Self-propulsion Tests Research Articles

Ship model self-propulsion instrument development and test verification

Abstract Aimed at the characteristics of high precision requirements and large environmental changes of the thrust and torque coupling test in the self-propulsion test of the ship model, the paper carries out the design of the instrument of the ship model test, the calculation of structural strength, the design of anti-jamming of the thrust and torque coupling, and the selection and realization of thrust and torque module. Based on the above, the instrument was calibrated with sensitivity coefficient, high and low temperature, and dynamic stability tests. Besides this, a self-propulsion test at the design speed point of a ship was carried out to verify the accuracy and environmental adaptability. From the static calibration result, the coefficient of determination is 1.0. The max zero drift of thrust and torque is 0.11% FS and 0.05% FS respectively from the low-high temperature test, and the max zero drift of torque under different revolutions is 0.23% FS from the dynamic test. In addition to the above, the max deviation between Maric-SP01 and R31 of thrust and torque is less than 0.78% and 0.65% respectively from the ship model self-propulsion test. So, in one word, the instrument has good reliability and accuracy and can meet the requirements of the ship model self-propulsion test.

Notes on Towed Self-Propulsion Experiments with Simulated Managed Ice in Traditional Towing Tanks

Efficiency estimation of a propeller behind a vessel’s hull while sailing through ice floes, together with the ship’s resistance to motion, is a key factor in designing the power plant and determining the safety measures of a ship. This paper encloses the results from the experiments conducted at the CEHINAV towing tank, which consisted of analyzing the influence of the concentration at the free surface of artificial blocks, simulating ice, in propeller–block interactions. Thrust and torque were measured for a towed self-propelled ship model through simulated broken ice blocks made of paraffin wax. Three block concentrations of different block sizes and three model speeds were studied during the experimentation. Open-water self-propulsion tests and artificial broken ice towed self-propulsion tests are shown and compared in this work. The most relevant observations are outlined at the end of this paper, as well as some guidelines for conducting artificial ice-towed self-propulsion tests in traditional towing tanks.

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.

Underwater noise measurements of a free-running ship model

ABSTRACT The high background noise and narrow widths of towing tanks, which cause sound wave reflections, make them unsuitable for noise measurements, leading to a lack of published hydroacoustic data. To address this, we developed a free-running test model of the benchmark DTC container ship at a 1/80 scale and conducted hydroacoustic tests in the artificial lake at Istanbul Technical University. The model was remotely controlled to pass a fixed water station equipped with a hydrophone. We present ship noise measurements at three different velocities, noting a strong correlation between the propeller rotation rates from self-propulsion tests and hydroacoustic signals at high speeds. However, accuracy decreases at lower speeds due to background noise interference.

Numerical Study of Self-propulsion Resistance of KCS Based on CFD

In this study, we used computational fluid dynamics (CFD) techniques to conduct self-propulsion tests to evaluate vessel resistance. We conducted self-propulsion calculations on the Korea Research Institute of Vessels and Ocean Engineering (KRISO) container ship (KCS) at a model scale, directly discretizing the propeller and rudder. We used the overset grid method, which allows the propeller to rotate arbitrarily during the calculation process, and used the volume of fluid (VOF) method for multiphase flow to handle the free surface effect. The accuracy of the computational results was verified by comparison with existing experimental data.

Numerical Analysis of The Effects of Propeller High Thrust Distribution on Propulsion System Performance

High ship propulsion performance is the main goal of designers, propeller is one component of the propulsion system that also affects the performance of the propulsion. In propeller planning, it is necessary to pay attention to the efficiency of the propeller, in addition to reducing ship operating costs and reducing CO2 gas emissions which is one of the requirements for ships built above 2013, the rules have been made into the Energy Efficiency Design Index (EEDI) standard. At this time the propeller that is widely used is the B Series propeller including the propeller design used on mini LNG ships, namely the B6.40 propeller, the B Series propeller has a pitch character from the Wageningen Propeller Series study. Innovations are made to get better propeller efficiency by varying the pitch distribution. The B6.40 propeller of the standard constant pitch type was modified to B6.40 variable pitch (high thrust). Propellers with high thrust have better efficiency especially for non-fast boats. This study was conducted to obtain the best propeller efficiency of a constant pitch propeller and three high thrust propeller units using Numeca's Computational Fluid Dynamics (CFD) numerical self-propulsion test. For validation of the simulation program by comparing the results of the open water test B6.40 Wageningen while resistance validation by comparing the ship resistance model test. The results of the self-propulsion test using Disc Actuator show that the propulsion coefficient (PC) of Modified-2 and Modified-3 high thrust propellers is better when compared to constant pitch. The magnitude of the increase in PC value reaches ± 4% higher than the constant pitch type on the Modified-3 propeller.

