Preliminary designs were completed for an iodine mixing chamber and the optical setup to be used with a modified wind tunnel in obtaining accurate, spatially resolved measurements of variables in the flowfield of a model nonreacting scramjet combustor. Schematics of the iodine-seeded wind tunnel and a sketch of the charcoal filter for removing the iodine are included along with a cutaway section of the laboratory

Mcdaniel, J. C., Jr.

English

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Semi-Annual Progress Report
Grant No. NAG-1-373
Reporting Period: July 1, 1983 - January 1, 1984
FLOWFIELD MEASUREMENTS IN A MODEL SCRAMJET COMBUSTOR
USING LASER-INDUCED IODINE FLUORESCENCE
Submitted to:
National Aeronautics and Space Administration
Langley Research Center
Hampton, VA 23665
Attention: Dr. G. Burton Northam
HSAD, Mail Stop 168
Submitted by:
James C. McDaniel, Jr.
Assistant Professor
Report No. UVA/528228/MAE84/101
March 1984
SCHOOL OF ENGINEERING AND
APPLIED SCIENCE
DEPARTMENT OF MECHANICAL AND AEROSPACE ENGINEERING
UNIVERSITY OF VIRGINIA?*j
CHARLOTTESVILLE, VIRGINIA 22901
https://ntrs.nasa.gov/search.jsp?R=19840011215 2020-03-21T00:11:46+00:00Z
Semi-Annual Progress Report
Grant No. NAG-1-373
Reporting Period: July 1, 1983 - January 1, 1984
FLOWFIELD MEASUREMENTS IN A MODEL SCRAMJET COMBUSTOR
USING LASER-INDUCED IODINE FLUORESCENCE
Submitted to:
National Aeronautics and Space Administration
Langley Research Center
Hampton, VA 23665
Attention: Dr. G. Burton Northam
HSAD, Mail Stop 168
Submitted by:
James C. McDaniel, Jr.
Assistant Professor
Department of Mechanical and Aerospace Engineering
RESEARCH LABORATORIES FOR THE ENGINEERING SCIENCES
SCHOOL OF ENGINEERING AND APPLIED SCIENCE
UNIVERSITY OF VIRGINIA
CHARLOTTESVILLE, VIRGINIA
Report No. UVA/528228/MAE84/101 Copy No.
March 1984
1. INTRODUCTION
The objective of the research supported by NASA Grant NAG-1-373
is to obtain accurate, spatially-resolved measurements of flowfield
variables, including pressure and velocity, in a model nonreacting
scramjet combustor flowfield. The diagnostic technique to be employed
is based on laser-induced fluorescence from iodine molecules seeded into
the flowfield.
Proposal No. MAE-NASA-2603-83 outlined phase 1 of the research
plan to be completed in the initial 12-month period of Grant NAG-1-373
(July 1, 1983 - June 30, 1984). The first 6 months of the grant period
was to be devoted to modifying an existing wind tunnel facility at the
University of Virginia to accommodate iodine seeding and to contain a
specially-designed combustor test section, to complete the optical system
setup, and to obtain preliminary measurements in an iodine static cell.
The second 6 months proposed to obtain preliminary data from the
scramjet flowfield in the form of flow visualizations and pointwise
measurements using the iodine fluorescence technique. The progress
made during the first six months of the grant period is reported
herein.
2. LABORATORY RENOVATION
Upon arrival of the principal investigator at the University of
Virginia in late June 1983, the proposed site for the research facility in
the basement of the A&M Building (Room B001A) was examined, deter-
mined to be adequate for the research (as judged previously by Dr.
Sam Fisher of U.Va. and Dr. G. Bert Northam of NASA/Langley) and
the necessary formal approvals were obtained for securing the
laboratory space for this purpose. The laboratory had been used for
many years as the site of an electromagnetic-suspension wind tunnel
facility and as of July 1, 1983 contained most of the apparatus required
to operate this facility. The top photograph in Figure 1 is a
photograph of the laboratory as viewed on July 1. A large
liquid-helium-cooled dewar was suspended on cement-block pillars above
an open pit in the center of the room. Large cables connected the
dewar to power supplies located just outside the laboratory.
