Propeller Open Water Research Articles

Experimental assessment of hull, propeller, and the gate rudder system interaction in calm water and oblique waves

This study focuses on the experimental assessment of the EU H2020 Innovation Action project GATERS' target ship, a 7241 DWT multi-purpose dry cargo ship (M/V ERGE), scaled to 1/27.1, in calm water and oblique wave (at a yaw angle of the ship model) conditions. M/V ERGE was initially built with a Conventional Rudder System (CRS) in 2010 but was later retrofitted with a newly introduced energy-saving device, the Gate Rudder System (GRS), in 2023 as part of the GATERS project. In this project, the interaction of the GRS with the hull and propeller was investigated using model tests of the vessel in the Kelvin Hydrodynamics Laboratory's (KHL) towing tank at the University of Strathclyde (UoS) and compared to the CRS. The main objectives of these tests were threefold. While they aimed to make experimental contributions toward the establishment of the best procedure for estimating the powering prediction of a ship with the GRS, they also aimed to investigate the hull, propeller and rudder interaction for the CRS and GRS configurations. In addition, a set of comparative pilot tests were conducted in waves to explore the effect of the oblique waves on the vessel's performance with the CRS and GRS. The resistance and self-propulsion tests were performed for both the CRS and GRS configurations, and performance predictions based on the model tests were compared with sea trials. Furthermore, tests at a yaw angle of the ship model were conducted to evaluate the effect of waves on the vessel's performance with the CRS and GRS, simulating the in-service conditions of commercial ships. These tests were conducted in regular waves with the hull at a yaw angle to simulate oblique wave conditions, with a wave height of 1.25 m in full scale (corresponding to moderate breeze, Beaufort 4) for a range of wavelengths. Numerical analyses were performed to obtain the full-scale propeller open water characteristics. The paper demonstrates the superior interaction of the GRS with the hull and propeller in both conditions compared to the CRS configuration, even improving its contribution to the vessel's performance in oblique waves.

Numerical simulations of the ONRT ship maneuvering in calm water and head waves with the partially rotating grid method

This research delves into the maneuverability aspects of a model-scale ONRT surface combatant ship using Computational Fluid Dynamics (CFD) simulations. A key aspect of this study is the comparison of the actuator disc (AD) model and the partially rotating grid (P) method in calm water, complemented by an in-depth analysis of the P method for simulations in waves. Utilizing these methods, the study investigates the performance of the ship in propeller open water, self-propulsion, and complex maneuvers like turning circle and zig-zag. Key findings highlight the superiority of the P method in closely aligning with experimental data, particularly in capturing complex dynamics of ship maneuvers. This research underscores the critical role of propeller side force in maneuvering simulations, a factor often neglected in simpler models like the AD. Maneuvers in head waves are also examined, revealing the nuanced effects of wave orientation on the stability and maneuverability of the ship. This study highlights the effectiveness of CFD in simulating ship maneuvers and the need for ongoing refinement of these techniques to improve accuracy and reliability.

Study on the interaction characteristics of hull-propeller-appendages of autonomous underwater vehicle based on unsteady conditions

In order to improve the hydrodynamic performance of autonomous underwater vehicle (AUV), a new method is proposed to study the AUV hull-propeller-appendages interaction in coupled mode, considering the coupling effect between the AUV hull, propeller and appendages, and to predict the self-thrust point. Based on the Reynolds mean Navier-Stokes (RANS) solver and the RNG k−ε turbulence model, the hydrodynamic performance of the propeller and AUV is predicted. The error between the predicted results and the experimental results is within 5%, which verified the correctness of the modeling method based on CFD. Finally, the thrust and torque generated by the open-water propeller and the propeller after the boat, the hydrodynamic characteristics of the naked AUV and the AUV with appendages, and the interaction between hull-propeller-appendages under different working conditions are studied. Experiments are carried out in Qiandao Lake, Zhejiang Province, China. The numerical simulation results of AUV at 1.76 m/s are compared with the experimental results of 1.5 m/s, and the correctness of the proposed interaction method is verified. The research results not only provide theoretical guidance for the design and operation of AUV, but also have important significance for improving the performance and reliability of AUV in complex underwater environments.

