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Determination of Supercavity Shape for Axisymmetric Cavitators at Different Non-Zero Attack Angles, Using Boundary Element Method

Published online by Cambridge University Press:  08 May 2012

R. Shafaghat ,
S. M. Hosseinalipour  and
A. Vahedgermi
R. Shafaghat*
Affiliation:
Department of Mechanical Engineering NIT, Iran
S. M. Hosseinalipour
Affiliation:
Department of Mechanical Engineering IUST, Iran
A. Vahedgermi
Affiliation:
Department of Mechanical Engineering IUST, Iran
*
*Corresponding author (rshafaghat@nit.ac.ir)
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Abstract

When fluid passes a cavitator in the supercavitating flow, a supercavity forms behind the cavitator. Variation of the cavitator attack angle can influence theshape of the formed supercavity behind the cavitator. Consequently, it will affect the stability of supercavity behind the supercavitating cavitator with after body. In this study, a direct boundary element method (DBEM) is being formulated and numerically solved for3D unbounded potential flowspassing supercavitating bodies of revolution at different attack angles. In the analysis of potential flows passing supercavitating bodies at non-zero attack angles, a cavity closure model must be employed in order to close the mathematical formulationand guarantee the solution uniqueness. In the present study, we employ modified Riabouchinsky closure model. Since the location of the cavity surface is unknown at prior, an iterative scheme is used and for the first stage, an arbitrary cavity surface is assumed. The flow field is then solved and by an iterative process, the location of the cavity surface is corrected. Upon convergence, the exact boundary conditions are satisfied on the body-cavity boundary. A powerful CFD codeis developed to solve the 3D supercavitating flows behind all types of axisymmetric cavitators (such as disk, cone, etc) at zero and non-zero attack angles. The predictions of the CFD code are compared with those generated by verified existing data. The predictions of the code for supercavitating cones and disks seem to be excellent. Using the obtained data from CFD code, we investigate the supercavity shapesand corresponding stability at different attack angles with a fixed cavitation number.

Keywords

Boundary element methodSupercavitating flowsCavitatorCavity closureCavitation number3DAttack angle
Type
Articles
Information
Journal of Mechanics , Volume 28 , Issue 2 , June 2012 , pp. 383 - 389
Copyright
Copyright © The Society of Theoretical and Applied Mechanics, R.O.C. 2012

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