Propulsion Machinery Research Articles

The rigid bi-functional sail, new concept concerning the reduction of the drag of ships

The policy of the European Union in the energy field, for the period to follow until 2020, is based on three fundamental objectives: sustainability, competitiveness and safety in energy supply. The “Energy - Climate Changes” program sets out a number of objectives for the EU for the year 2020, known as the “20-20-20 objectives”, namely: the reduction of greenhouse gas emissions by at least 20% from the level of those of 1990, a 20% increase in the share of renewable energy sources out of the total energy consumption as well as a target of 10% biofuels in the transports energy consumption. In this context, in order to produce or save a part of the propulsive power produced by the main propulsion machinery, by burning fossil fuels, we suggest the equipping of vessels designed for maritime transport with a bi-functional rigid sail. We consider that this device may have both the role of trapping wind energy and the role of acting as a deflector for reducing the resistance of the vessel's proceeding through the water by conveniently using the bow air current, as a result of the vessel's heading through the water with significant advantage in reducing the energy consumption for propulsion insurance.

Self-repairing symmetry in jellyfish through mechanically driven reorganization

What happens when an animal is injured and loses important structures? Some animals simply heal the wound, whereas others are able to regenerate lost parts. In this study, we report a previously unidentified strategy of self-repair, where moon jellyfish respond to injuries by reorganizing existing parts, and rebuilding essential body symmetry, without regenerating what is lost. Specifically, in response to arm amputation, the young jellyfish of Aurelia aurita rearrange their remaining arms, recenter their manubria, and rebuild their muscular networks, all completed within 12 hours to 4 days. We call this process symmetrization. We find that symmetrization is not driven by external cues, cell proliferation, cell death, and proceeded even when foreign arms were grafted on. Instead, we find that forces generated by the muscular network are essential. Inhibiting pulsation using muscle relaxants completely, and reversibly, blocked symmetrization. Furthermore, we observed that decreasing pulse frequency using muscle relaxants slowed symmetrization, whereas increasing pulse frequency by lowering the magnesium concentration in seawater accelerated symmetrization. A mathematical model that describes the compressive forces from the muscle contraction, within the context of the elastic response from the mesoglea and the ephyra geometry, can recapitulate the recovery of global symmetry. Thus, self-repair in Aurelia proceeds through the reorganization of existing parts, and is driven by forces generated by its own propulsion machinery. We find evidence for symmetrization across species of jellyfish (Chrysaora pacifica, Mastigias sp., and Cotylorhiza tuberculata).

Locomotion and the Cost of Hunting in Large, Stealthy Marine Carnivores.

Foraging by large (>25 kg), mammalian carnivores often entails cryptic tactics to surreptitiously locate and overcome highly mobile prey. Many forms of intermittent locomotion from stroke-and-glide maneuvers by marine mammals to sneak-and-pounce behaviors by terrestrial canids, ursids, and felids are involved. While affording proximity to vigilant prey, these tactics are also associated with unique energetic costs and benefits to the predator. We examined the energetic consequences of intermittent locomotion in mammalian carnivores and assessed the role of these behaviors in overall foraging efficiency. Behaviorally-linked, three-axis accelerometers were calibrated to provide instantaneous locomotor behaviors and associated energetic costs for wild adult Weddell seals (Leptonychotes weddellii) diving beneath the Antarctic ice. The results were compared with previously published values for other marine and terrestrial carnivores. We found that intermittent locomotion in the form of extended glides, burst-and-glide swimming, and rollercoaster maneuvers while hunting silverfish (Pleuragramma antarcticum) resulted in a marked energetic savings for the diving seals relative to continuously stroking. The cost of a foraging dive by the seals decreased by 9.2-59.6%, depending on the proportion of time gliding. These energetic savings translated into exceptionally low transport costs during hunting (COTHUNT) for diving mammals. COTHUNT for Weddell seals was nearly six times lower than predicted for large terrestrial carnivores, and demonstrates the importance of turning off the propulsive machinery to facilitate cost-efficient foraging in highly active, air-breathing marine predators.

