Marine Propulsion System Research Articles

Fault Diagnosis Method for Marine Electric Propulsion Systems Based on Zero-Crossing Tacholess Order Tracking

In marine electric propulsion systems (MEPS) driven by variable-frequency drives, motor current signals often exhibit complex modulation components, ambiguous spectra, and severe noise interference, rendering it challenging to extract fault-related modulation components. To address this issue, we propose a zero-crossing tacholess order tracking method based on motor current signals. This method utilizes zero-crossing estimation of the instantaneous frequency to perform angular resampling of stator current signals and demodulates the envelope spectrum to extract fault characteristic spectra, enabling the diagnosis of mechanical faults in MEPS. Given the synchronization of the synchronous motor speed with the inverter fundamental frequency, this method estimates instantaneous frequencies in the time domain without requiring integration or time–frequency representation, which is simple and computationally efficient. Data validation on a small-scale marine electric propulsion test platform demonstrates that the proposed method exhibits good robustness under variable-speed conditions and effectively detects imbalance faults caused by propeller breakages and gear faults resulting from bevel gear tooth defects. Therefore, the proposed method can be applied to diagnose faults in downstream mechanical equipment driven by motors.

Optimization of Fuel Consumption by Controlling the Load Distribution between Engines in an LNG Ship Electric Propulsion Plant

Due to growing environmental concerns and stringent emissions regulations, optimizing the fuel consumption of marine propulsion systems is crucial. This work deals with the potential in an LNG ship propulsion system to reduce fuel consumption through controlled load distribution between engines in Dual-Fuel Diesel Electric (DFDE) plant. Based on cyclical data acquisition measured onboard and using an optimization model, this study evaluates different load distribution strategies between setups according to the optimization model results and automatic (equal) operation to determine their effectiveness in improving fuel efficiency. The analysis includes scenarios with different fuel types, including LNG, MDO and HFO, at different engine loads. The results indicate that load distribution adjustment based on the optimization model results significantly improves fuel efficiency compared to conventional methods of uniform load distribution controlled by power management systems in almost all load intervals. This research contributes to the maritime industry by demonstrating that strategic load management can achieve significant fuel savings and reduce environmental impact, which is in line with global sustainability goals. This work not only provides a framework for the implementation of more efficient energy management systems on LNG vessels, but also sets a benchmark for future innovations in maritime energy optimization as well as in the view of exhaust emission reduction.

Influence of Propeller–Ice Loads on the Wear Development in Stern Tube Bearings of Marine Propulsion Systems and Identification of Critical Operating Conditions

Abstract Increasing ship traffic in ice-covered waters leads to more frequent collisions between ship propellers and sea ice which causes extreme impulse loads on the propeller. These loads are transferred through the propeller shaft to the sliding bearings of the stern tube, especially, the aft stern tube bearings. Extreme bearing loads can lead to mixed friction regimes that cause wear in the bearings and eventually result in a failure of the entire propulsion system. The effect of ice-induced loads on the contact conditions in the sliding bearings is widely unknown. Thus, a study of the influence of these loads on the contact conditions and wear behavior in stern tube bearings resulting from observed sea ice conditions and operating conditions of the ship is necessary. This article aims to investigate the influence of ice collision loads on the contact conditions in the bearings of the stern tube of the research vessel SA Agulhas II. For this purpose, an elastohydrodynamic simulation and a multibody simulation based on field measurements were performed. As a result, this article identifies the operating condition thresholds (i.e., propeller torque and rotational speed) during propeller–ice collisions that cause mixed friction conditions in the bearings. On the basis of these conditions, a risk map is generated to assess the actual wear risk by including the frequency of occurrence of the corresponding mixed friction condition over the duration of a voyage.

Alignment Prediction of Air Spring Vibration Isolation System for Marine Shafting Based on Genetic Algorithm-Back Propagation Neural Network.

