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.
Compact counter-recoil design of water cannon using a single nozzle with backward spray
A novel design of water cannons using off-the-shelf bullet and barrel was conceptualized, analyzed, prototyped and field-tested. The cannon was designed to be mounted on a remotely controlled carrier robot and its main propose was to utilize water impact to defuse explosives usually placed in metal or wooden containers. In the previous design, the firing created a large recoil force, which was likely to damage and/or immobilize the robot. In the new design presented here, the primary objective was to significantly reduce the recoil force by using backward spray near the muzzle, which allowed the cannon to maintain its destructive power without increasing the robot's payload. In this paper, the design process using a combination of Computational Fluid Dynamics simulations and experiments were presented. The combination was nontrivial but essential due to the limited prior knowledge of the employed bullet (for simulations) as well as firing safety regulation and high prototyping cost (for experiments). The final prototype of the cannon was field-tested and shown to be capable of reducing the recoil force to such an extent that the robot was visibly stationary.
DESIGN OF A WATER CANNON FOR ROCK TUNNELING EXPERIMENTS
A detailed design is presented for manufacturing a high pressure pulsed water cannon for rock-breaking experiments in a tunnel or quarry at jet pressures up to 1,000,000 psi. The test system includes a trailer for carrying the water cannon, and a separate dolly for the power system and controls. The water cannon incorporates components of a Terrapak hydro-pneumatic actuator and is designed to fire one pulse every 5 minutes, but can be modified to fire 20 pulses per minute with a pulse energy of 93,500 ft. lbs. This report covers the system analysis, design studies and detailed design of the water cannon system and discusses fabrication, operation and test procedures. (Author)