Main Propulsion Research Articles

PREMIUM YACHT PROPULSION FOR EXCLUSIVE PERFORMANCE

SCHOTTEL offers a wide range of main and auxiliary propulsion systems for yachts. This paper will present characteristics of different propulsion solutions: The 5-bladed controllable pitch propeller for highest propulsive efficiency for changing speed or load or the EcoPeller with best values in overall efficiency and course stability. It provides unprecedented performance and ensures that its owners benefit from low fuel consumption and thus reduced emissions and operating costs. Thanks to an installation flush with the hull, the pump jet is ideal for operation in extremely shallow waters. It can be used as manoeuvring aid, additional booster or take-home device. Low-vibration and low-noise rim thruster enables more comfort on board.

Modified predictive torque control method of induction machines for torque ripple reduction

ABSTRACTDirect torque control, model predictive control and field oriented control are control methods mostly used in high performance induction machine drives. In the direct torque control method, control variables are estimated from the stator variables, and the only parameter required is the stator resistance. The predictive torque control with horizon one has recently attracted much research attention but it requires the use of the induction machine speed, and both the stator and the rotor parameters, usually requires adjustment of the weighting factors, and has high computational burden. This paper proposes a modified predictive torque control method of induction machines. The estimated and predicted values are calculated from the stator variables, and the method uses the cost function without the weighting factor. When the two-level three-phase voltage source inverter is analyzed, it is shown that the predicted values should be calculated for three voltage vectors. The modified predictive torque control results in a better steady state performance regarding torque ripple in comparison with the conventional direct torque control and the predictive torque control methods. Simulation and experimental results for the main propulsion drive of the low-floor tram are presented in order to validate the effectiveness of the proposed method.

Robotic Fish Propelled by a Servo Motor and Ionic Polymer-Metal Composite Hybrid Tail

In this paper, a new robotic fish propelled by a hybrid tail, which is actuated by two active joints, is developed. The first joint is driven by a servo motor, which generates flapping motions for main propulsion. The second joint is actuated by a soft actuator, an ionic polymer-metal composite (IPMC) artificial muscle, which directs the propelled fluid for steering. A state-space dynamic model is developed to capture the two-dimensional (2D) motion dynamics of the robotic fish. The model fully captures the actuation dynamics of the IPMC soft actuator, two-link tail motion dynamics, and body motion dynamics. Experimental results have shown that the robotic fish is capable of swimming forward (up to 0.45 body length/s) and turning left and right (up to 40 deg/s) with a small turning radius (less than half a body length). Finally, the dynamic model has been validated with experimental data, in terms of steady-state forward speed and turning speed at steady-state versus flapping frequency.

Thermodynamic analysis and assessment of an integrated hydrogen fuel cell system for ships

In this thermodynamic investigation, an integrated energy system based on hydrogen fuel is developed and studied energetically and exergetically. The liquefied hydrogen fueled solid oxide fuel cell (SOFC) based system is then integrated with a steam producing cycle to supply electricity and potable water to ships. The first heat recovery system, after the fuel cells provide thrust for the ship, is by means of a turbine while the second heat recovery system drives the ship's refrigeration cycle. This study includes energy and exergy performance evaluations of SOFC, refrigeration cycle and ship thrust engine systems. Furthermore, the effectiveness of SOFCs and a hydrogen fueled engine in reducing greenhouse gas emissions are assessed parametrically through a case study. The main propulsion, power generation from the solid oxide fuel cells, absorption chiller, and steam bottoming cycle systems together have the overall energy and exergy efficiencies of 41.53% and 37.13%, respectively.

Dynamic ice contact load model for azimuthing thrusters

ABSTRACTFor ships operating in winter conditions, ice loads are important load scenarios for designing azimuthing main propulsion units. One such contact scenario is ice impacting into an azimuthing thruster. In this paper, the formulation of this type of load scenario is presented and existing calculation methods are investigated. A calculation method for dynamic contact load is proposed for ice impact against the main propulsion unit. The basic principle of the proposed load calculation method is an impact of moving bodies combined with dynamic reaction of the structure. The contact load determination is based on the contact pressure–area relationship between an ice block and a steel structure. The dynamic contact problem is solved with a forward difference method. The method is validated with a controlled laboratory-scale test and the test principle is introduced. The dynamic load model is applied to study the effect of dynamics on the response load level.

