• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.10
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• pp.1566-1573
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• 2004

When a projectile travels at high speed underwater, supercavitating flow arises, in which a huge cavity is generated behind the projectile so that only the nose, i.e., the cavitator, of the projectile is wetted, while the rest of it should be surrounded by the cavity. In that case, the projectile can achieve very high speed due to the reduced drag. Furthermore if the nose of the body is shaped properly, the attendant pressure drag can be maintained at a very low value, so that the overall drag is also reduced dramatically. In this study, shape optimization technique is employed to determine the optimum cavitator shape for minimum drag, given certain operating conditions. Shape optimization technique is also used to solve the potential flow problem fur any given cavitator, which is a free boundary value problem having the cavity shape as unknown a priori. Analytical sensitivities are derived for various shape parameters in order to implement a gradient-based optimization algorithm. Simultaneous optimization technique is proposed for efficient cavitator shape optimization, in which the cavity and cavitator shape are determined in a single optimization routine.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.82-85
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• 2008

When a projectile travels at high speed underwater, supercavitating flowarises, in which a huge cavity is generated behind the projectile so that only the nose, i.e., the cavitator, of the projectile is wetted, while the rest of it should be surrounded by the cavity. In that case, the projectile can achieve very high speed due to the reduced drag. Furthermore if the nose of the body is shaped properly, the attendant pressure drag can be maintained at a very low value, so that the overall drag is also reduced dramatically. In this study, shape optimization technique is employed to determine the optimum cavitator shape for minimum drag, given certain operating conditions. Simultaneous optimization technique is proposed for efficient cavitator shape optimization, in which the cavity and cavitator shape are determined in a single optimization routine.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1876-1881
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• 2003

When a projectile travels at high speed underwater, supercavitating flow arises, in which a huge cavity is generated behind the projectile so that only the nose, i.e., the cavitator, of the projectile is wetted, while the rest of it should be surrounded by the cavity. In that case, the projectile can achieve very high speed due to the reduced drag. Furthermore if the nose of the body is shaped properly, the attendant pressure drag can be maintained at a very low value, so that the overall drag is also reduced dramatically. In this study, shape optimization technique is employed to determine the optimum cavitator shape for minimum drag, given certain operating conditions. Shape optimization technique is also used to solve the potential flow problem for any given cavitator, which is a free boundary value problem having the cavity shape as unknown a priori. Analytical sensitivities are derived for various shape parameters in order to implement a gradient-based optimization algorithm. Simultaneous optimization technique is proposed for efficient cavitator shape optimization, in which the cavity and cavitator shape are determined in a single optimization routine.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.479-490
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• 2020

The hydrodynamic characteristic of transonic motion projectiles with different head diameters are investigated by numerical simulation. Compressibility effect in liquid-phase water are modeled using the Tait state equation. The result shows that with increasing of velocity the compression waves transfer to shock waves, which cause the significant increasing of pressure and decreasing the dimensions of supercavities. While the increasing of head diameter, the thickness, the vapor volume fraction and the drag coefficient of supercavities are all enhanced, which is conducive to the stability of transonic-speed projectiles. The cavity dynamics of the different head projectiles are compared, and the results shows when Mach number is in high region, the truncated cone head projectile is enveloped by a cavity which results in less drag and better stability.