scholarly journals Influence of Marine Main Engine Foundations on the Results of Vibration Calculations

2019 ◽  
Vol 26 (1) ◽  
pp. 95-101
Author(s):  
Lech Murawski
Keyword(s):  
Boundary Conditions ◽  
Ship Hull ◽  
Fem Model ◽  
Shaft Line ◽  
Marine Engines ◽  
Thermal Displacements ◽  
Engine Dynamic ◽  
Main Engine ◽  
Engine Power

Abstract The article presents an influence of foundations of slow-speed main engine body on the results of numerical analysis of the engine dynamic stiffnesses and thermal deformations. The engine body is much stiffer than its foundation pads and ship hull (double bottom) – boundary conditions of the engine. Especially for the high power, marine engines, the correct model of the boundary conditions plays a key role during the analyses. Therefore, modelling method of engine foundation (boundary conditions) of that kind of model is essential during the analyses. During shaft line alignment and crankshaft springing analyses, knowledge of dynamic stiffnesses characteristics and thermal displacements of radial (main) bearings is significant. Those data of marine main engine body are difficult to estimate because of lack of available documentation and complicated shape of the engine and ship hull. The article presents the methodology of the characteristics determination of the marine engine's body as well as the example of computations for a MAN B&W K98MC type engine (power: 40000 kW, revolutions: 94 rpm) mounted on a 3000 TEU (twenty-foot container equivalent unit) container ship (length: 250 m). Numerical analyses were performed with usage of Nastran software based on Finite Element Method. The FEM model of the engine body comprised over 800 thousand degree of freedom.

scholarly journals Numerical analysis of influence of ship hull form modification on ship resistance and propulsion characteristics

2010 ◽  
Vol 17 (1) ◽  
pp. 10-13 ◽  
Author(s):  
Tomasz Abramowski ◽  
Katarzyna Żelazny ◽  
Tadeusz Szelangiewicz
Keyword(s):  
Numerical Analysis ◽  
Velocity Field ◽  
Ship Hull ◽  
Hull Form ◽  
Ship Building ◽  
Ship Resistance ◽  
Design Office ◽  
Ship Speed ◽  
Engine Power

Numerical analysis of influence of ship hull form modification on ship resistance and propulsion characteristics After signing ship building contract shipyard's design office orders performance of ship resistance and propulsion model tests aimed at, apart from resistance measurements, also determination of ship speed, propeller rotational speed and propulsion engine power for the designed ship, as well as improvement of its hull form, if necessary. Range of ship hull modifications is practically very limited due to cost and time reasons. Hence numerical methods, mainly CFD ones are more and more often used for such tests. In this paper consisted of three parts, are presented results of numerical calculations of hull resistance, wake and efficiency of propeller operating in non-homogenous velocity field, performed for research on 18 hull versions of B573 ship designed and built by Szczecin Nowa Shipyard.

scholarly journals FEATURES OF POWER DETERMINATION OF AUXILIARY-EMERGENCY DRIVE MOTION OF A SHIP WITH A COMBINED DIESEL-ELECTRIC POWER PLANT

2020 ◽  
Vol 4 (52) ◽  
pp. 8-16
Author(s):  
A. Rak ◽  
◽  
V. Busher ◽  
O. Glazeva ◽  
◽  
...  
Keyword(s):  
Fuel Consumption ◽  
High Speed ◽  
Electric Capacity ◽  
Optimal Load ◽  
High Speed Diesel ◽  
Harmful Emissions ◽  
Diesel Generators ◽  
Main Engine ◽  
Engine Power

Purpose. The paper compares the traditional method of calculating the parameters of electric motion of ships in auxiliary emergency modes at low speeds of the vessel with another, simplified because it does not require the use of a large number of diagrams to determine the resistance of the vessel. But according to a simplified method for this example – a container ship with a capacity of 16,000 containers with the main engine capacity of 61776 kW, a synchronous machine with a capacity of up to 6 MW in engine mode, and three diesel generators with an electric capacity of 3187 kW – 39 % more power is obtained. Own experience of operation of the vessel in modes with electric movement – loading of diesel generators in this mode on the vessel about 70 % that is received by calculations. Thus, when upgrading the propulsion system or designing new vessels, it is advisable to compare the results of two calculations of the power of diesel generators at the limit of the minimum stable speed of the main engine and choose the larger of the results. Methodology. Comparison of specific and absolute fuel consumption, made on the basis of known approximation polynomials for low- and high-speed types of diesel of the company at auxiliary emergency movement shows that at the movement from high-speed diesel generators MAK8M32S fuel consumption decreases by 24 %, then at the maintenance of the main engine 12 RTflex-96C from WÄRTSILÄ-SULZER. Results. Therefore, the use of electric motion allows you to save engine power of the main engine, reduce fuel consumption. This ratio is observed on most maritime transport vessels. And given that diesel generators operate at almost optimal load, and the main engine – at idle, electric motion provides a significant reduction in harmful emissions into the atmosphere. The latter is also true for a ship where the synchronous engine is located behind the main engine, although fuel consumption, in this case, increases by 32 %. Figures 9, tables 6, references 15.