Impacts of regular head waves on thrust deduction at model self-propulsion point

The results obtained from the self-propulsion simulations using Computational Fluid Dynamics (CFD) in the current study, for a ship free to heave, pitch and surge with the means of a weak spring system, are combined with the formerly executed CFD results of the bare hull and propeller open water simulations to investigate the impacts of regular head waves on the propeller-hull interactions in comparison to calm water, at the self-propulsion point of the model. Despite a rather significant dependency of the nominal wake on the wave conditions, the Taylor wake fraction remains almost unchanged in different studied waves which is around 12% lower than the calm water value. The thrust deduction factor in waves is reduced (12.8%–26.1%) in comparison to the calm water value. The change of thrust deduction factor is found to be associated with the boundary layer contraction/expansion and vortical structure dynamics, originating from the wave orbital velocities as well as the significant shaft vertical motions and accelerations that resulted in a modified propeller action, and consequently diminished suction effect on the aft ship. The altered thrust deduction factor and wake fraction in waves in comparison to calm water underlines the significance of waves on the propulsive factors and propeller design.

Numerical Analysis and Validation of an Optimized B-Series Marine Propeller Based on NSGA-II Constrained by Cavitation

Constantly growing environmental concerns focused on reducing pollution, in addition to rising fuel costs in recent years, have led the maritime industry to develop and implement fuel-saving solutions. Among them is the optimization of marine propeller efficiency, as marine propellers are a crucial part of ship’s propulsion system. During the initial design stage, selecting the optimal propeller is considered a multi-objective optimization process. This research focused on maximizing propeller open water efficiency, while minimizing engine brake power constrained by thrust and cavitation. Optimization was applied to Wageningen B-series propellers and conducted using the Non-Dominated Sorting Genetic Algorithm II (NSGA-II). The algorithm selected optimum parameters to create the propeller model, which was then evaluated numerically through computational fluid dynamics (CFD) with a multiple reference frame (MRF) and under the SST k-ω turbulence model, to obtain the open water hydrodynamic characteristics. In addition, the cavitation effect was evaluated using the Zwart–Gerber–Belamri cavitation model. The numerical model results were validated through comparison with open water experimental data from the Netherlands Ship Model Basin for the Wageningen B-series propellers. The results showed errors of 3.29% and 2.01% in efficiency under noncavitating and cavitating conditions, respectively. Correct performance of the functions was shown, based on neural networks trained to estimate thrust and torque coefficients instead of polynomials. The proposed optimization process and numerical model are suitable for solving multi-objective optimization problems in the preliminary design of fixed-pitch marine propellers.

Design, Development and Commissioning of the Boldrewood Towing Tank – A Decade of Endeavour

The process of design, build and eventual commissioning of the towing tank on the Boldrewood Innovation Campus is described. The design brief required a facility that would have a capability to test models at a commercial scale but that would be effective as teaching environment for the next generation of Naval Architects as well as providing a flexible space for future fundamental research. Each of these provided their own challenges but the eventual solution of a 138 m long, 3.5 m deep, 6 m wide facility has more than met the initial aspirations. Equipped with 12 independent 0.5 m wavemaking flaps at the West end, a passive beach at the East end, a deployable side beach along the South wall for post run wave absorption and a monocoque Aluminium alloy carriage, the Boldrewood towing tank has now been successfully operating for more than a year. The carriage position and speed are controlled by a twin winch arrangement using a laser positioning system and low embodied energy composite cables. The carriage can reach a maximum speed of 10 m/s with controllable acceleration rates and can have up to four constant speed phases per run. Initial commissioning results and comparisons with benchmark data for the KCS hull confirm the accuracy and repeatability of the facility. In particular, the position and speed of the carriage are known to a high level of precision. To date research and consultancy work has spanned the performance of high speed vessels, uncrewed underwater and surface vessels, wave energy and tidal current systems, floating platforms for wind turbines, performance sport work for sailing, kayaking, rowing and swimming, open water propeller tests as well as conventional displacement vessel testing for self-propulsion and resistance. All ship science and maritime engineering students use the facility as part of their taught modules in every year of their programme as well as for individual, MSc and group projects as appropriate. It has also made a strong impact on the many thousands of visitors a year to the campus for science and engineering open days.

CFD Analysis on the Development of Pre-Duct Shape to Improve Propeller Performance

Energy saving contributions of Energy Saving Device (ESD) Pre-Duct are reducing energy losses and separation at the stern, increasing the ideal propeller efficiency, increasing the capture of viscous wake that passes through the propeller disk, and increasing the interaction of the propeller and ship hull. The effect of ESD Pre-Duct in front of the propeller on saving of energy is influenced by the accuracy and suitability of the geometry, position, and shape of pre-duct. In this study, the shape of the asymmetric un-circular pre-duct was develop and analysis conducted by compared the effect of the shape of pre-duct on the performance of propeller, the shape of pre-duct: circular (conventional), un-circular, and asymmetric un-circular. Computational Fluid Dynamics (CFD) modelling results using the ANSYS CFX software package with Propeller Open Water (POW) test simulations show that the installation of pre-ducts with several shape developments in general has a significant effect on increasing propeller performance at low propeller rotation speeds, whereas on high propeller rotation even though there is an increase in propeller performance but not significant.