Shafting alignment plays an important role in the marine propulsion system, which affects the safety and stability of ship operation. Air spring vibration isolation systems (ASVISs) for marine shafting can not only reduce mechanical noise but also help control alignment state by actively adjusting air spring pressures. Alignment prediction is the first and a key step in the alignment control of ASVISs. However, in large-scale ASVISs, due to factors such as strong interference and raft deformation, alignment prediction faces problems such as alignment measurement sensors failure and difficulty in establishing a mathematical model. To address this problem, a data model for predicting alignment state is developed based on a back propagation (BP) neural network, fully taking advantage of its self-learning and self-adaption abilities. The proposed model exploits the collected data in the ASVIS instead of the alignment measurement data to calculate the alignment state, providing another alignment prediction approach. Then, in order to solve the local optimum issue of BP neural network, we introduce the genetic algorithm (GA) to optimize the weights and thresholds of the BP neural network, and an improved GA-BP model is designed. The GA-BP model can leverage the advantages of the global search capability of GA as well as the BP neural network's fast convergence in local search. Finally, we conduct experiments on a real ASVIS and evaluate the prediction models using different criteria. The experimental results show that the proposed prediction model with the GA-BP neural network can accurately predict the alignment state, with a mean-square error (MSE) of 0.0114. And compared to the BP neural network, the GA-BP neural network reduces the MSE by approximately 74%.

A full-field structural displacement reconstruction method for large-scale floating rafts in marine propulsion systems

Large-scale floating rafts have been widely applied to marine propulsion. Due to the presence of elastic supports, it belongs to the elastic constraints rather than the fixed constraints found in aerospace and bridge structures. This leads to displacement is no longer just elastic deformation, but also includes some rigid-body displacement. However, the existing displacement reconstruction methods are all based on fixed constraints. To address this issue, an improved modal method (IMM) is proposed. The boundary conditions are extended from fixed constraints to elastic constraints and the displacement field is uniformly described. Firstly, by analyzing the modal characteristics of three types of constraints, the reasons for the failure of the current modal method under elastic constraints are presented. Secondly, the IMM is established based on a dimensionless error function between the discrete strain, finite displacement measurements, and their theoretical values. Finally, the feasibility of the IMM is verified by numerical analysis and experiment tests on an elastic support plate structure with high precision and excellent suitability. This method can be applied to the full-filled displacement reconstruction in large-scale floating rafts of marine propulsion systems, which provides significant engineering value for improving the shafting alignment and the raft attitude balance.

Оптимизация дизель-электрической судовой пропульсивной и энергогенерирующей системы с помощью генетического алгоритма

В последние десятилетия в процессе проектировании судовых силовых установок основное внимание уделяется энергоэффективности и низкому уровню выбросов загрязняющих веществ. В данном случае особую актуальность приобретает использование более совершенных вычислительных подходов, таких как генетический алгоритм, который имеет очень высокую точность для получения оптимального решения, поэтому он очень хорошо подходит для оптимизации дизель-электрической судовой пропульсивной и энергогенерирующей системы. В статье рассматривается вариант решения задачи по оптимизации дизель-электрической судовой пропульсивной и энергогенерирующей системы с помощью генетического алгоритма. Разработана блок-схема решения поставленной оптимизационной задачи с использованием генетического алгоритма. Описанный в статье подход позволяет подобрать режим более экономичных нагрузок для дизель-генераторов на основе спроса на мощность энергетической системы судна, в целом, в зависимости от конкретного режима плавания. Сделан вывод, что оптимизация дизель-электрической судовой пропульсивной и энергогенерирующей системы с помощью генетического алгоритм приводит к значительному снижению расхода топлива для двух из трех режимов работы (транзит (1) и динамическое позиционирование (3)). в статье описана процедура оптимизации, ориентированная на оптимальное проектирование дизель-электрической судовой силовой установки. В частности, генетический алгоритм был использован для нахождения топливно-эффективных нагрузок для дизель-генераторов на основе потребности в нагрузке энергетической системы судна. In recent decades, the design process of marine propulsion systems has focused on energy efficiency and low pollutant emissions. In this case, the use of more advanced computational approaches such as genetic algorithm, which has a very high accuracy to obtain the optimal solution, so it is very well suited for the optimization of diesel-electric ship propulsion and power generation system, is of particular relevance. The paper discusses a variant of solving the optimization problem of diesel-electric ship propulsion and power generating system using genetic algorithm. The block diagram of the solution of the set optimization problem with the use of genetic algorithm is developed. The approach described in the article allows to select the mode of more economical loads for diesel generators on the basis of demand for the power of the ship's power system, in general, depending on the specific mode of navigation. It is concluded that optimization of the diesel-electric ship propulsion and power generation system using a genetic algorithm leads to a significant reduction in fuel consumption for two of the three modes of operation (transit (1) and dynamic positioning (3)).The paper describes an optimization procedure focused on the optimal design of the diesel-electric ship propulsion system. In particular, a genetic algorithm was used to find fuel-efficient loads for diesel generators based on the load demand of the ship's power system.

