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.

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.

Comparison of Hydrodynamic Performance of Ducted Propeller and Ordinary Propeller on Trawler

2014 ◽  
Vol 908 ◽  
pp. 249-255
Author(s):  
Chao Li ◽  
Zhi Xin Chen
Keyword(s):  
Numerical Calculation ◽  
Pressure Distribution ◽  
Open Water ◽  
Experimental Results ◽  
Hydrodynamic Performance ◽  
Ducted Propeller ◽  
Thrust And Torque ◽  
Good Agreement

With the 42m trawler as object, an ordinary propeller and a ducted propeller are designed and their open water hydrodynamic performance are simulated by using CFD software. The computed results and experimental results of ducted propeller are in good agreement, which verified the reliability of numerical calculation. Then the computed results of ordinary propeller and ducted propeller are compared with each other, it is found that the thrust and torque of ducted propeller is bigger than ordinary propeller in trawling. This article also discusses the pressure distribution of their blade and the reason why ducted propeller has a better hydrodynamic performance is studied.

Unsteady Hydrodynamic Performance Prediction of Ducted Propeller Based on CFD

2013 ◽  
Vol 437 ◽  
pp. 32-35
Author(s):  
Li Jian Ou ◽  
Nan Huo Wu ◽  
De Yu Li
Keyword(s):  
Performance Prediction ◽  
Open Water ◽  
Hydrodynamic Performance ◽  
Moving Mesh Method ◽  
Ducted Propeller ◽  
Mesh Method ◽  
Bearing Force ◽  
Thrust And Torque ◽  
Wake Fields ◽  
Calculated Model

Firstly, the calculated model was created in UG and GAMBIT, and then the Moving Mesh method was adopted to simulate thrust and torque of ducted propeller using FLUENT in the open water. The thrust, torque and bearing force of ducted propeller in three different wake fields were calculated. And the influence on the performance of ducted propeller by the wake fields was analyzed.

Four Quadrants Numerical Prediction for Hydrodynamic Performance of Open-Water Propeller

2010 ◽  
Vol 143-144 ◽  
pp. 1143-1147
Author(s):  
Bing Xiao ◽  
Xiao Wang ◽  
Ai Guo Shi ◽  
Ming Wu
Keyword(s):  
Three Dimensional ◽  
Open Water ◽  
Mathematic Model ◽  
Hydrodynamic Performance ◽  
Computational Domain ◽  
Basic Parameters ◽  
Tank Test ◽  
Open Water Performance ◽  
Thrust And Torque ◽  
Good Agreement

In order to obtain the four quadrants hydrodynamic performance of open water propeller by means of CFD, a mathematic model of three dimensional coordinates points was established and programmed using Matlab based on the basic parameters of propeller. A smooth model propeller was made by importing these points into front end software. Then taking AU model for example, numerical simulations of propeller turning ahead while going ahead, turning ahead while going astern, turning astern while going ahead and turning astern while going astern were carried out. At the same time, the thrust and torque coefficients were presented. The simulation results showed good agreement with the results of tank test. The influence of mesh generation and computational domain on open-water performance were also discussed.

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.

scholarly journals Hydrodynamic and Acoustic Performance Analysis of Marine Propellers by Combination of Panel Method and FW-H Equations

2019 ◽  
Vol 24 (3) ◽  
pp. 81 ◽  
Author(s):  
Abouzar Ebrahimi ◽  
Mohammad Saeed Seif ◽  
Ali Nouri-Borujerdi
Keyword(s):  
Maximum Error ◽  
Panel Method ◽  
Experimental Results ◽  
Good Reliability ◽  
Acoustic Performance ◽  
Marine Propellers ◽  
University Of Technology ◽  
Propeller Noise ◽  
Thrust And Torque ◽  
Good Agreement

The noise emitted by ships is one of the most important noises in the ocean, and the propeller noise is one of the major components of the ship noise. Measuring the propeller noise in a laboratory, despite the high accuracy and good reliability, has high costs and is very time-consuming. For this reason, the calculation of propeller noise using numerical methods has been considered in recent years. In this study, the noise of a propeller in non-cavitating conditions is calculated by the combination of the panel method (boundary element method) and solving the Ffowcs Williams-Hawkings (FW-H) equations. In this study, a panel method code is developed, and the results are validated by the experimental results of the model tests carried out in the cavitation tunnel of the Sharif University of Technology. Software for numerical calculation of propeller noise, based on FW-H equations, is also developed and the results are validated by experimental results. This study shows that the results of the panel method code have good agreement with experimental results, and that the maximum error of this code for the thrust and torque coefficients is 4% and 7%, respectively. The results of the FW-H noise code are also in good agreement with the experimental data.

