ON THE PARTIALLY CAVITATING FLOW AROUND TWO-DIMENSIONAL HYDROFOILS

The steady partially cavitating flow around two-dimensional hydrofoils war simulated numerically by the low-order potential-based boundary integration method. The cavity shape and length are determined for given cavitating numbers in the course of iteration by satisfying the kinematic and dynamic boundary conditions. The re-entrant jet model and the pressure-recovery close model are adopted to replace the high turbulent and two-phase wake forming behind the cavity. The results are compared with the other published numerical ones.

Implicit large eddy simulation of unsteady cloud cavitation around a plane-convex hydrofoil

The present paper focuses on the erosive cavitation behavior around a plane convex hydrofoil. The Zwart-Gerber-Belamri cavitation model is implemented in a library form to be used with the OpenFOAM. The implicit large eddy simulation （ILES） is app- lied to analyze the three-dimensional unsteady cavitating flow around a plane convex hydrofoil. The numerical results in the cases under the hydrodynamic conditions, which were experimentally tested at the high speed cavitation tunnel of the l^cole Polytechnique F6d＆ale de Lausanne （EPFL）, clearly show the sheet cavitation development, the shedding and the collapse of vapor clouds. It is noted that the cavitation evolutions including the maximum vapor length, the detachment and the oscillation frequency, are captured fairly well. Furthermore, the pressure pulses due to the cavitation development as well as the complex vortex structures are reasona- bly well predicted. Consequently, it may be concluded that the present numerical method can be used to investigate the unsteady cavitation around hydrofoils with a satisfactory accuracy.

Numerical simulation of condensation shock in partial cavitating flow on a hydrofoil

We present a numerical simulation of the so-called condensation shock on a NACA 0015 hydrofoil with a finite mass transfer model for the first time.Most recently,condensation shock was indentified in the experimental measurement as a mechanism for partial cavity shedding in the flow past a hydrofoil.Compressible solvers,which were adopted in the previous simulations to study such phenomenon numerically,are extremely time consuming due to the limitation of acoustic Courant number.In this work,we consider a finite mass transfer model for cavitation flow with slightly modification.Our numerical results show that the finite mass transfer model can be successfully applied for calculating the condensation shock in the flow past a hydrofoil.The dynamics of the condensation shock on the hydrofoil is also discussed.The model is proved to be useful for further understanding of the underlying phyiscs of such flow.

Bubbly shock propagation as a mechanism of shedding in separated cavitating flows

Stable attached partial cavitation in separated flows can transition to cloud shedding, and the mechanism of transition has been attributed to the presence of a re-entrant liquid jet. Our findings have revealed the presence of propagating bubbly shock waves as an alternative dominant mechanism of shedding when the compressibility of the bubbly mixture is appreciable. In the present paper, we discuss dynamics associated with these bubbly shock waves, interaction of shock waves with obstacles in their path, and means to manipulate their properties to control the shedding process by non-condensable gas injection.