Ship Propulsion System Research Articles

Propeller performance on a model ship in straight and steady drift motions from single blade loads and flow field measurements

In the field of marine hydrodynamics, propeller operations in off-design conditions represent a challenging topic that has been increasingly attracting interest among industry and research institutions. Over the ship operating life, off-design conditions and the associated modifications of the propeller inflow are connected to a wide range of events such as degradation of the overall efficiency, amplification of unwanted side effects of propeller operations (pressure pulses, vibration and noise) and, ultimately, failure of the ship propulsion system. In this work, the performance of a propeller operating in off-design conditions is investigated by a comprehensive experimental activity aimed at synthesizing the cause-and-effect relation between the propeller loads and its inflow. To this purpose, two novel set-ups are employed: the first one is dedicated to the measurement of single blade loads, whereas the second, a boroscopic-based Stereo-PIV (SPIV) system, is focused on the inflow analysis. The overall measurement apparatus is installed on a twin-screw ship model. Experiments, carried out in the CNR-INM towing tank, consist of straight ahead and steady drift motions at drift angles ±13∘ and ±27∘. This test matrix is representative of weak and tight maneuvering conditions.

A Method for Blind Source Separation of Multichannel Electromagnetic Radiation in the Field

Considering the multichannel instability, spectral overlap and strong interference of electromagnetic radiation signals in the integrated electric propulsion systems of ships, a new method is proposed which combines multivariate empirical mode decomposition (MEMD) with independent component analysis (ICA) for synchronous blind source separation of multichannel electromagnetic radiation in the field. In order to construct virtual channels, noise-aided MEMD is first applied to decompose multichannel data in this approach. Then the comprehensive screening algorithm is used to filter the intrinsic mode functions (IMFs) produced by the decomposition procedure. Finally, the new multivariate input signal is analyzed after screening using ICA to obtain the original electromagnetic radiation source signal. This method is able to effectively addresses several limitations of EMD including the mode mixing problem, its inability to handle multichannel data, as well as the indeterminacy problem in ICA. The efficacy of the MEMD-ICA algorithm was evaluated using simulated signals and real world data from a cruise ship, and comparing ensemble empirical mode decomposition-ICA(EEMD-ICA).

Marine powertrain simulation for design and operational performance evaluation

This research investigates the performance of a propulsion system and the emissions parameters of a merchant ship by using the consequences derived via a modular ship simulation model that is executed in MATLAB/Simulink. In the model, numerous components of the drive system such as engine, shafting framework, propeller, and vessel are shown by separated blocks whereas proper interfaces and connections are utilised to swap the desired factors between the blocks. Therefore, the created model can be used to explore the steady state and transient behaviour of the ship propulsion system and investigate the engine/propeller/shafting framework and vessel connections. Using this model the performance parameters of a ship in normal speed and slow steaming were calculated and investigated. In addition, the ship's powertrain system was investigated using distributed-lumped parameter model. The shear stress analysis of the propeller shaft was performed using a distributed-lumped model and compared in two normal speed and slow steaming modes. Due to the model's modular structure, its components can be modified and extended to be used in future new technologies and fuel evaluation as a part of the ship designing process.

Remote interactive platform for matching design of ship screw propeller and diesel engine based on Internet Plus

In order to meet the requirements of the remote ship propeller matching design, and can feed the measurement data to the offshore calculation model to guide the design of the ship propulsion system...

High-Power Electric Ship Propulsion Systems with Advanced Frequency Converters

High-Power Electric Ship Propulsion Systems with Advanced Frequency Converters

Remote interactive platform for matching design of ship screw propeller and diesel engine based on Internet Plus

In order to meet the requirements of the remote ship propeller matching design, and can feed the measurement data to the offshore calculation model to guide the design of the ship propulsion system, this paper designed a screw propeller matching computing platform based on the internet. The platform was built on the B/S architecture, combined with MATLAB and C# for mixed programming, and used EasyUI plug-in set to design user interface. The open water characteristics of the ship were selected as the fundamental data of the whole process of matching calculation. The platform was tested by three parts: the preliminary matching, ultimate matching and cavitation checking. By comparison, the difference between calculated value and actual value is very small, which can meet the accuracy requirements. This platform can provide an engineering basis for the online working condition monitoring of the ship power system and the dynamic matching of the ship propeller in the 'Internet Plus' environment in future.