The W estern R iver S teamboat H eroine , 1832–1838, O klahoma, USA : propulsion machinery

This paper completes the description of the western river steamboat Heroine (1832–1838) (Crisman et al. 2013b; Crisman, 2014), with a detailed analysis of the steam propulsion machinery recovered. Heroine's place in the development of steam technology is analysed through historic sources and comparable finds, and the requirements of river navigation explored. Changes to the paddle flange and the short-lived use of flywheels are particularly noted. The many variations in the iron castings and evidence of makeshift repairs provide insight into the material, engineering and economic constraints faced by engine manufacturers and steamboat engineers in the second quarter of the 19th century.

Maritime Superconductivity Perspectives

The present paper reports on the ongoing studies into the perspectives of maritime superconductivity (SC). Maritime applications follow a similar pattern as on-shore applications when it comes to performance if the competition is weak. For large scale applications like propulsion, power supply, and other machinery, the character of an isolated energy system onboard greatly influences the perspectives of maritime SC. The paper compares the energy chains of propulsion configurations and discusses the relations with energy carriers, storage, and conversions. It is shown that perspectives more or less follow the developments on all electric shipping: i.e., as for energy efficiency short range shipping and dynamic behavior favor SC technology; high-temperature superconducting engines may also be an improvement if electric propulsion is selected for other reasons than efficiency. High-temperature superconductor degaussing is promising, but demands adjustments. Maritime SC perspectives often depend on developments in other areas like fuels, conversions, and power electronics.

Application of high-speed fiber bragg grating sensing system for safety monitoring of modern ships

Structural health monitoring (SHM) can be understood as the integration of sensing intelligence and possibly also actuation devices to allow the structure loading and damaging conditions to be recorded, analyzed, localized and predicated. SHM sensing requirements are very well suited for fiber optic technology. The fiber Bragg grating (FBG) sensor is a promising sensor of SHM for many applications because of its good optical properties, small size, low insertion loss, antiRF, anti-electromagnetic interference, breakdown voltage, radiation-resistant, light weight, small and large signal bandwidth. There also are reports of the application of FBG sensors for SHM of large industrial and civil works such as dams, bridges [1−2] , aero plane [3] , and tunnels [4,5] . The development of ship’s SHM takes advantage of multidisciplinary work that is being done, and most of the applications reported are about ship hull monitoring systems [6,7] . Previous studies mostly focus on the measurement of static stress [8] . For a modern ship, the thruster is a key part of the propulsion machinery, and the stability of its related equipments has a great influence on the propulsion efficiency of the ship. Electric resistance strain sensors are difficult to be used for the stress measurement for the thruster because of the electromagnetic disturbance and other complicated environment. Low-speed FBG sensors cannot meet the requirements due to the propulsion machinery’s 100 Hz arising vibration frequency. The high-speed FBG sensing system can be used to measure dynamic stress and achieve the goal of safety monitoring in advanced ships. In this letter, the application of a high-speed FBG sensing system for SHM of modern ships is proposed. We apply this sensing system to give on-site tests to an advanced ship. Strain distribution of the bases and supporting frames of its large turbine thrusters are measured both onshore and in the sea when it runs at different work conditions. The maximum natural frequency of this measured structure is 335 Hz. To test all the monitoring points synchronously, an 8-channel senor system is applied, and the data acquisition frequency was 1000 Hz. Most monitoring points are set with single-line sensors for unilateral stress, and the others are set with triple directions sensors to measure shear stress. Temperature compensation is taken with additional FBGs to eliminate the effect of cross-sensitivity between temperature and strain on FBG sensors. As for every single monitoring point, the max and average stress-gas turbine power factor (GTPF): N/Ne curves are analyzed. Then we synthesize all the results from three-time onshore tests and acquire the static stress-GTPF curves. Results from the test at sea are discussed together, thus we can accomplish completely prediction of the dynamic stress-GTPF curve when we did not obtain dynamic data in every work condition because of some objective reason. We examine the vibration amplitude of the wave length of signal light from each specific monitoring point under the same work condition for all tests and find it barely affected by the environment factors, unlike the absolute wave length. Those experimental results are accordant with mechanical theories, and the final reports have obtained clients’ approval. FBGs are periodic alterations in the index of refraction of the fiber core, and only the specified wavelength (Bragg wavelength) related to its grating period is reflected for an input light wave form a broadband source.

