An introduction to the design of marine propulsors

A summary of methods for marine propulsion design is presented. A list of reports dealing with the design of open propellers, ducted propellers or pumpjets, and waterjets is included. The major problems involved in marine propulsion design are discussed

Robust global sliding model control for water-hull-propulsion unit interaction systems - part 2: model validation

Unexpected severe hull deformation caused by wave loads poses alignment problem to the propulsion shaft line in large scale ships, which would significantly influence the dynamical performance of the marine propulsion system. How to suppress negative disturbance imposed by the interaction between water-hull-propulsion and ensure the normal operation of the marine propulsion system is a challenging task. To address this issue, a new global sliding model control (GSMC) for marine water-hull-propulsion unit systems is proposed and investigated to obtain more accurate control performance in a series of researches. In Part 1 the GSMC controller has been developed and the bounded nonlinear model uncertainties have been derived based on the experiments and sea trial. In this work the upper boundary of 1,85 % was introduced into the GSMC controller to derive the total control law realising the robust control of the marine propulsion system. Numerical simulations based on the real bulk carrier parameters show a high effectiveness of the GSMC for speed tracking, compared with the traditional sliding model controller and Proportional Integral Derivative (PID) controller. By the proposed and investigated control system in this paper may be developed a simple practical-effective robust control strategy for marine propulsion systems subject to some complex unknown uncertainties through further investigations, validations and modification

Vibration analysis of marine propulsion shafting by the coupled finite element method

Marine propulsion shafting connects the main engine and propeller, and plays an important role in promoting the movement of ships. Along with the operation of shafting system, various vibration forms couple with each other and cause different kinds of coupled vibrations, which seriously threaten the safety and reliability of ships. In this paper, a finite element model of marine propulsion shafting is established with coupled constraint on the elements of propeller, and the coupled torsional and transverse vibration under idling and loading conditions are studied at different rotational speeds. According to comparison of numerical simulation results and experimental tests, the coupled finite element method can reveal the basic principles of coupled dynamics of marine propulsion shafting and provide good technical support for predicting the coupled vibration, thus improving the safety and reliability of sailing performance of the ships

Marine propulsion using battery power

Abstract: The global demand to reduce CO2 emissions requires effort from the shipping industry which currently emits about 2% of anthropogenic global Greenhouse Gases (GHGs) and which is predicted to increase due to growth of world trade. Therefore, it is important to find new ways to reduce CO2 emissions from shipping using new operational strategies, improved ship designs and new technologies. Battery technologies have been developing rapidly leading the road transport industry into a greener future with hybrid and electric vehicles but such a change is not so apparent in the shipping industry. This paper provides an overview of the state of the art battery technology and important future developments that may potentially exploit batteries in future ship’s power and propulsion systems. Through case studies, the paper assesses the applicability of battery power to ships, more specifically small ones. Approximately 14,000 ships, 22% of the global commercial fleet are below 400 gross tonnes, most of which are small coastal ships, e.g. tugs and passenger ships/ferries. Existing battery-powered ship system configurations are summarised; battery developments are considered, impacts of battery application on ship performance are discussed in the paper supported by a case study

The Design of Pumpjets for Hydrodynamic Propulsion

A procedure for use in the design of a wake adapted pumpjet mounted on the aft end of a body of revolution is presented. To this end, a pumpjet is designed for the Akron airship. The propulsor mass flow is selected to minimize kinetic energy losses through the duct and in the discharge jet. The shaft speed and disk size are selected to satisfy specified limits of cavitation performance and to provide acceptable blade loading. The streamtubes which pass through a propulsor mounted on a tapered afterbody follow essentially conical surfaces. A method is provided for defining these surfaces as a function of shroud geometry, rotor head distribution, and the energy distribution of the ingested mass flow. The three-dimensional effects to which the conical flow subjects the cylindrical blade design sections are described and a technique is presented which permits incorporation of these effects in the blade design procedure

Comparizon of Conventional and Unconventional 5-phase PM Motor Structures for Naval Applications

Multi-phase motors are widely used in marine propulsion. In this paper, a Multi-machine modeling of Surface Mounted PM motors is presented and applied to a 5-phase one. The latter is proved to be equivalent to a set of two-phase fictitious machines each ones being characterized by a set of specific harmonic rank. A simple control consists in supplying each fictitious machine by a current which contains only one harmonic. A five phase machine is then supplied by currents with only both first and third harmonics. Considering this kind of control, it is proved that for given stator resistance and average torque the Joule losses and the torque ripple are minimized if a simple criterion on the harmonics of electromotive force at constant speed is fullfilled. Different structures of rotor are then compared to examine numerically which improvements can be practically obtaine