Energijska analiza glavne propulzijske parne turbine konvencionalnoga tankera za ukapljeni plin pri trima različitim opterećenjima

Energijska analiza glavne propulzijske parne turbine konvencionalnoga tankera za ukapljeni plin pri trima različitim opterećenjima

A Novel Network Scheduling Approach Based on Genetic Algorithm for Autonomous Underwater Vehicle Control

Autonomous Underwater Vehicle (AUV) is one type of important equipments for conducting ocean exploration missions. The AUV control system typically employs a common communication network to connect various function nodes such as Doppler meter, compass/inertial navigation unit, sonar, water depth sensor, main propulsion, and rudder motor. Each of these function nodes has its own information transmission requirements that need to be served by the limited bandwidth of the common communication network. In order to obtain a good control performance, an elaborate information transmission schedule in the communication network should be planned in such a way that all information transmission requirements in the AUV control system can be satisfied with as less network-induced delay and data packet dropout as possible. This paper proposes a novel network scheduling approach based on the Genetic Algorithm (GA) and the time-triggered architecture for meeting information transmission requirements in the Controller Area Network (CAN) of the AUV control system. The proposed network scheduling approach divides the whole transmission period into a serial of time slices with equal lengths, and defines a large cycle consisting of multiple time slices. For the periodical information transmission, the transmission schedule in one large cycle is determined by solving one nonlinear integer optimization problem with the Genetic Algorithm. This GA-based network scheduling approach maximizes the available bandwidth of each single time slice in all the periodic time slices of the whole schedule period, and aims to achieve a balanced information transmission in the CAN network. Meanwhile, the available bandwidth in each time slice of the whole schedule period is then allocated for the event-triggered information transmission. In this way, the proposed network scheduling approach satisfies the transmission requirements of both periodical and event-triggered information in the AUV. Finally, simulation experiments demonstrate the performance of the proposed GA-based network scheduling approach, and verify its performance improvement on an AUV heading motion control using TrueTime toolbox.

Reliability Assessment of a Main Propulsion Engine Fuel Oil System- What are the Failure-prone Components?

The main propulsion engine is the heart of a vessel which carries the entire load of the ship and propels to move ahead. The main engine consists of various sub‐systems, the fuel oil system is the most important one. Fuel oil system provides fuel to the engine via a fuel injector mounted on the engine cylinder head. During the voyage, the main engine of a ship encounters a variation in loads and stresses due to rough weather to harsh manoeuvring, which sometimes leads to the breakdown of the main engine. Fuel oil systems are identified as one of the main reasons for engine breakdown. Many accidents happened due to the failure of the main engine fuel oil system in the last two decades. To ensure safe and reliable main propulsion engine operation, it is required to assess the reliability of a fuel oil system. However, there is a significant lack of appropriate data to develop the reliability assessment techniques for fuel oil system. This study proposes appropriate data collection and analysis procedure for the reliability assessment of a fuel oil system. Data related to Failure Running Hours (FRH) of a fuel oil system is collected from 101 experienced marine engineers through a questionnaire. The collected data processed using a box plot and analysed for a normality test. It helps to identify the generalization of the data. Moreover, this study identified failure‐prone components of a fuel oil system. The collected data will help in developing reliability assessment techniques for accurate reliability analysis of a fuel oil system. The identified failure‐prone components will assist in future reliability analysis and risk mitigation strategies for improving the overall safety and reliability of the shipping industry.

Parameterization of the operating conditions of the vessel’s turbine engine in the aspect of the pollutant exhaust emission assessment

Abstract Pollution emission tests from turbine engines used for the main propulsion of vessels require measurement of the concentration of harmful compounds in the exhaust and assessment of the exhaust gases mass generated by the engine. The concentration of harmful compounds can be determined in a direct way by measuring it in the stream of exhaust gases. However, due to the large output of exhaust gases, the mass of exhaust gases must be determined indirectly. To do this it is necessary to carry out a series of tests and analyzes that will enable parameterization of operating conditions. The article presents the relationships between the concentration of harmful compounds in the exhaust and the load on the marine gas turbine engine. These relationships were obtained on the basis of the tests carried out on the LM 2500 engines used on the FFG-7 missile frigate ship.

A Study on Heuristic Berthing System Design with Winch and Damper Assistance

Vessel maneuvering problem in the harbor area is generating considerable interests in terms of marine cybernetics. In this sense, the vessel is operated and moves at ultimately low or zero speed in shallow water area. So the vessel is usually aided by the cooperation with thrusters, main propulsion system, tugboats and pilots, etc. In this paper, we suggest a new vessel berthing technique using dampers and winches as a solution for excessively complicate and dangerous berthing work. In the proposed berthing method, in order to manipulate the actuators (winches and dampers), a simple and heuristic control strategy is applied for a basic experiment. Finally, experiments are conducted to verify the effectiveness of the proposed automatic vessel berthing strategy based on the heuristic control method.