B304 自然エネルギーを利用したグライダー型海中ロボットの制御(OS10 海洋におけるシステムと制御2)

Power supply is one of the most important issues for autonomous underwater vehicles (AUVs) which have no umbilical cable connecting with their mother ships. Underwater robotic glider can go forward without any propulsive machinery and it is extremely efficient in energy consumption. The purpose of this research is to study the feasibility of a solar-powered underwater robotic glider so as to improve its long-term endurance, The SORA glider equipped with two thrustors and amorphous-silicon solar panels was developed as a test-bed vehicle of the solar-powered underwater robotic glider, and the authors have demonstrated that SORA has an ability to go underwater using solar energy. This paper deals with development of the SORA glider and the feasibility of the solar-powered underwater robotic glider use in the surface layer of ocean.

1P1-B01 主翼独立制御型水中グライダーの動力学に関する研究

An underwater glider with independently controllable main wings for applications in oceanographic surveying, monitoring of the marine environment and ocean exploration is under development. Power-driven propulsive machinery is unnecessary for this underwater glider so that it is applicable to long-term and wide-range operations. The purpose of this research is to offer an underwater glider with high manoeuvrability and this paper deals with motion simulation of an experimental vehicle named 'ALEX' as a test-bed for an underwater glider with independently controllable main wings. ALEX was designed to realise high performance manoeuvrability. Results of the motion simulation were compared with the experiment. The authors have concluded that a feasible model could be verified and an 'underwater glider with independently controllable main wings' will show high performance of motion.

C28 主翼独立制御型水中グライダーの運動制御(OS11 海洋におけるシステムと制御2)

Abstract: An ocean-going underwater glider with independently controllable main wings is under development for applications in oceanographic surveying, monitoring of the marine environment, and ocean exploration. Power-driven propulsive machinery is unnecessary for this underwater glider so that it is applicable to long-term and wide-range operations. And this silent and safe underwater vehicle can be maintained with relative ease and does not cause any harm to the ocean environment and underwater marine life. The purpose of this research is to establish a method to control an experimental vehicle named 'ALEX' as a test-bed for an underwater glider with independently controllable main wings. ALEX was designed to realise high performance manoeuvrability. The six servomotors for the right and left main wings, upper rudder, elevator, movable balance weight and combination valve can be controlled by the on-board microcomputer system MAVC2 (Micro Aerial Vehicle Controller 2^<nd> model) through a servomotor controller. Three axes acceleration, three axes angular velocity, depth and direction by magnetic compass during a cruise can be measured in 10 samples per second and stored in the EEPROM (Electrically Erasable Programmable ROM) as the flight recorder for a maximum of 20 minutes. The ALEX glider is navigated by dead reckoning under water but accurate positioning can be obtained by GPS when it is at the surface. These sensor data are transmitted to a PC station by a wireless modem system when positioned at the surface. Various kinds of experiments and motion observation have illustrated that an underwater glider with independently controllable main wings exhibits a high performance of motion and has remarkable capabilities for diving / surfacing with a much smaller gliding angle as compared with a conventional fixed-wing underwater glider.

2A1-A02 主翼独立制御型水中グライダー「ALEX」の開発 : 自律型運動制御システムの構築(水中ロボット・メカトロニクス)

Underwater glider has no propulsive machinery, so that this silent and safe underwater vehicle can be maintained with ease and is easy on ocean environment. The authors developed an underwater glider with independently controllable main wings named 'ALEX'. Main wings, upper rudder, diving rudder, movable balance weight, and vent-blow valves can be controlled by on-board microcomputer system. The ALEX has linear acceleration sensors, angular velocity sensors, pressure gauge, and magnetic compass. These sensor data in storage will be transmitted to PC when the ALEX is at the surface. The purpose of this research is to implement the MAVC2 system for motion control with a microcomputer in three types of methods; pre-programme control, open control, and feedback control. Motion performance of the ALEX was observed in the Ocean and Underwater Engineering Tank of Research Institute for Applied Mechanics, Kyushu University and it was verified that the implemented programme and wireless communication function work well.

