Submersible Vessels Research Articles

CFD Study on the Influence of Exostructure Elements on the Resistance of a Submarine

Submersible vessels designed to operate at low speeds are often designed with an intricate exostructure, as well as other elements that are located outside of the main pressure hull. Exostructure elements are often of cylindrical or rectangular shape, positioned perpendicularly to the flow direction. For this reason, their resistance coefficient is relatively large compared to the pressure hull or appendages of a classical submarine. In some cases, the exostructure can significantly increase the wetted surface of the vessel and dominate its resistance. This paper presents a study on how different exostructure elements impact the overall resistance of a submarine relative to the resistance of the cylindrical, smooth, pressure hull. Additionally, the effect of depth is also considered. The study is conducted using the RANS-based CFD method. The subject of the study is a 25 m long tourist submarine designed for depths up to 40 m and a speed of up to 3 knots.

Influence of Geometric Parameters of Conical Acrylic Portholes on Their Stress-Strain Behaviour.

Translucent elements in the form of truncated cones, which are made of organic glass, are widely used in the structures of portholes, submersible vessels, space vehicles, pressure chambers, teleboxes and other types of technical equipment. The decisive factor in designing portholes is to ensure the strength of their translucent elements. In order to reduce the weight of portholes and, accordingly, to increase the payload, it is necessary to optimise the geometric parameters of the translucent elements, which include the tapering angle and the ratio of thickness to radius of the smaller base. The paper deals with development of the applied (engineering) method for determining the stress–strain behaviour of the conical translucent elements of portholes made of organic glass under the action of a uniform hydrostatic pressure. Finite-element modelling of the translucent element of the conical porthole is performed, with the calculation of its stress–strain behaviour. External hydrostatic pressure of 10 MPa, absence of loads from the inside and continuous sliding of the translucent element with friction along the conical supporting surface of the porthole metal body are the boundary conditions for the computational model. Full-scale tests of translucent elements of portholes made of organic glass were performed under the action of uniform hydrostatic pressure. Analysis of the influence of geometric characteristics of the portholes on stress–strain behaviour showed that the increase in the tapering angle at the constant relative thickness of the translucent element reduced its axial displacement in all cases. Equivalent stresses acquire minimum values when the tapering angle is in the range from 75° to 105° (when the relative thickness increases, the optimal tapering angle becomes smaller). It is shown that the developed method for determination of the stress–strain behaviour of the conical translucent elements of portholes made of organic glass reflects the real picture of deformation and agrees with the results of full-scale tests. Results of the work allow us to choose the rational parameters of the translucent element for increasing the reliability of portholes through the creation of an effective distribution of stresses and strains in the translucent element, and improving its optical characteristics due to a relatively small deflection in operation.

Создание передовой технологии и оборудования для изготовления титановых шар-баллонов

The most promising in the world practice are launch vehicles using titanium spherical vessels in a cryogenic medium at high pressure. The paper deals with an import-substituting technology, which provides a closed production cycle for the manufacture of titanium spherical vessels at the JSC “Chemical Automatics Design Bureau” and analyzes existing manufacturing technologies. We developed an innovative method of shaping and machining hemispheres from hard-to-deform advanced titanium alloys, providing maximum automation and productivity of the process. For hydraulic and cryogenic tests of submersible titanium vessels, bench equipment was developed and introduced into production. For simulating the facility operating conditions in order to reduce the cost and increase the safety of tests, liquid oxygen was replaced with liquid nitrogen and helium was replaced with high-pressure nitrogen. Within the study, we substantiated the area of ??effective use of the import-substituting technology and developed production facilities of a closed cycle for the production of titanium vessels with a capacity of 25 and 130 liters.

Investigation on the thermohaline structure of the stratified wake generated by a propagating submarine

The in situ thermohaline distribution of the wake contains a critical source of information for submersible detection. In this work, a stratified thermohaline wake model, in which major fluid properties vary with temperature and salinity, is presented to address heat and mass transfer characteristics in the stratified wake signatures induced by a propagating submarine via Large-Eddy Simulation (LES) approach. Of particular interests are the range and intensity of the wake signatures. The instantaneous fields reveal the evolutions of the temperature and salinity fields, showing the regional features of wake signatures. As the key diagnostic variables, the perturbation variations in temperature and salinity are quantified at the wake region defined by wake amplitude. Subsequently, the range and intensity of the wake signatures generated by submarines with different velocities are analyzed to illustrate the effects of velocity. The magnitudes of the perturbations in stratified flows are at significantly detectable levels, indicating that the submersible detection based on the temperature and salinity variations is a feasible and promising approach. The scientific findings provide useful insight for the deep understanding of the evolution of stratified flow, and support further research on optical and lidar tracking of the submersible vessels.

