Experiments on shock wave structure were conducted in the 12 inch shock tube facility, and it is shown that this work was motivated by the need for improved kinetics for the modeling of NO production in space shuttle flow fields. The experiments on shock structure involved simultaneous observations of pressure and temperature on the wall of the shock tube during reflection of normal shock waves in inert gases

Hanson, R. K.

Kruger, C. H.

English

NASA Technical Reports Server

FINAL TECHNICAL REPORT
on
KINETICS OF NITRIC OXIDE FORMATION AND DECOMPOSITION
NASA Grant NGR-05-020-583
covering the period
December 1, 1971 - November 30, 1974
Submitted to the
National Aeronautics and Space Administration
Washington, D.C.
(NASA-CR-141272) KINETICS OF NITRIC OXIDE N75-14848
FOMATION AND DECOMPOSITION Final Technical
Report, 1 Dec. 1971. - 30 Nov. 1974 (Stanford
Univ.) 9 p HC $3.25 CSCL 07B Unclas
G3/25 06555
by
Co-Principal Investigators:
Professor C. H. Kruger
Dr. R. K. Hanson 0 .
Department of Mechanical Engineering
Stanford University
Stanford, California 94305
NASA Technical Officer: Dr. Chul Park
NASA-Ames
Moffett Field, California
https://ntrs.nasa.gov/search.jsp?R=19750006776 2020-03-23T01:37:59+00:00Z
1. Summary
This grant was initiated by the Physics Branch at NASA Ames on December 1,
1971, and has been supported since December 1, 1972, by the Physical Gas
Dynamics and Lasers Branch, also at Ames. Originally there were two research
topics:
a. Nonequilibrium Shock-Wave Structure
b. Kinetics of Nitric Oxide Formation and Decomposition
Work on the first topic, nonequilibrium shock-wave structure, continued for only
one year and resulted in two publications, but was not considered of sufficient
interest to NASA to merit further support.
During the last two years of the grant, our research has centered entirely
on the second topic dealing with'the kinetics of nitric oxide. This work was
motivated by the need for improved kinetics data for use in modeling NO produc-
tion in the space shuttle flow field. Our activities included assembly of a
shock tube facility, development of suitable diagnostics, and finally a series
of experiments to measure appropriate rate constants. Most of this work has
been completed and reported in the open literature. One project on NO formation
kinetics is still in progress and will be completed later.
2. Publications
During the 3-year period of this grant, the following papers have been
presented or published:
1. R. K. Hanson, "Experimental Study of Shock-Wave Reflection from a
Thermally Accommodating Wall", Physics of Fluids, 16, 369 (March 1973).
2. G. S. Deiwert and R. K. Hanson, "The Reflection of a Thick Planar
Shock Wave from a Coplanar Surface", Proceedings of the Eighth Inter-
national Symposium on Rarified Gas Dynamics, K. Karamcheti, editor
(Academic Press, 1973).
-1-
3. R. K. Hanson, "The Dissociation of Shock-Heated Carbon Monoxide",
Recent Developments in Shock Tube Research, D. Bershader and W. Griffith,
editors (Stanford University Press, 1973), p. 365.
4. R. K. Hanson and W. Flower, "Verification of a Simple Relationship
for Shock-Wave Reflection in a Relaxing Gas", AIAA Journal, 11, 1.777
(December 1973).
5. R. K. Hanson, "Shock Tube Study of Carbon Monoxide Dissociation Kinetics",
Journal of Chemical Physics, 60, 4970 (June 1974).
6. R. K. Hanson, W. L. Flower and C. H. Kruger, "Determination of the Rate
Constant for the Reaction 0 + NO - N + 02", Journal of Combustion
Science and Technology (December 1974).
7. W. L. Flower, R. K. Hanson and C. H. Kruger, "Investigation of Nitric
Oxide Decomposition in the Temperature Range 2500-41000 K, paper presented
at the Spring 1974 Meeting of the Western States Section of the Combustion
Institute, Pullman, Wash., May 6-7, 1974.
8. W. L. Flower, R. K. Hanson and C. H. Kruger, "Kinetics of the Reaction
of Nitric Oxide with Hydrogen", Fifteenth Symposium (International) on
Combustion, (The Combustion Institute, 1974).
9. R. K. Hanson, W. L. Flower, J. P. Monat and C. H. Kruger, "Decomposition