ВЛИЯНИЕ МАТЕРИАЛА ДЕЙДВУДНЫХ ПОДШИПНИКОВ НА ЧАСТОТУ ПОПЕРЕЧНЫХ КОЛЕБАНИЙ СУДОВОГО ВАЛОПРОВОДА

The article describes the ship shaft line which is a constructive complex linking kinematically the main propulsion engine to the thruster and designed to pass torque moments and axial loads, appearing in the operation process of the ship propulsion system. Service life of the ship shaft line depends on operational condition of stern bearings in the shaft tube, that is why they should have high resistance against actual loads and preserve operational characteristics. There is studied the influence of elastic properties of stern bearings on numerical value of eigen frequency under cross oscillations if the ship shaft line. Assessment of influence of the deadwood bearing material on the rigidity coefficient is made. The settlement scheme for studying cross fluctuations represents a beam with constant cross section that leans on one hinged immovable elastic support with a rigidity coefficient c . At the end of a beam there is a concentrated load. The elastic support and the concentrated load model the stern bearing and the propeller screw, respectively. The technique of determining the rigidity coefficient subject to mechanical and geometrical parameters of the ship shaft line and its deadwood bearings is described. The importance of the numerical value of the rigidity coefficient of different materials of plugs of deadwood bearings when calculating cross fluctuations of the ship shaft line has been estimated. The real ship shaft line is investigated.

A REVIEW ON FUELS USED FOR MARINE DIESEL ENGINES

In the maritime industry, most commercial vessels use diesel engines as the main propulsion for propeller, generators or auxiliary equipment. They have consumed a very large amount of fossil fuels and produced high levels of emissions into the environment. Currently, one of the most renewable and environmentally friendly alternative fuels available are known as bio-based fuels. In the maritime sectors, bio-based fuels show many advantages in comparison to fossil fuels due to its renewability and biodegradation. Bio-based fuels can be used directly or in the blend of fossil fuels, and thus, the fuel systems for the application of bio-based fuels to marine diesel engines need to be adjusted aiming at the harmony between fuel properties and fuel system of the as-used marine diesel engines. This report examines the use of traditional and alternative fuels for the marine shipping industry to satisfy the strict strategies of emissions. Some fuel systems are suggested in the case of using bio-based fuels for marine diesel engines. In addition, the experiences of marine diesel engine manufacturers related to the use of alternative fuels are also reported in this study.

Непосредственный преобразователь частоты для стартер-генераторной системы маршевого двигателя

Непосредственный преобразователь частоты для стартер-генераторной системы маршевого двигателя

An Analysis of Basic Parameters of Ro-Pax Ferries in the Baltic Sea as Guidelines for its Preliminary Design

Abstract This paper presents results of an analysis of the operating and maneuvering parameters (length, width, draft, main propulsion power and maneuvering equipment, and windage area) of the Ro-Pax ferries over 150m in length. The analysis takes into accounts all ferries operating in the Baltic Sea in 2017. The work also includes route analysis of the collected Ro-Pax units. The influence of port infrastructure is also discussed. The mean optimal Baltic Sea Ro-Pax ferry and its parameters for short term and long term forecasts are presented. This paper may be used as a primary guideline for the determining the optimal Ro-Pax ferry dimensions size for the Baltic lines in terms of preliminary ship design.

Метод рециркуляції відпрацьованих газів суднових дизелів для зме-ншення їх токсичності

В даний час має місце інтенсивне посилення норм на токсичні викиди відпрацьованих газів суднових дизелів при плаванні суден в прибережних морських районах і на внутрішніх водних шляхах. Постійне зростання числа суден призводить до збільшення об’єму палива, що спалюється ними, а отже до збільшення викидів токсичних компонентів з відпрацьованими газами. В роботі проаналізовано зниження шкідливих викидів судновими дизелями за рахунок методу рециркуляції відпрацьованих газів.

