- The purpose of this study is to investigate strand and erosive burning characteristics of NOSOL-363 stick propellants. Strand burning rates were measured for deducing burning-rate exponents at two different pressure ranges. Fine-wire thermocouples were used to determine thermal wave structures of the propellants. Important thermal and chemical information on NOSOL-363 stick propellants was deduced from temperature-time traces. A unique real-time X-ray radiography system and a digital image processing system were set up to record instantaneous internal burning surface locations and to deduce instantaneous erosive-burning rates of center-perforated propellant samples. A comprehensive theoretical model with special emphasis on the interaction of turbulence and combustion was formulated to simulate erosive-burning processes occurring inside the center perforation of the propellant. The combustion processes of stick propellants are described by a quasi-steady, axisymmetric, chemically reacting turbulent pipe flow. A two-variable joint probability density function (pdf) is adopted in the theoretical model to take into account the interaction of turbulence and combustion. The theoretical model comprised of a set of partial differential equations was solved numerically. From strand burning tests, three modes (fizz burning, unsteady flame and steady flame) of gas-phase combustion were observed. Two different burning-rate exponents were deduced from strand burning rate data. The activation energies are 8.13 kcal/mole in fizz burning and unsteady flame modes and 14.80 kcal/mole in flame burning modes. From erosive burning tests, real-time X-ray radiography system proved to be a nonintrusive powerful and reliable tool for determining erosive-burning rates under confinement conditions. Based upon the recorded X-ray images, the instantaneous burning rates of NOSOL-363 stick propellants were determined under test motor operating conditions. Results show the strong influence of crossflow velocity on propellant burning rates. From the numerical solution of the theoretical model, it is shown that the erosive-burning phenomenon is caused by enhanced heat feedback from the gas phase to solid propellant resulting from the combined effect of increased turbulent mixing and reduction in flame stand-off distance from the burning surface.
- Dissertation Note:
- Ph.D. The Pennsylvania State University 1987.
- Source: Dissertation Abstracts International, Volume: 48-10, Section: B, page: 3083.
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