Ultralow friction of PEEK composites under seawater lubrication

Water-lubricating bearings made of polymer-matrix composites have provided a new approach to prolong the service lifetime of key component in marine propulsion system. However, it was still crucial to find a convenient and effective material to manufacture the water-lubricating bearing with ultralow friction. Herein, a new kind of polyetheretherketone (PEEK) composite with ultralow coefficient of friction (COF), high mechanical strength and thermal stability has been developed. An 80.7% decrease in the COF of PEEK was achieved by incorporating the fillers. A possible mechanism between the heterogeneous nucleation and mobility hindrance of PEEK chain segment caused by different fillers was proposed. The ultralow COF endowed the water-lubricating bearing with low running noise and reduced energy consumption. The high mechanical strength and thermal stability caused the superior carrying capacity and reliability. Therefore, the prepared PEEK composites can be a possibility to realize the water-lubricating bearing with high durability and long service lifetime.

The risk matrix application to assess the installation of torsional vibration monitoring systems on ships

According to statistics, the number of accidents related to the failures of ship engine and propulsion systems remains in second place among the total number of accidents. One of the reasons for the destruction of diesel crankshafts, intermediate and propeller shafts, elastic couplings and other elements of shaft lines are torsional vibrations in combination with other types of fluctuations and vibrations. The main method for monitoring the level of torsional vibrations in ship’s shaft lines remains periodic torsiography or strain measurement. The widespread introduction of diagnostic and control systems on ships leads to the technical possibility of constant monitoring of the level of torsional vibrations, which will allow you to reduce the risks of accidents in the periods between torsiography. Like any new technical solution, the introduction of torsional vibration monitoring systems requires a scientific justification of the need for their application, which can be carried out with using risk theory. The results of applying the risk matrix to justify the installation of torsional vibration monitoring systems in marine propulsion systems are presented in the paper. As a result, a risk matrix with quantitative parameters is obtained to justify the installation of torsional vibration monitoring systems and reduce the risks of ship’s shaft line breakdowns. As an example, the application of the risk matrix for “OT” type tugs, which are widely used for various operations on the Russian waterways, is considered. It is established that for these types of vessels, the use of a monitoring system will be justified to reduce the risks of accidents, serious accidents and catastrophes that may arise from the development of dangerous torsional vibrations. A method for applying the assessment of the damage degree from an accident occurrence to determine the reduction of economic costs when using torsional vibration monitoring systems is proposed in the paper. It is found that for the “OT” type tugs, the installation of torsional vibration monitoring systems will be justified, both from the point of view of economics and reducing the accidents risks of ship engine and propulsion systems.

Сравнительная оценка применения микроэлектромеханических акселерометров для измерения крутильных колебаний судовых машинно-движительных комплексов

Microelectromechanical accelerometers are investigated, and their applicability to measuring torsional vibrations occurring in marine propulsion systems is evaluated. The calculated and experimental assessment of the applicability of accelerometers of the ADXL345, ADXL375 and H3LIS331DL models for measuring torsional vibrations of marine shaft lines has been carried out and recommendations for their practical application have been developed. The materials used were the rules of the Russian Classification Society, scientific and technical literature in the field of torsional vibrations and the authors' own research. The methods used were analysis, numerical and physical experiment. Recommendations on the use of accelerometers of the ADXL345, ADXL375 and H3LIS331DL models depending on the rotational speed and diameter of the torsiographed shaft are obtained. The results obtained give grounds to recommend the ADXL375 accelerometer as the basic basic model for measuring torsional vibrations of most marine propulsion systems with rotation frequencies up to 1,025 min–1. At rotational speeds of less than 135 min–1, the use of the ADXL345 accelerometer with a measuring range of ±2g is recommended, and when setting the range of ±16g, it can be used at rotational speeds up to 380 min–1. If it is necessary to measure torsional vibrations at a rotational speed of more than 1,025 min–1, it is recommended to use a less accurate, but more reliable accelerometer model H3LIS331DL in terms of overload shutdown threshold.

