scholarly journals Fishing trawl modernization methods under ship thrust deficiency during voyage

2021 ◽  
Vol 2021 (3) ◽  
pp. 52-59
Author(s):  
Tat'yana Ryazanova
Keyword(s):  
Traction Force ◽  
Technical Condition ◽  
Full Scale ◽  
Propulsion System ◽  
Hydrodynamic Resistance ◽  
Fishing Vessel ◽  
Numerical Examples ◽  
Linear Dimensions ◽  
Trawl Fishing ◽  
Main Engine

The article considers the problems of compatibility between the hydrodynamic resistance of the trawl and the actual trawler's thrust, which have lost the ability to provide the necessary traction force due to the increase in the resistance of the ship's hull and wear of the engine-propulsion system. The area of resistance of the trawl system is proposed to be reduced by reducing the linear dimensions of the layers of the trawl part, as well as by replacing some layers of the trawl with a smaller mesh by those with larger meshes. It is noted that during fishing vessel masters often make an intuitive decision to replace trawls with those of less powerful vessels. Methods of reducing the area of trawl resistance are considered, which will lead to a decrease in its hydrodynamic resistance of the trawl fishing system. Numerical examples of the considered technique are given. The trawl plate P-K-120/1120, full-scale and modernized parts of the trawl are illustrated. The results of the trawl part modernization are presented, and the formula for calculating the fictitious trawl area is presented. The method of modernization of the trawl due to the increase in the size of the trawl in some parts of the trawl is analyzed, the average weighted step of the mesh in the full-scale trawl is calculated. The developed methodology should allow solving the problem of trawl modernization promptly, in the conditions of the fishing deck, by the forces of the ship’s crew. The proposed methods for the modernization of a fishing trawl will allow avoiding large costs for the repair of the main engine of a fishing vessel operating a trawl that does not correspond to the technical condition of the trawler, or to reduce the underfishing with a smaller trawl.

scholarly journals Mathematical model for determining the roll angle of a fishing vessel when purse seine sampling

2021 ◽  
pp. 153-157
Author(s):  
Н.Л. Великанов ◽  
О.В. Шарков
Keyword(s):  
Traction Force ◽  
Sufficient Accuracy ◽  
Roll Angle ◽  
Fishing Gear ◽  
Fishing Vessel ◽  
Calculation Algorithm ◽  
Fishing Vessels ◽  
Trawl Fishing ◽  
The World ◽  
The Stability

Лов рыбы с применением кошельковых неводов является наиболее распространенным в мире после тралового лова. Процессы кошелькования невода, выборки улова могут существенно влиять на остойчивость рыболовного судна (сейнера). В данной работе рассматривается влияние на угол крена силы, действующие со стороны орудия лова. Приведен алгоритм расчета, учитывающий координаты точки приложения силы натяжения троса, идущего к орудию лова, углы наклона троса, величину силы. Составлены расчетные зависимости для процессов крена, получены выражения для угла наклона корпуса судна. Приведены примеры расчетов. В частности, рассмотрено изменение угла крена от тягового усилия, высоты подъема канифас-блока для промыслового судна. Проведенные расчеты свидетельствуют о достаточной для инженерных расчетов точности и возможности использовать приведенный алгоритм при оценочных расчетах на различных стадиях проектирования. Важно учитывать возможность одновременного наложения ветровых нагрузок, действия волн на корпус судна. В этих случаях крен и дифферент будут возрастать. Поэтому спецификой промысловых судов является необходимость учета поведения судна при проведении промысловых операций. Fishing with the use of purse seines is the most common in the world after trawl fishing. The processes of pursing and seine sampling can significantly affect the stability of a fishing vessel (seiner). In this paper, the influence of forces acting from the fishing gear on the roll angle is considered. The calculation algorithm is given, taking into account the coordinates of the point of application of the tension force of the cable going to the fishing gear, the angles of inclination of the cable, the magnitude of the force. Calculated dependences for roll processes are compiled, expressions for the angle of inclination of the vessel's hull are obtained. Examples of calculations are given. In particular, the change in the roll angle from the traction force, the lifting height of the snatch–block for a fishing vessel is considered. The calculations carried out indicate sufficient accuracy for engineering calculations and the possibility of using the above algorithm for evaluation calculations at various stages of design. It is important to take into account the possibility of simultaneous imposition of wind loads, the action of waves on the hull of the vessel. In these cases, the roll and trim will increase. Therefore, the specifics of fishing vessels is the need to take into account the behavior of the vessel during fishing operations.

scholarly journals Performance Analysis of Combined Cycle with Air Breathing Derivative Gas Turbine, Heat Recovery Steam Generator, and Steam Turbine as LNG Tanker Main Engine Propulsion System