A study on the interaction among hull, engine and propeller during self-propulsion of a ship

Hull-engine-propeller matching is one of the key issues of ship design. It plays an important role in improving the economy and safety of ship navigation. The hull-engine-propeller matching is generally based on the Factory Acceptance Test of engine and the Sea Acceptance Test of ship. These conventional methods cost money and time. To overcome these defects, this paper proposes a simulation method based on the quasi-steady model of engine and CFD for ship hydrodynamics to study the interaction among the hull, engine and propeller, which provides the basis for ship-engine-propeller matching. Taking the PA6 diesel engine and the ONR tumblehome ship as the study objects, the quasi-steady model of engine is constructed by using simulation software and applied to carry out simulation under the operation conditions; the ship resistance test, propeller open-water test and self-propulsion test are simulated by using CFD method. Based on the simulation results, an integrated simulation platform is established for studying the hull-engine-propeller interaction. Further, the external characteristics of diesel engine under the effects of hull-engine-propeller interaction are predicted for the ship sailing straight ahead at different speeds. This paper provides a new method for studying the characteristics of hull-engine-propeller interaction.

Experimental assessment of the hydrodynamic characteristics of a bulk carrier in off-design conditions

This paper presents an extensive experimental study on the resistance and propulsion characteristics of the Japan Bulk Carrier in off-design conditions. The experimental campaign is carried out for a ship model at a scale of 40.264 for three loading conditions. Resistance, open water, and self-propulsion tests were performed at the Brodarski Institute for a wide range of speeds. Four extrapolation methods, based on different assumptions, were applied to predict the resistance and propulsion characteristics of the full-scale ship from model-scale experiments. The differences between the results obtained by different extrapolation methods and the effect of loading conditions on ship resistance and propulsion characteristics are discussed. This study provides a benchmark database for the validation of Computational Fluid Dynamics simulations.

Direct CFD simulations of standard maneuvering tests for DARPA Suboff

Maneuvering abilities of underwater vehicles are one of the primary concerns for navies and in the civil field they provide great flexibility in working in confined environments. Numerical simulations of the motions of these vessels may be conducted via system-based or direct CFD approaches. In this study, we focus on direct CFD simulations of the benchmark DARPA Suboff AFF8 Configuration. The paper starts by showing the submarine's lack of course-keeping stability using the C-index. After validation of the numerical approach by self-propulsion tests (and the determination of the propeller rotation rate to achieve the required velocity), the results of an extensive set of standard maneuvering tests are presented. Turning circle, pullout and zig-zag tests confirm that the DARPA Suboff does not have course-keeping ability. The submarine leans to the starboard side at neutral rudder angle. The maneuvering indices are investigated with respect to changing rudder angle with turning circle tests. High residual yaw rates are found in both side turnings in the pullout tests and the zig-zag tests show the submarine's inadequacy in making sharp turns. Numerical simulations reveal that the DARPA Suboff has high turning ability but no course-keeping ability.

A CFD investigation of the propulsion performance of a low-speed VLCC tanker at different initial trim angles

The backbone of global trade is now the maritime sector. In response to worries about global warming, a thorough analysis of ship greenhouse gas emissions (GHG) has been conducted recently. The International Maritime Organization (IMO) claims that trim optimization is an economical way to lower greenhouse gas emissions while increasing the economic efficiency of ships. This study uses computational fluid dynamics to optimize trim in low-speed situations on the KVLCC2 tanker model based on how trim affects propulsion and viscous resistance factors (CFD). This was achieved by simulating the double-body, resistance, and self-propulsion tests in two Froude numbers less than 0.15. The results validated with the available experimental data showed excellent agreement. Based on the analysis, 0.2° trim by bow decreased the total resistance, decreased propeller thrust, and enhanced hydrodynamic propulsive efficiency.