Effect of salinity on marine propeller performance

In order to analyse problems with fluid flow, computational fluid dynamics is one of the most helpful tools available. This paper presents a numerical simulation of the effect of salinity on a marine propeller of an aircraft carrier in advance of the propeller open water (POW) test. A five-bladed fixed-pitch propeller is analysed using an unstructured mesh in the flow domain (PPTC - VP1304). Solving the RANSE equations describing the flow with a streamlined solver To begin, the accuracy of the numerical model was checked by comparing the results to previously published experimental data on the propeller. The verified model was then used to investigate how salinity impacted propeller performance in open water. The effect of fluctuating salinity was investigated by adjusting the properties of the flow fluid in a computational model. Lower advance ratios are where the effect of salinity, a decrease in efficiency of up to 4%, really shows up. However, it had little to no effect at higher advance ratios.

Noise field properties of marine propellers in open water

Aim of the paper is to gain a physical understanding of the main noise generating mechanisms related to vorticity and turbulence downstream the disk of a marine propeller in open water. Through the application of the Ffowcs Williams and Hawkings acoustic analogy (FWH) for permeable surfaces, the analysis of the noise field generated by the INSEAN E779A propeller model at different advancing ratios allows to detect correlations between acoustic signatures in the near/mid field and wake evolution. Turbulence noise-induced effects are captured by combining the FWH formulation with a Detached Eddy Simulation (DES) of the flow past the propeller. Besides, a phase-locked post-processing of the unsteady DES data on the acoustic surface is used to yield FWH signatures governed by vorticity effects, which are then compared with the pressure fluctuations predicted by the Bernoulli equation, within a potential hydrodynamics platform solved by a Boundary Integral Element Method (BIEM). It is found that turbulence is the most annoying source of propeller noise, whereas vorticity-driven phenomena are important only in a narrow region surrounding the propeller. Moreover, numerical results highlight that acoustic pressures are correlated to the vortex pairing hydrodynamic phenomenon associated to a blade-to-shaft harmonic energy transfer, detected in literature by time-resolved visualizations and velocimetry measurements.

A CFD-based evaluation of ship speed at EEXI draft

This paper presents a simulation of ship speed for an existing containership at EEXI draft using Computational Fluid Dynamics (CFD). The simulation is divided into two steps namely (a) the numerical prediction of ship performance at model scale, and (b) the extrapolation of results to full scale. Model scale numerical simulations of ship resistance, open-water propeller and ship-propeller-rudder interactions at demonstrated. The method is at first validated by comparing against available experiments and at second stage full-scale ship performance is assessed by an extrapolation method. Comparison of the ship speed predicted by CFD against experiments demonstrates a difference of 0.05 knots when the same extrapolation coefficients are applied.

A Calibration Study with CFD Methodology for Self-Propulsion Simulations at Ship Scale

This paper summarises the main findings from the full-scale Computational Fluid Dynamics (CFD) analyses conducted at SINTEF Ocean on the case of MV REGAL, which is one of the benchmark vessels studied in the ongoing joint industry project JoRes. The numerical approach is described in detail, and comparative results are presented regarding the propeller open water characteristics, ship towing resistance, and ship self-propulsion performance. The focus of numerical investigations is on the assessment of the existing simulation best practises applied to a ship-scale case in a blind simulation exercise and the performance thereof with different turbulence modelling methods. The results are compared directly with full-scale performance predictions based on model tests conducted at SINTEF Ocean and sea trials data obtained in the JoRes project.

Hydrodynamic Tests of Innovative Tourist Submarine

This paper deals with the resistance, towing, seakeeping, and open water propeller tests of an innovative tourist submarine model. Tests were performed in a 276 m long towing tank. As the submarine model is a complex structure composed of various parts attached to the pressure hull, the largest possible model, in the scale of 1:5.0, was produced, considering the towing tank depth and the capabilities of the measurement equipment. Resistance tests were performed in deep water and on the surface in calm water. The tested speed range in both cases was up to 5.5 knots. To ensure the avoidance of free surface effects, resistance tests in deep water were performed for different draughts and then extrapolated to infinite water depth. Smaller effective powers were found for the surface condition. The results are compared to an independently performed computational fluid dynamics (CFD) analysis using OpenFOAM. A fair agreement between the experimentally and numerically predicted effective power is found, while the reasons for the differences found are explained. The free submarine model was towed with a rope performed for the speed range 1.7 kn–3.5 kn, and the towing force in the rope was measured. Seakeeping tests in irregular beam waves at zero speed were performed to check the flooding risk on open hatches. Open water tests of the main thrusters for propelling the submarine were conducted, indicating that both power demand and propeller thrust are slightly larger compared to the initial estimates.

