Numerical study of CFD simulations for compact counter-recoil design of EOD water cannon
Explosive Ordnance Disposal (EOD) robots armed with a water cannon are deployed to disarm the improvised explosive devices. It is critical that the water cannon produces as little recoil force as possible when fired. Otherwise, the robot may be rendered immobile or damaged. In a previous work, a recoilless water cannon was designed through a specific combination of firing experiments and Computational Fluid Dynamics (CFD) simulations. The final design was conceived, prototyped and tested with real bullets. The testing results were found to be satisfactory. In this work, the CFD simulations of the final design was carried out and closely investigated. Numerical study and error analysis were performed in an attempt to find the most suitable and efficient CFD setups for this problem. Two different CFD programs, three different flow domains, and various mesh resolutions were tested.
Dynamic Analysis of Shoulder-Fired Weapons
Abstract : A recoil analysis to assess several recoil mitigating technologies applied to shoulder-fired weapons such as a grenade launcher or shotgun has been conducted. Parameters such as weapon weight, recoil impulse, recoil velocity and recoil energy were identified as critical. A range of values were selected for evaluation. In order to monitor and assess the dynamics occurring during its cyclic motion, a mathematical model for a 12 Gauge weapon has been developed. The model defines each major component and the relative connectivity between them is defined in terms of kinematic joints. A Lagrangian methodology is utilized to formulate the rigid body dynamic equations of motion. Three commercial recoil reducing devices were evaluated in the model to determine their specific effect on recoil motion, both on the weapon and on the soldier firing the weapon. A full test program was conducted at the Armaments Research Laboratory (ARL) on a modified 12 Gauge shotgun to measure recoil control for each of the recoil devices. An additional model was formulated for this fixture. Comparisons between model and experimental test results were made. Further tests and evaluation include combinations of recoil devices. Documentation of sample model output is included.
The first ground cricket (Orthoptera: Trigonidiidae: Nemobiinae) from mid-Cretaceous Burmese amber
Abstract A new genus and species, Birmaninemobius hirsutus gen. et sp. nov., is described on the basis of a well-preserved orthopteran specimen in mid-Cretaceous Burmese amber and attributed to the subfamily Nemobiinae (ground crickets) of the family Trigonidiidae (Grylloidea). As the first record of Nemobiinae from mid-Cretaceous Burmese amber, this new taxon not only provides novel morphological diversity in ground crickets but also indicates that the ground crickets lived in Burma (Tethyan islands) as early as the mid-Cretaceous.