International Journal of Innovative Research and Development

R. Vijayakumar , S. K. Rao , R. V. Shashank Shankar

Abstract

The near field flow and drag estimation on cylindrical bodies moving concentrically inside tubes in an incompressible medium always fascinated Naval Platform designers while designing large projectile launchers. This paper presents the flow field numerical simulation on the published experimental work by Naval Underwater System Center, Newport, using the commercially available CFD software FLUENT based on the Reynolds averaged Navier Stokes Equations and k-epsilon turbulence model. Axisymmetric model was used in the simulation without considering appendages such as fins, rudders and propeller. Numerical analysis of such complex confined flows involving relative motion of the bodies is a challenging task. Dynamic mesh was used to solve the relative movement problem of the projectile and tube using user define programme to update the mesh. The results presented include, the characteristics of flow field in the annulus gap, pressure distribution on the moving object and the relation between increased drag and the annulus gap. The simulation results can be employed as reference in designing of such projectiles.

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S. K. Rao , R. Vijayakumar

Abstract

The study of underwater explosions (UNDEX) on ship/submarines became of interest during World War II when torpedo explosions near a ship created more damage than a direct hit. Following the war, many full scale ship shock trials were conducted by various countries providing the empirical data that is widely employed. The biggest threat to any marine platform is due to underwater weapons and hence understanding the phenomenon is essential. The sequence of events involved in an UNDEX starting from the detonation, shock wave, bubble pulses and cavitation have been introduced and the dynamics of the process including governing laws have been enumerated in the paper. The associated aspects of loading and method of analyzing the fluid structure interaction have also been highlighted. The development of such numerical methods to analyze the explosion and its effect on the fluid-structure can lead to design of safer ships and submarines. Moreover, the numerical simulation will eliminate the need for conducting expensive shock tests and trials.

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