The Evaluation of Sanitary-Epidemiological Service Conditions On a Submarine

Abstract Service on a submarine is the most stressful and psychologically challenging form of military service. It is characterised by specific living and sanitaryepidemiological conditions which are far from typical. This work is based on the analyses of reports formulated from research conducted by a working environment laboratory, and on the control protocols of the sanitary supervision and control team (WOMP) Gdynia, from the Kobben submersible vessels in the years 2014 and 2015. Military Centres of Preventive Medicine hold supervision over Military Units pursuant to generally applicable regulations in the civil environment and standardised NATO norms. Measurements concern the level of noise, mechanical vibrations, chemical agents, electromagnetic radiation, physiochemical and biological water and kitchenware tests. The objective of the research is to evaluate the service conditions on a submersible vessel with regard to sanitary-epidemiological aspects such as exposure to infectious and occupational diseases. In selected stations, the conducted measurements indicate an increased level of noise, electromagnetic radiation and excess quantities of bacteria colonies on kitchenware.

Interview: John Ramsay

CTO of Triton Submarines John Ramsay is a product design engineer who has spent his career perfecting a new generation of small submersible vessels for subsea filmmaking, leisure and treasure hunting.

The Revolutionary Armed Forces of Colombia (FARC) and the Development of Narco-Submarines

The Revolutionary Armed Forces of Colombia (FARC) have been one of the world's most consistently formidable violent non-state actors over the last forty years. Unsurprisingly, the group has provided one of the most compelling and concerning examples of the level of technical sophistication attainable by sub-state organizations. Over the last two decades the group has carried out an iterative and innovative process that, in reaction to improved detection capabilities, has brought them from depending on disposable go-fast boats to transport drugs to possessing fully submersible and reusable covert vessels for transportation. The following case study will discuss the development of narco-submarines and the underlying motivations behind the pursuit of this complex engineering task. The case study will outline the different phases of the narco-submarine development and highlight FARC’s determination to overcome the challenges present in each design. This discussion will show how FARC’s systematized acquiring of information and expertise has resulted in the accomplishment of fully submersible vessels, capable of transporting more than 10 tons of illicit product. Disclaimer Editor’s Note: This article forms part of a series of related case studies collected in this Special Issue and should be viewed in the context of the broader phenomenon of complex engineering by violent non-state actors. Readers are advised to consult the introductory and concluding papers for a full explanation and comparative analysis of the cases. Acknowledgements This work was supported by Sandia National Laboratories, Contract #1525332. Any opinions, findings, conclusions and recommendations in this issue are those of the authors and do not necessarily reflect views of Sandia National Laboratories or the U.S. Department of Energy. This article is available in Journal of Strategic Security: http://scholarcommons.usf.edu/jss/vol9/iss1/6

A soft-bottom sublittoral mesocosm by the Oslofjord: Description, performance and examples of application

Abstract Controlled experiments and detailed studies of behaviour in the subtidal require diving, submersible vessels or instruments placed in situ. These methods often limit experimental design. Furthermore, experiments with toxic chemicals in the field may not be possible due to lack of dosage control, environmental consequences, and public welfare. Such problems can be overcome by the use of mesocosms. In this paper a soft-bottom mesocosm in the Oslofjord, Norway is described. The mesocosm consists of two indoor basins each with a surface area of 100 m2 and a maximum water depth of 1.7 m. Each basin is divided into three compartments. Soft-bottom sediment sections were collected in the field by a modified USNEL box-corer (0.25 m2). The sediment was transferred to boxes and brought into the mesocosm. The water level in the mesocosm can be lowered so that the sediment surfaces are easily accessible for sampling, manipulation, inspection, or measurements requiring equipment or techniques not compatible with field conditions. The performance of the mesocosm in terms of pore-water chemistry, bacterial production, sedimentation, animal recruitment and mortality are compared to field conditions. Examples of application of the system are given. It is concluded that the mesocosm provides unique experimental conditions for biological, chemical and physical experiments on subtidal soft-sediment communities.

