Computational fluid dynamic investigations of propeller cavitation in the presence of a rudder

Yilmaz, Naz and Atlar, Mehmet and Fitzsimmons, Patrick A. and Sasaki, Noriyuki (2018) Computational fluid dynamic investigations of propeller cavitation in the presence of a rudder. In: 3rd International Symposium on Naval Architecture and Martime (INT-NAM 2018), 2018-04-24 - 2018-04-25, Yildaz Technical University.

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    Abstract

    This paper presents the preliminary results of a computational study for cavitation modelling of marine propellers particularly developing tip vortex cavitation in the presence of a rudder. The main purpose of the study is to estimate the propeller’s performance in cavitating conditions and to investigate the propeller-rudder interaction especially due to the tip-vortex cavitation. The cavitation simulations were conducted using commercial Computational Fluid Dynamics (CFD) software, Star CCM+. In the study, the INSEAN E779A model propeller was used as a benchmark. Firstly, validation studies were conducted in cavitating conditions using only the propeller in isolation. The cavitation on the propeller was simulated by using a numerical model, which is known as Schnerr–Sauer cavitation model, based on the Rayleigh-Plesset equation. Then, the rudder with an airfoil section was introduced behind the propeller and the simulations were repeated to investigate the effect of the rudder on the propeller performance as well as to study the propeller-rudder interaction from the cavitation point of view. Two cases with different advance coefficients (J) and cavitation numbers (σ) were simulated to compare the computational results with experiments which were obtained from open literature. For the tip vortex cavitation modelling, recently developed volumetric control method using spiral geometry was applied to generate finer mesh around the propeller tip region where the tip vortex cavitation may occur. The comparison with the benchmark experimental data showed good agreement in terms of thrust and torque coefficients as well as sheet and tip vortex cavitation patterns for the propeller in the absence of the rudder. The comparisons also showed good agreement in terms of the velocity and pressure distributions and hence enabled accurate extension of the tip vortex cavitation until the rudder to focus on the interaction of the tip vortex cavitation with the rudder.