2020 ◽  
Vol 8 (9) ◽  
pp. 726
Author(s):  
Wahyu Nirbito ◽  
Muhammad Arif Budiyanto ◽  
Robby Muliadi
Keyword(s):  
Performance Analysis ◽  
Steam Turbine ◽  
Gas Turbine ◽  
Steam Generator ◽  
Heat Recovery ◽  
Combined Cycle ◽  
Propulsion System ◽  
Heat Recovery Steam Generator ◽  
Main Engine ◽  
Ship Speed

This study explains the performance analysis of a propulsion system engine of an LNG tanker using a combined cycle whose components are gas turbine, steam turbine, and heat recovery steam generator. The researches are to determine the total resistance of an LNG tanker with a capacity of 125,000 m3 by using the Maxsurf Resistance 20 software, as well as to design the propulsion system to meet the required power from the resistance by using the Cycle-Tempo 5.0 software. The simulation results indicate a maximum power of the system of about 28,122.23 kW with a fuel consumption of about 1.173 kg/s and a system efficiency of about 48.49% in fully loaded conditions. The ship speed can reach up to 20.67 knots.

Numerical Simulation of the Added Mass of the Fluid Adjacent to the Ship Hull in Vibration Measured During Sea-Trials in Tanker Ships to be Converted to Offshore Construction Vessel

2012 ◽  
Author(s):  
Severino Fonseca Silva Neto ◽  
Silvia Ramscheid Figueiredo ◽  
Marta Cecilia Tapia Reyes ◽  
Luiza de Mesquita Ortiz
Keyword(s):  
Numerical Model ◽  
Kinetic Energy ◽  
Natural Frequencies ◽  
Three Dimensional ◽  
Added Mass ◽  
Vertical Vibration ◽  
Full Scale ◽  
Experimental Results ◽  
Vibration Velocity ◽  
Main Engine

This study aims to analyze the influence of the kinetic energy of the fluid adjacent to the hull of a tanker ship in its vertical vibration frequencies, comparing them with experimental measurements obtained during sea-trials. The one-dimensional modeling of ships allows the construction of simple finite element models from the structural elements of its master section, with structural and added masses, and their frequencies are verified by full-scale measurements, during the sea-trials. The numerical results of these models, with the value of the effective shear area as a fraction of the total area of the strength steel are compared to those obtained in full-scale measurements during sea trials of an oil tanker to be converted to Offshore Construction Vessel. Global vibration measurements were carried out in two of the six ships with the same hull. Accelerometers were installed in eleven strategic points of each hull. Vibration data acquisition was performed simultaneously for these locals in thirteen rotations of the main engine. The amplitude spectra of vibration velocity on the frequency range of measurements were obtained and were plotted graphs of the evolution of the main harmonics, depending on the rotation of the main engine, in order to identify four natural frequencies of the overall vibration of the hull, which were compared to the numerical model. The calculation is performed by the added mass formulations from Burrill, Todd, Kumay and Lewis/Landweber [8] curves, including in all three-dimensional effect by Townsin [17] coefficients, which is checked against the experimental results. The comparison between numerical and experimental results allows assessing the influence of the kinetic energy of the fluid surrounding the hull in the natural frequencies of vibration of the numerical model of the tanker ship and simulating their dynamic behavior after conversion in Offshore Construction Vessel.

scholarly journals Estimation of Maneuverability of Trawl Fishing Vessel Using an Analytical Method

2021 ◽  
Vol 9 (8) ◽  
pp. 854
Author(s):  
Su-Hyung Kim ◽  
Chun-Ki Lee
Keyword(s):  
Regression Analysis ◽  
Empirical Formula ◽  
Estimation Error ◽  
Design Stage ◽  
Test Results ◽  
Fishing Vessel ◽  
Empirical Formulas ◽  
Hull Form ◽  
Fishing Vessels ◽  
Trawl Fishing

Most fishing vessels are less than 100 m in length between the perpendiculars, for which adherence to the International Maritime Organization maneuverability standards are not mandatory. In the design stage of fishing vessels, maneuverability is estimated using empirical formulas—mainly analytical methods—rather than costly and time-consuming model tests. However, the empirical formula is developed through the process of regression analysis on the model test results from merchant ships’ hull form and applying the same to the fishing vessels’ hull form may result in an estimation error due to the differences in the vessels’ characteristics—e.g., L/B, B/d and Cb·B/L—. In a previous study, the authors of this paper derived a modified empirical formula by adding the hull form parameters of trawl fishing vessels to the existing empirical formula based on those of merchant ships. This study analyzes the validity of the modified empirical formula in depth by applying it to a newly-built training vessel that has the hull form of a trawl fishing vessel. As a result of the study, the estimation results were improved by including the parameters of the hull form of trawl fishing vessels in the empirical formula developed for merchant ships.

