the non-rotating mode at
quite close spacing of the Reynolds number at angles of attack of 45, 60, 75
and 90 degrees. These tests showed a strong dependence on Reynolds number and
angle of attack in a rather , unexpected way. To pursue this, oil flow,
pressure distribution and sublimation tests were run. The sublimation tests
indicated that some of the observed behavior was due to inflexional instabil-
ity in the laminar boundary layer. This work was presented at the AIAA 15th
Aerospace Sciences Meeting held in Los Angles in January 1977, AIAA paper 77-
180. A slightly shortened version of this paper was published in the December
1978 issue of ehe AIAA Journal.2
A transparent hemisphere cyclinder model was constructed at the Univer-
sity of Florida with an 8 = camera located inside the model on a traversing
mechanism. Some interesting footage of boundary layer flow was obtained by
mounting the model on a pontoon boat and testing in a clear water lake in
Florida. However, it wasn"t clear whether the observed flow was related to
the inflexional instabilities mentioned above so it was decided to perform a
rotating disk experiment in water. This experiment was performed in air by
Newell H. Smith (NACA TN 1227, May 1947), and by Gregory, Stuart and Walker
(Philosophical Transactions of the Royal Soc. of London, July 1955); and in
water by Faller and Kaylor (Dynamics of Fluids and Plasmas, Edited by S. 1.
Pai, Academic Press, 1966). However, the experimental set-up of Faller and
Kaylor differed in substantial respects from our experiment. Our rotating
2
fdisk experiment proved that the vortices would be observed provided care was
taken with injection of the dye. We also noted secondary .instabilities that
appear to be different than those reported by Faller and Kaylot.
These tests were repeated during the fall of 1979 using a disk with
carefully scribed concentric circles and radial lines on the upper surface of
the transparent disk. Thus, quantitative measurements could be readily
carried out. The number of vortices with axes fixed with respect to the plate
ranged from 29 to 40. Stuart, Gregory and Walker reported between 25 and 34
using a boundary layer probe and 28 to 31 using the china clay technique. The
angle of the axis of the vortex was about 11° compared to 13° of the above
referenced work. In addition it was found that the spiral flow about the
fixed vortex axis lagged behind the disk being only about 30% of the disk
velocity at a given radius. this corresponds roughly to the tangential
velocity at the point of inflexion of the radial profile.
The secondary instabilities mentioned above were also examined in
detail. The lifespan of these were about .020 seconds.
Two undergraduate students who assisted the principal investigator wrote-
up the experiment and presented the results at the Southeastern AIAA Student
Paper Competition in Atlanta, Georgia on April 5, 1979. Their paper won third
place. An expanded version of the paper was presented at the annual AIAA
meeting in January `1980, and also was published.3
An extension of the above work to paraboloids was supported by NASA
Langley under grant NAG-1-104. Additional work on flat disks under this grant
showed that the vortex angle was a function of radius.
II. SUMMARY OF WORK UNDER NCC2-23
Work under this grant was pursued both at Ames Research Center and at the
University of Florida. Water tunnel vistyalization of the flow about
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bodies at high angles of attack was done at the University of Florida.
Results of some of this work are summarized in a Master's thesis by Victoria
Brittain. 4
 Miss Brittain also waa ,awarded second place in the Graduate
Division of the Southeastern AIAA Student paper Competition in 1980. A paper
was also given by the principal investigator at the "High Angle of Attack
Missile Aerodynamics Working Group Meeting" held October 14-16, 1981 at Singer
Island, Florida.
The flow visualization work on bodies with non-circular cross sections
led to a contract with the U.S. Air Force Armament Laboratory under contract
no. F08635-81-K-0281. Some of this work will be reported on at the January
1983 Aerospace Sciences Meeting in Reno, Nevada in a paper co-authored by the
principal investigator and Dr. Gary Chapman of the Ames Research Center.
The work peLLVL1LLC at nm8tf t.'Vll.=S1LfLC OY W.LL1U LZ1L1Lle1 {.es1.D .L II the Hotta
12-foot pressure tunnel on a series of models with non-circular cross sections
and the analysis of the data. A portion of this work was reported on at the
1982 Aerospace Sciences Meeting.6
A data report was prepared in the summer of 1982 summarizing the results
of the tests in the 12-foot tunnel on the bodies with non-circular cross
sections. The number of this report is not available at this writing but
will be published by NASA ARC.
