Contrarotating Propeller Propulsion— A State-of-the-Art Report

1969 ◽  
Vol 6 (03) ◽  
pp. 281-290
Author(s):  
J. B. Hadler
Keyword(s):  
State Of The Art ◽  
Model Tests ◽  
Performance Data ◽  
Ship Propulsion ◽  
Propulsive Performance ◽  
Merchant Ship ◽  
Current Alternative ◽  
Twin Screw ◽  
Vibration Problems

This report presents a synthesis of existing knowledge, albeit limited, on CRP as applicable to merchant ship propulsion. It presents propulsive performance data for two types of ships, tankers and containerships, based on model tests, and discusses briefly the stopping, cavitation, and propeller-induced vibration problems of CRP. From the analysis it appears that the greatest potential for employment of such a propulsive device, offering significant reductions in installed shp, is on high-powered, fine-formed ships for which the only current alternative is a twin-screw installation.

Potential advantages of molten salt reactor for merchant ship propulsion

2021 ◽  
Vol 9 (2B) ◽  
Author(s):  
Luiz Gonzaga de Freitas Neto ◽  
Luciano Ondir Freire ◽  
Adimir Dos Santos ◽  
Delvonei Alves De Andrade
Keyword(s):  
Molten Salt ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Operational Conditions ◽  
Ship Propulsion ◽  
Surface Vessels ◽  
Merchant Ship ◽  
Nuclear Propulsion ◽  
Thorium Cycle ◽  
Fuel Costs

Operating costs of merchant ships, related to fuel costs, has led the naval industry to search alternatives to the current technologies of propulsion power. A possibility is to employ nuclear reactors like the Russian KLT-40S, which is a pressurized water reactor (PWR) and has experience on civilian surface vessels. However, space and weight are critical factors in a nuclear propulsion project, in addition to operational safety and costs. This work aims at comparing molten salt reactors (MSR) with PWR for merchant ship propulsion. The present study develops a qualitative analysis on weight, volume, overnight costs, fuel costs and nuclear safety. This work compares the architecture and operational conditions of these two types of reactors. The result is that MSR may produce lower amounts of high-activity nuclear tailings and, if it adopts the 233U-thorium cycle, it may have lower risks of proliferating nuclear weapons. Besides proliferation issues, this 4th generation reactor may have lower weight, occupy less space, and achieve the same levels of safety with less investment. Thus, molten salt regenerative reactors using the 233U-thorium cycle are potential candidates for use in ship propulsion.

scholarly journals Optimization of Polymer Processing: A Review (Part I—Extrusion)

Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 384
Author(s):  
António Gaspar-Cunha ◽  
José A. Covas ◽  
Janusz Sikora
Keyword(s):  
State Of The Art ◽  
Polymer Processing ◽  
Optimization Techniques ◽  
Practical Situation ◽  
Twin Screw Extruders ◽  
Extrusion Dies ◽  
Twin Screw ◽  
Processing Techniques ◽  
Screw Extruders ◽  
Modelling Approach

Given the global economic and societal importance of the polymer industry, the continuous search for improvements in the various processing techniques is of practical primordial importance. This review evaluates the application of optimization methodologies to the main polymer processing operations. The most important characteristics related to the usage of optimization techniques, such as the nature of the objective function, the type of optimization algorithm, the modelling approach used to evaluate the solutions, and the parameters to optimize, are discussed. The aim is to identify the most important features of an optimization system for polymer processing problems and define the best procedure for each particular practical situation. For this purpose, the state of the art of the optimization methodologies usually employed is first presented, followed by an extensive review of the literature dealing with the major processing techniques, the discussion being completed by considering both the characteristics identified and the available optimization methodologies. This first part of the review focuses on extrusion, namely single and twin-screw extruders, extrusion dies, and calibrators. It is concluded that there is a set of methodologies that can be confidently applied in polymer processing with a very good performance and without the need of demanding computation requirements.