of NO Studied by Infrared Emission and CO Laser Absorption",
submitted for presentation at the Tenth International Shock Tube
Symposium, Tokyo, August 1975.
-2-
3. Discussion of Work Completed or in Progress
In this section we present a summarized account of all research 
conducted
under support of this grant.
During the first year of the grant, while the Physics Branch 
was still
functioning, work was conducted both at Stanford and at Ames. 
Experiments on
shock-wave structure were conducted at Ames, in the 12-inch shock-tube 
facility,
while research on NO kinetics was performed at Stanford University.
The experiments on shock structure involved simultaneous observations 
of
pressure and temperature on the end wall of the 
shock tube during reflection of
normal shock waves in inert gases. The data were compared 
with Monte Carlo
calculations of the reflection process to infer parameters both for the 
gas-
surface collision model and for the intermolecular potential used 
to specify
collisions in the gas phase. These data made an essential 
contribution to the
verification of Monte Carlo computational techniques under 
development at Ames.
After completing the study of shock reflection, using monatomic gases 
(see
publications 1 and 2 in Section 2), we proposed a study 
of shock structure in
diatomic gases where inelastic collision processes, particularly involving
rotational excitation, would play a major role. Again the objective 
was to
compare experimental data with Monte Carlo calculations. 
Several months were
spent in formulating an experimental technique capable 
of providing time histories
of population density in particular rotational quantum 
states through the shock,
an experiment not previously attempted. Our proposal involved 
use of a tunable
infrared laser. Unfortunately, at about this time the Physics 
Branch was dis-
banded and it was necessary to terminate this promising project.
Fortunately, our work on NO kinetics was of more general 
interest to workers
at Ames and received continued support from the Physical Gas 
Dynamics and Lasers
Branch after support from the Physics Branch was lost. During the first year
-3-
of this grant, we performed a literature survey of related past work and
began to plan experiments. There were major gaps in knowledge of NO kinetics
particularly at high temperatures where most NO formation and decomposition
occurs, and we set out to close these gaps with some careful experiments.
Following selection of shock-wave heating as the most useful method for testing,
we acquired a shock tube on loan from Ames and completed the necessary instal-
lation and modifications at Stanford by January, 1973.
An important aspect throughout our research has been the development of suit-
able diagnostic techniques: a laser-schieren system for monitoring post-shock
density gradients (pub. 4 in Sec. 2), an infrared emission system for monitoring
concentrations of NO and N20 (pub. 6), and most recently, a tunable CO
laser for resonance absorption measurements of NO (pub. 9).
Utilizing particularly the IR emission system, we studied, in the second
year of the grant, the kinetics of NO decomposition in an extensive series
of tests. Although many reactions occur during decomposition of NO, the rate-
limiting step is often
0 + NO + N + 02, (1)
the well-known Zel'dovich reaction. We determined the rate constant.for this
reaction over the temperature range 2500-4100 0K by shock heating mixtures of
NO, N20 and Ar (or Kr) and comparing observed the predicted NO concentra-
tions behind the shock. The purpose of the added N20 was to serve as a source
of 0 atoms for reaction (1), the atoms being produced by the rapid reaction
N20 + M - N2 + 0 + M (2)
Our results for the rate constants of reactions (1) and (2) were presented in
publications (6) and (7) of section 2.
After completing our work on NO decomposition kinetics, and before turning
to a study of NO formation kinetics, we asked for and obtained approval to
