Laminar burn rates of gun propellants measured in the high-pressure strand burner Page: 3 of 10
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LAMINAR BURN RATES OF GUN PROPELLANTS MEASURED IN THE HIGH-PRESSURE STRAND
BURNER'
J. E. Reaugh, J. L. Maienschein, and J. B. Chandler
Lawrence Livermore National Laboratory,
Livermore, CA
ABSTRACT
The pressure dependence of the laminar burn rate of gun propellants plays a role in the design
and behavior of high-performance guns. We have begun a program to investigate the effects of
processing variables on the laminar bum rates, using our high-pressure strand burner to measure these
rates at pressures exceeding 700 MPa. We have burned JA2 and M43 propellant samples, provided by Dr.
Arpad Juhasz, ARL, from propellant lots previously used in round-robin tests. Our results at room
temperature are in accord with other measurements. In addition, we present results measured for
propellant that has been preheated to 50 0C before burning.
We used our thermochemical equilibrium code, CHEETAH,1 to help interpret the simultaneous
pressure and temperature measurements taken during the testing, and show examples of its use. It has
been modified to provide performance measures and equations of state for the products that are
familiar to the gun-propellant community users of BLAKE.2
INTRODUCTION
Design of the interior ballistics cycle for advanced, high-performance guns relies on accurate
knowledge of the laminar bum rate throughout the entire pressure range. To first order, the burn rate is
correlated with the flame temperature, which, in turn, depends on the chemical formulation. It is well-
known that the energetic material particle size has significant effects on that burn rate. Other effects,
for example the dependence of the burn rate on the time of mixing, which alters the intimacy of mixing,
are not so well understood. A step in achieving such understanding is the detailed measurement of the
burning rate and correlation with quantified processing and particle size variations. The LLNL high-
pressure strand burner permits accurate burning rate measurements over a pressure range that exceeds
normal operating pressures for guns. We present the first phase of work in this program.
EXPERIMENTAL METHOD
APPARATUS
The LLNL high pressure strand burner, described in detail at this conference,3 combines the
features of a traditional closed-bomb burner with those of a traditional strand burner. The LLNL high-
pressure strand burner confines a burning sample in a small volume, high-pressure chamber. We measure
pressure as it changes during the run, and the bum front time-of-arrival to get the laminar bum rate
over a range of pressure in one experiment. In a standard closed-bomb burner, only the pressure in the
combustion chamber is measured, so that calculating the bum rate requires accurate knowledge of the
equation of state of the product gases and accurate treatment of heat losses. The standard strand burner
provides direct measurement of the surface regression rate in a large volume at a constant, but
relatively low, pressure.
Our strand burner has a volume of about 75 cm3, and is designed to reach pressures of 1 GPa
(150,000 psi). The pressure vessel body is built from two concentric shells of high-strength steel with
Approved for public release, distribution is unlimited.
* This work performed under the auspices of the U. S. Department of Energy by the Lawrence Livermore
National Laboratory under contract number W-7405-Eng-48.
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Reaugh, J. E., LLNL. Laminar burn rates of gun propellants measured in the high-pressure strand burner, article, October 1, 1997; (https://digital.library.unt.edu/ark:/67531/metadc618712/m1/3/: accessed April 17, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.