There has been a realisation for many years that advanced charge designs, comprised of low vulnerability ammunition (LOVA) propellant, may present challenges for ignition. For this reason, research has been undertaken in the UK, sponsored by the MOD Research Acquisition Organisation - Defence Technology and Innovation Centre, to study the ignition phenomena of solid gun propellant. The aim of the work is to increase the underpinning understanding on ignition phenomena, and the validation and development of ignition and flamespread submodels to result in a substantial improvement in the prediction of ignition delays and initial charge temperature effects. Experimental work has involved the study of ignition delay as a function of black powder mass (igniter energy) for double base and cellulose acetate butyrate based LOVA gun propellant compositions. Closed and vented vessel firings, using a piccolo tube ignition system and conducted at 40 mm, established relationships between ignition delay and igniter energy for the gun propellants. Comparisons of the pressure-time profiles with those obtained using inert propellant showed higher than expected pressures before ignition had occurred. It was hypothesised that the higher pressures were caused by hot jets of BP combustion products ablating the gun propellants. A similar, scaled-up piccolo tube ignition system has been used to investigate the ablation and ignition of these gun propellants at 155 mm calibre using both open-ended and closed-ended piccolo designs. This paper describes the results from these investigations.
展开▼
