Study of the relevant geometric parameters of the channel leak method for blast overpressure attenuation for a large caliber cannon

This study examines the effect of relevant geometric parameters on blast overpressure attenuation and projectile exit velocity loss due to the channel leak method on a muzzle-loaded large caliber cannon. There are four basic geometric parameters which can be varied independently. These include the number of channels, channel length, channel height and channel width. From these basic parameters, three relevant parameters are selected which are expected to be most influential. These three relevant parameters include total leak volume, channel length, and total aspect ratio. Reduction in blast overpressure, and thus peak overpressure, is most affected by the leak volume, however, leak volume needs to be selected carefully to limit the loss in the projectile exit velocity. On the other hand, use of shorter channels is found to be detrimental for peak overpressure attenuation while a lower total aspect ratio has a positive effect. The best configuration, CLM-A1, shows over 50% reduction in peak overpressure at all monitored locations with about 4.8% loss in the projectile exit velocity which translates to the largest average Figure of Merit of 0.534. Shock structure and strength are also examined for the three best leak configurations, CLM-A1, CLM-E1 and CLM-E2, as well as the baseline configuration.