III. ACCOMPLISIiME,NTS
A. Wind Tunnel Tests
1. The rotary tests were the first ever performed over a wide range
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of Reynolds numbers at constant Mach number. 	 7
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2. Hysteresis effects at high angles of attack were documented.
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3. Effect of inflexional instabilities on aerodynamic characteristics
of bodies at high angles of attack determined for several bodies.
4
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4. Important effects of nose shape on aerodynamic characteristics
of bodies with non-circular cross gections determined over a
wide range of angles of attack and Reynolds numbers.
5. Reasonable explanations provided for most of the complex flow
patterns observed.
B. Flow Visualization
1. The method of a continuous distribution of dye sources was
developed for flow visualization under this grant. Tests using
this technique proved, experimentally, the existence of an
"open" type of separation and helped to interpret, generally,
separated flows.
C. Student Involvement
This work has been very instrumental in providing support and
motivation to a number of undergraduates as well as graduate
students. As a result of this program, five papers have been entered
in the AIAA student paper competition resulting in two awards. Three
Master's theses were supported by this work. In all, four graduate
students and six undergraduates have participated. One of the
graduate students is now working for NASA, and the rest of the
students are employed in the aerospace industry.
IV. SUGGESTIONS FOR FUTURE WORK
A. The present sublimation methods of detecting the presence of inflex-
ional instabilities in the boundary layer are not very satisfactory
and need improving.
B. The research bodies used in the last series of tests should be tested
to determine the b.,undaries of inflexional instabilities.
C. The same research bodies should be tested for roughness effects which
are known to be substantial.
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44
D. The applicability of the impulsive flow analogy should be thoroughly	 f'
investigated.
E. now visualization techniques for determining the flow patterns in
cross-flow planes should be developed further.
r. now visualization techniques for use at higher Reynolds numbers
should be developed.	 fr
V. ACKNOWLEDGEMENTS
The author would like to express his appreciation to members of the
Aerodynamic Research Branch for their efforts in making this cooperative
grant both technically rewarding and intellectually stimulating. In
particular, I would like to thank Jerry Malcolm and Gary Chapman who made
the word ''cooperative" in cooperative grant have real meaning. This work
would not have been possible without them.
Thanks are also due to Murray Tobak who provided insight and help on
numerous occasions during the course of the work.
6
^,
1. Clarkson, M. H., Malcolm, G. N. and Chapman,, G. T., "Experimental Deter-
mination of Post-Stall Rotary Derivatives for Airplane-Like Configura-
tions at Several Reynolds Numbers," AIAA Journal of Aircraft, Vol. 13,
No. 8, Aug. 1976.
2. Malcoln, G. N. and Chapman, G. T., "A Subsonic Flow Investigation at High
Angles of Attach on a Research Body at Several. Reynolds Numbers," AIAA
Journal, Vol. 16, No. 1, Jan. 1978.
3. Clarkson, M. H., Chen, S. Co and Shater, P., "Visualization of Flow
Instabiliti -1 , on an Rotativg Disk," AIAA Journal, Vol. 18, No, 12, Dec.
1980.
4. Brittain, V. A., "A Study of Flow Separation Using a Continuous Distri-
bution of Dye Sources," Master Thesis, University of Florida, June 1981.
5. Clarkson, M. H. and Chapman, G. T., "Flow Visualization Studies of Bodies
with Square Cross Sections," AIAA Paper No. 83-0563, Jan. 1983.
6. Clarkson, M. H., Malcolm., G. N. and Brittain, V. A., "Aerodynamic
Characteristics of Bodies with Noncircular Cross Sections at High Angles
of Attack," AIAA Paper No. 82-0056, Jan. 1982.
7. Clarkson, M. H., Malcolm, G. N., Brittain, V. A. and Intewtnn, P. A.,
"Aerodynamic Characteristics of Bodies with Noncircular Cross Sections at
High Angles of Attack," Data Report to be published by NASA ARC.
7


The investigation of the flow about general fuselage shapes at high angles of attack

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