Miscellaneous electronic equipment, hardware and an assortment of
paperwork collected over the years of operation of the facility filled the
room. Since the facility had not been used for several years
everything was covered with a thick layer of dust. However, it was
obvious that the necessary components for the proposed research were
available in the lab: air supply, plenty of water and power for lasers
and adequate space, completely enclosed and isolated from adjacent
labs.
The first task was, therefore, the disassembly, removal and stor-
age of the equipment from the electromagnetic-suspension wind tunnel.
Figure 1. Photographs of laboratory before (top) and after (bottom)
removal of electromagnetic-suspension wind tunnel facility and
equipment.
Items identifiable as belonging to departments in the engineering school
were returned, faculty members involved in the electromagnetic-
suspension work removed and stored items purchased under old con-
tracts, and remaining items were either retained for possible future use
in the proposed research, stored or scrapped. The bottom photograph
in Figure 1 shows the laboratory after removal of the old
electromagnetic-suspension tunnel and equipment.
After clearing out the lab, the two cement-block supports were cut
off and finished with concrete caps to support an optical table. Since
these cement supports extend into the building foundation and are
mechanically isolated from it by plywood spacers, they make ideal
supports for an optical table.
With the laboratory stripped of old equipment and the cement
supports shortened, the second task, renovation of the space for the
future research, began. After repeated attempts to remove dust from
the lab it was realized that a major problem had to be faced: the ceiling
was covered with a thick layer of asbestos and dirt which showered
down on the lab whenever someone walked on the floor above. This
was not only a hazard to personnel working in the lab but completely
unacceptable for a clean optical area. After consulting with the
Environmental Health and Safety Department at U.Va. it was determined
that the dirt could not be removed without removal of the asbestos and
this would require approximately 510,000 and 6-12 months to complete.
In order to solve the problem more reasonably it was proposed that a
suspended ceiling be installed below the exist ing ceiling so as to
completely entrap the dust and asbestos in an area to which access is
not needed. The suspended ceiling was installed by the Department of
Physical Plant at U.Va. with the expense shared between the Office of
the Dean and the Department of Mechanical and Aerospace Engineering.
The top photograph in Figure 2 shows the lab in the process of
renovation after installation of the suspended ceiling. The resulting
space is not only very clean but much more adequately lighted than
before. This photograph shows the optical table (still in shipping
crate) mounted on the cement supports and a new raised wooden floor
constructed over approximately one-half of the laboratory. The floor
spans the pit area below and beside the optical table. Electrical power
and water lines were installed under the floor to provide the optical
table area with both 110V and 220V power and cooling water for lasers.
A partition was constructed at the end of the raised floor area to
support laser safety curtains (thereby, isolating the optical area from
the remainder of the lab) and to provide railings around the steps
leading to the pit area beneath the optical table. The bottom
photograph in Figure 2 shows the laboratory after completion of the
above-described renovation. This phase of the work extended well into
the Fall due primarily to the delay caused by the unforeseen presence
of asbestos on the ceiling.
Figure 2. Photographs of laboratory during (top) and at completion
(bottom) of renovation phase.
3. MODIFICATION OF WIND-TUNNEL FACILITY
All sections of the previous wind tunnel downstream of the pres-
sure regulator were removed as these sections were not useable in the
new design. Figure 3 is a sketch of the overall iodine-seeded wind
tunnel. The compressor, dryer, storage tanks and regulator remain
from the old tunnel. The chamber for mixing iodine into the air, the
new test section and the filter for removing the iodine before
exhausting to the atmosphere will complete the new tunnel. This tunnel
layout is essentially the same as Figure 5 of the original research
proposal but without the pump downstream of the filter. The available
Stokes 412 vacuum pumps at U.Va. were found to be incapable of
running at the high pressure levels and throughput rates required
without drastic modification. It was decided to simply exhaust the
tunnel to the atmosphere and eliminate the pump in the initial operation
of the tunnel. This raises the operating pressure in the test section at
Mach 2 from approximately 150 torr to 290 torr (using a 3 atm reservoir
pressure), causing a reduction in fluorescent signal level by a factor of
about two. However, there should be ample fluorescence at this
pressure level to permit quantitative measurements without using a large
pump or fan to lower the back pressure.