scholarly journals DETERMINATION OF ELEMENTS AND CHARACTERISTICS OF RIVER SUCTION DREDGERS AT INITIAL DESIGN STAGES

2020 ◽  
pp. 71-80
Author(s):  
Ernest G. Rumyantcev ◽  
Evgeniy P. Ronnov
Keyword(s):  
Statistical Method ◽  
Research Design ◽  
Soil Productivity ◽  
Technical Data ◽  
Total Displacement ◽  
Wide Range ◽  
Main Engine ◽  
Analytical Expressions ◽  
Engine Power

The article provides a methodology for calculating the basic elements and characteristics of river dredgers at the stages of research design by means of the statistical method. For the study, the most common projects of river non-self-propelled dredgers with both a residential superstructure and without it, in a wide range of soil productivity, were used. The dependences of the total displacement and the main engine power on such basic technical data as suction dredger performance and loosening depth were analyzed in detail. Graphic dependencies and analytical expressions for determining the main suction dredger dimensions were obtained. The issue of choosing the length of the main dredger compartments is considered, which allows to solve the problem of pre-splitting the hull into compartments. The analysis of the accuracy of the obtained statistical dependencies for determining the length of the vessel is provided.

scholarly journals Stiffness Estimation and Equivalence of Boundary Conditions in FEM Models

2021 ◽  
Vol 11 (4) ◽  
pp. 1482
Author(s):  
Róbert Huňady ◽  
Pavol Lengvarský ◽  
Peter Pavelka ◽  
Adam Kaľavský ◽  
Jakub Mlotek
Keyword(s):  
Boundary Condition ◽  
Finite Element ◽  
Boundary Conditions ◽  
Model Updating ◽  
Element Model ◽  
Computational Time ◽  
Stiffness Coefficients ◽  
First Case ◽  
Numerical Approaches

The paper deals with methods of equivalence of boundary conditions in finite element models that are based on finite element model updating technique. The proposed methods are based on the determination of the stiffness parameters in the section plate or region, where the boundary condition or the removed part of the model is replaced by the bushing connector. Two methods for determining its elastic properties are described. In the first case, the stiffness coefficients are determined by a series of static finite element analyses that are used to obtain the response of the removed part to the six basic types of loads. The second method is a combination of experimental and numerical approaches. The natural frequencies obtained by the measurement are used in finite element (FE) optimization, in which the response of the model is tuned by changing the stiffness coefficients of the bushing. Both methods provide a good estimate of the stiffness at the region where the model is replaced by an equivalent boundary condition. This increases the accuracy of the numerical model and also saves computational time and capacity due to element reduction.

Vectorial thin-element approximation: a semirigorous determination of Kirchhoff's boundary conditions

2007 ◽  
Vol 24 (4) ◽  
pp. 1074 ◽  
Author(s):  
Norbert Kerwien ◽  
Thomas Schuster ◽  
Stephan Rafler ◽  
Wolfgang Osten ◽  
Michael Totzeck
Keyword(s):  
Boundary Conditions ◽  
Element Approximation

Generalized plane stress in a semi-infinite strip under arbitrary end-load

1964 ◽  
Vol 281 (1385) ◽  
pp. 184-206 ◽  
Keyword(s):  
Differential Equation ◽  
Ordinary Differential Equation ◽  
Boundary Conditions ◽  
Fourth Order ◽  
Plane Stress ◽  
Stress Function ◽  
Infinite Strip ◽  
Order Ordinary Differential Equation ◽  
Orthogonal Functions

The problem involves the determination of a biharmonic generalized plane-stress function satisfying certain boundary conditions. We expand the stress function in a series of non-orthogonal eigenfunctions. Each of these is expanded in a series of orthogonal functions which satisfy a certain fourth-order ordinary differential equation and the boundary conditions implied by the fact that the sides are stress-free. By this method the coefficients involved in the biharmonic stress function corresponding to any arbitrary combination of stress on the end can be obtained directly from two numerical matrices published here The method is illustrated by four examples which cast light on the application of St Venant’s principle to the strip. In a further paper by one of the authors, the method will be applied to the problem of the finite rectangle.

Sign in / Sign up

Export Citation Format

Share Document