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Dynamic wave loads are the most significant factor for the hull design of a ship. But experimental works for the motion responses of a ship and sea loads on her are expensive and time consuming for individual ship design. Therefore the development of theoretical and numerical methods for predicting ship motions and dynamic loads on a ship in waves is very important. Numerical analyses on ship motions and wave loads are presented for ships with forward speed advancing in regular waves. 3D Green function techniques are used to carry out the numerical computations for the radiation problem and wave loads for a moving ship. Based on the 3D linearised potential theory dynamic wave loads are computed for a bulk carrier in regular waves where experimental measurements are available. The computations are carried out for various heading angles between head sea and following sea and various ranges of frequencies. The results for motions and vertical and horizontal bending moments are presented. Computed results are compared with the experimental data. The results calculated by the present method are found to be in fairly good agreement with experimental results and those calculated by the other researchers. Using developed computer code some parametric studies are also carried out for the ship design criteria and discussed.

Conf was held in June 1988 in Trondheim - Norway Papers cont... Probablistic assessment of the foundation collapse strength of piled offshore platforms A new offshore soil investigation tool for measuring the in situ coefficient of permeability and sampling pore water and gas Simulation of erosion and sedimentation around marine structures by means of a numerical model Behaviour of pile foundations supporting tension leg platforms (End of Vol 1) VOLUME 2 - Computation of the characteristics of the wake past and oscillating cylinder Wave loading experiments on circular cyclinders at large scale Measurements of the drag forces on an inclined circular cylinder in a uniformly accelerated or decelerated motion Non-linear forces on horizontal cylinders in the inertia regime in waves at high Reynold's numbers Storm driven current profiles for design of offshore platforms Oscillations of a flexible cylinder in waves A full-scale experiment and theoretical study of the dynamics of underwater vehicles employing very long tethers Vibrations of pipelines in scour trenches Calculation of hydrodynamic damping of offshore structures Low frequency heave damping of semi-submersibel platforms; some experiment results The computation of wave loads on large offshore structures Wave current interaction effects on large volume structures Wave drift force on slender bodies Advances in the prediction of low frequency drift behaviour Model tests on non-linear slow-drift oscillations compared to numerical and analytical data

The safety issues that govern cargo pumping systems onboard chemical tankers are considered. The aim is to provide an understanding of the risks associated with managing technological advances in electric cargo pump designs for liquid cargoes. This topic is becoming more and more relevant to ship owners managers and other parties that try to keep up with technologies advances in electric pump designs. Here the IEC standards for hazardous area definitions are considered and how they correspond to the given provisions in IMO's IGC and IBC codes chapter 10 for electrical installations. On chemical tankers IMO still does not yet permit the submerged electrical driven cargo pumps whereas on gas tankers it is allowed for electricity in the tank. Therefore today the electrical frequency converter driven deepwell cargo pump system is designed with the motor on the deck and the pump in the tank. Technology has revolutionised the deepwell cargo pump systems for the last 3-5 years and the electrical alternative has enjoyed much support from the industry players concerned about high noise hydraulic power generation risk of hydraulic oil pollution vast maintenance and service as well as high power consumption. These benefits are documented in the associated Delta Marin study on comparison between hydraulic and electrical driven frequency converter deepwell cargo pumping systems.

In the world of yacht design rudders although an important part of the vessel have never been a major factor in yacht testing. Research has always focused on the hull keel and sail. This does not allow the model to simulate an actual sailboat on course and also means that the resistance tests for rudders without hulls can be misleading since a major drag appendage has been neglected. The effects of aspect ratio of spade rudders on the balance and resistance of a sailing yacht are investigated. Tests of a five-foot model of an 80-foot Maxi sailing yacht with four different aspect ratio rudders were carried out in the Robinson Model Basin. The four rudders were constructed so that the planform area and cross-section shape were held constant while the aspect ratio was varied. A yacht dynamometer was used to measure drag side force and the yaw moment of the model. The tests were done at two speeds one heel angle six rudder angles and four leeway angles for all four rudders. The rudder aspect ratios tested were 12 3 and 4. Results are presented. Evaluation of the data led to determining the rudder with the least resistance and the effects of aspect ratio on the balance of the sailboat using plots of resistance and balance arm (lead) versus rudder angle. Conclusions are drawn and recommendations for further work are made.

