Numerical Modelling of Propeller Flow Inside a Cavitation Tunnel

A theoretical and computational methodology to study marine propeller flows inside a closed tunnel is presented. The hydrodynamic model is based on a boundary integral formulation for the velocity potential that is valid for inviscid irrotational flows. The flowfield around a rotating propeller inside the tunnel is studied by a transient flow analysis in which both propeller and tunnel walls are simultaneously taken into account. An efficient numerical solution procedure is proposed by introducing a domain decomposition technique and a Fourier series representation of the influence coefficients. An outline of the theoretical methodology and of the numerical solution approach is described in the paper. Numerical scheme performance is discussed in detail and preliminary numerical results are presented. In particular, the evaluation of flow confinement effects for tunnel test sections of arbitrary shape and dimensions is discussed. It is also shown that the proposed methodology allows to predict tunnel velocity corrections based on the thrust identity approach, and numerical results are compared to those by classical analytical theory.