Propeller Open Water Research Articles

Marine propeller parametric optimisation and matching to electric motor

There is still room to establish a methodology to optimise marine propellers, considering design requirements of the vessel, and match it to an electric motor. The method proposed herein consists in an optimisation whose objective function is power required in the electric motor shaft, and design variables are the parameters of Wageningen B-screw series propellers. A differential evolution optimisation algorithm was programmed in MATLAB environment to assess a number of propeller designs. Technical constraints of strength, cavitation, and peripheral velocity were considered. An actual ferryboat designed to operate in a lake in south-eastern Brazil is proposed as the case study. The worst individual of the final population of propellers had its objective function increased by 25%, compared with the worst individual of the initial population, within only 123 s processing time. Substantially dissimilar propeller designs were found for direct and geared drive with open water propeller efficiency between 36.18 and 40.49%. The approach has shown significant gains as an early-stage design tool and highlighted the need for exploring a broad range of propellers to find the optimal motor–propeller matching.

Energy balance analysis of a propeller in open water

This paper proposes a methodology based on control volume analysis of energy, applied on Computational Fluid Dynamics (CFD) results, for analyzing ship propulsion interaction effects as a complement to the well-established terminology, including thrust deduction, wake fraction and propulsive efficiency. The method, titled Energy Balance Analysis, is demonstrated on a propeller operating in open water. Through consideration of a complete energy balance, including kinetic energy flux, turbulent kinetic energy flux, internal energy flux (originating from dissipation) and pressure work, all possible hydrodynamic losses are included in the analysis, implying that it should be possible to avoid sub-optimized solutions. The results for different control volumes and grid refinements are compared. The deviation of the power obtained from the proposed energy balance analysis relative to the power based on integrated forces on the propeller is less than 1%. The method is considered promising for analyzing and understanding propulsor hull interaction for conventional, as well as novel propulsion configurations. The energy balance analysis is conducted as a post-processing step and could be used in automated optimization procedures.

On the influence of transition modeling and crossflow effects on open water propeller simulations

At model scale propellers, conventional turbulence models assume turbulent regimes all over the blade surface, and consequently do not obtain accurate predictions that can be compared to experimental results. Two aspects could be improved in order to produce a better description of the flow complexity generated in these turbulent rotating systems: the inclusion of transition phenomena assumptions that normally take place in these flows and a particular modeling of those transition mechanisms, such as cross flow, that appear at model scale propellers.In this paper, a new modified γ−Reθ correlation-based model for transition prediction, that takes into account crossflow effects is applied to model scale ship propellers for a wide range of advanced ratios, and its results are compared to their corresponding experimental results. The average values of the skin friction coefficients on different parts of the blade and the streamlines distribution are studied and compared between different propellers. The results obtained with these improvements show an agreement of about 1% in terms of efficiency, and below 5% in terms of thrust and torque coefficients when compared to the experimental results at the design point.The dependance of the cross flow mechanism on the Reynolds number is studied by changing the rotating velocity of the different propellers. Results show that the relevance of this mechanism grows when the rotating velocity, the centrifugal forces and Reynolds number increase. Consequently, when the Reynolds numbers grows, the cross flow transition mechanism is stimulated by the action of the centrifugal forces.

Investigation of self-propulsion of DARPA Suboff by RANS method

In this study, the resistance and self-propulsion analyses of the benchmark DARPA Suboff with E1619 propeller have been done using Computational Fluid Dynamics (CFD) method. Single phase analyses have been carried out by assuming 3-D, turbulent, incompressible and steady flow, thus the governing equations (RANS Equations) have been discretized with finite volume method (FVM). First, verification and validation studies have been carried out in order to determine the optimum grid numbers for resistance analyses of bare and appended forms, and then for open water propeller analyses. The numerical studies have been done by taking the propeller-hull interaction into consideration by two methods for different velocities. First, the propeller has been modeled as an actuator disc based on body force method coupled with the experimental open water data. The propeller itself has later been modeled behind the hull with a rotating region. Performance analyses have been carried out at the self-propulsion points determined by these two methods. Self-propulsion characteristics have been estimated using thrust identity method. Finally, a comprehensive investigation of wake has been carried out by comparing the present results with those of other studies and the applicability of CFD on self-propulsion prediction of the underwater vehicles has been discussed.

