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Report and Suggestions: DARPA (Defense Advanced Research Projects Agency) Workshop on Advanced Cannon Propellant (ACP) Diagnostics

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The central techniques difficulty encountered in the Liquid Propellant Gun program has been the, yet unsolved, problems connected with non- reproducible combustion processes which led to essentially three distinct types of pressure-time histories during the combustion phase of the gun firings, as classified by TRW, namely alpha-type no delay in ignition, rapid pressure rise to about 150,000 psi with subsequent drop to a reasonable plateau of about 60, 000 to 80,000 psi Beta-type ignition delays of about 0.5-1 msec with sporadic pressure rises around 3,000 to 10,000 psi followed by a very rapid pressure rise to 60,000 to 120,000 psi and subsequent pressure drop and burn out Gamma-type typical misfire initiated by an ignition delay similar to that observed in the Beta-type pressure profiles but without any further pressure rise. These phenomena were studied with the aim to understand the combined chemical kinetics and fluid dynamics phenomena governing LPG operation during the start-up processes. These experiments involved visible high-speed observations - as far as they were possible under the circumstances of opaque layers being formed in the combustion chambers after ignition - besides heat flux, chamber pressure, igniter voltage and current, and projectile velocity measurements. Additional studies related to non-reproducible gun operation were initiated with emphasis on the sensitivity of NOS 365 propellants to ignition by pressure pulses when air bubbles were entrained in the liquid. AW

Subject Categories:

  • Ammunition and Explosives
  • Guns
  • Ballistics

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