Transient and Unstable Torsional Vibrations on a 4-Stroke Marine Diesel Engine

2003 ◽  
Author(s):  
D. C. Lee ◽  
J. D. Yu
Keyword(s):  
Diesel Engine ◽  
Torsional Vibration ◽  
Marine Diesel Engine ◽  
Torsional Vibrations ◽  
Steady State Condition ◽  
Marine Propulsion ◽  
Friction Clutch ◽  
Marine Diesel ◽  
Noise Measurements ◽  
Unstable Vibration

Under steady state condition, unstable torsional vibration normally does not occur in shafting systems using 4stroke diesel engine due to hysteresis damping of shafting system and relative damping of standard fitted damper. However, the unstable torsional vibration occurs on marine propulsion shafting systems due to slippage of a multi-friction clutch installed between increasing gear box and shaft generator. To identify this unstable vibration and make proper counter measure, the simulation for transient torsional vibration using the Newmark method is introduced in this paper. The mechanism of this unstable vibration is verified by vibration and noise measurements of the shafting system.

Probabilistic Torsional Vibration Analysis of a Marine Diesel Engine Shafting System: The Level Crossing Problem

1989 ◽  
Vol 56 (4) ◽  
pp. 953-959 ◽  
Author(s):  
Efstratios Nikolaidis ◽  
Anastassios N. Perakis ◽  
Michael G. Parsons
Keyword(s):  
Diesel Engine ◽  
Torsional Vibration ◽  
Probabilistic Approach ◽  
Series Representation ◽  
Harmonic Series ◽  
Complex Conjugate ◽  
Time Interval ◽  
Marine Diesel Engine ◽  
Level Crossing ◽  
Marine Diesel

A probabilistic approach to the torsional vibration problem of a marine diesel engine shafting system has been developed. In this analysis, the shafting shear stress is found to be a Gaussian, harmonizable cyclostationary process with a harmonic series representation consisting of two complex conjugate components. In this paper, the level crossing problem for this stress process is studied. Two methods for estimating the probability that the stress exceeds a specified threshold at least once over a given time interval are presented. In the first method, a local maximum of the process is approximated by the value of the corresponding envelope at the time of occurrence of this maximum. A Markov-type condition is assumed to hold for the local maxima. The second method assumes that the maximum of the process over a reasonable number of cycles is approximately equal to that of the envelope process. The envelope crossings are assumed to constitute a Poisson process. The two methods are applied to estimate the upcrossing probability in various cases. The results of both approaches are found to be in good agreement with those from Monte Carlo simulation.

scholarly journals Development and Validation of 4 Stroke Marine Diesel Engine Numerical Model

2020 ◽  
Vol 3 (3) ◽  
pp. 359-372
Author(s):  
Vladimir Pelić ◽  
Tomislav Mrakovčić ◽  
Ozren Bukovac ◽  
Marko Valčić
Keyword(s):  
Diesel Engine ◽  
Numerical Model ◽  
Zone Model ◽  
Marine Diesel Engine ◽  
Test Bed ◽  
Conservation Of Energy ◽  
Engine Model ◽  
Marine Propulsion ◽  
Marine Diesel ◽  
Development And Validation

Increasing demands on energy efficiency and environmental acceptance are being imposed on marine propulsion plants. The fulfilment of the conditions set by the MARPOL Convention, Annex VI, regarding the emissions from exhaust gases of marine diesel engines is of particular interest. This paper presents the development and validation of a zero-dimensional, single-zone diesel engine numerical model. Presented numerical model is based on the law of conservation of energy and mass and solving the resulting differential equations. The single-zone model will serve as the basis for a model where the cylinder space is divided into two or three zones during combustion. In this way, the multi-zone model will allow the modelling of nitrogen oxide emissions with satisfactory accuracy. Validation of the diesel engine model was carried out for the Wärtsilä 12V50DF 11700 kW motor designed to drive a synchronous alternator. Obtained results and deviations of certain parameters in the operation of the engine with respect to the data obtained from the measurements on the test bed, are more than satisfactory regarding complexity of the numerical model. This confirmed the usability of the model for research purposes to optimize the marine diesel engine.

The All-British High-Powered Marine Diesel Engine

1975 ◽  
Vol 189 (1) ◽  
pp. 21-32
Author(s):  
J. F. Butler
Keyword(s):  
Diesel Engine ◽  
Marine Diesel Engine ◽  
Steam Turbines ◽  
Fuel Distribution ◽  
Automotive Engine ◽  
Computer Methods ◽  
Detail Design ◽  
Stage Of Development ◽  
Marine Propulsion ◽  
Marine Diesel

Over the past quarter of a century, British-designed marine propulsion diesel engines have more than doubled their power output per cylinder. During the same period weight per kilowatt, and engine length per kilowatt, have both been reduced by nearly 75 per cent, specific fuel consumption has been reduced, and reliability has improved. This progress has been achieved by detail design improvements to even out stresses in components and to reduce temperature differences between hot and cold surfaces, combined with the application of the results of advanced computer methods to air flow, fuel distribution, and separation of rubbing surfaces by oil films. At the present stage of development the marine diesel engine is in many ways more advanced than the small automotive engine and can also compete in economic power production with prime movers at the opposite end of the scale such as super-large high-pressure steam turbines.

Sign in / Sign up

Export Citation Format

Share Document