Induction rim-drive for a marine propulsor

2010 ◽  
Author(s):  
P.M. Tuohy ◽  
A.C. Smith ◽  
M. Husband
Keyword(s):  
Marine Propulsor

scholarly journals Predicting Unsteady Loads in Marine Propulsor Crashback Using Large Eddy Simulation

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Hyunchul Jang ◽  
Aman Verma ◽  
Krishnan Mahesh
Keyword(s):  
Large Eddy Simulation ◽  
Reverse Flow ◽  
Reverse Direction ◽  
Unsteady Forces ◽  
Eddy Simulation ◽  
Large Eddy ◽  
The Mean ◽  
Submarine Hull ◽  
Marine Propulsor ◽  
Good Agreement

Propulsor crashback is an off-design operating condition where a propulsor rotates in the reverse direction to yield negative thrust. Crashback is characterized by the interaction of the free stream with the reverse flow generated by propulsor rotation. This causes a highly unsteady vortex ring which leads to flow separation and unsteady forces and moments on the blades. Large eddy simulation (LES) is performed for marine propulsors in crashback for various configurations and advance ratios and validated against experiments. The predictive capability of LES as a tool for propulsor crashback is demonstrated on an open propulsor, open propulsor with a submarine hull, and ducted propulsor with and without stator blades. LES is in good agreement with experiments for the mean and RMS levels, and spectra of the unsteady loads on the propulsors.

Computational Fluid Dynamics of Four-Quadrant Marine-Propulsor Flow

1999 ◽  
Vol 43 (04) ◽  
pp. 218-228
Author(s):  
Bin Chen ◽  
Frederick Stern
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Stokes Equations ◽  
Flow Characteristics ◽  
Verification And Validation ◽  
Navier Stokes ◽  
Ring Vortex ◽  
Reynolds Averaged Navier Stokes ◽  
Four Quadrant ◽  
Marine Propulsor

Computational fluid dynamics results are presented of four-quadrant flow for marine-propulsor P4381. The solution method is unsteady three-dimensional incompressible Reynolds-averaged Navier-Stokes equations in generalized coordinates with the Baldwin-Lomax turbulence model. The method was used previously for the design condition for marine-propulsor P4119, including detailed verification and validation. Only limited verification is performed for P4381. The validation is limited by the availability of four-quadrant performance data and ring vortex visualizations for the crashback conditions. The predicted performance shows close agreement with the data for the forward and backing conditions, whereas for the crashahead and crashback conditions the agreement is only qualitative and requires an ad hoc cavitation correction. Also, the predicted ring vortices for the crashback conditions are in qualitative agreement with the data. Extensive calculations enable detailed description of flow characteristics over a broad range of propulsor four-quadrant operations, including surface pressure and streamlines, velocity distributions, boundary layer and wake, separation, and tip and ring vortices. The overall results suggest promise for Reynolds-averaged Navier-Stokes methods for simulating marine-propulsor flow, including offdesign. However, important outstanding issues include additional verification and validation, time-accurate solutions, and resolution and turbulence modeling for separation and tip and ring vortices.

Computation of Unsteady Viscous Marine-Propulsor Blade Flows—Part 1: Validation and Analysis

1997 ◽  
Vol 119 (1) ◽  
pp. 145-154 ◽  
Author(s):  
E. G. Paterson ◽  
F. Stern
Keyword(s):  
Stokes Equations ◽  
External Flow ◽  
Navier Stokes ◽  
Massachusetts Institute Of Technology ◽  
Propeller Blade ◽  
Navier Stokes Equations ◽  
Displacement Thickness ◽  
Unsteady Interaction ◽  
Institute Of Technology ◽  
Marine Propulsor

In this two-part paper, time-accurate solutions of the Reynolds-averaged Navier-Stokes equations are presented, which address through model problems, the response of turbulent propeller-blade boundary layers, and wakes to external-flow traveling waves. In Part 1, the Massachusetts Institute of Technology flapping-foil experiment is simulated and the results validated through comparisons with data. The physics of unsteady blade flows are shown to be complex with analogy to Stokes layers and are explicated through visualization and Fourier analysis. It is shown that convection induced steady/unsteady interaction causes deformation of the external-flow waves and is responsible for the upstream- and downstream-traveling pressure-gradient waves over the foil and in the wake, respectively. The nature of the unsteady displacement thickness suggests viscous-inviscid interaction as the mechanism for the response. In Part 2, a parametric study is undertaken to quantify the effects of frequency, foil geometry, and waveform.