Partial Frequency Assignment for Torsional Vibration Control of Complex Marine Propulsion Shafting Systems

With the large-scale and complexity of ship propulsion shafting, it is more difficult to analyze and control the torsional vibration of shafting. Therefore, an effective control method for the torsional vibration of shafting is of great significance in the field of ship engineering. The main strategy of torsional vibration control adopted in this paper is to keep the natural frequency of a shaft system away from the excitation frequency through structural modifications. In addition, because the basic parameters of much of the equipment in engineering applications cannot be changed, this restriction cannot be ignored when seeking solutions related to structural modifications. This paper studies the partial eigenvalue assignment for the torsional vibration control of complex ship propulsion shafting using the gradient flow method, which can shift a “dangerous” natural frequency to a safe value, while satisfying complex physical constraints. The models of a ship propulsion system and a diesel generator set are established to demonstrate several different desired modification schemes and constraint conditions in practice. In particular, close frequencies are shifted. The numerical simulation results demonstrate that it is effective and feasible to make a partial frequency assignment of torsional vibration, which provides a reliable approach for the control of torsional vibration for complex shaft systems in practical engineering.

Hybrid fuel cell and battery propulsion system modelling and multi-objective optimisation for a coastal ferry

Efforts from all sectors of society including the shipping industry are needed to limit the overall global temperature rise to within 2°C of pre-industrial levels by 2050. The hybridisation of Proton Exchange Membrane Fuel Cells (PEMFC) and Lithium-ion batteries for coastal ship propulsion systems may potentially offer beneficial emission performance. However, such hybrid systems are constrained by power and energy density limitations, lifetime; and costs as well as life-cycle emissions of alternative fuel/energy. There is a lack of holistic design methodology dealing with these uncertainties in the literature. This paper proposes a holistic design methodology for coastal hybrid ships based upon a developed model. The power source sizing problem is solved using constrained mixed-integer multi-objective optimisation in the external layer. The global optimum energy management strategies for an averaged operating profile are obtained from deterministic dynamic programming in the inner layer, while considering power source degradations in the sizing algorithm. The proposed methodology was applied to a coastal ferry to investigate the feasibility and benefit potential of adopting the hybrid PEMFC and battery propulsion system in Matlab. The case studies indicate that the proposed propulsion system can achieve at least a 65% life-cycle greenhouse gas reduction for the considered two cases.

함정 추진체계 동적 시뮬레이션을 위한 가변추진기 수학 모델 개발

함정 추진체계 동적 시뮬레이션을 위한 가변추진기 수학 모델 개발

Random response of highly skewed propeller-shafting system induced by inflow turbulence

The random responses of a highly skewed propeller-shafting system in both axial and radial direction induced by inflow turbulence are numerically studied. Firstly, a fine finite element model is established, including propeller, shaft and surrounding fluid. The force-force transfer function matrix between each exciting node on the blade surfaces and the corresponding transmitted force is formed based on the FEM model. Secondly, the unsteady hydrodynamic pressure spectrum acting on the blade surface is calculated on the basis of strip theory and mapped onto all nodes that distribute on the blade surfaces. Finally, the random response of the system and the power spectral densities of the transmitted forces from both axial and radial bearings are obtained. By employing the numerical method, the relationship between the force amplification effect and the modal characteristics of the highly skewed propeller-shafting system is discussed. Furthermore, the influence of system dynamic parameters, such as propeller elasticity, axial and radial bearing stiffness on the random vibration is analyzed, which can thus provide a reference for the design of low noise propulsion system for ships.

Influence of EEDI (Energy Efficiency Design Index) on Ship–Engine–Propeller Matching

With the increasingly strict international GHG (greenhouse gas) emission regulations, higher requirements are placed on the propulsion system design of conventional ships. Playing an important role in ship design, construction and operation, ship–engine–propeller matching dominantly covers the CO2 emission of the entire ship. In this paper, firstly, a ship propulsion system matching platform based on the ship–engine–propeller matching principle and its application on WinGD 5X52 marine diesel engine have been investigated. Meeting the energy efficiency design index (EEDI) regulation used to calculate the ship CO2 emission is essential and ship–engine–propeller matching has to be carried out with EEDI into consideration. Consequently, a procedure is developed combining the system matching theory and EEDI calculation, which can provide the matching results as well as the corresponding EEDI value to study the relationship between EEDI and ship–engine–propeller matching. Furthermore, a comprehensive analysis is performed to obtain the relationship of EEDI and system matching parameters, such as ship speed, effective power and propeller diameter, reflecting the trend and extent of EEDI when changing these three parameters. The results of system matching parameters satisfying different EEDI phases indicate the initial value selection in matching process to provide reference for the design of ship, engine and propeller under the EEDI regulations.

