Numerical study on the transient behavior of water-entry supercavitating flow around a cylindrical projectile influenced by turbulent drag-reducing additives

Simulation of the unsteady behavior of water-entry supercavitating flows influenced by turbulent drag reducing additives is very complicated. This paper attempts to introduce a numerical simulation procedure to simulate such problems in viscous incompressible two-phase and three-phase media, respectively. Firstly we performed a numerical investigation on water-entry supercavities in water and turbulent drag-reducing solution, respectively, at an impact velocity of 28.4 m/s to confirm the accuracy of the numerical method. Based on the verification, projectile entering water and turbulent drag-reducing solution at relatively high velocity of 142.7 m/s (phase transition is considered) is simulated. The Cross viscosity equation was adopted to represent the shear-thinning characteristic of aqueous solution of drag-reducing additives. The configuration and dynamic characteristics of water-entry supercavity, flow resistance and the radial velocity of cavity boundary were discussed respectively. It was obtained that the numerical simulation results are in consistence with experimental data, verifying the established numerical procedures. Numerical results show that the supercavity length in drag-reducing solution is larger than that in water; the velocity attenuates faster at high impact velocity than at low impact velocity. Turbulent drag-reducing additives have the potential in enhancement of supercavitation and further drag reduction. (C) 2016 Elsevier Ltd. All rights reserved.