RANS Simulation of Ducted Marine Propulsor Flow Including Subvisual Cavitation and Acoustic Modeling

2005 ◽  
Vol 128 (4) ◽  
pp. 799-810 ◽  
Author(s):  
Jin Kim ◽  
Eric G. Paterson ◽  
Frederick Stern
Keyword(s):  
Vortex Core ◽  
Bubble Dynamics ◽  
Leading Edge ◽  
Suction Side ◽  
Interaction Region ◽  
Trailing Edge ◽  
Experimental Fluid Dynamics ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Marine Propulsor

High-fidelity Reynolds-averaged Navier Stokes (RANS) simulations are presented for the ducted marine propulsor P5206, including verification and validation (V&V) using available experimental fluid dynamics data, and subvisual cavitation, and acoustics analysis using the modified Rayleigh-Plesset equation along the bubble trajectories with a far-field form of the acoustic pressure for a collapsing spherical bubble. CFDSHIP-IOWA is used with the blended k−ω∕k−ε turbulence model and extensions for a relative rotating coordinate system and overset grids. The intervals of V&V analysis for thrust, torque, and profile averaged radial velocity just downstream of rotor tip are reasonable in comparison with previous results. The flow pattern displays the interaction and merging of the tip-leakage and trailing edge vortices. In the interaction region, multiple peaks and vorticity are smaller, whereas in the merging region, there is better agreement with the experiment. The tip-leakage vortex core position, size, circulation, and cavitation patterns for σi=5 also show good agreement with the experiment, although the vortex core size is larger and the circulation in the interaction region is smaller. The simulations indicate globally minimum Cp=−σi=−8.8 on the suction side of the rotor tip at 84% chord from the leading edge and locally minimum Cp=−6.4 in the tip-leakage vortex at 8% chord downstream of the trailing edge, whereas EFD indicates σi=11 and the location in the tip-leakage vortex core 50% chord downstream of the trailing edge. Subvisual cavitation and acoustics analysis show that bubble dynamics may partly explain these discrepancies.

scholarly journals Hydrodynamic State of Art Review: Rotor – Stator Marine Propulsor Systems Design

2021 ◽  
Vol 28 (1) ◽  
pp. 72-82
Author(s):  
Przemysław Król
Keyword(s):  
System Design ◽  
Energy Saving ◽  
State Of The Art ◽  
Systems Design ◽  
Design Criteria ◽  
Efficiency Gain ◽  
Current State ◽  
Screw Propeller ◽  
Marine Propulsor ◽  
State Of Art

Abstract The paper covers the important topic of rotor–stator propulsor system design and operation. For the stand-alone marine screw propeller, both the design criteria for loading distribution and the theoretical efficiency limits are well described in the basic literature. This is in contrast to the combined propulsor system like a propeller cooperating with a pre-swirl device. The paper describes the current state of the art, summarising results obtained by various researchers by installing energy-saving devices on particular vessels. The design methods utilised are briefly outlined, with the main characteristics underlined. Rough analysis of the gathered data confirms the expected trend that a higher efficiency gain due to ESD installation is possible for a higher propeller loading.

scholarly journals Modeling of Unsteady Sheet Cavitation on Marine Propeller Blades

2003 ◽  
Vol 9 (4) ◽  
pp. 263-277 ◽  
Author(s):  
Spyros A. Kinnas ◽  
HanSeong Lee ◽  
Yin L. Young
Keyword(s):  
Cavity Model ◽  
Sheet Cavitation ◽  
Panel Model ◽  
Unsteady Wake ◽  
Alignment Process ◽  
Propeller Blades ◽  
Detachment Criterion ◽  
Marine Propulsor ◽  
Wake Alignment ◽  
Unsteady Cavitating Flow

Unsteady sheet cavitation is very common on marine propulsor blades. The authors summarize a lifting-surface and a surface-panel model to solve for the unsteady cavitating flow around a propeller that is subject to nonaxisymmetric inflow. The time-dependent extent and thickness of the cavity were determined by using an iterative method. The cavity detachment was determined by applying the smooth detachment criterion in an iterative manner. A nonzeroradius developed vortex cavity model was utilized at the tip of the blade, and the trailing wake geometry was determined using a fully unsteady wake-alignment process. Comparisons of predictions by the two models and measurements from several experiments are given.

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