The Use of CAD Systems to Manage Modularity in Multi-Role Warships

Modulation requires new approaches to the entire shipbuilding process, general arrangement for the warships need careful analysis of interaction and physical connection between modules: electrical, water, air conditioning, etc. and between modules and the elements surrounding them. The analysis of areas with high potential for modulation will lead, by the application of the criteria decided, to a selection of several standard modules to be designed in CAD systems for those cases where it is expected to achieve significant savings by producing series of modules. The appropriate application of the modularization theories demands a difficult exercise of coordination among the design of all the units, systems, zones or disciplines present in the compartments and also direct implications in constructive strategy which will require specific protocols for the correct implementation of the modules during the constructive stages. The implementation of new tools to handle modules in warships is particularly important since it remarkably simplifies the analysis, what leads to a high potential in the improvement of the coordination among design areas and disciplines, and consequently to a more efficient design. The typical outfitting and equipment modules for these areas shall be defined, interfaces to the equipment and specification of cables, pipes and air conditioning systems needed for the module. The goal will be to define a limited number of standard modules, which allows exploiting serial effects and containing a significant part of outfitting in order to achieve savings from pre-outfitting. But the concept of modularization has even a wider meaning for warships when thinking in modularity, not only oriented to the design and constructive advantages but also in the future evolution of these kind of ships in order to be reoriented easily towards different uses, future upgrades or changes that should be realized to be able to undertake different kind of missions thanks to an efficient Plug and Play system. The aim of this paper is to develop concepts and design solutions for modular machinery space, on-board automation and warship equipment. To achieve those possibilities, not only the modularity concept will be necessary, it also needs a clear vision of which will be the lifecycle of the warship and its present and future purposes or possible upgrades in order to create a design. CAD systems are essential tools to provide the vision and the base to design and simulate the different possibilities that a warship would be able to provide thanks to the application of a modular concept during its complete lifecycle.

Machinery Space Fire Fighting – Modern Alternatives

Machinery spaces in the majority of Royal Navy (RN) vessels use carbon dioxide (CO2) as the primary fire suppressant. While CO2 is very effective for firefighting, particularly in machinery space application, it is harmful to life in the concentrations required for effective fire suppression; exposure to concentrations greater than 15% can cause death within sixty seconds. The use of CO2 and similar fire suppressant systems in machinery spaces presents a risk due to the potential exposure of personnel. This may occur in a fire scenario where personnel are unable to escape the affected compartment, if there is a leak in the system, or due to accidental discharge. These risks are typically mitigated through physical means and procedural controls. However, in the hierarchy of safety controls the primary means should always be the elimination of the hazard. Babcock Energy and Marine undertook a study for the United Kingdom Ministry of Defence (MoD) into alternative methods of firefighting on Royal Navy minor warship machinery spaces with the safety of personnel considered a key requirement. The study identified five alternatives to CO2 available on the market. One particular aerosol fire suppression system was found to be superior to the others for application in small craft. This system is not toxic, non-ozone depleting and leaves almost no residue after application to the affected space, enabling re-entry (provided that the space has been ventilated to remove the products of combustion). The study concluded that traditional methods of fire suppression should be reconsidered across all small craft due to the health and safety issues associated with CO2 and the availability of improved alternatives. This paper considers the use of traditional firefighting systems on naval vessels in light of 21st century health and safety regulations. An assessment of current fire extinguishing agents is presented followed by a case study to determine the most appropriate solution for a minor warship concept with a particular aerosol system being justified as the preferred option. The paper also considers if the same conclusions would be reached for major warships or if the difference in scale results in an alternative solution.

Modelling and collaboration across organizations: Issues and a solution

This article describes the results of the space cluster of the Use-it-wisely project, which is investigating new business models implementing continuous product-service adaptation through a sequence of small innovative steps in six key industry sectors (clusters): energy, machinery, space, office workspace, vehicles manufacturing and shipbuilding. Six independent cluster developments and a common platform compose the main output. The space cluster (composed by TAS-I, ALTEC and Vastalla) researches a quick response through the use of model-based and simulation-based processes enabled by distributed environments across different organizations. TAS-I and ALTEC study the use of a web-based environment, a model-based tool and virtual reality and its interfaces with potential customers, using an internal project as reference case, including space and ground segments. Vastalla studies and develops the infrastructure able to connect different environments in different networks, including a customer front-end. This article shows the identified issues on collaboration with model-based approaches and the expected benefits.

Dual-Fuel-Electric Propulsion Machinery Concept on LNG Carriers

Human efforts to devise optimum propulsion for their vessels are as old as the vessels themselves. Today these efforts are even more determined as modern shipping requires propulsion systems that are increasingly reliable, available, cost-efficient and able to meet high ecological criteria. The heat transfer towards liquefied gas stored in tanks results in boil-off during cargo handling or voyage. The rate of the evaporated gas amounts to 0.13% per day during the voyage of a fully loaded ship. Steam turbines have been a dominant form of propulsion on liquefied natural gas - LNG carriers for over forty years. Until recently, the possibility of using boil-off gas as fuel for boilers has been the reason for installing steam plants as the only means of propulsion of LNG carriers. However, it has been proved that these plants are not sufficiently efficient due to adverse impacts on both emissions and the vessel’s operating expenses. It has also been found out that dual-fuel-electric propulsion is the most effective alternative to steam. Shipping companies select electric propulsion primarily because it provides excellent manoeuvrability and increased availability, allows reduction of the machinery space and better arrangement of shipping capacity and, naturally, because of lower fuel costs. This paper discusses the newest technologies and the operation principle of the low-pressure four-stroke dual-fuel diesel engine, specificallythe 12V50DF and 9L50DF types produced by Wärtsilä company, and the concept of the dual-fuel-electric propulsion for the new generation of LNG carriers.

Auxiliary Turbine Generator Set Isolation System Design for US Naval Vessel

The RR4500 Auxiliary Turbine Generator (ATG) incorporates an isolation system addressing four main design requirement environments. These environments include high-impact shock, structureborne vibration, sea state motion, and installation/integration into the machinery space. Multiple design iterations were performed, beginning with a simplified system representation and expanding to full system finite element models. Specific resilient isolation mounts were selected to satisfy the competing criteria from the different requirement sets. Design resolutions passed specific requirements down to the component level and were addressed during detail design. Structures, system components, and flexible ship connections were adapted to meet the requirements needed by the isolation system. Testing of the system indicates good correlation between system predictions and actual performance.