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.
The mechanics of the impulsive water cannon
Abstract A model is proposed to describe the operating characteristics of the impulsive water cannon. The important parameters governing the system dynamics are identified and the influence of these on performance is studied with the aid of a unique ‘ 1 1 2 D ’ finite-difference code. The algorithm upon which this code is based is described as are its principle features. The results of the calculations are compared with recently developed incompressible theory and with experiment.
STRESS WAVE EFFECTS IN INHOMOGENEOUS AND POROUS EARTH MATERIALS
Abstract : The studies described in this report are directed to the construction of reliable techniques for calculating stress wave propagation in a geologic medium in the pressure range from 300 kbar down to a few bars. The medium is considered to be a composite consisting of rock matrix with water in its pores and a description of its wave propagation characteristics is sought in terms of the behavior of the isolated rock and water components. Nevada tuff is selected for the rock matrix in order to be specific in formulating its equation of state from available experimental data. The equation of state for water is constructed in convenient analytic forms for the expanded and condensed states as well as the transition through the steam dome. The shock pressure of saturated wet tuff media with varied mass fractions of water is treated under three assumptions related to the homogeneity of the media: (1) complete homogenization--equation of state for wet tuff is calculated under the assumption that the water and tuff components are in local pressure and thermal equilibrium; (2) no homogenization- -detailed wave propagation calculations for composite water/tuff configurations of varied substructure; and (3) theory of interacting continua.