Structural reliability predictions for fixed jacket structures often involve calculating the probabilities of structural members failing and the overall collapse probabilities of the jackets existing in the corresponding damaged condition. It is current best practice to consider only single member failure conditions and to ignore multi member failure conditions since the probability of more than one member failing has been considered to be negligibly small. This approach assumes that the failure of a member is in no way related to the failure of another member which implies that the two events are statistically independent. However in reality the two events are not statistically independent since the failure of one member changes the stress state and therefore the failure probability of the remaining members. Two studies carried out to investigate the effects of stress redistribution on platform reliability predictions concluded that by ignoring the effects of stress redistribution platform reliability predictions could be significantly overestimated. However they both concentrated on shallow water jackets and consequently a further study was carried out to extend the existing work on stress redistribution to consider jacket structures in greater water depths. The study considered single and dual member failure conditions and compared the effects of including and excluding stress redistribution in reliability calculations. The findings of this work suggest that including stress redistribution reduces the predicted platform reliability. From the resultsX30475 The impact of subsea boosting on deepwater field development

Class societies are extending the scope of acommadation comfort guidelines to tackle unwanted noise and vibration in machinery spaces. This article gives details on some of the main guidelines on sound limitations and torsional vibration

This paper was printed by ASEA. It approaches the use of electricity on board of ships, focusing on generators that are driven by its own individual auxiliary prime mover. It also brings generators developed by ASEA.

Water collection due to the interaction of a vessel's motion and ocean waves usually causes significant problems for ferries and fishing vessels. This research sought to find a relationship between the geometric characteristics of an opening on deck and the water discharge rate and aimed for the stability of open deck ferries and fishing vessels. The effective parameters on the discharge rate are the beam depth of the water collected on the deck and the discharge gap height. In this study CFD analyses for water discharge from a ship deck were carried out and the commercial code FLUENT was used to carry out the simulations. A 2D unsteady second-order solver in time and space was used for the simulation. The two-phase free-surface model was simulated by the VoF (volume of fluid) method. Using the water discharge the instantaneous depth Froude number was calculated as a part of the non-dimensional simulation. The effect of geometric parameters on the water discharge rate was investigated by keeping two parameters fixed while changing the third parameter. For each parameter three different values were evaluated and the comparisons of all 27 possible combinations of the effective parameters were presented. Results were compared with the experimental results obtained earlier at UBC.

It is well known that the ribs can break up the viscous sub-layer of the flow and promote local wall turbulence which in turn enhances the heat transfer from the rib- roughened heated wall. In addition the rib-roughened wall provides a greater surface area for heat transfer than that of the plain wall. In the case of cooling of gas turbine airfoils rib turbulators are cast mostly on two opposite sides of the cooling channel since the heat transfer takes place from both the inner walls of the pressure side and the suction side of the blade. However in some cases like electronic equipment heat exchangers and nuclear reactors rib turbulators are mounted on one side two sides three sides or all four sides of the cooling channel. Several publications have addressed the state-of-the art review of turbine blade cooling and the analysis of heat transfer and friction characteristics in the channel with two opposite ribbed walls. Further study of the combined effects of rib geometry and channel aspect ratio on the local values of heat transfer and pressure drop has also been reported. An objective of this research is to investigate the effects of the number of ribbed walls on wall friction and heat transfer coefficient in the square channel. In the past the majority of investigations have been related to turbine blade cooling in the channels with two opposite ribbed walls. However

Flow-induced self-noise on moored and drifting hydrophones arises when the sensors are subjected to oceanic currents such as those due to wave motion and changing tides. Flow-induced self-noise on underwater acoustic particle velocity (or acceleration) sensors and on intensity probes that measure particle velocity and pressure simultaneously is examined. The sensors considered are configured as neutrally buoyant spheres that encase an accelerometer or geophone. These velocity sensors are very sensitive to the turbulent fluctuations in the free stream or those which are generated by the flow over the sensor body itself. The flow-induced self-noise is thus determined by the level of unsteady force created by the turbulence and unsteady flow. Experiments are carried out by towing a spherical velocity sensor from 0.5 to 2.0 knots in a quiet basin of water that is 9 m long. A model is developed for the flow-induced unsteady drag and side force of the sphere. This is based on integrating the local wall pressure fluctuations over the surface of the sphere. Wind tunnel experiments are carried out to obtain the necessary statistics of these pressure fluctuations. The semi-empirical model is then validated using the towed sensor unsteady velocity spectra which are easily converted to unsteady drag or side force spectra by Newton's Second Law. Predictions of the flow noise response of neutrally buoyant spherical velocity sensors of various sizes are then carried out. It is concluded that at the same flow velocity a large inertial sensor is less responsive than a small one to the turbulent flow over its surface and in the near wake.