A sketch of the charcoal filter which has been designed for
removal of the iodine from the air stream is shown in Figure 4. The
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filter is made of a 55-gallon steel drum, with sealed lid, attached to the
tunnel exhaust line and containing 130 pounds of Nuchar WV-H granular
activated charcoal. A dead air space is provided above and below the
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charcoal to force better utilization of the entire charcoal volume. A
PVC plastic liner prevents direct contact of the drum with iodine. The
design removes more than 99% of the iodine from the flow, allows
200-800 wind tunnel runs before the charcoal becomes saturated with
iodine (at 5-20% pore loading by weight) and provides an internal filter
velocity of 40 ft/min., in the desired range of 10-100 ft/min. for an
optimized filter with minimum pressure drop. The charcoal can easily
be replaced when it becomes saturated with iodine and will be disposed
of by the Environmental Health and Safety Department at U.Va. All
components for the filter have been received and are ready for
assembly.
Preliminary designs for the iodine mixing chamber and the tunnel
test section was completed in the Fall of 1983. The mixing chamber will
consist of a large tank (approximately one-half cubic meter in volume)
with interior manifolds to produce turbulent mixing over layers of iodine
crystals. Access ports in one end of the chamber allow easy access for
removal and replacement of the iodine crystals. The chamber will be
located under the raised wooden floor below the optical table, as shown
in Figure 5. The wind tunnel test section shown schematically in this
figure will consist of a Laval nozzle producing Mach 2 flow for the
scramjet combustor model, followed by a second throat and diffuser
section. Extensive effort has gone into the design of both the mixing
chamber and the test section in this reporting period but since the final
designs were not complete as of January 1, 1984 these will be included
in the next semi-annual progress report.
11
4. OPTICAL SETUP
As shown in the photograph of Figure 2 a Newport Research
Corporation 5'x8' optical table was installed on the cement-block sup-
porting pillars. This provides an ultra-stable platform for lasers and
optical mounts.
The main piece of permanent equipment in the research budget was
a Spectra-Physics Model 380A Scanning Single Frequency Ring Dye Laser.
A demonstration-model laser (with full warranty) plus Spectra-Physics
Model 404 laser power meter were purchased for a package price of
$32,855 and have been delivered. Miscellaneous optical components (for
example, an optical spectrum analyzer provided by the Office of the
Dean) have been purchased and added to the optical system. A Lexel
Model 95 argon laser, loaned to the research project by another research
group in the Department of Mechanical and Aerospace Engineering (as
mentioned in the original research proposal) was set up on the optical
table to pump the ring dye laser. However, the output power of this
argon laser proved to be inadequate to pump the dye laser significantly
above its threshold level. It is, therefore, not adequate for the
laser-induced fluorescence measurements with iodine. A larger argon
laser with an output of at least 5 watts (all-lines) is needed and was
searched for in labs known to the principal investigator around the
country. The installation of the dye laser and subsequent completion of
the required optical system depends upon and awaits the arrival of a
suitable argon pump laser. The acquisition of a large argon pump laser
is a priority item in the second six-month period of the research program.
12
5. STATIC-IODINE-CELL MEASUREMENTS
Measurements are needed in a static cell for the iodine transitions
selected for excitation by the tunable dye laser in the scramjet
combustor flowfield. These measurements were not initiated in the first
semi-annual reporting period since the dye laser installation awaited a
suitable argon pump laser. As soon as the lasers are operational these
measurements will be completed before the first quantitative flowfield
measurements are attempted.