Экономическая эффективность применения систем мониторинга крутильных колебаний на судах

A torsional vibration monitoring system is being investigated, and an assessment of the economic efficiency of its implementation on ships is made. A schematic diagram of the torsional vibration monitoring system is illustrated and a photograph of an experimental sample of the monitoring system is provided. An assessment of the economic efficiency of the implementation of torsional vibration monitoring systems on ships is being carried out to prevent the occurrence of emergency situations with marine propulsion systems. The rules of classification societies, scientific and technical literature in the field of torsional oscillations and industrial economics, and the authors' own research were used as materials. The methods used are analysis and computational experiment. Data on the economic costs of the shipowner in the event of emergency situations in case of fatigue failures of elements of ship's engine and propulsion systems were obtained. An assessment of the costs for the development, installation and maintenance of a torsional vibration monitoring system on ships was made; as well as an approximate assessment of the volume of the Russian domestic market for installation and maintenance of torsional vibration monitoring systems on ships. It is noted that the cost of the consequences of propeller shaft failures ranges from several million to tens of millions of rubles. It is concluded that the development and implementation of torsional vibration monitoring systems will reduce the cost of the shipowner for a routine assessment of the technical condition of torsional vibration dampers and reduce the risks of costly accidents with shipboard engine complexes.

Особенности создания трансформаторов судовых систем электродвижения

The necessity of new organizational and technical solutions in shipbuilding to ensure the quality of marine transformer transformers is substantiated. The analysis of the requirements of the Russian Maritime Register of Shipping, the current ISS for dry transformers is carried out, the experience of enterprises of related industries and foreign companies, the design features of power transformers of the ship's electric propulsion system are considered. The results of the analysis of the requirements for power transformers of marine electric propulsion systems, the features of their design and operation are presented. The main parameters of the converters in operating and emergency modes are considered and analyzed. The organizational and technical directions of ensuring increased reliability of marine converter transformers are proposed. Unlike converter transformers for land transport, there are no regulatory documents for power converter transformers in shipbuilding. The regulatory documents in force in shipbuilding do not fully take into account the specifics of marine conversion transformers. The existing main features of marine converter transformers are noted. High economic losses in the event of an accident of marine converter transformers determine higher requirements for their electrodynamic stability compared with converter transformers for land transport. In shipbuilding, there are no requirements for determining the partial short-circuit voltage and the splitting short-circuit voltage during testing of transformers necessary for the analysis of their characteristics and modes. When creating marine converter transformers, it is necessary to justify the characteristic modes of marine transformers using computer modeling, develop methods for measuring and calculating the parameters of selected modes and perform process calculations for the most likely accidents in the transformer – rectifier system. With the increase in the power of shipboard electric propulsion systems, the development of state regulatory documentation to ensure the quality of development and operation of converter transformers is becoming increasingly relevant.

Разработка алгоритма комплексной методики оценки технического состояния цилиндропоршневой группы судовой двигательной установки на основе показателей масляной системы

The algorithm of a complex methodology for assessing the technical condition of the cylinder piston group of a marine propulsion system is being investigated. Wear is a continuous process characteristic of all working mechanisms. Studies aimed at identifying factors contributing to the degradation of system elements of devices provide the basis for the development of preventive measures to reduce their effects. Knowledge of the technical condition of marine engine components is important for the development of measures that increase the reliability of equipment and reduce the risks of emergency situations. Some of the main approaches to modeling and evaluating the state of the cylinder-piston system of marine diesel engines are presented. To solve the problems of assessing the technical condition of the cylinder piston group during operation, classical methods of statistical data analysis are considered, methods that artificially increase the size of the data sample are proposed, machine learning methods are analyzed and the most effective for use are determined. An integrated approach is being created to study the operation process of a cylinder-piston group of diesel marine engines based on a combination of statistical methods, machine learning methods and probabilistic forecasting. A diagram of the properties of the studied parameters is illustrated for constructing a model for analyzing a cylinder-piston group system. Machine learning algorithms used to study systems are presented. The proposed technique allows, using the results of indirect measurements (data from lubrication analyses), to determine the technical condition of the engine system, in particular the cylinder piston group.