Prediction of ship power and speed performance based on RANS method

This paper adopts virtual tank experimental technology to study ship rapidity performance. Based on RANS method, a new method is put forward to predict the speed and power performance of full scale ship. The open water performance of propeller model, the resistance performance of ship model and the self-propulsion performance of ship model are numerically calculated. Through the analysis of rapidity numerical results of fishing ship and the change law of wake flow field, some conclusions can be drawn. The numerical prediction accuracy of propeller open water efficiency has a direct influence on total thrust efficiency. The interference between hull, propeller and rudder leads to the formation of a lower pressure zone on stern hull surface and rudder surface. The axial velocity and radial velocity are affected by the interference between the flow of hull stern and propeller, the absolute value of axial velocity on blade leaf is smaller than that on blade back, and the radial velocity induces vortices on the blade tip of the propeller. The increase of propeller rotation speed nearly has no effect on the free surface wave pattern. The prediction results deviations of full scale ship speed and propeller rotation speed between RANS method and EFD method are 0.04 kn and 0.4 r/min, and therefore they are negligible. The proposed method can provide reference for engineering application.

A practical approach to the dynamic modelling of an underwater vehicle propeller in all four quadrants of operation

This article presents the open water propeller characteristics and the four-quadrant propeller models as applied to a torpedo-shaped underwater vehicle. A series of experiments with a Gavia autonomous underwater vehicle propeller were conducted in the towing tank using a rotor testing apparatus. The purpose of these tests was to measure the propeller thrust and torque under varying flow conditions and then to be used as the basis of the developed propeller models. These mathematical models were constructed using two regression models, a polynomial and a Fourier series. Model coefficients were derived using the method of least squares and a comparison analysis was also conducted to test the robustness of the methodology. Results show that the Fourier series models were able to produce a reasonable and accurate approximation of thrust and torque coefficients with a small number of parameters in the examined condition of this study. The obtained four-quadrant open water characteristics of the autonomous underwater vehicle propeller model would be utilised to improve the system mathematical model for more accurate simulation and controller design, to compare the autonomous underwater vehicle performance equipped with different propulsion units, and to validate computational fluid dynamic results.

Numerical Simulations for the Wake Prediction of a Marine Propeller in Straight-Ahead Flow and Oblique Flow

This paper presents the capability of a numerical code, isis-cfd, based on the solution of the Navier–Stokes equations, for the investigation on the hydrodynamic characteristics of a marine propeller in open water. Two propellers are investigated: the Istituto Nazionale per Studi ed Esperienze di Architectura Navale (INSEAN) E779A model in straight-ahead flow and the Potsdam Propeller Test Case (PPTC) model in oblique flow. The objectives of this study are to establish capabilities of various turbulent closures to predict the wake propeller and to predict the instability processes in the wake if it exists. Two Reynolds-averaged Navier–Stokes (RANS) models are used: the k–ω shear stress transport (SST) of Menter and an anisotropic two-equation explicit algebraic Reynolds stress model (EARSM). A hybrid RANS–large eddy simulation (LES) model is also used. Computational results for global flow quantities are discussed and compared with experimental data. These quantities are in good agreement with the measured data. The hybrid RANS–LES model allows to capture the evolution of the tip vortices. For the INSEAN E779A model, the instability of the wake is only predicted with a hybrid RANS–LES model, and the position of these instabilities is in good agreement with the experimental visualizations.