Computational fluid dynamics analysis of different propeller models for a ship maneuvering in calm water

High-fidelity numerical analysis is performed to compare two common propeller models for surface ship maneuvering in calm water. The propeller models consist of a body force model based on an open water propeller test and a discretized propeller model. Turning circle and zig-zag maneuver are performed for the Office of Naval Research Tumblehome (ONRTH) with different propeller models to compare the predicted maneuvering characteristics against model test data. The results show that the discretized propeller model offers a more accurate prediction of ship maneuvering compared to the body force model adopted in this study. Lack of the propeller side force in the body force model is one of the contributors to the lower accuracy of the body force model compared to discretized propeller model. Detailed analysis of the flow field also reveals some of the shortcomings of the body force model in accurately predicting the hull, propeller and rudder interactions.

Enhancement of the Robustness on Advancing Layer Method with Trimmed Hexahedral Volume Mesh for the Generation of the Boundary Layer Grids

When performing simulations using computational fluid dynamics, the grid systems in the viscous boundary layer regions are important because the velocity and pressure change very rapidly in these regions. Especially for the turbulent flows, thin grids should be arranged densely in the direction perpendicular to the wall. In this study, the advancing layer method, which has been applied mostly to tetrahedral meshes, is applied to trimmed hexahedral meshes. To generate boundary layer meshes with non-intersecting grid lines near the wall boundaries having concave corners and narrow gaps, the directional vectors of grid lines and faces are smoothed, and the displacement vector fields calculated using the Laplace equation were utilized. Firstly, the details on the newly developed methods are introduced showing simple two-dimensional cases as examples. After applying the methods for a complex three-dimensional geometry to check its applicability and investigating the generated grid systems, the numerical simulations of propeller open water test for INSEAN E779A marine propeller were carried out by simpleFoam, one of the standard solvers of OpenFOAM. The computational results showed good agreement with the experimental results. Therefore, in conclusion, the developed advancing layer method is an appropriate method for generating boundary layer grids of a trimmed hexahedral mesh.

Design optimization of an AUV for performing depth control maneuver

A methodology for optimizing the inertial characteristics, propeller, battery capacity and PID (Proportional Integral Derivative) controller for propeller of an Autonomous Underwater Vehicle (AUV) is proposed in this paper. The AUV is launched at high speed in horizontal orientation, thereafter it pitches bow down and finally hovers at a particular desired water depth. The study involves both positively and negatively buoyant AUV. Four quadrant propeller open water model and quaternion are incorporated in the Maneuvering Modeling Group (MMG) type maneuvering model to make it suitable for 7 degree of freedom (DoF) dynamics. The bow down orientation is performed due to the inertial characteristics of the AUV, while the depth control maneuvering of the AUV is carried out by using PID controller for propeller revolutions. A cost function is proposed in terms of energy consumed and the distance traveled by AUV during the desired maneuver. The numeral value of cost function can be computed by carrying out numerical simulations. The numerical simulations can estimate when the AUV's propeller works in turbine mode. This information is useful for protecting the electric/electronic components of the AUV.

UNCERTAINTY QUANTIFICATION OF SELF-PROPULSION ANALYSES WITH RANS-CFD AND COMPARISON WITH FULL-SCALE SHIP TRIALS

RANS-CFD is a well-established tool with widespread use in maritime industry and research. Valuable information might be extracted from the results of such simulations in terms of ship resistance and flow field variables. With recent advancements in computational power, it became possible to investigate the performance of ships in self-propulsion conditions with RANS method. This paper presents the results of a study in which self-propulsion analyses of a small size product/oil tanker has been carried out at ship scale. The methodology proposed in this study makes use of open water propeller performance predictions, resistance analyses at model scale and self-propulsion computations at ship scale for a minimum of 2 different propeller loadings to obtain the self-propulsion point and respective performance parameters. In order to speed up the time-consuming self-propulsion computations, these cases have been solved with a single-phase approach. Resistance predictions have been compared with experimental findings. Uncertainty associated with prediction of resistance and thrust has been quantified. Additionally, sea trials have been conducted on the subject vessel and its two sisters and measured delivered power data have been used for evaluating the capability of the numerical method in self-propulsion predictions. Comparison of results indicate that the proposed self-propulsion computation methodology with RANS CFD at ship scale is capable of predicting delivered power with sufficient accuracy at an acceptable computational cost.