Operating Speed Profles and the Ship Design Cycle

AbstractOne key, but little documented and empirically supported, input in the ship design cycle is the expected operating speed profile. This real‐world constraint affects many decisions regarding hull form and power systems, from fuel tanks to main propulsion and ship's service machinery selection and operation. These decisions, in turn, ripple through the design of a ship in ways that are often hard to discern, but clearly impact acquisition and life cycle costs. Recent studies of DDG 51 operating speed profiles demonstrate that the Navy regularly operates with speed profiles considerably different than used to design the ship. In general, warships operate in standard engine order telegraph increments (e.g., Ahead 2/3) and at lower speeds than designed for.

Enhanced Maritime Safety Through Diagnosis and Fault Tolerant Control

Faults in steering, navigation instruments or propulsion machinery are serious on a marine vessel since the consequence could be loss of maneuvering ability, and imply risk of damage to vessel, personnel or environment. Early diagnosis and accommodation of faults could enhance safety. Fault-tolerant control is a methodology to help prevent that faults develop into failure. The means include on-line fault diagnosis, automatic condition assessment and calculation of remedial action to avoid hazards. This paper gives an overview of methods to obtain fault-tolerance: fault diagnosis; analysis of properties of a faulty system; means to determine remedial actions. The paper illustrates the techniques by two marine examples, sensor fusion for automatic steering and control of the main engine.

The Development of Water Mist Fire Protection Systems for U.S. Navy Ships

ABSTRACTDuring the past 20 years, the U.S. Navy has undertaken an extensive evaluation of water mist for fire protection applications aboard ship. Both small and full‐scale tests have been conducted to study water mist as a replacement for Halon 1301 and to explore the possible use of mist in lieu of conventional sprinklers. Tests have been conducted at the David Taylor Ship Research and Development Center in Annapolis, Maryland, at the Naval Research Laboratory, Chesapeake Division, and aboard the Navy'S fire research vessel, the Ex‐Shadwell in Mobile, Alabama. Engineering analysis and trade‐off studies have been conducted to compare ship impact (cost, space and weight) of water mist versus Halon and other gaseous alternatives. As a result of the testing and analysis completed thus far, the Navy has specified water mist to protect the propulsion machinery spaces on the Navy'S next new ship, the USS San Antonio (LPD‐17), currently undergoing final design at Avondale Industries.

アジポッド推進システム―商船への搭載実績―

The Azipod (Azimuthing Electric Propulsion Drive) propulsion system has been developed jointly by ABB and Kvaerner Masa Yards. The Azipod concept is a main propulsion system based on the ac-ac electric propulsion concept. Development work and references of ABB Azipod Oy are described. Also vessels ordered with the Azipod propulsion system are described.As an example of the concept the propulsion machinery of the earlier Fantasy-class vessels and the seventh vessel of the series, the M/S Elation, are compared. Practical experience of the system is presented in a description of the sea trial experiences.

Fault monitoring and re‐configurable control for a ship propulsion plant

Minor faults in ship propulsion and their associated automation systems can cause dramatic reduction on ships' ability to propel and manoeuvre, and effective means are needed to prevent simple faults from developing into severe failure. The paper analyses the control system for a propulsion plant on a ferry. It is shown how fault detection, isolation and subsequent reconfiguration can cope with many faults that would otherwise have serious consequences. The paper emphasizes analysis of re-configuration possibilities as a necessary tool to obtain fault tolerance, showing how sensor fusion and control system reconfiguration can be systematically approached. Detector design is also treated and parameter adaptation within fault detectors is shown to be needed to locate non-additive propulsion machinery faults. Test trials with a ferry are used to validate the principles. © 1998 John Wiley & Sons, Ltd.

Fault monitoring and re-configurable control for a ship propulsion plant

Minor faults in ship propulsion and their associated automation systems can cause dramatic reduction on ships' ability to propel and manoeuvre, and effective means are needed to prevent simple faults from developing into severe failure. The paper analyses the control system for a propulsion plant on a ferry. It is shown how fault detection, isolation and subsequent reconfiguration can cope with many faults that would otherwise have serious consequences. The paper emphasizes analysis of re-configuration possibilities as a necessary tool to obtain fault tolerance, showing how sensor fusion and control system reconfiguration can be systematically approached. Detector design is also treated and parameter adaptation within fault detectors is shown to be needed to locate non-additive propulsion machinery faults. Test trials with a ferry are used to validate the principles. © 1998 John Wiley & Sons, Ltd.

