On the Accurate Calculation of Effective Wake/Application to Ducted Propellers

2014 ◽  
Vol 58 (02) ◽  
pp. 70-82
Author(s):  
Ye Tian ◽  
Chan-Hoo Jeon ◽  
Spyros A. Kinnas
Keyword(s):  
Numerical Simulation ◽  
Potential Flow ◽  
Navier Stokes ◽  
Experimental Measurements ◽  
Control Points ◽  
Interpolation Scheme ◽  
Accurate Calculation ◽  
Flow Solver ◽  
Effective Wake ◽  
Ducted Propellers

A hybrid method that couples a potential flow solver with a Reynolds-Averaged Navier-Stokes (RANS) solver for calculating the effective wake of a propeller is proposed. Two improvements are addressed in this method:a conservative interpolation scheme that conserves the total forces when passing information from the potential flow solver to the RANS solver; anda novel option that evaluates the effective wake at the control points in the blade zone. The proposed method is first assessed in the case of an open propeller subject to uniform inflow and then applied to predict the performance of the ducted propellers under uniform inflow. The results of the numerical simulation are correlated with available experimental measurements.

A Hybrid Viscous/Potential Flow Method for the Prediction of the Performance of Podded and Ducted Propellers

2009 ◽  
Author(s):  
Spyros A. Kinnas ◽  
Shu-Hao Chang ◽  
Yi-Hsiang Yu ◽  
Lei He
Keyword(s):  
Viscous Flow ◽  
Lattice Method ◽  
Viscous Potential Flow ◽  
Flow Solver ◽  
Vortex Lattice Method ◽  
Ducted Propeller ◽  
Hybrid Numerical Method ◽  
Convergence Study ◽  
Effective Wake ◽  
Ducted Propellers

This paper presents the analysis of the performance for podded and ducted propellers using a hybrid numerical method, which couples a vortex lattice method (MPUF-3A) for the unsteady analysis of propellers and a viscous flow solver (NS-3X or FLUENT) for the prediction of the viscous flow around propulsors and the drag force on the pod and duct surfaces. The time averaged propeller force distributions are considered as source terms (body force) in the momentum equations of NS-3X and FLUENT. The effects of viscosity on the effective wake and on the performance of the propeller blade, as well as on the predicted pod and duct forces, are assessed. The convergence study of circulation distributions with number of lattices is reported in the ducted propeller case. Finally, the prediction of the performance for podded propellers (both single pull-type and twin-type) and ducted propellers from the present method is validated against existing experimental data.

Surface Ship Total Resistance Prediction Based on a Nonlinear Free Surface Potential Flow Solver and a Reynolds-Averaged Navier-Stokes Viscous Correction

2007 ◽  
Vol 51 (01) ◽  
pp. 47-64
Author(s):  
James C. Huan ◽  
Thomas T. Huang
Keyword(s):  
Free Surface ◽  
Surface Potential ◽  
Potential Flow ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Navier Stokes ◽  
Total Resistance ◽  
Flow Solver ◽  
Resistance Prediction ◽  
Nonlinear Free Surface

A fast turnaround and an accurate computational fluid dynamics (CFD) approach for ship total resistance prediction is developed. The approach consists of a nonlinear free surface potential flow solver (PShip code) with a wet-or-dry transom stern model, and a Reynolds-averaged Navier-Stokes (RANS) equation solver that solves viscous free surface flow with a prescribed free surface given from the PShip. The prescribed free surface RANS predicts a viscous correction to the pressure resistance (viscous form) and viscous flow field around the hull. The viscous free surface flow solved this way avoids the time-consuming RANS iterations to resolve the free surface profile. The method, however, requires employing a flow characteristic-based nonreflecting boundary condition at the free surface. The approach can predict the components of ship resistance, the associated wave profile around the hull, and the sinkage and trim of the ship. Validation of the approach is presented with Wigley, Series 60 (CB = 0.6), and NSWCCD Model 5415 hulls. An overall accuracy of ±2% for ship total resistance prediction is achieved. The approach is applied to evaluating the effects of a stern flap on a DD 968 model on ship performance. An empirical viscous form resistance formula is also devised for a quick ship total resistance estimate.

scholarly journals Preliminary Parameter Characterization for Numerical Optimisation of Ducted Propellers

2019 ◽  
Vol 1 (2) ◽  
pp. Manuscript
Author(s):  
Jean-Marc Laurens ◽  
Margot Remaud ◽  
Pierre-Michel Guilcher
Keyword(s):  
Steady State ◽  
Potential Flow ◽  
Steady State Flow ◽  
Flow Solver ◽  
Flow Problems ◽  
Performance Predictions ◽  
Preliminary Study ◽  
Unsteady Problems ◽  
Numerical Optimisation ◽  
Ducted Propellers

In this paper, a preliminary parameter characterization for the numerical optimisation of ducted propellers was performed. The ENSTA Bretagne in-house solver used is based on the potential flow theory. Although the potential flow solver is able to solve unsteady problems, in this preliminary study only steady state flow problems are considered. Different parameters were analysed, such as the gap between the propeller tip and the inner duct surface as well as the propeller location in the duct tube. The analyses were carried out on a standard advance coefficient range. A quick study showed that a neutral NACA profile for the duct section could provide higher performance predictions than the classical accelerating Kort nozzle 19A.

