A Panel Method with a Full Wake Alignment Model for the Prediction of the Performance of Ducted Propellers

2015 ◽  
Vol 59 (03) ◽  
pp. 246-257 ◽  
Author(s):  
Spyros A. Kinnas ◽  
Hongyang Fan ◽  
Ye Tian
Keyword(s):  
Panel Method ◽  
Navier Stokes ◽  
Ocean Engineering ◽  
Local Flow ◽  
University Of Texas ◽  
Alignment Model ◽  
Rans Simulations ◽  
Wake Alignment ◽  
Thrust And Torque ◽  
Ducted Propellers

An improved perturbation potential-based panel method is applied to model the flow around ducted propellers. One significant development in this method is the application of full wake alignment scheme in which the trailing vortex wake sheets of the blades are aligned with the local flow velocity by also considering the effects of duct and duct wake. A process of repaneling the duct is simultaneously introduced to improve the accuracy of the method. The results from the improved wake model are compared with those from a simplified wake alignment scheme. At the same time, full-blown Reynolds-averaged Navier-Stokes (RANS) simulations are conducted via commercial solvers. The forces, i.e., thrust and torque, on the propeller predicted by this panel method under the improved wake alignment model show good agreement both with experimental measurements, a hybrid method developed by the Ocean Engineering Group of University of Texas at Austin, and the full-blown RANS simulations. Moreover, predicted pressure distribution on the blades and duct are compared among the various methods.

scholarly journals Panel Method for Ducted Propellers with Sharp Trailing Edge Duct with Fully Aligned Wake on Blade and Duct

2018 ◽  
Vol 6 (3) ◽  
pp. 89 ◽  
Author(s):  
Seungnam Kim ◽  
Spyros Kinnas ◽  
Weikang Du
Keyword(s):  
Present Method ◽  
Panel Method ◽  
Trailing Edge ◽  
Ducted Propeller ◽  
Wide Range ◽  
Rans Simulations ◽  
Propeller Blades ◽  
Wake Alignment ◽  
Low Order ◽  
Ducted Propellers

A low-order panel method is used to predict the performance of ducted propellers. A full wake alignment (FWA) scheme, originally developed to determine the location of the force-free trailing wake of open propellers, is improved and extended to determine the location of the force-free trailing wakes of both the propeller blades and the duct, including the interaction with each other. The present method is applied on a ducted propeller with sharp trailing edge duct, and the predicted results over a wide range of advance ratios, with or without full alignment of the duct wake, are compared with each other, as well as with results from RANS simulations and with measurements from an experiment.

scholarly journals A Wake Model for the Prediction of Propeller Performance at Low Advance Ratios

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Ye Tian ◽  
Spyros A. Kinnas
Keyword(s):  
Experimental Data ◽  
Panel Method ◽  
Model Based ◽  
Pressure Distributions ◽  
Alignment Model ◽  
Wake Model ◽  
Propeller Performance ◽  
Wake Alignment ◽  
Low Order

A low order panel method is used to predict the performance of propellers. A wake alignment model based on a pseudounsteady scheme is proposed and implemented. The results from this full wake alignment (FWA) model are correlated with available experimental data, and results from RANS for some propellers at design and low advance ratios. Significant improvements have been found in the predicted integrated forces and pressure distributions.

A flow separation model for hydrofoil, propeller and duct sections with blunt trailing edges

2018 ◽  
Vol 861 ◽  
pp. 180-199 ◽  
Author(s):  
Weikang Du ◽  
Spyros A. Kinnas
Keyword(s):  
Flow Separation ◽  
Computational Effort ◽  
Panel Method ◽  
Navier Stokes ◽  
Pressure Distributions ◽  
Ducted Propeller ◽  
Trailing Edges ◽  
Extension Zone ◽  
Zero Moment ◽  
Thrust And Torque

The panel method does not apply to hydrofoils, propellers and ducts with blunt trailing edges due to the flow separation downstream. In this paper, a model is proposed to represent the flow separation with an extension, and a low-order panel method coupled with a boundary layer solver is used. The criteria of zero lift and zero moment are adopted to determine the end of the extension zone, and flow separation criteria are used to determine the starting points on either side of the section. The model is applied to hydrofoil, bare duct and ducted propeller sections with blunt trailing edges. The pressure distributions and skin frictions along the hydrofoils and ducts correlate well with those from the Reynolds-averaged Navier–Stokes method. The thrust and torque of the propeller agree much better with experimental measurements when the extension is determined from this model rather than choosing random locations. This model requires much less computational effort while preserving high accuracy, and thus can be used reliably in designing and analysing hydrofoils and propeller ducts with blunt trailing edges.