13
6. PERSONNEL
Two Master-of-Science degree candidates have been involved in
this research. Miss Linda Nicholson started on July 1, 1983 and
worked full-time during the summer months under salary from the NASA
grant. She continued her involvement through the Fall by enrolling in
a 3-unit thesis research course while fully supported by a department
fellowship. Her master's thesis will focus on quantitative pressure and
velocity measurement using laser-induced iodine fluorescence.
A second student, Mr. John Graves, joined the project in
September 1983. He also enrolled in a 3-unit thesis research course
while being employed as a graduate teaching assistant in the
department. His master's thesis topic is flowfield visualization in the
model scramjet combustor using laser-induced iodine fluorescence.
Extensive use has been made of laboratory technicians during the
initial stages of setting up the new laboratory. Mr. Curtis Wood, chief
laboratory technician, was employed essentially full-time during the
summer and part-time during the Fall. His time and that of the other
technicians utilized was provided by the department without charge to
the research contract.
7. PUBLICATIONS
A paper entitled "Nonmtrusive Pressure Measurement with Laser-
Induced Iodine Fluorescence" has been written by the principal
investigator and accepted for publication in the Thermophysics Volume
of the AIAA Progress Series by the volume editor. This paper was
motivated by a desire to measure pressure in the scramjet combustor
and discusses how this can be done using laser-induced fluorescence
from iodine. The support of NASA Grant NAG-1-373 is acknowledged in
this paper.
15
8. CONCLUSIONS
The initial six-month phase of the work has concentrated on reno-
vation of the laboratory, preliminary designs for modifications to the
wind tunnel facility, and preliminary assembly of the optical compo-
nents. No initial static iodine cell measurements were accomplished, as
originally planned within the first 6 months. Unanticipated delays were
encountered due to the asbestos ceiling problem and the low output
power of the available argon laser.
During the second half of the first year of the research program
the optical setup will be completed, the new tunnel design and assembly
will be completed and tunnel running conditions will be verified.
Measurements will be made in a static iodine cell to verify the
fluorescence behavior for the iodine transitions to be utilized in the
flowfield. Preliminary flowfield visualizations will be acquired to
characterize to overall behavior of the scramjet combustor flowfield over
a range of step heights and transverse sonic jet configurations.
16
DISTRIBUTION LIST
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Space Administration
Langley Research Center
Hampton, VA 23665
Attention: Dr. G. Burton Northam
HSAD, Mail Stop 168
4 - 5 * NASA Scientific and Technical
Information Facility
P.O. Box 8757
Baltimore/Washington International Airport
Baltimore, MD 21240
6-7 J. C. McDamel, Jr .
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Sci./Tech. Information Center
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UNIVERSITY OF VIRGINIA
School of Engineering and Applied Science
The University of Virginia's School of Engineering and Applied Science has an undergraduate
enrollment of approximately 1,500 students with a graduate enrollment of approximately 500 There are
125 faculty members, a majority of whom conduct research in addition to teaching
Research is a vital part of the educational program and interests parallel academic specialties These
range from the classical engineering disciplines of Chemical, Civil, Electrical, and Mechanical and
Aerospace to newer, more specialized fields of Biomedical Engineering, Systems Engineering, Materials
Science, Nuclear Engineering and Engineering Physics, Applied Mathematics and Computer Science
Within these disciplines there are well equipped laboratories for conducting highly specialized research
All departments offer the doctorate; Biomedical and Materials Science grant only graduate degrees In
addition, courses in the humanities are offered within the School
The University of Virginia (which includes approximately 1,500 full-time faculty and a total full-time
student enrollment of about 16,000), also offers professional degrees under the schools of Architecture,
Law, Medicine, Nursing, Commerce, Business Administration, and Education In addition, the College of
Arts and Sciences houses departments of Mathematics, Physics, Chemistry and others relevant to the
engineering research program The School of Engineering and Applied Science is an integral part of this
University community which provides opportunities for interdisciplinary work in pursuit of the basic goals
of education, research, and public service


Flowfield measurements in a model scramjet combustion using laser-induced iodine fluorescence

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