Steep Wave Loads From Irregular Waves on an Offshore Wind Turbine Foundation: Computation and Experiment

2013 ◽  
Author(s):  
Bo Terp Paulsen ◽  
Henrik Bredmose ◽  
Harry B. Bingham ◽  
Signe Schløer
Keyword(s):  
Free Surface ◽  
Potential Flow ◽  
Surface Elevation ◽  
Irregular Waves ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Free Surface Elevation ◽  
Fully Nonlinear ◽  
Flow Solver ◽  
Nonlinear Potential

Two-dimensional irregular waves on a sloping bed and their impact on a bottom mounted circular cylinder is modeled by three different numerical methods and the results are validated against laboratory experiments. We here consider the performance of a linear-, a fully nonlinear potential flow solver and a fully nonlinear Navier-Stokes/VOF solver. The validation is carried out in terms of both the free surface elevation and the inline force. Special attention is paid to the ultimate load in case of a single wave event and the general ability of the numerical models to capture the higher harmonic forcing. The test case is representative for monopile foundations at intermediate water depths. The potential flow computations are carried out in a two-dimensional vertical plane and the inline force on the cylinder is evaluated by the Morison equation. The Navier-Stokes/VOF computations are carried out in three-dimensions and the force is obtained by spatial pressure integration over the wettet area of the cylinder. In terms of both the free surface elevation and the inline force, the linear potential flow model is shown to be of limited accuracy and large deviations are generally seen when compared to the experimental measurements. The fully nonlinear Navier-Stokes/VOF computations are accurately predicting both the free surface elevation and the inline force. However, the computational cost is high relative to the potential flow solvers. Despite the fact that the nonlinear potential flow model is carried out in two-dimensions it is shown to perform just as good as the three-dimensional Navier-Stokes/VOF solver. This is observed for both the free surface elevation and the inline force, where both the ultimate load and the higher harmonic forces are accurately predicted. This shows that for moderately steep irregular waves a Morison equation combined with a fully nonlinear two-dimensional potential flow solver can be a good approximation.

On the Accurate Calculation of Effective Wake/Application to Ducted Propellers

2014 ◽  
Vol 58 (2) ◽  
pp. 70-82 ◽  
Author(s):  
Ye Tian ◽  
Chan-Hoo Jeon ◽  
Spyros A. Kinnas
Keyword(s):  
Accurate Calculation ◽  
Effective Wake ◽  
Ducted Propellers

Experimental and Numerical Investigation of a Centrifugal Compressor

2010 ◽  
Author(s):  
Hadi Karrabi ◽  
Ali Hajilouy-Benisi ◽  
Mahdi Nili-Ahmadabadi
Keyword(s):  
Numerical Simulation ◽  
Gas Turbine ◽  
Centrifugal Compressor ◽  
Navier Stokes ◽  
Experimental Measurements ◽  
Flow Parameters ◽  
Wide Range ◽  
Compressor Inlet ◽  
Sst Turbulence Model ◽  
Good Agreement

In this research, centrifugal compressor of a gas turbine is investigated experimentally and numerically. Operation line of the compressor as a component of the gas turbine is obtained experimentally by measurements of impeller rotational speed, and flow parameters at the compressor inlet and outlet during the gas turbine operation. The flow field inside the impeller and diffusers are analyzed numerically using a full 3D Navier-Stokes program with SST turbulence model. Boundary conditions for the numerical simulation are specified from the experimental measurements. The operation line of the compressor is obtained numerically, which is compared with that of the experimental results, and shows good agreement. Having validated the numerical results, the performance characteristic curves of the compressor are obtained numerically in a wide range.

A Hybrid Viscous/Potential Flow Method for the Prediction of the Wetted and Cavitating Performance of Ducted Propellers

2015 ◽  
Author(s):  
Spyros A. Kinnas ◽  
Chan-Hoo Jeon ◽  
Ye Tian
Keyword(s):  
Present Method ◽  
Vortex Lattice ◽  
Navier Stokes ◽  
Propeller Blade ◽  
Lattice Method ◽  
Viscous Potential Flow ◽  
Vortex Lattice Method ◽  
Hybrid Numerical Method ◽  
Effective Wake ◽  
Ducted Propellers

This paper presents the analysis of the performance for various ducted propellers using a hybrid numerical method, which couples a vortex lattice method (VLM) for the analysis of propellers and a Reynolds-Averaged Navier-Stokes solver for the prediction of the viscous fluid flow around the duct. The effects of viscosity on the effective wake and on the performance of the propeller blade, as well as on the predicted duct forces, are assessed. The prediction of the performance for those ducted propellers from the present method is validated against existing experimental data.

A Hybrid Viscous/Potential Flow Method for the Prediction of the Wetted and Cavitating Performance of Ducted Propellers

2012 ◽  
Author(s):  
Spyros A. Kinnas ◽  
Chan-Hoo Jeon ◽  
Ye Tian
Keyword(s):  
Present Method ◽  
Vortex Lattice ◽  
Navier Stokes ◽  
Propeller Blade ◽  
Lattice Method ◽  
Viscous Potential Flow ◽  
Vortex Lattice Method ◽  
Hybrid Numerical Method ◽  
Effective Wake ◽  
Ducted Propellers

This paper presents the analysis of the performance for various ducted propellers using a hybrid numerical method, which couples a vortex lattice method (VLM) for the analysis of propellers and a Reynolds-Averaged Navier-Stokes solver for the prediction of the viscous fluid flow around the duct. The effects of viscosity on the effective wake and on the performance of the propeller blade, as well as on the predicted duct forces, are assessed. The prediction of the performance for those ducted propellers from the present method is validated against existing experimental data.

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.

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