scholarly journals Prediction of Unsteady Developed Tip Vortex Cavitation and Its Effect on the Induced Hull Pressures

2020 ◽  
Vol 8 (2) ◽  
pp. 114 ◽  
Author(s):  
Seungnam Kim ◽  
Spyros A. Kinnas
Keyword(s):  
Panel Method ◽  
Ship Hull ◽  
Tip Vortex ◽  
Added Value ◽  
Navier Stokes ◽  
Solid Boundary ◽  
Maritime Industry ◽  
Unsteady Wake ◽  
Propeller Performance ◽  
Wake Alignment

Reducing the on-board noise and fluctuating pressures on the ship hull has been challenging and represent added value research tasks in the maritime industry. Among the possible sources for the unpalatable vibrations on the hull, propeller-induced pressures have been one of the main causes due to the inherent rotational motion of propeller and its proximity to the hull. In previous work, a boundary element method, which solves for the diffraction potentials on the ship hull due to the propeller, has been used to determine the propeller induced hull pressures. The flow around the propeller was evaluated via a panel method which solves in time for the propeller loading, trailing wake, and the sheet cavities. In this article, the propeller panel method is extended so that it also solves for the shape of developed tip vortex cavities, the effects of which are also included in the evaluation of the hull pressures. The employed unsteady wake alignment scheme is first applied, in the absence of cavitation, to investigate the propeller performance in non-axisymmetric inflow, such as the inclined-shaft flow or the flow behind an upstream body. In the latter case, the propeller panel method is coupled with a Reynolds-Averaged Navier–Stokes (RANS) solver to determine the effective wake at the propeller plane. The results, including the propeller induced hull pressures, are compared with those measured in the experiments as well as with those from RANS, where the propeller is also simulated as a solid boundary. Then the methods are applied in the cases where partial cavities and developed tip vortex cavities coexist. The predicted cavity patterns, the developed tip vortex trajectories, and the propeller-induced hull pressures are compared with those measured in the experiments.

Numerical Simulation of the Resistance and Self-Propulsion Model Tests1

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Adrian Lungu
Keyword(s):  
Complex Structure ◽  
Turbulence Models ◽  
Open Water ◽  
Numerical Approach ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Local Flow ◽  
Complex Investigation ◽  
Flow Features ◽  
Thrust And Torque

Abstract The paper proposes a series of numerical investigations performed to test and demonstrate the capabilities of a Reynolds-averaged Navier–Stokes equation (RANSE) solver in the area of complex ship flow simulations. The focus is on a complete numerical model for hull, propeller, and rudder that can account for the mutual interaction between these components. The paper presents the results of a complex investigation of the flow computations around the hull model of the 3600 TEU MOERI containership (KCS hereafter). The resistance for the hull equipped with a rudder, the propeller open-water (POW hereafter) computations, as well as the self-propulsion simulation are presented. Comparisons with the experimental data provided at the Tokyo 2015 Workshop on Computational Fluid Dynamics (CFD) in Ship Hydrodynamics are given to validate the numerical approach in terms of the total and wave resistance coefficients, sinkage and trim, thrust and torque coefficients, propeller efficiency, and local flow features. Verification and validation based on the grid convergence tests are performed for each computational case. Discussions on the efficiency of the turbulence models used in the computations as well as on the main flow features are provided aimed at clarifying the complex structure of the flow around the ship stern.

scholarly journals Open-Water Thrust and Torque Predictions of a Ducted Propeller System with a Panel Method

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
J. Baltazar ◽  
J. A. C. Falcão de Campos ◽  
J. Bosschers
Keyword(s):  
Boundary Layer ◽  
Open Water ◽  
Panel Method ◽  
Tip Vortex ◽  
Trailing Edge ◽  
Ducted Propeller ◽  
Performance Predictions ◽  
Wake Alignment ◽  
Thrust And Torque ◽  
Good Agreement

This paper discusses several modelling aspects that are important for the performance predictions of a ducted propulsor with a low-order Panel Method. The aspects discussed are the alignment of the wake geometry, the influence of the duct boundary layer on the wake pitch, and the influence of a transpiration velocity through the gap. The analysis is carried out for propeller Ka4-70 operating without and inside a modified duct 19A, in which the rounded trailing edge is replaced by a sharp trailing edge. Experimental data for the thrust and torque are used to validate the numerical results. The pitch of the tip vortex is found to have a strong influence on the propeller and duct loads. A good agreement with the measurements is achieved when the wake alignment is corrected for the presence of the duct boundary layer.