선미 부가물 수정에 따른 프로펠러 캐비테이션 성능 향상 연구

In order to improve the propeller cavitation performance composed of Cavitation Inception Speed (CIS), cavitation extent and pressure fluctuation, it needs to improve the wake distribution that flows into the propeller. The warship propeller cavitation is strongly influenced by the wake created at the V-strut of various appendages. The inflow characteristics of the V-strut were investigated using Computational Fluid Dynamics (CFD) and the twisted angles of the V-strut were aligned with upstream flow. The resistance and self-propulsion tests for the model ship with the existing and modified V-struts were conducted in Towing Tank (TT), and wake distribution, CIS, cavitation observation and pressure fluctuation tests were conducted in Large Cavitation Tunnel (LCT). The propeller behind the modified V-strut showed better cavitation characteristics than that behind the existing V-strut. Another model test was conducted to investigate rudder cavitation performance by the change of the V-strut. The rudder cavitation characteristics were not improved by the change of the operating conditions. On the basis of the present study, it is thought that the stern appendages for better propeller cavitation performance would be developed.

Investigation of the Effects of the Pre-Duct in a Ship on Propeller–Hull Interactions Using the CFD Method

The power requirement of a ship propulsion system is directly proportional to the fuel consumption and the emissions released. By reducing the engine power, the fuel consumption and emissions can be reduced. One of the energy saving devices (ESDs) that is positioned in a region between the stern hull and propeller is the pre-duct. The ESD can improve the propulsive coefficient of the propulsion system. This research explains the effect of a circular pre-duct on the hull-propeller interaction. A numerical simulation uses the Japan bulk carrier (JBC) standard model for the hull and propeller. A circular pre-duct was applied to the ship with different diameters, stands, and lengths of the chord. The simulation has already been validated with the result of the resistance and self-propulsion test in the towing tank. The results show that the diameter of the pre-duct affects the water flow to the propeller. The model with 1Dp can make the positive value of the propulsive coefficient be about 1.72%. The size of the foil chord of the pre-duct can improve the performance until 2.88% at 1D 2S NS model. The stand of the pre-duct has a bad effect on the propulsive coefficient. The enlarged shape of the foil pre-duct can increase the water flow on the suction side. Also, making the diameter larger than the propeller diameter and eliminating the stand on the pre-duct make the incoming flow has no resistance or damages the rotary flow before the propeller. So that, the rampant flow to the propeller becomes larger and there are no significant obstacles until the propulsive coefficient value increases significantly.

구속모형시험을 통한 잠수함 선형의 수상 조건 조종성능 추정 연구

In this paper, the results of Planar Motion Mechanism (PMM) test for a 1/15 scaled model of the MARIN Joubert BB2 submarine is dealt with to derive the maneuvering coefficients for surface condition. For the depth of surface navigation, the top of the sail was exposed 0.46 m above the water surface in the model scale, and it corresponds to 6.9 m in the full scale. The resistance and self-propulsion tests were conducted, and the model’s self-propulsion point was obtained for 1.328 ㎧, which corresponded to 10 knots in the full scale. The maneuvering tests were performed at the model’s self-propulsion point, and the maneuvering coefficients were obtained. Based on the maneuvering coefficients, a turning simulation was performed for starboard 30 degree of stern fins. The straight-line stability and control effectiveness in the horizontal plane were analyzed using the maneuvering coefficients and compared with the appropriate range. For the analysis of the neutral fin angle of the X-type stern fin, the stern fin test with drift angles was carried out. As a result, the flow straightening effect at lower and upper parts of the stern fin was discussed.

