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1

Influence of marine main engine foundations on the results of vibration calculations

Murawski Lech

Journal of KONES

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2019

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Vol. 26, No. 1

95--101

EN

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.

2

The influence of shaft line alignment accuracy on the operational reliability of marine propulsion systems

Murawski L.

Journal of KONES

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2016

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Vol. 23, No. 1

247--254

EN

The paper presents a method of identification parameters of shaft line alignment and its influence on operational reliability of marine propulsion system. The discussion about shaft line parameters (bearings' reactions, bending moment and shear forces acting on crankshaft or gear box, and stresses distribution in the shaft line) which has an influence on marine propulsion system reliability was presented. Proper shaft line alignment is often a problem for repair shipyards, for aged ships without sufficient documentation. Some data can be draw by measurements; e.g. shaft line dimensions or intermediate bearings' reactions. Other data (stern tube bearing load, real axis of shaft line) have to be determined on the base of calculations. Author proposed combined experimental-analytical method for identified and optimization (correction) some existing parameters and checking power transmission system’s foundation. Specialised software (based on Finite Element Method) has been developed for shaft line alignment calculations. Main novelties of the software are elastic supports (model of bearings – boundary conditions) of the shaft line, continuous support as a model of stern tube bearing and influence coefficients calculations. An example analysis with discussion has been performed for cargo ships with medium-speed main engine. Multi-variant computations supported by measurements of the ships’ shaft line have been carried out. Changes in shaft line alignment have been proposed in order to increase reliability of propulsion system.

3

Stiffness characteristics of main bearings foundation of marine engine

Murawski L.

Journal of KONES

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2016

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Vol. 23, No. 1

239--246

EN

During shaftline alignment and crankshaft springing analyses, knowledge of stiffness of radial bearings is essential. Dynamic stiffness's characteristics of marine main body are difficult to estimate because of lack of available documentation and complicated shape of the body. In the literature, there is a lack of the detailed data on the stiffness of the crankshaft foundation in the frame of marine main engine. Those parameters are crucial for the shaft line alignment analysis as well as for the analysis of interactions between the shaft line and the crankshaft. Especially for the high power engines, the correct model of the boundary conditions plays a key role during the analysis. The paper 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 mounted on a ~3000 TEU container ship. The model of main engine body is relatively big – it contains over 800 thousand degree of freedom. The elasticity of ship hull has been estimated and taken into account during analysis. It has been found, that static stiffness parameters recommended by the producer for the shaft line alignment are evaluated correctly, however they represent only the flexibility of the engine’s body, not taking into account the flexibility of the ship’s hull. What is more, the dynamic magnification of vibration amplitudes is not taken into account.

4

Wpływ prawidłowości ułożenia linii wałów na niezawodność pracy okrętowych układów napędowych

Murawski L.

Logistyka

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2015

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nr 3

3405--3415, CD 1

PL

W pracy przedstawiono metodę identyfikacji parametrów ułożenia linii wałów, w przypadku niewystarczającej ilości danych producentów. Przeprowadzono dyskusję nad wpływem różnych parametrów (reakcje łożyskowe, momenty gnące i siły tnące oddziaływujące na wał korbowy lub przekładnię oraz rozkład naprężeń wzdłuż linii wałów) ułożenia linii wałów na niezawodność pracy okrętowych układów napędowych. Poprawne ułożenie linii wałów jest często trudne dla stoczni remontowych, w przypadku starych statków z powodu niepełnych danych. Autor proponuje obliczeniowo-pomiarową metodę identyfikacji i optymalizacji (korekcji) wybranych parametrów ułożenia linii wałów wraz ze sprawdzeniem posadowienia układu napędowego. Wykonano specjalistyczne oprogramowanie (bazujące na Metodzie Elementów Skończonych) do analiz ułożenia linii wałów. Główne nowości oprogramowania to: elastyczne podparcie (model łożysk - warunki brzegowe) linii wałów; zamodelowanie łożyska rufowego, jako podparcia ciągłego oraz wyznaczanie współczynników wpływu. Przykładowe obliczenia wraz z dyskusją zostały przeprowadzone dla uniwersalnego statku zaopatrzeniowego z średnio-obrotowymi silnikami napędu głównego. Przeprowadzono wielowariantowe obliczenia wsparte przez badania pomiarowe okrętowej linii wałów.

EN

The paper presents a method of identification parameters of shaft line alignment in case of the lack of producers’ data. The discussion about shaft line parameters (bearings' reactions, bending moment and shear forces acting on crankshaft or gear box, and stresses distribution in the shaft line) which has an influence on marine propulsion system reliability was presented. 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 and optimization (correction) some existing parameters and checking power transmission system’s foundation. Specialised software (based on Finite Element Method) has been developed for shaft line alignment calculations. Main novelties of the software are: elastic supports (model of bearings - boundary conditions) of the shaft line, continuous support as a model of stern tube bearing and influence coefficients calculations. An example analysis with discussion has been performed for cargo ships with medium-speed main engine. Multi-variant computations supported by measurements of the ships’ shaft line have been carried out.

5

Optymalizacyjny model synchronizacji ruchu tramwajów w sieci

Murawski L.

Logistyka

|

2015

|

nr 3

3405--3415, CD 1

PL

W pracy przedstawiono metodę identyfikacji parametrów ułożenia linii wałów, w przypadku niewystarczającej ilości danych producentów. Przeprowadzono dyskusję nad wpływem różnych parametrów (reakcje łożyskowe, momenty gnące i siły tnące oddziaływujące na wał korbowy lub przekładnię oraz rozkład naprężeń wzdłuż linii wałów) ułożenia linii wałów na niezawodność pracy okrętowych układów napędowych. Poprawne ułożenie linii wałów jest często trudne dla stoczni remontowych, w przypadku starych statków z powodu niepełnych danych. Autor proponuje obliczeniowo-pomiarową metodę identyfikacji i optymalizacji (korekcji) wybranych parametrów ułożenia linii wałów wraz ze sprawdzeniem posadowienia układu napędowego. Wykonano specjalistyczne oprogramowanie (bazujące na Metodzie Elementów Skończonych) do analiz ułożenia linii wałów. Główne nowości oprogramowania to: elastyczne podparcie (model łożysk - warunki brzegowe) linii wałów; zamodelowanie łożyska rufowego, jako podparcia ciągłego oraz wyznaczanie współczynników wpływu. Przykładowe obliczenia wraz z dyskusją zostały przeprowadzone dla uniwersalnego statku zaopatrzeniowego z średnio-obrotowymi silnikami napędu głównego. Przeprowadzono wielowariantowe obliczenia wsparte przez badania pomiarowe okrętowej linii wałów.

EN

The paper presents a method of identification parameters of shaft line alignment in case of the lack of producers’ data. The discussion about shaft line parameters (bearings' reactions, bending moment and shear forces acting on crankshaft or gear box, and stresses distribution in the shaft line) which has an influence on marine propulsion system reliability was presented. 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 and optimization (correction) some existing parameters and checking power transmission system’s foundation. Specialised software (based on Finite Element Method) has been developed for shaft line alignment calculations. Main novelties of the software are: elastic supports (model of bearings - boundary conditions) of the shaft line, continuous support as a model of stern tube bearing and influence coefficients calculations. An example analysis with discussion has been performed for cargo ships with medium-speed main engine. Multi-variant computations supported by measurements of the ships’ shaft line have been carried out.

6

Identification of shaft line alignment with insufficient data availability

Murawski L.

Polish Maritime Research

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2009

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nr 1

35-42

EN

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.