XFV-12A Propulsion System Development

1976 ◽  
Author(s):  
J. T. Delany ◽  
G. M. Jenkins
Keyword(s):  
System Design ◽  
Development Process ◽  
System Development ◽  
Full Scale ◽  
Propulsion System ◽  
Design And Development ◽  
Plug Nozzle ◽  
Design Philosophy ◽  
Thrust System ◽  
Testing And Evaluation

The XFV-12A total powered lift/thrust system being developed under contract for the U. S. Navy is described. The description includes design and development to date of the inlets, engine integration, the diverter valve with plug nozzle, the lift system augmenter supply ducting, and lift/thrust augmenter hardware. The development process description includes system design philosophy and criteria, analysis, test facilities utilized, model and full-scale testing and evaluation.

FEASIBILITY ANALYSIS OF LIQUID PROPELLANT SETTLING IN THE TANKS OF A SPACE PROPULSION SYSTEM AFTER FLYING IN ZERO GRAVITY USING A SEPARATING TURN MANUEVER OF THE ORBITAL UNIT

2021 ◽  
pp. 78-87
Author(s):  
Nikolay N. TUPITSIN
Keyword(s):  
Attitude Control ◽  
Feasibility Studies ◽  
Propulsion System ◽  
Zero Gravity ◽  
Liquid Propellant ◽  
Propulsion Systems ◽  
Rocket Propulsion ◽  
Liquid Rocket Propulsion ◽  
Liquid Rocket ◽  
Main Engine

The paper presents results of preliminary design feasibility studies of using inertial settling of liquid propellant in tanks of space liquid rocket propulsion systems and separating from the propellant the ullage gases formed in zero gravity by means of centrifugal forces generated when the orbital unit performs the programmed turn maneuver proposed by the author. It shows that performing propellant settling and ullage gas separation by means of the separating turn maneuver makes it possible to significantly reduce propellant consumption in propulsion systems for attitude control and ullage engines. Key words: space liquid rocket propulsion system, main engine, separation of ullage gases from liquid propellant, separating turn maneuver of the orbital unit.

Feasibility analysis of liquid propellant settling in the tanks of a space propulsion system after flying in zero gravity using a separating turn maneuver of the orbital unit

2021 ◽  
pp. 78-87
Author(s):  
Nikolay N. TUPITSYN
Keyword(s):  
Attitude Control ◽  
Feasibility Studies ◽  
Propulsion System ◽  
Zero Gravity ◽  
Liquid Propellant ◽  
Propulsion Systems ◽  
Rocket Propulsion ◽  
Liquid Rocket Propulsion ◽  
Liquid Rocket ◽  
Main Engine

The paper presents results of preliminary design feasibility studies of using inertial settling of liquid propellant in tanks of space liquid rocket propulsion systems and separating from the propellant the ullage gases formed in zero gravity by means of centrifugal forces generated when the orbital unit performs the programmed turn maneuver proposed by the author. It shows that performing propellant settling and ullage gas separation by means of the separating turn maneuver makes it possible to significantly reduce propellant consumption in propulsion systems for attitude control and ullage engines. Key words: space liquid rocket propulsion system, main engine, separation of ullage gases from liquid propellant, separating turn maneuver of the orbital unit.

Roll Stabilization for Small Fishing Vessels Using Paravanes and Anti-Roll Tanks

1998 ◽  
Vol 35 (02) ◽  
pp. 74-84
Author(s):  
D.W. Bass
Keyword(s):  
Full Scale ◽  
Fishing Vessel ◽  
Small Vessels ◽  
The Third ◽  
Fishing Vessels ◽  
Roll Stabilization ◽  
Full Scale Tests ◽  
Design And Testing ◽  
Constant Source ◽  
Passive Stabilization

Excessive roll is a constant source of discomfort and danger for small fishing vessels. The paper describes two methods of reducing roll: paravane stabilizers and passive stabilization tanks. In particular an analysis is presented of the possible hazards of paravane use in severe seas, based on the capsize of a small fishing vessel after the loss of one paravane. Anti-roll tanks, as an alternative to paravanes for some small vessels, have been proposed and successfully tested on three boats. The design and testing at model and full scale of such a system is described. Full scale tests were carried out on three sister vessels, two with tank systems and the third with paravanes.

scholarly journals Identification of shaft line alignment with insufficient data availability

2009 ◽  
Vol 16 (1) ◽  
pp. 35-42 ◽  
Author(s):  
Lech Murawski
Keyword(s):  
Analytical Method ◽  
Power Transmission ◽  
Propulsion System ◽  
Data Availability ◽  
Insufficient Data ◽  
Slow Speed ◽  
Shaft Line ◽  
Influence Coefficients ◽  
Medium Speed ◽  
Main Engine

Identification of shaft line alignment with insufficient data availability The paper presents a method of identification parameters of shaft line alignment in case of the lack of producers' data. Proper shaft line alignment is often a problem for repair shipyards, for aged ships without sufficient documentation. Author proposed combined experimental-analytical method for identified some existing parameters and checking (and eventually correcting) power transmission system's foundation. Specialised software has been developed for shaft line alignment calculations with influence coefficients. An example analysis has been performed for cargo ships with medium-speed main engine and second one with slow-speed propulsion system. Multivariant computations supported by measurements of the ships' shaft line have been carried out.

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