APPROXIMATE EVALUATION OF PRESSURE FIELDS IN LIQUID WITH GAS CAVITIES
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Abstract
The issues of protection of underwater objects using cylindrical air cavities are studied. In a number of tasks, it is fundamentally important to have not only the distribution of the pressure field in the liquid because of the movement of the boundaries of the deformable system, but also the parameters of the movement of the liquid itself. In this case, the parameters of the liquid movement have a significant effect on the fastening conditions of the gas cavities. The shock wave, spreading in water with gas inclusions, undergoes significant deformation. Preliminary experiments conducted to determine the parameters of underwater shock wave in water with air cavities have shown the possibility of controlling pressure peaks and, therefore, creating conditions for the safety of the underwater structure. Analyzing theoretical studies, it can be seen, that a dispersion of the wave process occurs inside the liquid region with gas cavities. The initial pressure peak decreases dramatically. In the area of the protected object, it decreases by almost two orders of magnitude compared to the maximum pressure in the initial shock wave. The pressure is mainly determined by the pulsation of the gas cavities generated by the explosive air wave. The duration of the load in the presence of gas cavities increases sharply.
Subject. Determination of explosion loads in water with gas cavities. The organization of the protection of the object according to the specific parameters of the object itself and the estimated power of sabotage explosions.
Materials and methods. In order to predict the loads on an underwater object in water with gas inclusions, a mathematical model of deformation of a shock wave passing through a system of gas cavities has been developed.
Results. Under the influence of a cylindrical air cavity, the pressure in the shock wave front decreases by about 3.5 times. At the same time, the wave front stretches somewhat. The pure shock wave of an underwater explosion does not pass through the gas cavity. The main parameter determining the unsteady pressure field at the depth of the protected object is the total pressure pulse, and not the pressure itself rapidly changing over time in the incident wave.
Conclusions. One of the approximations of the equations of hydrodynamics is proposed, which makes it possible to predict the qualitative patterns of processes in a liquid using simple models in the presence of a system of gas cavities approximated by cylinders. A method of physical modeling of the processes of interaction of an underwater shock wave with a protected object is proposed.
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References
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