Theory of one-element pumps for propulsion

A basic theory for one-element propulsion pumps is developed. A limit to the obtainable efficiency is established and relationships among pump-performance parameters that result in the greatest efficiency are indicated. It is shown that the peripheral velocity of the pump is directly related to ship speed and some relationships between performance parameters and pump geometry are developed. Mathematical models of pump performance are included

Application of theory to propeller design

The various theories concerning propeller design are discussed. The use of digital computers to obtain specific blade shapes to meet appropriate flow conditions is emphasized. The development of lifting-line and lifting surface configurations is analyzed. Ship propulsive performance and basic propeller design considerations are investigated. The characteristics of supercavitating propellers are compared with those of subcavitating propellers

SMR technology’s potential for merchant marine propulsion

Abstract. Shipping accounts for about 2,9 % of global greenhouse gas emissions. Although the main objective of the sector has been to reduce emissions for years, in 2050 shipping could cause up to 17 % of global CO2 emissions if no further action is taken. In 2018, the United Nation’s International Maritime Organization decided that the sector’s emissions must decrease by half by 2050 comparing to the 2008 level. The growth in emissions is due to the growth of economies and trade in developing countries, which leads to an increase in travelled distances. 90 % of world trade is transported by sea, and although shipping is the most environmentally friendly mode of transportation, the sector requires new fossil-free fuels to achieve their emission reduction goals. The aim of this work is to explore the potential of SMR technology as a source of commercial maritime propulsion. The work examines the current state of nuclear power and development of SMR technology. The paper also studies operating and former nuclear-powered ships. The first nuclear-powered vessel was launched in 1955 and technology has been developed ever since. Due to the development of small modular and fourth generation reactors, nuclear power is much safer than it was 70 years ago. The work states that strict standardization and regulation of nuclear-powered ships makes it possible to make operating safe. The work also concluded that the operation of nuclear commercial ships would be technologically feasible, but there are considerable legislative problems and social acceptance challenges.SMR teknologian potentiaali kaupallisessa laivaliikenteessä. Tiivistelmä. Merenkulku aiheuttaa noin 2,9 % maailman kasvihuonekaasupäästöistä. Vaikka alan keskeisimpänä tavoitteena on jo vuosia ollut päästöjen vähentäminen, vuonna 2050 merenkulku saattaa aiheuttaa jopa 17 % maailman hiilidioksidi päästöistä, jollei lisätoimiin ryhdytä. YK:n alainen merenkulkujärjestö IMO päätti vuonna 2018, että alan päästöjen on vähennyttävä puoleen verrattuna vuoden 2008 tasoon. Päästöjen kasvun syynä on kehittyvien maiden talouksien ja kaupankäynnin kasvu, joka johtaa myös maantieteellisten etäisyyksien kasvuun. Maailmankaupasta 90 % kuljetetaan meritse ja vaikka merikuljetus onkin varsinkin suuria kuormia kuljetettaessa ympäristöystävällisin kuljetusmuoto, vaativat laivat uusia fossiilivapaita polttoaineita päästötavoitteiden saavuttamiseksi. Tämän työn tavoitteena on tutkia SMR teknologian potentiaalia kaupallisen merenkulun työntövoiman lähteenä. Työssä tutkitaan ydinvoiman ja SMR teknologian kehityksen nykytilaa sekä tutustaan entisiin ja nykyisiin ydinkäyttöisiin laivoihin. Ensimmäinen ydinkäyttöinen alus otettiin käyttöön vuonna 1955 ja teknologiaa on kehitetty siitä lähtien. Pienten modulaaristen- ja neljännen sukupolven reaktoreiden kehityksen takia ydinvoima on huomattavasti turvallisempaa kuin 70 vuotta sitten. Työssä todettiin, että tiukalla standardisoinnilla ja säännöstelyllä ydinkäyttöisten laivojen operoinnista on mahdollista tehdä erittäin turvallista. Työssä johtopäätöksenä todettiin, että ydinkäyttöisten kaupallisten laivojen operointi olisi teknologisesti täysin mahdollista, mutta siihen liittyy huomattavia lainsäädännöllisiä ongelmia sekä ennakkoluuloj

The Success of the Light Armoured Vehicle

In order to understand the purchase of military vehicles, one must understand the vehicle and where it falls in the evolution of vehicle procurement. This article, written in response to an earlier article in response to an earlier article in Canadian Military History by Frank Maas, examines the chronology and motivations behind the Canadian acquisition of wheeled armoured fighting vehicles