Propulsion System Simulations: Making the Right Choice for the Application

ABSTRACT The effective use of simulation for the design and analysis of propulsion systems, and for operator training of these systems, requires a clear definition of the simulation's intended purpose and expected results. Issues such as model fidelity, computational performance and data requirements must be carefully balanced against the development effort and costs. The relative importance of each of these factors can only be determined once the purpose and expected outputs from the simulation are known.Experience with some recent marine propulsion simulation initiatives has highlighted the need for clear definitions of model requirements, especially with regard to simulation fidelity and the use of physics‐based models. Marine propulsion system simulations can be used for a variety of purposes ranging from machinery performance analysis through maneuvering and seakeeping analysis to equipment health monitoring studies. This wide range of applications, with differing requirements, provides an excellent forum for examining the influence of fidelity on simulation computational performance, data requirements, and development cost. Examples from various marine propulsion machinery simulations are used to illustrate the discussion.

Dynamic Analysis: Sail the Ship Before It's Built

ABSTRACT A combatant ship is a complex system that involves the integration of many subsystems and components. Everyone agrees that systems integration is essential; nevertheless, the ability to deal with it is viewed as being elementary at one end of the spectrum to overly complex at the other end.Past emphasis has been on the development of the necessary tools and organizations needed to produce components that can be used to configure systems. As a consequence, when dealing with systems integration, the focus is primarily on what the system is and how its components fit, rather than what it does.Computer technology is benefiting the marine industry in many ways. Although it has been used to progressively improve the capability to deal with the component issues related to systems integration, the marine industry has yet to recognize the merits of effectively using the technology to address system functionality issues.This paper elaborates on the difficulty in dealing with system functionality and describes a way in which computer based simulation of propulsion machinery systems can be used to deal with the functionality aspects of systems integration. When procuring a ship, propulsion system simulation permits us to “sail it before we build it.”

Advanced Bridge Automation

The past thirty years have seen great advances in many areas of the technologies used in naval vessels. Propulsion systems, machinery automation, and information management systems have all undergone revolutionary changes. The bridges of these ships have similarly seen the advent of many new sources of navigational and environmental data. The process of correlating and interpreting all of this information has until now remained very labor-intensive, subject to human error at many stages of the process. In response to this challenge, a suite of new equipment has been developed for distributing, displaying, correlating, and logging shipboard data. This equipment automates most of the low-level, routine tasks involved in navigating a vessel at sea, significantly reducing the stress and workload of bridge personnel. This gives the humans on the bridge more time for doing the job that they do so much better than machines: making decisions. This paper focuses on the key technologies that are used in these new products and the advances in bridge design and automation they make possible. The benefits of these new capabilities to system designers, to shipbuilders, and to ship operators are also explored.

Surface Ship Machinery—A Survey of Propulsion, Electrical, and Auxiliary System Development

Propulsion, auxiliary, and electric machinery developments for surface combatants are surveyed---overall system characteristics are covered to permit a broad coverage of related activities. Prime movers in both propulsion and ship service sizes are discussed. All will demonstrate improved economy, especially at part power, and increased attention to thermal and acoustic signatures. Gas turbines are the source of propulsion power, but diesels join turbines in ship service application. Electric drives may be selected where machinery is widely separated or geometries are restrictive. Reversing motors or reversing gears will provide backing power without the inefficiencies of controllable--pitch (CP) propellers. Transmission component improvements, including surface-hardened gears and composite shafts, will increase power density. Shaftline elements compatible with contrarotating propellers may lead to significantly increased propulsive coefficients. Auxiliary machinery developments are driven by the need to improve performance in smaller, simpler packages with lower acquisition and operating costs. This encourages the development and adaption of new materials and design approaches such as composite structures, rotary screw pump and compressor arrangements, variable speed or geometry units, and molecular sieves and membrane separation for gas and fresh-water production. Ventilation system requirements will be expanded and integrated with the new demands of collective protection. The ship's service generation and distribution system will reflect the increasingly nonlinear character of electric loads. Developments will emphasize power quality and continuity in system arrangements which promote both survivability and energy efficiency. Propulsion-derived ship's service, uninterruptible power at the system and component levels, and variable-speed auxiliary motor drives reflect these thrusts.