Condition Monitoring of Ship Propulsion Systems: State-of-the-Art, Development Trend and Role of Digital Twin

2021 ◽  
Author(s):  
Amir R. Nejad ◽  
Etienne Purcell ◽  
Mostafa Valavi ◽  
Roman Hudak ◽  
Benjamin Lehmann ◽  
...  
Keyword(s):  
Condition Monitoring ◽  
Performance Monitoring ◽  
State Of The Art ◽  
Development Trend ◽  
The Arctic ◽  
Special Focus ◽  
Shipping Industry ◽  
Propulsion Systems ◽  
Digital Twin ◽  
Ship Propulsion

Abstract This paper describes the current implementations and development trends of condition monitoring as it pertains to ship propulsion systems. In terms of total incidents in the shipping industry in the last five years, failures relating to the propulsion system represent the majority. Condition monitoring offers effective early detection of failure which translates to increased reliability and decreased maintenance costs. Current industrial practices are often limited to performance monitoring rather than condition monitoring. Special focus is afforded to how condition monitoring is implemented on board ships, which regulatory codes are relevant and the summary of state-of-the-art research in marine machinery. Moreover, operation and monitoring in extreme environmental conditions, such as the Arctic and Antarctic with ice impact on the propulsion has been discussed. The new developments, in particular, digital twin approaches in health and condition monitoring have been highlighted, considering its pros and cons and potential challenges.

Model Testing for Vortex Induced Motions of Spar Platforms

2004 ◽  
Author(s):  
Mehernosh Irani ◽  
Lyle Finn
Keyword(s):  
Gulf Of Mexico ◽  
Model Test ◽  
State Of The Art ◽  
Model Testing ◽  
Model Tests ◽  
The State ◽  
Test Results ◽  
Test Set ◽  
Vortex Induced Vibrations ◽  
Set Up

The state-of-the art in model testing for Vortex Induced Vibrations (VIV) of Spars is presented. Important issues related to Spar VIV model testing are highlighted. The parameters that need to be modeled including hull geometry, strake configuration, mass and mooring properties and, considerations of test set-up and instrumentation are discussed. Results are presented from model tests of an as-built Spar deployed in the Gulf of Mexico. It is shown that the model test results compare well with the VIV responses measured in the field.

Design, Manufacture, and Testing of Large Reduction Gears for Diesel Ship Propulsion Systems

1990 ◽  
Vol 27 (01) ◽  
pp. 30-41
Author(s):  
Peter Gold ◽  
K. Heinz Watzlawek ◽  
Zbigniew J. Karaszewski
Keyword(s):  
Carrying Capacity ◽  
Cost Reduction ◽  
State Of The Art ◽  
Reduction Gear ◽  
Large Reduction ◽  
Propulsion Systems ◽  
Ship Propulsion ◽  
The Past ◽  
Long Life

The dramatic increase in both the size of ships and the power of propulsion systems over the past 15 years has led to a desire for shorter machinery spaces and lighter equipment in order to provide additional cargo carrying capacity. Many equipments and reduction gears in particular have experienced a growing number of problems due to compact designs with reduced scantlings. Consequently, high-horsepower and low-rpm gear units were developed that resulted in incompatibility of machinery and ship. Those marginal designs combined with manufacturing inaccuracies were in most cases the result of overzealous cost reduction programs. This paper presents some of the elements of a state-of-the-art reduction gear evolution cycle that will result in successful gear operation and continued long life.

SEAKEEPING AND MANOEUVRING FOR WIND ASSISTED SHIPS

2019 ◽  
Author(s):  
R Eggers ◽  
A. S. Kisjes
Keyword(s):  
Wind Tunnel ◽  
Model Tests ◽  
Scale Model ◽  
Ship Propulsion ◽  
Free Running ◽  
Set Up

Research on Wind Assisted Ship Propulsion (WASP) has until now focussed on performance in steady conditions whereas unsteady behaviour is an important part of ship behaviour. For “conventional” manoeuvring and seakeeping, performing direct “free running” scale model tests has been successful to gain understanding and to improve ship designs. In the “WindLab” project the opportunity was taken to extend that approach to aerodynamics: modelling real wind with a simplified wind tunnel in the basin. A unique set-up was tested for its suitability and first data was collected on the performance of wind assisted ships in unsteady scenarios.

On the Scalability of Model-Scale Ice Experiments

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Rüdiger U. Franz von Bock und Polach ◽  
Sören Ehlers
Keyword(s):  
Mechanical Properties ◽  
Sea Ice ◽  
State Of The Art ◽  
Model Tests ◽  
Qualitative Assessment ◽  
Model Scale ◽  
Research Findings ◽  
Ice Model

Ice model tests are a frequently used mean to assess and predict the performance of ships and structures in ice. The model ice composition is adjusted to comply with Froude and Cauchy similitude. Recent research indicates that the internal mechanics of Aalto model-scale ice and sea ice differ significantly. This consequently limits the scalability and challenges state-of-the-art scaling procedures. This paper presents a qualitative assessment on selected topics to assess the differences between model-scale ice and sea ice and the influence of related experiments on determined mechanical properties. Furthermore, existing scaling approaches are discussed in context of recent research findings.

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