A BEM/RANS Interactive Method Applied to an Axial Tidal Turbine Farm

2020 ◽  
pp. 1-26
Author(s):  
Seungnam Kim ◽  
Yiran Su ◽  
Spyros A. Kinnas
Keyword(s):  
Computational Cost ◽  
The Body ◽  
Navier Stokes ◽  
Mass Source ◽  
Flow Solver ◽  
Interactive Method ◽  
Tidal Turbine ◽  
Coupling Approach ◽  
Rans Simulations ◽  
Wake Alignment

In this study, an interactive method coupling a boundary element method (BEM) with a viscous flow solver solving the Reynolds-averaged Navier-Stokes (RANS) equations is applied to multiturbine interaction problems. The BEM is first applied to a single turbine problem to predict its performance with/without yaw in noncavitating/ cavitating conditions. Improved wake alignment models, the full wake alignment and the unsteady wake alignment, are used to align the blade wake. The former is adequate for steady state with zero yaw, and the latter is used for unsteady predictions in the case of nonzero yaw in the incoming flow. The BEM results are compared with the experimental measurements and the results from full-blown RANS simulations for a range of tip speed ratios. The comparisons show satisfactory agreement between the numerical and experimental approaches. Afterward, the BEM/RANS coupling method is applied to multiturbine interaction problems with different layouts and different turbine-to-turbine offsets in an axial turbine farm. The method is shown to work well in this multiturbine interaction problem because of the capability of using a strictly Cartesian grid in the RANS method, which minimizes the artificial diffusion and improves the numerical accuracy of long-range flow development. Representation of a turbine by the body force/mass source fields in the BEM/RANS coupling approach reduces the number of cells required for 3D full-blown RANS simulations, and therefore reduces the computational cost in an efficient way.

Recent Developments in Computational Methods for the Analysis of Ducted Propellers in Open Water

2019 ◽  
Vol 63 (4) ◽  
pp. 219-234
Author(s):  
João Baltazar ◽  
José A. C. Falcão de Campos ◽  
Johan Bosschers ◽  
Douwe Rijpkema
Keyword(s):  
Computational Methods ◽  
Open Water ◽  
Boundary Element Methods ◽  
Navier Stokes ◽  
Hydrodynamic Analysis ◽  
Numerical Predictions ◽  
Ducted Propeller ◽  
Recent Developments ◽  
Propeller Performance ◽  
Ducted Propellers

This article presents an overview of the recent developments at Instituto Superior Técnico and Maritime Research Institute Netherlands in applying computational methods for the hydrodynamic analysis of ducted propellers. The developments focus on the propeller performance prediction in open water conditions using boundary element methods and Reynolds-averaged Navier-Stokes solvers. The article starts with an estimation of the numerical errors involved in both methods. Then, the different viscous mechanisms involved in the ducted propeller flow are discussed and numerical procedures for the potential flow solution proposed. Finally, the numerical predictions are compared with experimental measurements.

scholarly journals CFD Simulation for Estimating Efficiency of PBCF Installed on a 176K Bulk Carrier under Both POW and Self-Propulsion Conditions

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1192
Author(s):  
Dong-Hyun Kim ◽  
Jong-Chun Park ◽  
Gyu-Mok Jeon ◽  
Myung-Soo Shin
Keyword(s):  
Cfd Simulation ◽  
Open Water ◽  
Navier Stokes ◽  
Water Efficiency ◽  
Ocean Engineering ◽  
Bulk Carrier ◽  
Incompressible Viscous Flow ◽  
Korea Research Institute ◽  
Torque Coefficient ◽  
Viscous Flow Field

In this paper, the efficiency of Propeller Boss Cap Fins (PBCF) installed at the bulk carrier was estimated under both Propeller Open Water (POW) and self-propulsion conditions. For this estimation, virtual model-basin tests (resistance, POW, and self-propulsion tests) were conducted through Computational Fluid Dynamics (CFDs) simulation. In the resistance test, the total resistance and the wake distribution according to ship speed were investigated. In the POW test, changes of thrust, torque coefficient, and open water efficiency on the propeller according to PBCF installation were investigated. Finally, the International Towing Tank Conference (ITTC) 1978 method was used to predict the effect of PBCF installation on self-propulsive coefficient and brake horsepower. For analyzing incompressible viscous flow field, the Reynolds-Averaged Navier–Stokes (RANS) equation with SST k-ω turbulence model was calculated using Star-CCM+ 11.06.010-R8. All simulation results were validated by comparing the results of model tests conducted at the Korea Research Institute of Ships and Ocean Engineering (KRISO). Consequently, for the self-propulsion test with the PBCF, a 1.5% reduction of brake horsepower was estimated in the simulation and a 0.5% reduction of the brake horsepower was estimated in the experiment.

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