Enhanced Model Predictive Control for Induction Motor Drives in Marine Electric Power Propulsion System

Marine electric propulsion is an important topic in the research of modern ships and underwater vehicles. The propulsion motor drives based on model predictive control (MPC) are becoming increasingly popular in marine propulsion systems as an emerging technology. However, the multi-objective optimization in conventional MPC requires cumbersome weighting factor tuning. The relatively large computational cost is also detrimental to the industrial application of MPC. Aiming at reducing the computational complexity of multi-objective optimization without weighting factors, this paper proposes an enhanced ranking-based MPC method for induction motor drives in marine electric power propulsion. The presented control set pre-optimization aims to reduce the computational complexity of enumeration and ranking. Based on the sign of torque prediction deviation, the proposed method avoids enumerating all fundamental voltage vectors. Consequently, the number of candidate elements in the initial control set are reduced to four without excessively excluding feasible solutions. By converting predicted numerical errors into ranking results, the proposed MPC seeks the optimal solution among the candidates through improved ranking evaluation. Considering the situation of simultaneous optimal ranking, the normalization error judgment is developed to further optimize the optimal solution selection process. The simulation and experimental results confirm that the proposed MPC is simple and effective. Without the involvement of tuning the weighting factors, the proposed method achieves good performance.

Dynamic investigation of the influence of propeller on the vibro-acoustic characteristics of marine propulsion systems

Dynamic investigation of the influence of propeller on the vibro-acoustic characteristics of marine propulsion systems

Sensor Set Decomposition for Enhanced Distributed Sensor Fault Isolability of Marine Propulsion Systems

This paper proposes a greedy stochastic optimization algorithm for the sensor set decomposition used in the sensor fault monitoring of marine propulsion systems, based on fault isolability criteria. These criteria are expressed mathematically in terms of the number of unique columns in the theoretical fault signature matrices (FSMs) used during the sensor fault isolation process. Due to the large scale and complexity of marine propulsion plants, the diagnostic layer follows a distributed architecture with a combinatorial logic used for fault isolation in two cyber levels; the local and global decision logic. As a result, the FSMs of both levels are formulated as an integrated optimization problem. Each solution regarding the sensor set decomposition is then used to generate the respective distributed monitoring architecture, using semantic (qualitative) knowledge for the propulsion plant. Thus, the need for an analytical model of the plant is removed. Moreover, based on the design of the distributed monitoring architecture, the respective theoretical FSMs (quantitative) are Automatically generated and used for the evaluation of the objective function. Finally, simulation results are used to illustrate the application of the greedy stochastic optimization algorithm and its efficiency.

PV Powered Improved Quasi-Z-Source Inverter Fed Five Phase PMSM for Marine Propulsion Systems

PV Powered Improved Quasi-Z-Source Inverter Fed Five Phase PMSM for Marine Propulsion Systems

