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Closed-Bomb Combustion of Hivelite-Based, Very High Burn Rate (VHBR) Propellant

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An experimental investigation of the combustion characteristics of a Hivelite-based, very-high-burn-rate VHBR propellant was conducted. The experiments were performed in a closed chamber, called the VHBR bomb, that was specially designed and constructed for these experiments. The device was designed with the same diameter as the propellant samples in order to maintain one dimensional combustion processes and transient wave phenomena to simplify subsequent interpretation and analysis. Propellant combustion was characterized by a low burn rate about 1 ms until a pressure in the vicinity of 15-20 MPa is reached. After this pressure, which may represent the propellant crushing or break pressure, the combustion rate accelerated to levels from 10 to 180 ms, depending on other test parameters. Tests conducted at different loading densities indicated that combustion rate was a strong function of pressure. Variation of sample weight at constant loading density demonstrated that increasing the amount of unburned propellant at the time the break pressure was reached also causes burn rate and thrust to increase. A coating that makes the outside surface of the sample slippery tended to reduce the apparent burn rate but use of a coating which retarded transmission of gas pressure along the periphery of the sample increased the apparent burn rate as well as thrust. Change of mounting interface properties caused significant differences in the dynamic characteristics leading to increased thrust.

Subject Categories:

  • Ammunition and Explosives
  • Combustion and Ignition

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