-4- REPRODUCILITY Op HEORIGINAL PAGE IS POOR
renew a study of CO kinetics,which had been initiated under NASA support
during 1968-1970. A principal motivation for returning to this project was the
recognition of the similarity between the reaction mechanisms important 
in NO
and CO decomposition; our experience with NO kinetics having provided
important new insight into our earlier CO data. The project on CO kinetics
was completed within 6 months by September, 1973, and was reported in publi-
cations (3) and (5).
This last year of the grant, under reducing funding, we've concentrated on
development of tunable laser spectroscopy as a technique for studying NO
formation kinetics. Finally, within the last few months we've completed 
construc-
tion and checkout of a CO laser and successfully identified several spectral
coincidences between CO and NO suitable for shock-tube absorption 
measure-
ments. This work is still in progress, and will be continued without NASA
support. We report here our most recent results with the laser.
The governing equation for absorption of radiation is Beer's Law
I = I o exp(-B nNO L)
where I and I are the incident and transmitted radiation fluxes, nNO is the
3
number density of NO (cm-), L is the path length through the absorbing
gas (15 cm in our shock tube) and is the absorption coefficient 
or cross-
section (cm2). The absorption coefficient is related to the line strength S
and the line-shape function 4 through the relation
where jfdv = 1.
Our measurements of B for a range of temperatures are shown in Fig. 1, all
for V = 1935.5 cm- , produced by V = 7+6, J = 12+13 laser line of CO. Note
that all the results are for a static pressure of about 0.4 atm. The data
were obtained by shock heating known mixtures of NO and Ar (or Kr) and
-5-
recording the fractional absorption. For purposes of an approximate calculation,
- 1 9  3
S 1019m nNO = XNOn - XNO 1018/cm3 , where XNO is the mole fraction of
NO, and L = 15cm; therefore
B nNo L = 1.5 XNO*
Thus a 1% concentration of NO gives 1.5% absorption and so on. The method
of CO laser absorption is therefore sufficiently sensitive to measure NO
concentrations below 1%, since absorptions of 1% are straightforward to measure
and absorptions of 0.1% are within reason.
As a final check of our laser absorption method, before undertaking a study
of NO formation, we've made comparative measurements of NO concentrations
using both laser absorption and IR emission. For simplicity, these measure-
ments were made behind strong shocks in NO-Kr mixtures, where NO decomposition
is the dominant process. The experimental setup is shown schematically in Fig. 2;
good agreement is obtained between both measurement techniques and kinetic
calculations, thereby validating, we feel, the new laser absorption technique.
Some of this work will be reported at the forthcoming International Shock Tube
Symposium (see pub. 9).
Our next objective will be to apply the technique of laser absorption to a
study of NO formation kinetics. Sample calculations have been made and the
work is now underway. Although our grant has expired, we plan to complete
this work with partial support from the National Science Foundation.
-6-
3x10 20  3xlO-1 9
0 5o
o U
000 0
2 0 0
©,
0 0
300 1000 2000 3000 4000
T,oK
Fig. 1 Calculated line strength S and measured absorption coefficient 8 in NO
for the ground state 2113/2, R(J=18.5) at v-=1935.5 cm-1. The post-shock
pressure is about 0:4 atmospheres in all cases.
i 
BaF
2
S Window
Filter
Tunable
CO Laser
InSb Detector
Fig. 2. Experimental Setup
CO laser absorption data
IR emission data
Kinetic calculation
.8
.6
z .4
T = 40000K '
P = 0.5 atm O
.2- O
'O - -
0 20 40 60 80LAB TIME, PSEC
Fig. 3. Absorption and emission data and kinetic calculations 
of
[NO]/ [NO]max. Shock conditions: P1=6.94 Torr
(N20/NO/Kr 2.2/9.8/88), V = 1.53 mm/psec.
-8-


Kinetics of nitric oxide formation and decomposition

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