An alternative Vorticity based Adaptive Mesh Refinement (V-AMR) technique for tip vortex cavitation modelling of propellers using CFD methods

Abstract

This study focuses on the investigation of cavitating flow around the benchmark INSEAN E779A model propeller with the main aim of further improving the computational efficiency of the tip vortex cavitation (TVC) modelling by using a commercial CFD solver. Also, the effects of various key computational parameters including, numerical modelling, grid size, timestep, water quality and boundary layer resolution, on the TVC formation and its extension in the propeller slipstream are investigated systematically.The numerical simulations are conducted in uniform and open water conditions using RANS, DES and LES solvers implemented in the commercial CFD code, Start CCM+. In order to achieve the aim of the study, an alternative and new Vorticity-based Adaptive Mesh Refinement (V-AMR) technique is introduced for enhanced modelling of the TVC on the blades and downstream. For the CFD modelling of cavitation, the Schneer Sauer cavitation model based on the reduced Rayleigh Plesset equation is used for the sheet, tip and hub vortex cavitation. The hydrodynamic results and cavity patterns are validated with the experimental data. The results show that the application of the V-AMR technique further improves the representation of the TVC with minimal increase in computational cost. However, the eddy viscosity at the propeller blade tips increases with applying the V-AMR technique using the RANS solver due to its inherent modelling errors for the solution of the flow inside the tip vortex. This consequently results in an insufficient extension of TVC in the propeller slipstream compared to the predictions by the DES and LES based numerical solvers. Also, the evolution of the TVC is found to be sensitive to the boundary layer resolution when the standard RANS solver is used. The study will help to widen further applications of the CFD methods involving TVC, particularly for propeller induced underwater noise prediction and analysis.

Hydrodynamic Numerical Calculation Method of Small-scale Objects in Ocean Engineering Based on Immersion Boundary Method

“…(3) Solve the NS equation in the entire flow field: (4) According to the new velocity field, solve the new position of the discrete points of the solid boundary [5][6] .…”

Marine propeller underwater radiated noise prediction with the FWH acoustic analogy Part 2: Assessment of model scale propeller hydroacoustic performance under non-uniform flow conditions

“…In this regard, the authors have recently introduced the Vorticitybased Adaptive Mesh Refinement (V-AMR) technique for the accurate solution of the tip vortex flow and hence tip vortex cavitation (TVC) observation in the propeller slipstream (Sezen and Atlar, 2021). Using the V-AMR technique, the grid is refined as local as possible in the vicinity of tip vortex areas to reduce the computational cost of the solution.…”

“…Therefore, in this study, the same V-AMR technique was implemented for the observation of TVC under non-uniform flow conditions. Detailed information about the application of this technique can be found in the study of Sezen and Atlar (2021). The grid quality is also crucial for accurately predicting propeller URN.…”

“…The sheet and tip vortex cavitation was modelled using the mass transfer model. To better realise the TVC in the propeller slipstream, the Vorticity-based Adaptive Mesh Refinement procedure (V-AMR) developed and proposed by the authors (Sezen and Atlar, 2021) was utilised. The non-uniform wakefield data, measured in the Ata Nutku Towing tank of Istanbul Technical University, was used for the numerical calculations.…”

Cavitation funnel effect: Bio-inspired leading-edge tubercle application on ducted marine propeller blades

“…Long et al, (2019Long et al, ( , 2020Long et al, ( , 2021 has conducted multiple numerical studies related to the verification and validation of cavitating flows around marine propellers and hydrofoils using high-fidelity models such as DES and LES. In addition, meshing techniques have been developed such as adaptive mesh refinement (AMR) which can resolve the tip vortex cavitation from marine propellers at reduced computational effort, where mesh is refined in the trajectory of the tip vortex cavitation which is predicted through various threshold parameters (Sezen and Atlar., 2021). The accurate prediction of cavitation within CFD is crucial for the development of novel cavitation mitigation technologies on devices such as marine propellers in the early design stages and although there are still many challenges to overcome, this is only possible with continued research in this area.…”