Propulsion Systems in Marine Navigation

Abstract This paper presents variants of propulsion systems as the main factor in the analysis and design of the power system of a sea-going or river vessel; this topic is also under research study within two doctoral theses. The analysis of the ship - main propulsion- thruster assembly is made according to the requirements imposed by the market economy. The parameters to be considered when choosing a propulsion system are: the cost of the investment, the specific cost of transport that depends both on the specific fuel consumption and on the number and level of pay of the crew members operating the propulsion system, the propulsion efficiency, the high safety in handling, and the control accessibility during operation. The Pod and Azipod propulsion systems are analyzed in terms of advantages and disadvantages compared to conventional propulsion systems. The azimuth thrusters can ensure maximum push in any direction regardless the speed of the ship, and thus can change the course of the ship according to its handling needs. The azimuth thrusters do not only operate in horizontal but also in oblique angles, providing the ship with great maneuverability, even at low speeds, where classical rudder systems have poor performance

Steam Turbine Stage Modernisation in Front of the Extraction Point

Abstract The paper presents modernisation of the steam turbine stage situated in front of the turbine extraction point, based on a 225 MW turbine LP stage as an example. The modernised design is intended to better control the steam flow in this area. In the presented design a special ring is used to drive the steam leakage flow directly to the heat exchanger. The performed experiments and numerical analyses confirmed measurable exploitation and efficiency advantages of the introduced modernisation. So far, it has been successfully applied in a number of turbines working in inland power plants, but its use can be easily extended, without need for further modification and without advantage loss, to marine turbines, especially those used as main propulsion in sea-going vessels.

Modelling the Stages of Turbocharger Dynamic Reliability by Application of Exploitation Experience

Turbocharger is an important part of marine diesel engine installed as main propulsion on board. It is in operation from the outset and throughout the marine diesel engine exploitation. In order to meet high reliability criteria, a combination of mathematical, IT and simulation methods should be used. The original mathematical model of turbocharger has been shown in five stages. The paper presents database link from the AMOS maintenance software package, a mathematical model elaborated by using Markov chains and a systematic-dynamic simulation model elaborated in the POWERSIM simulation programme. Results will be used to monitor and predict reliability and availability of turbocharger in ship’s propulsion system.

SOLID ROCKET MOTORS INTERNAL BALLISTIC MODEL WITH EROSIVE AND CONDENSED PHASE CONSIDERATIONS

ABSTRACTSolid rocket motors are used for propulsion units of both suborbital and orbitalaerospace vehicles. Their main advantages are their simplicity, low cost andreliability. Due to attainable high thrust they have a wide application as boosters (asspace shuttle boosters, Delta rocket boosters). They were also used as main stages,retrorocket units, stage separation control units, main propulsion units for suborbitalvehicles. An interior ballistics model is implemented and applied for a double baseand composite propellant boosters to be used for a boosted dart suborbital vehicle.Erosion and condensed phase are taken into account and numerical results areshown in comparison with experimental data obtained on test firings for each motor.The advantages of the implementation are that it offers a fast calculation of the mainparameters of the solid rocket motor unit (thrust, burn time, specific impulse, totalimpulse). The solid fuel characteristics and the geometry of the motor are containedwithin two input files while the results of the calculations are presented to the user ina several output files. The motors are built using steel as a casing material and testfirings are performed on a horizontal test bench.

Techno-economic analysis of a decarbonized shipping sector: Technology suggestions for a fleet in 2030 and 2040

Growing concerns about anthropogenic climate change and its effects on the environment have encouraged significant recent developments towards decarbonizing the energy system. Developments in transportation technology, such as vehicle electrification, can result in significant CO2, particulate matter, and SOx reductions over the lifetime of a vehicle. The shipping industry alone accounted for 2.1% of global greenhouse gas emissions in 2012, however, due to energy requirements and weight restrictions, batteries and direct electrification cannot be used to mitigate emissions. Synthetic fuels, as an indirect electrification option, are a viable solution to achieve emission reduction goals. The purpose of this study is to determine the most cost effective combination of synthetic fuels and fuel cells or internal combustion engines to replace fossil oil as the main propulsion fuel in the shipping industry in 2030 and 2040. The fuels, namely RE-FT-Diesel, RE-LNG, RE-LH2 and RE-MeOH, are analysed for both an internal combustion engine and a fuel cell. The scenarios were analysed by comparing the levelised cost of mobility (LCOM). The LCOM was composed of 5 different facets including the capex of the engines/fuel cells and the tanks, the opex of the engines/fuel cells, the cost of lost cargo space, fuel cost and the CO2 cost. The final unit of comparison was €/1000DWT-km. It was determined that hydrogen fuel cells were the most likely to replace fossil internal combustion engines if the fuel cells follow their expected development. Significant gains in fuel cell average efficiency and decreases in production cost between today and 2030 and 2040 are factors contributing to the competitiveness. A CO2 cost was set to 61 €/tCO2 in 2030 and 75 €/tCO2 in 2040. Most of the other technology combinations are close to competing with fossil diesel with a CO2 price in 2040; however, hydrogen fuel cells are close to competing with fossil fuel without a CO2 cost in 2040.