A Validation Simulation using OpenFOAM: Nozzle Length and Angle Effect on the Ducted Propeller Performance

The use of numerical simulation is needed for predicting the performance of the ship. The Computational Fluid Dynamics (CFD) method is based on the improvement of Reynold-Average Navier Stokes (RANS) equation, in order to compute the simulation for solving the engineering problem. The simulation was begun by conducting several calculations to validate the numerical method applied in open water propeller test. A Kaplan type propeller is selected with 19A nozzle. The Moving Rotating Frame (MRF) method was selected to test the ducted propeller performance by modifying the nozzle length and angle. The model was designed in Computer-Aided Design (CAD) program and predicted the performance using the OpenFOAM. The OpenFOAM was used as open source CFD tool. The results are validated by comparing with experimental value of J from 0.2 to 0.8 and produced the thrust, torque and efficiency trends in good agreement with experimental data. Due to the results, can be conclude that by increasing the nozzle length to 10% and 20%, the thrust was decreased about 2.25% and 3.01% at low advance coefficient to 7.06% and 9.41% at high advance coefficient. By increasing the nozzle angle, both thrust and torque were increased while efficiency decreased especially at low coefficient.

Analysis of Uncertainties in Open Water Test of B-Series Propeller at Indonesian Hydrodynamic Laboratory

A propeller’s performance characteristics in open water typically refer to the variation of its thrust, torque, and efficiency with speed and revolution rate. This investigation provides a method for gaining a better understanding of the achievable accuracy. of the open water propeller test and presents an example of how to conduct a comprehensive uncertainty analysis of prediction models4 blades B-series model propeller, diameter 157.59 mm, pitch ratio 1.133 and Blade Area Ratio (BAR) 0.65 was carried out for this study. The methodologies presented using the ITTC recommended procedure to obtain individual measurement systems, measurement of individual variables, data reduction and experimental results. The bias limits for the individual measurement systems are estimated: propeller geometry, speed, thrust, torque, propeller rate of revolution, and temperature/density. The precision limits for single and multiple runs have been determined for the thrust coefficient (K T ) and torque coefficient (K Q ) for one advance coefficient (J), 5 sets of tests with 3-speed measurements in each set are conducted, totaling 15 test runs. The experimental test results have represented as relative numbers the bias for K T represents 98.1 % and the bias for K Q represents 99.4 % of the total uncertainty for the mean value of 15 tests. The uncertainty analysis results of the open water propeller were recommended in an acceptable range of the 95% level of confidence.

Numerical Study of Scale Effects on Open Water Propeller Performance

The present study aims to investigate the scale effects of the open water propeller performance using computational fluid dynamics (CFD). The results are presented for the propeller which was previously 3D scanned and digitized. The results obtained using two turbulence models within the numerical simulations are compared. The verification study is conducted to assess the numerical uncertainty and thus obtain the optimal grid size for the numerical simulations. A transition model is used at the model scale to account for the partially laminar flow. The propeller is then scaled, and numerical simulations are performed to assess the scale effects on the open water performance of the considered propeller. The results demonstrate the significant scale effects on open water characteristics however, scale effects are considerably lower when the transition model is applied within the numerical simulations at the model scale.

Effects of Rudder and Blade Pitch on Hydrodynamic Performance of Marine Propeller Using CFD

Abstract The use of computational fluid dynamics (CFD) to predict internal and external flows has risen dramatically in the past decade. This research aims to use the commercial software, ANSYS Fluent V.14.5, to illustrate the effects of the rudder and blade pitch on the hydrodynamic performance of the marine propeller by experimenting with propellers and rudders of the M/V Tan Cang Foundation ship, which has designed conditions as follows: diameter of 3.65 m; speed of 200 rpm; average pitch of 2.459 m; boss ratio of 0.1730. Using CFD, the characteristic curves of the marine propeller and some important results showed that the maximum efficiency of the propeller is 0.66 with the open water propeller and 0.689 with the rudder‒propeller system at the advance ratio of 0.6. The obtained outcomes of this research are a significant foundation to calculate and design an innovative kind of propulsion for ships with high performance.