Numerical and experimental investigation of propulsion in waves

The effects of head waves on propulsion characteristics of a single and a twin screw ship were investigated based on a Reynolds-averaged Navier-Stokes (RANS) solver and physical tests. Initially, propeller open water characteristics were determined in a homogeneous inflow. Next, computations of the towed models without propeller(s) in calm water and in waves were performed to obtain calm water resistances and waves added resistances. Finally, forces acting on the self-propelled models in calm water and in regular head waves were computed. Using obtained results propulsion characteristics in calm water and in waves were determined. Computations were performed using a RANS based flow-solver coupled with the nonlinear six-degrees-of-freedom equations of motion. When needed, the sliding interface method was used, enabling rotation of the geometrically modeled propeller. All computations were performed on the same numerical grid to keep errors originating from different spatial and temporal discretizations as small as possible. Grid studies were conducted to evaluate discretization errors. Computational results were compared to experimental results obtained from physical model tests. It was shown that the RANS solver is capable of investigating the propulsion behavior of a ship in regular head waves. Fair agreement between numerical and experimental results was obtained.

Numerical Flow Simulation around HSP Propeller in Open Water and behind a Vessel Wake Using RANS CFD Code

Numerical Flow Simulation around HSP Propeller in Open Water and behind a Vessel Wake Using RANS CFD Code

An investigation of load change of propeller in a four-propulsion vessel using CFD

In this paper, an attempt has been made to investigate the effects of propeller load changes against its performance in open water conditions. Load change of different propellers in a multi-propulsion vessel varies and there is scarce research in this area. The authors have made an endeavor to get a better understanding of the factors causing the load changes in a four-propulsion vessel. The load change of propeller has been linearly decomposed into three parts: ship hull influence, pure interference of other propeller, and coupled effect. A series of CFD simulations has been carried out to realize the decomposition of the load change of propeller. Simulations of single propeller in open water were used to obtain the basis for load change calculation. Simulations of self-propulsion with four propellers were used to obtain the total load change of propellers. To estimate the influence of ship hull, simulations of self-propulsion with only inner or outer propellers were carried out and the load change of propeller in this condition was evaluated. Simulations of four propellers in open water were used to determine the pure interference on one by the other three propellers. The existence of coupled effect appears as the sum of ship hull influence and pure interference does not equate to the total load change of self-propulsion with four propellers. The coupled effect arises, because the interference of other propellers is influenced by the wake. It is found that the influence of ship hull accounts for most significant amount of 75.38% for inner propeller and 45.38% for outer propeller. It has been determined that pure interference accounts for about 10% for both inner and outer propellers. The coupled effect accounts 15.36% for inner propellers and 45.8% for outer propellers.

Two medium size cavitation tunnel hydro-acoustic benchmark experiment comparisons as part of a round robin test campaign

The increase in marine transportation in the last decades has resulted in a rise of the different emissions linked to it. Amongst various detrimental emissions of shipping activities, underwater noise is known to affect ambient noise levels and hence threaten the life (or even survivability) of marine mammals. This concern brought the underwater radiated noise (URN) to the attention of regulators, considering the possible need to limits for commercial ships, thus resulting in a surge of interest.As being the main contributor to the URN of ships, the accurate prediction of propeller cavitation and hence associated noise in the design stage is crucial for achieving reductions in terms of emitted sound pressure levels. Whilst computational methods are developing at an exponential pace and so are prospective tools for the future, model scale experiments still represent the most reliable and largely adopted approach for the prediction of propeller radiated noise. Despite the importance of model tests, being the only reliable tool for cavitation noise prediction, a benchmark data is non-existent for facilities all over the world to compare and correlate their noise measurements.Within this framework, this paper presents the first comparison of a round robin test campaign amongst the Noise CoP (Community of Practice) of Hydro Testing Forum (HTF). Based on the extensive experiments conducted first at Emerson Cavitation Tunnel (ECT), a reduced test matrix is proposed to the forum members. University of Genoa (UNIGE) is the first member to complete the tests specified in the reduced matrix and this paper presents comparisons between the test results of ECT and UNIGE cavitation tunnel in terms of measured sound pressure levels, propeller open water performance, cavitation observations and cavitation inception characteristics. Moreover, in order to shed a light on the issue of propeller cavitation noise measurements, a series of investigations are carried out by UNIGE scrutinizing the effect of hydrophone position, oxygen content, propeller shaft revolution rate, sensitivity to thrust coefficient and cavitation number.