Nonlinear optimal control for ship propulsion systems comprising an induction motor and a drivetrain

The article proposes a nonlinear optimal [Formula: see text] control method for electric ships’ propulsion systems comprising an induction motor, a drivetrain and a propeller. The control method relies on approximate linearization of the propulsion system’s dynamic model using Taylor series expansion and on the computation of the state-space description’s Jacobian matrices. The linearization takes place around a temporary operating point which is recomputed at each time-step of the control method. For the approximately linearized model of the ship’s propulsion system, an H-infinity (optimal) feedback controller is developed. For the computation of the controller’s gains, an algebraic Riccati equation is solved at each iteration of the control algorithm. The stability properties of the control method are proven through Lyapunov analysis.

Thrust Prediction of an Active Flapping Foil in Waves Using CFD

A horizontally submerged passive flapping foil can generate thrust force against the wave propagation using wave energy. This renewable method has been used for the design of propulsion and maneuvering systems of ships and other floating structures. Recently, the passive flapping foils were applied to design the station-keeping system of deep-water floaters. Studies proved that the passively flapping foil system was ineffective in short waves and drift of the floater beyond the design limit was recorded. Therefore, an active flapping foil was investigated as a potential solution to this problem. A computational fluid dynamics (CFD) numerical tool “ANSYS Workbench 19.2” was used to predict the thrust force generated by the active flapping foil in a short wave. Results proved that the active flapping foil can effectively convert wave energy into propulsive energy in short waves and the magnitude of the thrust force depends on the flapping frequency.

Choice of fuel system for the offshore support fleet

The stringent requirements of the IMO’s emission regulations call for alternative fuels and new ways of powering ships. However, the IMO predicts that technology which could reduce ship emission to zero, will either not be available, nor cost-efficient over the next 40 years. However, technological innovations in ship power & propulsion systems; such as duel-fuel LNG engines, and the utilization of energy storage technology in the form of lithium-ion batteries have been found to reduce harmful emissions; and are already utilized to quite some extent in the offshore support fleet. This paper elaborates on the reliability and sustainability of newer ship power technologies, where equal to existing levels of reliability are expected as a minimum.

Energy effectiveness of ocean-going cargo ship under various operating conditions

The increasing economic cost and environmental impact of maritime transportation necessitate the reduction of fossil fuel consumption of ocean-going cargo ships. Although fundamental ship propulsion system theory is well-known and is at a mature stage of development, there is still an enormous variety in the assessment methodology of (environmental) transport performance of ships. Furthermore, calibration of ship propulsion system model parameters with testbed, towing tank and full-scale measurement data is rare, as these measurements are both difficult and expensive. Finally, the effects of different power management strategies on the ultimate energy conversion effectiveness of typical cargo ships have rarely been investigated systematically. In this paper these three issues are discussed, addressed and solved for a representative benchmark chemical tanker. This ship was chosen to investigate the so-called energy conversion effectiveness under various propulsion control and electric power generation modes, as ample real ship data is available. The transport performance assessment of the ship's power plant is generalised for hybrid arrangements with either Power-Take-Off or Power-Take-In. The results show that an optimal combination of propulsion control, power management and voyage planning will further reduce the global fuel consumption and CO2 emissions produced by the shipping industry.

A Concept Design of Diesel – Hydraulic Propulsion System for Passenger Ship Intended for Inland Shallow Water Navigation

Abstract This paper presents an analysis of environmental and technical conditions necessary for working out a possibly most favourable propulsion system for a two – segment passenger ship intended for navigation between Berlin and Kaliningrad. There are presented various types of propulsion systems for small ships as well as analyzed their possible applications and consequences. In this work there were taken into account system’s reliability, efficiency, dimensions, mass and costs of manufacturing, assembling and possible replacing the system components as well as an impact on maneuverability and natural environment. With taking into account the above mentioned criteria it was finally found that the diesel-hydraulic system fitted with two azimuthal ducted solid propellers is the most favourable. There are also presented a schematic propulsion and control diagram, three-dimensional arrangement drawing of system components as well as assembly drawing of the designed azimuthal propulsion system.

