Undersea Application Research Articles

Active cathodic protection for HV power cables in undersea application

This paper focuses on the performance analysis of the corrosion protection system of HV power cables for undersea applications. The aim of the work is to describe the relations between the main electrical parameters affecting the electric potential distribution in the cable layers and in the surrounding medium, when an active cathodic protection (CP) arrangement is used. In particular, the analysis focuses on the design of an active CP for reducing corrosion phenomena of the cable metallic shield. This study is based on a 2D analytical approach supported by a detailed 3D finite element analysis (FEM). It gives evidence to the relation between the electrical variables and the design criteria of the active cathodic protection system.

Experiments on the effects of aging on compliant coating drag reduction

We report the experimental results from a collaborative effort between USA, Russia, and UK on the development of compliant coatings for undersea application of reduction of drag. The focus is on “shelf-life” of coatings. The coatings are based on a linear interference theory of interaction between turbulence pressure fluctuation and the viscoelastic coating. The phase shift between boundary displacement and pressure fluctuation embodies the interference effect. The natural frequency of the coating is matched to the turbulent boundary layer region of maximum Reynolds stress production. Low-molecular weight rubber-like silicone coatings have been manufactured whose properties include slow and fast damping, slow and fast aging, and varying magnitudes of elasticity, density, and thickness as well as transparency. The dynamic modulus and loss tangent vary weakly over a range of frequencies and temperature allowing compatibility with broad spectrum of turbulence. Drag measurements have been carried out over a year by the three teams in their water tunnels independently of identical coated models. We show that, with some exceptions, drag reduction generally deteriorates with the age of the coatings.

Demonstration of a fiber optic array of three-axis magnetometers for undersea application

We describe an undersea array of eight fiber-optic, three-axis magnetic sensors. The interferometric sensors employ magnetostrictive metallic glass strips as the transducer elements. We discuss the operating principles and the performance of the system during actual undersea operation.

Non‐Linear Optical Transmission Systems

AbstractIn recent years much research has focussed on the development of high capacity optical transmission systems for terrestrial and undersea application. The development of optical amplifier repeaters has led to the situation where multigigabit transmission is required over very large distances. In this situation the effects of fibre dispersion pose a serious limitation to performance. This paper considers the effects of fibre dispersion and discusses the technique of non‐linear propagation which has been proposed to overcome the problem. The main design equations for a soli‐ton system are presented and discussed.

Flanged Acrylic Plastic Hemispherical Shells for Undersea Application

The effects of an equatorial flange and a nonuniform wall thickness upon the critical pressure and stress distribution in acrylic plastic hemispheres have been investigated by experimental and analytical methods. Forty acrylic hemispheres were fabricated and tested to destruction under short term hydrostatic pressure applied on the convex surface. Dome apex displacements were obtained from each specimen and strains were obtained from a selected few. A finite element elastic analysis was performed on one window configuration for two different boundary conditions and the experimentally derived stresses were used to determine which boundary conditions was the best for analytical analysis.

SUBMERSIBLE LIFE SUPPORT COMPONENTS AND SYSTEMS

ABSTRACTThe present state‐of‐the‐art of Life support Systems for undersea application is defined. Restrictions that have been Placed on undersea exploration due to lack of advancement in submersible and diver life support equipments are reviewed. Areas are identified where additional development is required to overcome technical limitations of current under. sea life support systems.

Undersea Reactor Siting

An underwater siting guide for use in international and territorial waters must be created to evaluate the consequences of the release of fission products from a nuclear reactor sited in the ocean. This paper is an initial attempt to develop the basic equations for such a guide. A very conservative fission-product-release inventory to illustrate undersea application is developed consisting of 100% of the soluble and 1% of the insoluble fission products or ∼66% of the gross fission-product inventory. The ocean is divided into four distinct zones for which current velocity profiles and characteristic diffusion parameters are established. Based upon a three-dimensional diffusion model incorporating shear effect and with the assumptions of no current variance, zero mean vertical current velocity, and depletion of the inventory by radiological decay only, equations are presented which describe the physical transport and dispersion of the radioisotopes. A computer program, SEADIF, is applicable to a person immersed in the water and is used to determine, for both contained and uncontained systems, the distance factors and the radioisotope concentrations as a function of time and position. Representative results for a 10 MW(th) system are given.

Closed Cycle Gas Turbine as a Proposed Undersea Power Source

Undersea application of compact and lightweight closed Brayton cycle power systems currently being developed for space is discussed. Design details of a 50 kwe hydrogen-oxygen fueled system for a short-duration undersea mission of 1000 kw-hr are presented. For this same mission, a new hydrogen-oxygen injection gas turbine cycle is described. Performance characteristics of undersea long-duration 10 to 150 kwe power systems, using radioisotope and nuclear reactor heat sources, are also presented. Development status of closed Brayton cycle power conversion systems is presented.