Propulsion performance prediction for towing ship

Towing of various objects is a common marine operation. There is a whole group of ships intended for this work, like tugs, fishing vessels, seismic survey ships and industrial vessels. Towing operations of these ships typically proceed at the speeds of 1–4 m/s. The assumptions used to determine pulling performance parameters of towing ships are usually over-simplified. This paper suggests an analytical and experimental method intended to determine pulling performance of propulsion systems for towing ships.Typically, pulling and propulsion performance parameters of ships are obtained through a calculation using the results of towing and self-propulsion model tests. However, this conventional approach is not applicable to pulling performance calculations of towing ships because self-propulsion test results for towing ships at the speeds corresponding to this operation scenario give absurd values for propeller-hull interaction coefficients. The classic system of propeller-hull interaction coefficients does not work for towing ships at low advance ratios.To overcome these difficulties, this paper suggests an alternative system of propeller-hull interaction coefficients that is applicable to towing ships and gives a calculation method of pulling performance calculation for towing ships based on this alternative system, taking Yuribei tugboat as a case study.

An improved BEMT model based on agent actuating disk with application to ship self-propulsion simulation

Propeller body-force model is a low-cost tool for numerical simulation of the ship self-propulsion test compared with discretized propeller model. As one of the most traditional theories of propeller model, Blade Element Momentum Theory (BEMT) has been proved to have considerable application potential with stability and accuracy. However, it's still hard for BEMT to keep accuracy in a relatively large range of working conditions due to unproved prior assumptions, which limits the application of BEMT in complex inflow conditions like ship self-propulsion. In the application of BEMT, the calculation method of Angle of Attack (AOA) has a great influence on the accuracy. In this paper, an "Agent Actuating Disk (AAD)" method is proposed to determine the AOA. AAD-BEMT method uses AAD to obtain the relationship between local velocity and inflow velocity so that the AOA can be defined by geometric Angle of Attack. This consideration avoids the inaccuracy of determining AOA by local velocity from discretized propeller flow field. The KP505 propeller open-water test is chosen to verify the accuracy of the proposed AAD-BEMT method. Then the numerical simulation of a KRISO Container Ship (KCS) self-propulsion test (Fr = 0.26) is carried out to investigate the performance of the AAD-BEMT body-force model as well as other different propeller models when dealing with non-uniform ship's wake. The open-water curve, propeller load distribution, and self-propulsion factor are presented and compared with the available experimental data. The results show that the predicted load distribution is accurate. In addition, not only the thrust and torque of the AAD-BEMT model can have a stable accuracy in a wide operating condition, but also the wake agrees well with the experimental result, which means that the proposed AAD-BEMT model can economically and accurately simulate the momentum transport of propeller under complex hull-propeller interaction condition.

대형 캐비테이션터널에서 펌프젯 추진기 자항성능 시험 및 해석 기법 연구

In order to study the self-propulsion test and analysis techniques for the submerged body with pumpjet propulsors in the Large Cavitation Tunnel (LCT), at the Korea Research Institute of Ships and Ocean Engineering, a set of test equipment was designed and manufactured. The pumpjet propulsor is composed of rotor, stator and duct which results in the strong interaction between the components. To measure the thrust and torque for duct and stator, a ring-shaped sensor was applied. The test equipment including pumpjet is installed on the stern of the submerged body. As the whole pumpjet including duct and stator was considered as the propulsor from pumpjet open-water test, the self-propulsion test was conducted in the same way. The total thrust, combined thrust of rotor, duct and stator was used for the pumpjet self-propulsion test analysis. Accordingly, the self-propulsion test and analysis were conducted in the same way as those of the conventional propeller. The full-scale performances of the pumpjet propulsor were compared with those of the reference propeller. On the basis of the present study, it is thought that the pumpjet propulsor would be designed optimally.