Experimental investigation of blade and propeller loads: Steady turning motion

This paper is the continuation of the work described in [14], dedicated to the presentation of the results of propeller performance in behind-hull during straight ahead motion obtained by a novel experimental set-up for the measurements of single blade loads. In the present case, the study shows and discusses the single blade and propeller loads developed during steady turning conditions, that were simulated by means of free running, self propelled maneuvering tests for a twin screw configuration. Maneuvering conditions are critical for the ship propulsion system, because the performance of the propeller and the side effects related to its functioning (propeller–hull induced pressure and vibrations, noise) are completely different with respect to the design condition in straight ahead motion. Thrust and torque and generation of in-plane loads (force and moments), developed by the blade during the period, evolve differently for the two propellers, due to different propeller–wake interactions. The understanding and the accurate quantification of propeller loads, in these realistic operative scenarios, are pivotal to design low emission and comfortable ships, fulfilling the requirements of safety and continuity of operations at sea. The analysis is carried out revisiting the investigation in [14] for three different speeds (FN = 0.26, 0.34 and 0.40) and a large set of rudder angles that span moderate and tight maneuvers.

Identification of coherent flow structures and experimental analysis of the hydroacoustic emission of a hubless propeller

The progress in drive technology and the increasing needs for compact ship propulsion systems has brought a new class of hubless propellers into the field of operation. So far, no detailed analyses have been done concerning the unsteady flow structures which are important for the hydroacoustic emission. The objective of this paper is to analyze the unsteady flow topology and the related hydroacoustic emission of a hubless propeller with numerical and experimental methods. In order to capture the unsteady wake flow structures, a stress-blended eddy simulation (SBES) has been done. Experimental investigations in a circulating water channel provided the validation data in terms of integral quantities like thrust, wall pressure fluctuation and the hydroacoustic noise emission. The wake flow can be characterized by a multi-helix vortex system which develops from the blade root and tip region as well as from the trailing edge. The transition length of the helixes is larger compared to hub propellers in conjunction with an accelerated dissipation. The application of the proper orthogonal decomposition (POD) onto the unsteady wall pressure fields obtained from the SBES simulation was capable to assign different flow structures to the measured hydroacoustic emissions.

Design and Characteristic Analysis of a 1 MW Superconducting Motor for Ship Propulsions

Electric motors tend to be large in size because they have low speed and high torque characteristics. A superconducting motor (SCM) can be a key technology used to solve these problems. Using the characteristics of a superconductor, the SCM can reduce the volume and weight. This paper deals with the design and characteristic analysis of a 1 MW SCM for ship propulsion. An effective design of the SCM was suggested considering the electromagnetic, thermal, and mechanical properties of the motor. The SCM was designed using Y-Ba-Cu-O (YBCO) wires focusing on size, operating filed current, magnetic flux density, heat load, and mechanical stress. The current leads were also designed to minimize the heat loss in the motor, and the thermal contraction and mechanical force were calculated to design the torque tube. Electromagnetic, mechanical, and thermal characteristics were analyzed using a 3D finite element method program. As a result, the size of SCM was minimized, and the heat loss was also reduced by an effective current lead design. The designed torque tube was structurally stable with a 70% stress margin. These results will help to expand the electric propulsion motor capacity and improve the efficiency of the ship propulsion system.

Design and Implementation of Energy Saving System for Electric Propulsion of Unmanned Vehicle

Ocean exploration technology has become a key technology in the research and development of countries all over the world. As a new intelligent platform for ocean exploration, unmanned ship has also become one of the important equipment of ocean exploration technology. At the same time, in response to the call of global green energy, the application of energy-saving technology and new energy schemes in unmanned ship electric propulsion system has increasingly become a hot area of ocean exploration technology. In this paper, the electric propulsion system of unmanned ship is designed based on photovoltaic technology, and the mathematical modeling and simulation experiments of the system are carried out. The experimental results show that the proposed UAV electric propulsion system has obvious advantages in energy saving compared with the traditional UAV electric propulsion system. At the same time, the energy-saving electric propulsion system proposed in this paper also has strong dynamic performance and stability performance.