P.O.W 상태에서의 Tip Rake Propeller에 대한 성능연구

P.O.W 상태에서의 Tip Rake Propeller에 대한 성능연구

Computation and Experiment of Propeller Thrust Fluctuation in Waves for Propeller Open Water Condition

Computation and Experiment of Propeller Thrust Fluctuation in Waves for Propeller Open Water Condition

Numerical Simulations Of Hydrodynamic Open-Water Characteristics Of A Ship Propeller

Abstract The paper presents the results of numerical simulations of ship propeller operation bearing the name of Propeller Open Water (POW) Tests. The object of tests was a sample ship propeller (PPTC1), the geometrical and kinematic data of which are available, along with the results of model tests, on the official page of the research centre involved in the measurements. The research aimed at verifying the correctness of results of numerical simulations performed in the model and real scale. The results of numerical analyses performed in the model scale were confronted with those measured in the experiment. Then, making use of dimensionless coefficients which characterise propeller’s operation, the recorded model data were extrapolated to real conditions and compared with corresponding results of simulations. Both the numerical simulations and the experimental research were performed for the same propeller load states. The reported research is in line with other activities which aim at developing advanced numerical methods to support the process of ship propeller designing.

Influence of Design Parameter Variations for Propeller-Boss-Cap-Fins on Hub Vortex Reduction

The present study aimed to identify significant design parameters on the propeller open water efficiency and characteristics of the wake field of a propeller with propeller-boss-cap-fins (PBCFs), with special attention to hub vortex dynamics. A towed underwater stereoscopic particle image velocimetry system was used to measure the near wake fields of a five-bladed propeller and a PBCF model. Through model tests, it was confirmed that the disappearance of a low-pressure area behind a boss cap, i.e., a reduction of the hub vortex, was the dominant contribution to open water efficiency gains from PBCF rather than a decrease in net torque. Global force and wake fields were also measured in response to design parameter variations of PBCF, i.e., fin chord length, fin span height, pitch angle, and phase lag. In the cases of pitch angle and fin chord length variations, PBCF with a light loading configuration had better open water efficiency than the baseline PBCF. However, in the case of a short fin span height for light loading configuration, the hub vortex was not entirely prevented, and the total open water efficiency decreased. Under heavy loading configurations, excessive negative and torque degraded the open water efficiency. Phase lag variations were less effective with respect to the open water efficiency than other design parameter variations.

Underwater radiated noise prediction for a submarine propeller in different flow conditions

International Maritime Organisation (IMO) and other bodies have been trying to set-up guidelines and regulations to reduce/limit noise levels at sea which influence marine life in particular marine mammals and certain fish types. Ships with low noise characteristics will be a must in the near future for almost all ship types. However for special ships, such as naval surface vessels, fishing vessels, submarines, etc. this has already been an issue because of their operational requirements. The propeller is one of the main sources of underwater noise generated by ships. Therefore, it is important to predict and control the underwater noise characteristics of propellers. In this respect, the main objective of this study is to calculate propeller radiated noise numerically. Propeller noise has been investigated numerically for the INSEAN E1619 submarine propeller in open water, behind a generic DARPA suboff submarine and within imposed wake cases at non-cavitating conditions due to their deeply submerged operations. Flow around the propeller is solved with a commercial CFD software using Unsteady Reynolds Averaged Navier–Stokes (URANS), while hydro-acoustic analysis is performed using a model based on Ffowcs-Williams and Hawkings equation. This paper reports the results of the study. The paper also includes the details of the bodies and discusses further improvement of the methodology applied.

