A DES-SST Based Assessment of Hydrodynamic Performances of the Wetted and Cavitating PPTC Propeller

Abstract

The paper describes an investigation of the hydrodynamic performances of a five-bladed controllable pitch propeller, whose geometry was provided by Schiffbau-Versuchsanstalt (SVA) Potsdam GmbH Model Basin. Both cavitating and non-cavitating regimes are numerically simulated for different advance ratio coefficients. The numerical approach is based on a finite volume approach in which closure to the turbulence is achieved through detached eddy simulation (DES). Propeller open water (POW) characteristics are computed, and the numerical solutions are validated through extensive comparisons with experimental data. In addition, the bi-phasic flow for the cavitating regime is simulated, for which comparisons with the cavitation sketches are performed to check the ability of the solver to estimate the cavitation extent. Grid convergence tests are performed for both working regimes together with validation and verification checks, not only to size the level of the numerical errors, but also to prove the robustness of the chosen numerical approach. Finally, a set of final remarks will conclude the present research.

Large Flow Separations around a Generic Submarine in Static Drift Motion Resolved by Various Turbulence Closure Models

“…Comparative simulations employing all the turbulence models have proven that the degree of deformation of the tube cores shed at the downstream part of the separated shear layer is much larger in the IDDES model case. Obviously, this is providing additional information on the mechanism for the amplification of the vertical vorticity in the aft near-hull region, with immediate consequences for the velocity field structure needed for an optimal design of a performant propeller, as shown previously by the author in [65,66]. Trial computations that employed the IDDES model, not reported here, have proven that due to the richer eddy content of the separated shear layer, the intensity of the nondimensional pressure root mean square fluctuations beneath the separated shear layer has been found to be more than twice larger in the highest velocity simulations.…”

“…The major contribution of this work is the overall quality of solutions brought by the combined use of adaptive mesh refinement along with the DES or IDDES-based turbulence closure models. Comparing the solutions reported here with the otherwise faster but less accurate RANS methods [15,20], or with the more expensive LES-based methods [23,35,66] one may notice not only the efficiency, but also the accuracy of the method proposed here.…”

Cavitation Prediction of Ship Propeller Based on Temperature and Fluid Properties of Water

“…The models were added to the CFX solver using CFX Expression Language (CEL), considering that the mass transfer model is needed to improve the accuracy and stability of numerical simulations by providing empirical coefficients to adjust the mass transfer rate due to evaporation and condensation [19]. Lungu [20] performed cavitation modeling on the PPTC model VP1304 using a numerical approach based on the finite volume method with the turbulent closure approach through Detached Eddy Simulation (DES). Regener [21] performed a numerical analysis of cavitation on propellers by considering the interaction of flow between the water and the ship's hull.…”

Energy-Saving Devices in Ship Propulsion: Effects of Nozzles Placed in Front of Propellers

“…The tip and root vortical structures, well-defined inside the near-wake, become unstable and eventually vanish to form the far wake. The mechanism of their formation was previously described by the author in [14] for the tip vortices and in [30] for those released by the intersection between the blades and hub, therefore no more assertions will be provided here. The vortex cores' positions correspond strictly to the restricted regions of lowest pressure values in the wake domain, as well as to the velocities and turbulent kinetic energy fields.…”

“…Both wetted and cavitating propellers were considered to fit the purpose and some encouraging results have been reported so far [12][13][14]. Moreover, various experimental and numerical studies were continuously attempting at defining atypical propellers such as tip rake propellers [15][16][17] or contracted load tip propellers [18,19] meant to contribute to the improvement of the overall propulsive performances.…”