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 Investigation on the Performance of a Ducted Propeller in Oblique Flow

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Qin Zhang ◽  
Rajeev K. Jaiman ◽  
Peifeng Ma ◽  
Jing Liu
Keyword(s):  
Open Water ◽  
Flow Dynamics ◽  
Navier Stokes ◽  
System A ◽  
Oblique Flow ◽  
Ducted Propeller ◽  
Blade Tip ◽  
Propeller Blades ◽  
Les Model ◽  
Thrust And Torque

In this study, the ducted propeller has been numerically investigated under oblique flow, which is crucial and challenging for the design and safe operation of the thruster driven vessel and dynamic positioning (DP) system. A Reynolds-averaged Navier–Stokes (RANS) model has been first evaluated in the quasi-steady investigation on a single ducted propeller operating in open water condition, and then a hybrid RANS/LES model is adapted for the transient sliding mesh computations. A representative test geometry considered here is a marine model thruster, which is discretized with structured hexahedral cells, and the gap between the blade tip and nozzle is carefully meshed to capture the flow dynamics. The computational results are assessed by a systematic grid convergence study and compared with the available experimental data. As a part of the novel contribution, multiple incidence angles from 15 deg to 60 deg have been analyzed with different advance coefficients. The main emphasis has been placed on the hydrodynamic loads that act on the propeller blades and nozzle as well as their variation with different configurations. The results reveal that while the nozzle absorbs much effort from the oblique flow, the imbalance between blades at different positions is still noticeable. Such unbalance flow dynamics on the blades, and the nozzle has a direct implication on the variation of thrust and torque of a marine thruster.

Prediction of Performance of Tip Loaded Propeller and its Induced Pressures on the Hull

2020 ◽  
Author(s):  
Seungnam Kim ◽  
Spyros A. Kinnas
Keyword(s):  
Open Water ◽  
Tip Vortex ◽  
Navier Stokes ◽  
Paper Briefly ◽  
Water Characteristics ◽  
Cavitation Performance ◽  
Numerical Predictions ◽  
Unsteady Wake ◽  
Wake Alignment ◽  
Initial Knowledge

Abstract In this paper, a boundary element method (BEM) is applied to a tip loaded propeller (TLP) to predict its open water characteristics and induced hull pressures under fully-wetted and uniform inflow. Tip of a TLP blade has a winglet-like tip plate on the pressure side to improve the overall propeller efficiency over the traditional open tip propellers by preventing circulation loss toward the tip region. TLPs are also used to reduce the tip vortex strength and thus free from the trade off the propeller efficiency against the cavitation performance; therefore, predicting their performance early in the designing stage via numerical applications can provide the initial knowledge on the loading distributions and cavitation performance. In the present method, the trailing wake is first aligned using the full wake alignment (FWA) scheme by aligning the wake surface to the local stream in order to satisfy the force free condition. The FWA is shown to improve the open water characteristics of the TLPs compared to the simplified alignment scheme that ignores the details of the flow behind the trailing edge due to the simplicity of the method. Afterwards, a pressure-BEM solver is used to solve for the diffraction potentials on the hull and estimate the propeller-induced hull pressures. In this case, both the FWA and the unsteady wake alignment scheme (UWA), which considers the time dependency of the problem, produce the same results as the testing flow is assumed to be uniform. This paper briefly introduces the model TLP, proper ways to consider the viscous effect on the blade surface, wake alignment scheme, and the pressure-BEM solver. Then, the predicted open water characteristics of the benchmark TLP and its induced hull pressures are compared to the experimental data, as well as the results from unsteady full-blown Reynolds-Averaged Navier-Stokes simulations for validations of the numerical predictions.

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