RETRACTED: A new perspective on structural, materials, and simulation of flow and cavitation around the propeller with energy saving system

The propeller is the predominant propulsion device used in ships. It is difficult to determine the cavitation characteristics and determine the cavitation of a full-size propeller in open water by varying the speed and the revolution rate over a range. This paper presents review of erosion resistance materials, cavitation and effects of energy saving on the shape of current after propeller, on Waginigen B Series ship propeller type in open water system. Experiments are very expensive and time consuming, so the present paper deals with a complete computational solution for the flow using Ansys Fluent 14.0 software. When the operating pressure was lowered below the vapor pressure of surrounding liquid it simulates cavitation conditions. In the present work, Ansys Fluent 14.0 software is also used to solve advanced phenomena like cavitation of propeller. The simulation results of cavitation and open water characteristics of propeller are compared with the result of cavitation around marine propellers with energy saving devices.

프로펠러와 허브 보오텍스 조절장치 상호작용 CFD 해석

Many researchers have been trying to improve the propulsion efficiency of a propeller. In this study, the numerical analysis is carried out for the POW(Propeller Open Water test) performance of a propeller equipped with an energy saving device called PHVC(Propeller Hub Vortex Control). PHVC is aimed to control the propeller hub vortex behind the propeller so that the rotational kinetic energy loss can be reduced. The unsteady Reynolds Averaged Navier-Stokes(URANS) equations are assumed as the governing flow equations and are solved by using a commercial CFD(Computational Fluid Dynamics) software, where SST k-ω model is selected for turbulence closure. The computed characteristic values, thrust, torque and propulsion efficiency coefficients for the target propeller with and without PHVC and the local flows in the propeller wake region are validated by the model test results of KRISO LCT(Large Cavitation Tunnel). It is concluded from the present numerical results that CFD can be a good promising method in the assessment of the hydrodynamic performance of PHVC in the design stage.

Accounting for ship manoeuvring motion during propeller selection to reduce CO2 emissions

The aim of this research is to reduce Carbon Dioxide emission through enhanced propeller selection achieved by a more realistic identification of the true propeller operating point. By recognising that the ‘dead-ahead steady speed in flat calm water’ condition is not representative of the true operation of a ship in a seaway, a new paradigm is proposed. By taking into consideration the effects of wind and waves on the ship's true speed through the water and thus the probable load condition of the propeller, throughout the ship's mission, a probable propeller operating condition is identified. Propellers are then selected for both the original condition and the adapted condition, and their performance compared using time-domain mission simulations. The objective of the study is to demonstrate how the alternative propeller selection methodologies proposed, can on average provide greater overall efficiency.Results from the case studies are encouraging, with a gain of 2.34% in open water propeller efficiency for a 3600 Twenty foot Equivalent Unit container ship, equating to a saving of 3.22% in Carbon Dioxide emissions.

Steady cavitating propeller performance by using OpenFOAM, StarCCM+and a boundary element method

Accurate and reliable numerical predictions of propeller performance are a fundamental aspect for any analysis and design of a modern propeller. Prediction of cavitation and of cavity extension is another important task, since cavitation is one of the crucial aspects that influences efficiency in addition to propagated noise and blade vibration and erosion. The validation of the numerical tools that support the design process, including open-source codes, is, consequently, essential. The public availability of measurements and observations which cover not only usual thrust and torque in open water conditions (including cavitation) but also unsteady functioning with pressure pulse measurements in the case of the Potsdam Propeller Test Case certainly represents an extremely useful source of information and an excellent chance for verification and validation purposes. In the present work, the prediction of the Potsdam Propeller Test Case propeller performance using the OpenFOAM computational fluid dynamics package is proposed. After a preliminary validation and calibration of the OpenFOAM native Schnerr–Sauer interphase mass transfer model for cavitating flow, based on the experimental results on a 2D NACA66Mod hydrofoil, open water propeller performance and cavitation predictions are carried out. The OpenFOAM results are finally compared both with the available experimental measurements and with calculations carried out with StarCCM+ and with a proprietary boundary element method code, in order to assess the accuracy and the overall capabilities of the open-source tools (from meshing to post-processing) available in the OpenFOAM package. The comparison, in addition to assessing the accuracy of the open-source approach, is aimed to verify its advantages and drawbacks with respect to widely used solvers and to further verify the reliability of traditional boundary element method approaches that are still widely adopted for design and optimization (thanks to their extremely higher computational efficiency) in a very demanding test case.