FeCrAl alloys are used in a large number of high temperature applications. The growth rate and adhesion of protective alumina scales on heat resistant FeCrAl alloys are known to strongly depend on minor metallurgical additions of reactive elements such as Y La Ti Zr etc. Using high purity model as well as commercial FeCrAl alloys it is shown that the actual effect of the reactive elements on the oxide scale properties can be strongly affected by carbon and-or nitrogen impurities. It has been found that the carbon and nitrogen can interact with reactive elements forming carbide and-or carbo-nitride precipitates in the ferritic alloy matrix. This interaction changes the distribution of the reactive elements in the alloy and the way in which they are incorporated into the surface scale. Consequently the oxide growth and-or adherence can be affected in a positive as well as in a negative way depending on the exact amounts of the reactive element additions and the C-N-impurities. Experiments are described and results presented and discussed.

Deterioration in propellers performance occurs in a variety of ways including corrosion cavitation impingement and marine fouling and these can have a considerable negative effect on propulsion efficiency. Appropriate coatings can mitigate the effects of certain types of deterioration but historically coating of propellers has not generally been used for this purpose. In recent years coatings based on a new technology for prevention of fouling have been developed. Known as 'Foul Release' these now have a proven track record on the outer hulls of fast and active ships. These ultra-smooth coatings rely on low-surface energy and water movement over the surface to keep fouling from attaching thus they are ideal for use on propellers where the water velocity around the blades is very high. Trials on propellers of ships using the Foul Release coating 'Intersleek' have shown that prevention of fouling can be achieved over long in-service periods. There is usually detachment on the blade edges due to the high cavitation forces but since fouling never occurs in these locations coating detachment in these areas does not have a deleterious effect overall. Some ship owners have reported reduced cavitation-induced noise and increased speed after coating their propellers with Intersleek. In order to quantify these more accurately sea trials were carried out over a measured mile using Newcastle University's dedicated research vessel Bernicia

Third int conf held in Delhi February 21 - 23 1980 Papers are Computer calculations of thermodynamic properties of refrigerant absorbent combinations Flow boiling of refrigerants The influence of turbulent prandtl number in numerical studies of convective heat transfer Heat transfer during fluidised bed plastic coating Turbulence measurements behind ribs in fully developed turbulent chennel flow Numerical study of swirling flow through annular diffusers using a modified mixing length model Effect of wind tunnel walls on the flow over a sphere Experimental investigation of swirling flow through annular diffusers Some of the aerodynamic characteristics of blade nozzle annular cascades in transonic flow regime Design and off design performance of a vaned diffuser for a centrifugal turbomachine A model of two dimensional incompressible flow through a biplaner cascade of aerofoils Optimum performance chart of flat symmetrical profile for an axial pump turbine runner Effect of swirl on turbulence intensity in a diverging flow passage Experimental investigation on the performance of multi hole nozzle jet pump with various nozzle configurations Some unsteady flow models in turbomachines Performance map of a reciprocating compressor fow low mass flow rates Investigation of rotating stall inception and propagation in axial flow compresors Hazardous effects of sulphur dioxide and particulate matter emission on vegetation - a case study in the City of Baroda

The study of the effects resulting from the interaction of a combined wave-current field with any ocean structure is important for the design and performance evaluation of that structure. The prudent computation of forces exerted by waves and currents is essential in the study of the stability of an offshore structure. A study on the loading of an oblique wave and a current field on a fixed vertical slender cylinder in a 3D flow frame is illustrated in Zaman and Baddour (2004). The 3D expressions describing the characteristics of the combined wave-current field in terms of mass momentum and energy flux conservation equations are formulated. The parameters before the interaction of the oblique wave-free uniform current and current-free wave are used to formulate the kinematics of the flow field. These expressions are also used to formulate and calculate the loads imparted by the wave-current fluid flow on a bottom mounted slender vertical cylinder. In this work a 2D version of the above 3D model called Model 1 has been used for the numerical computations presented. The second model denoted model 2 is based on Euler equations. This model is formulated through the vertical integration of the continuity equation and the equations of motions Zaman et al (1997).

In order to extend lives of ageing ships it is necessary to make a study on feasibility for extending their planned life. In this paper studies on fatigue strength for hull structure with mild and high tensile steels and maintenance procedures for good protection from corrosion are briefly reviewed. Some discussions are made to procedures and analytical techniques of an assessment for life extension of ageing ships.

A mathematical method for analysing propeller-induced ship-hull vibrations is based on a special application of Green's Theorem. Comparison is made with the conventional approach which estimates diffraction pressure. Predictions from the theory are compared with published data on the DE 1040 hull.