Sea Ice Forces and the State of Technology of Offshore Arctic Platforms

Distinguished Author Series articles are general, descriptive representations that summarize the state of the art in an area of technology by describing recent developments for readers who are not specialists in thetopics discussed. Written by individuals recognized as experts in the area, these articles provide key references to more definitive work and present specific details only to illustrate the technology. Purpose: to informthe general readership of recent advances in various areas of petroleum engineering. The oil industry is in the infancy of offshore arctic operations. The capability to conduct exploration during part of the year has been demonstrated, and in the next few years production will begin in shallow waternear Prudhoe Bay. Year-round operations in deep water are at least a few yearsin the future. This paper is a summary evaluation of the industry's currentcapability, and of the ice forces that will control the design of offshorestructures in depths of 100 to 200 ft [30 to 60 m] in the arctic. The technology of arctic offshore operations still is being developed, and we willlearn a lot before production begins in deepwater arctic areas. It will be surprising if the opinions expressed in this paper do not change in the next 5or 10 years. Much of the industry's arctic experience has been gained in the CanadianBeaufort Sea. The. Alaskan Beaufort presents greater challenges. In the wordsof Weeks and Weller: . . . ice conditions are generally more severe north of Alaska with more multiyear ice, more ridging, and large ice motions occurring." The oil industry's technical capability to explore and produce in the Alaskan Beaufort Sea varies with a number of factors but mainly with water depth. Fig. 1 shows the variation of ice conditions on a cross section of thecontinental shelf of the Beaufort Sea. There is a dramatic change in iceconditions at about 50 to 70 ft [15 to 21 m] water depth, where the groundedridge zone is found. The grounded ridge zone marks the change from the relatively stationarylandfast ice to much more mobile ice farther offshore. The amount of motion andthe speed of motion increase by about a factor of 10 at this boundary. Indeeper water, the faster sea-ice motion will result in larger ice forces actingon fixed structures. Fig. 2, a map of the Diapir field (OCS Sale 87) area, gives the water depth ranges of the Beaufort Sea over which various exploration and production technologies will be applicable. The general categories given on the map, however, deserve further explanation. Depth Range 0 to 100 ft [0 to 30 m] Current Technology is Adequate Exploration. Three basic systems available for drilling in less than 100 ft[30 m] of water in the Alaskan Beaufort Sea include earthfill islands, caisson-retained islands, and submersible drilling vessels. In less than about 60 ft [18 m] of water, earthfill islands can be built. Beyond the edge of the landfast ice, dredged or barge-hauled gravel may berequired, rather than gravel trucked over ice roads, because the sea icefarther offshore moves too much to maintain an ice road over a period of weeks. From 60 to 100 ft [18 to 30 m] of water, caisson-retained systems (Fig. 3)may be used. In these systems, large box structures, called caissons, are usedas retaining walls at the surface of the island. This reduces the volume offill required. Caisson-retained islands may have a cost advantage over 100%earthfill islands, depending on the relative costs of the caissons and of dredged fill. The first two caisson-retained islands were built in the CanadianBeaufort Sea at Tarsuit and Kadluk. Submersible drilling vessels, such as the Global Marine concrete is land drilling system (CIDS) especially built for arctic ice loading, also may beused in this range of water depth. The first CIDS, designed for a maximum 60-ft[18-m] water depth, was deployed in the Alaskan Beaufort Sea in Summer1984. P. 21^

Acoustic under sea position measurement system

The invention concerns acoustic under-water measurement apparatus for determining the location with respect to a surface vessel of objects such as submersible vessels, pipe-riders, mining apparatus, or the like, including tethered submersible vessels. A receiver hydrophone set located on the tethered vehicle receives acoustic reply pulses from sea bottom transponders, telemetering the times of reception to a surface support ship via conductors in the tether cable. Signals obtained at the surface ship directly from the transponders and indirectly via the tether cable conductors are combined aboard the surface ship for computing the positions of both vessels with respect to a base line established by the sea bottom transponders. The system is self-calibrating, so that an expensive survey to determine the actual locations of the bottom transponders is no longer required.