Erosive and strand burning of stick propellants. I - Measurements ofburning rates and thermal-wave structures

Abstract

Burning-rate characteristics and thermal-wave structures of NOSOL-363 stick propellant under erosive-and strand-burning conditions were studied using a real-time x-ray radiography system, a strand burner setup, and fine-wire thermocouples. For the erosive-burning rate measurements, locations of instantaneous burning surfaces along the center perforation of a cylindrical propellant grain were determined by comparison of x-ray images obtained during a test and calibration images. The burning rates under strong crossflow conditions, deduced from the instantaneous burning-surface locations, were found to be much higher (up to 2.5 times) than the strand-burning rate of NOSOL-363 stick propellant. This study demonstrated that real-time x-ray radiography is a powerful and reliable tool for nonintrusive measurements of instantaneous burning rates in an optically opaque test chamber. From the strand-burning rate data and thermal-wave structures, a set of important thermochemical properties of NOSOL-363 stick propellant was deduced. Nomenclature= preexponential factor, m/s = normalized cross correlation = activation energy, J/mole = x-ray intensity arriving at the input screen of the image intensifier at an angle of 6, R/s = initial x-ray intensity = interaction length of x-ray and propellant, m = linear attenuation coefficient of photoelectric absorption, 1/m = total number of pixels = universal gas constant, J/mole-K = burning rate, m/s = strand burning rate, m/s = burning surface temperature, K = room temperature, K = intensity of x-ray at the nth pixel location of a calibration image, R/s = intensity of x-ray at the nth pixel location of an actual test-firing image, R/s a p = thermal diffusivity of a propellant, m 2 /s

Experimental Investigation on Combustion of High-Metal Magnesium-Based Hydroreactive Fuels

“…During the test, a small amount of ambient-temperature argon gas flowed continuously from the right end to the left end of the combustor. The argon gas flow was used to carry the combustion product gases far from the strand, so that the windows would remain clean for observing combustion phenomena and for recording the instantaneous location of the burning surface of the hydroreactive fuel strand [17]. The extinguished surfaces of the fuel samples were also examined in the SEM.…”

Development and characterization of high performance solid propellants containing nano-sized energetic ingredients

“…A Solid Propellant Strand Burner (SPSB) was utilized to determine the burning rates of the samples up to a pressure of 66 MPa [8]. A non-optical Ultra High Pressure Strand Burner (UHPSB) was used to measure the burning rates between 66-190 MPa.…”

Interior Perforation Flow Field Study of Partially Cut 7-Perforated Stick Propellants

“…Long stick propellant charges offers many advantages over conventional multi-perforation granular propellants in large caliber gun systems [1][2][3][4]. The flow resistance of stick propellant is lower than that of a random grain charge, thus flame spreading is faster and more reproducible.…”