Ship maneuverability modeling and numerical prediction using CFD with body force propeller

To obtain an accurate ship maneuverability model for motion prediction and autonomous navigation, a ship maneuverability modeling and numerical prediction method is proposed based on Computational Fluid Dynamics (CFD). A Mathematical Model Group (MMG) model is utilized to describe the ship maneuverability with data from virtual captive model and free-running tests. Static Oblique Towing Test (OTT) and dynamic Circular Motion Test (CMT) are both performed to acquire necessary data for the MMG model identification. The forces and moments acting on ship hull are predicted by solving unsteady Reynolds-Averaged Navier–Stokes (RANS) equations. The MMG hydrodynamic derivatives are obtained with the results of captive model tests. In the free-running simulations, to reduce the computational cost of considerable propeller grids, a body force propeller method is introduced to provide thrust forces directly, and the ship motion is handled by overset grids of ship hull and rudder. A 3-degree of freedom MMG model is identified with numerical simulation results, i.e., the self-propulsion test, rudder angle 35°turning test and 15/1 zig-zag test, for a standard KRISO Container Ship (KCS). These tests show that the motion prediction and free-running maneuvering results can agree with the standard experimental data well.

Analysis of Self-propulsion Test for Propeller KP-505 with and without Pre-Swirl Stator

In recent times, environmental issues have become a major concern. The installation of Energy Saving Device (ESD) on ships is an alternative method developed to reduce energy use. One type of ESD that is widely used is the installation of a Pre-Swirl Stator (PSS). PSS consists of stator blades mounted in front of the propeller to regulate flow before entering the propeller. This paper describes the effect of PSS installation on the hull of a KP-505 propeller. The asymmetrical PSS design was developed with three blades on the port side and one on the starboard side. The analysis was carried out to obtain the Propulsive Coefficient (PC). The research was conducted using Computational Fluid Dynamic (CFD)-based simulation. The simulation results show that the addition of PSS increases the ship’s resistance up to 4%. However, the PC has also increased significantly up to 10.3, so it can reduce power requirements by up to 5.6%.

대형 캐비테이션터널에서 펌프젯 추진기 단독성능 시험 및 해석 기법 연구

In order to study the open-water test and analysis techniques for pumpjet propulsors in the Large Cavitation Tunnel (LCT), at the Korea Research Institute of Ships and Ocean Engineering, a set of test equipment was designed and manufactured. The pumpjet propulsor is composed of rotor, stator and duct resulting in the strong interaction between the components. A ring-shaped sensor was developed to measure the thrust and torque for duct and stator. The test equipment including the pumpjet is installed on an existing POW dynamometer in the reverse direction. The results from the reverse POW test setup were validated against those from the conventional POW test setup in the Towing Tank (TT) as well as in the LCT. The pumpjet open-water test was conducted at the Reynolds number of around 1.0×106, at which the obtained experimental data became stable in the Reynolds number effect test. The open-water test for the rotor (rotor-only) was conducted to study whether the duct and stator should be considered as a part of the hull or the propulsor. On the basis of the test results, it was shown that the duct and stator could be included in the propulsor. The total thrust, combined thrust of rotor, duct, and stator was used for the pumpjet open-water test analysis. As the whole pumpjet is defined as a propulsor, it is thought that the self-propulsion test and analysis could be conducted in the same way as that of the conventional propeller.

Propeller–hull interaction beyond the propulsive factors—A case study on the performance of different propeller designs

The propulsive factors are critical for scaling of model-test data, and hence important for the final power prediction. When comparing different propulsion systems based on model-scale tests, differences in propulsive factors, and hence the propeller–hull interaction, are often not well understood. In this study the propeller–hull interaction is instead described and compared using CFD for three different propulsion systems, a tip-unloaded ice-classed propeller, an ice-classed propeller with conventional radial load distribution and a non ice-classed propeller with conventional radial load distribution. To post-process the results KT/KQ is evaluated for one blade around a revolution and complemented with radial distributions of the same measure. Both tip-unloaded blades and sharp leading edges suffer in-behind due to poor performance at low load. Open water performance dependency on Reynolds number reveals that ice-classed propellers are more negatively influenced by the low Reynolds numbers of self-propulsion tests. Further, it is noted that a more even radial load distribution favours a low thrust deduction factor. Since the propulsive factors to a large extent are influenced by scale-effects and also due to that their association to the observed hydrodynamics makes the commonly applied scaling procedure of them questionable, they are not considered representative for ship-scale power prediction.