FOREWORD

As we conclude another year of outstanding contributions to the field of engineering and science, we are pleased to present the final issue of the Journal of Naval Sciences and Engineering for 2023. In this issue, we are proud to feature three research articles that reflect the diversity and depth of engineering research, as well as a timely book review that offers insights into a recently published work. Our commitment to providing a platform for a wide array of engineering disciplines is evident in the selection of articles for this issue. Each article showcases the innovative thinking and technical prowess that continue to drive our field forward. From exploring the hydrodynamics of marine propulsion systems to the development of advanced steganography algorithms for securing data, and the design and optimization of dual-band polarizers, these articles represent the cutting edge of engineering research. Additionally, the book review provides an in-depth analysis of the latest edition of a seminal work in electromagnetics, offering valuable perspectives for both academics and professionals. I would like to extend my heartfelt gratitude to all the authors for their invaluable contributions and to our anonymous reviewers for their diligent efforts in maintaining the high standard of the journal. Your expertise and dedication are the backbone of our publication's success. Looking ahead, we are excited to announce that our next issue is planned for publication in June 2024. We anticipate another collection of high-quality papers that will continue to enrich the body of knowledge in naval sciences and engineering, as well as other related fields of engineering. As we bid farewell to 2023, I would like to express my sincere appreciation to our readers, contributors, and reviewers. May the upcoming year be filled with new discoveries, innovative research, and continued collaboration within our vibrant scientific community. Fatih ERDEN, Ph.D. Editor-in-Chief

Corrosion of Brass Fishing Vessel Propeller in Artificial Seawater

The propeller was an important component in the fishing vessels marine propulsion system. Brass was widely used as a fishing vessel propeller. Brass was chosen because it has good mechanical properties and good corrosion resistance. The content of seawater in Indonesia has levels of 3% – 3.5% NaCl. In addition to the level of Ion Cl-, environmental factors can affect corrosion rate of material or metal. The environmental factors that affect the corrosion rate are the level of salinity, pH, DO, temperature and TDS. The objective of the present work was to explain the corrosion rate of brass in artificial seawater in Indonesia with exposure time. The material used for research is fishing vessel propeller commercial in Indonesia market. Measurement of the corrosion rate of brass used the principle of weight loss according to ASTM G31-72 (2004). During the corrosion test, the artificial seawater solution was tested for its pH and salinity quality over time of immersion. The result of immersion brass in the artificial seawater shows that the corrosion rate decreases in 1-to-10-days exposure time due to the increase in salinity levels above 30‰. While the results of exposure time immersion above 15 days tends to increase the corrosion rate due to a decrease in pH level. pH level of seawater depends on the environmental conditions and tends not to change significantly.
 Keyword: Artificial Seawater, Brass, Corrosion Rat, pH, Salinity.

Enhancing resilience in marine propulsion systems by adopting machine learning technology for predicting failures and prioritising maintenance activities

With the rapid transition towards Industry 4.0, many industries have recognised the need to develop intelligent maintenance systems and predictive analytics tools that are able to optimise the performance of complex assets throughout their entire lifecycle. This paper adopts a machine learning (ML) technology to enhance the resilience of marine propulsion systems by predicting mean-time between failures (MTBF) and prioritising condition-based maintenance (CBM) activities. The factors considered for the analysis include a series of attributes (in total 16 features) which directly or indirectly represent the state of the system subject to degradation. From the results obtained, it is found out that the feed-forward neural network (FFNN) has the least mean square errors (MSE) and, thus, it is the most suitable method for numerical and discretized estimations. The results from a greedy search algorithm also show that two attributes of ‘gas generator rate of revolutions’ and ‘gas turbine rate of revolutions’ are the most significant parameters influencing system reliability, and therefore, they require closer monitoring. Furthermore, a decision support system (DSS) dashboard is designed to help marine propulsion system operators make informed maintenance decisions and find an improved balance in their spare parts inventory.

Influence of bearings on the open water performance of a rim-driven thruster

The rim-driven thruster (RDT) represents an important advance in the marine propulsion system. Its innovative structure introduces several outstanding advantages but also rises some major challenges. This paper aims to investigate the influence of bearings on the rim-driven thruster in terms of hydrodynamic performance with computational fluid dynamics. Bearing parameters including the shape of the contact surface and the number of grooves are considered. The simulation results indicate that the presence of the bearings in the gap has an influence on the overall performance of the thruster by changing the flow regime in the gap and the interactions between different components in the RDT. The shape of the bearings also exhibits significant impacts: the conical bearings, even though with simpler structure, shows the worst performance among all three bearing configurations, while the ordinary bearings always have a higher hydrodynamic efficiency than the other two bearing configurations under all considered advance coefficients. The difference in efficiency at the design point can reach up to 3% between the ordinary and conical bearing configurations.