Solid State Phenomena Vol. 236

Abstract: The paper presents problems related to testing of the technical condition of high-speed marine diesel engines that are not equipped with indicated valves, as it is in the case of larger medium-and low-speed marine internal combustion engines. In this case, in assessment of technical condition of engine fuel injection system and valve gear system a vibration signals (in time / angle domain) analysis modified method called HFRT (High Frequency Resonance Technique) can be used. This method indirectly helps also to evaluate the fuel combustion process in the engine cylinders. The paper presents the theoretical basis of a modified HFRT method, physical implementation of the marine diesel engine system’s analyzer used for marine engines testing built at the Institute of Construction and Operation of Ships at Polish Naval Academy (PNA) in Gdynia. The paper also includes a description of the vibration signal processing methodology and examples of measurements made in the ships conditions for a few selected types of engines.

Abstract: The paper presents the results of study concerning the determination of operating characteristics of the examined engine in steady states. The study concerned main propulsion engines of an Oliver Hazard Perry class frigate operated by the Polish Navy. The studies were conducted in the ship's engine room when the ship was at sea. Operating characteristics were determined on the basis of the measurements recorded over the entire load range of the engine, from minimum to rated load. During the studies, the load of both engines of the ship was simultaneous and balanced. In order to facilitate the comparison of the operating characteristics of the tested engines, as well as to make a reference to various weather conditions, the data obtained was reduced to standard reference state. For the aforementioned characteristics approximation relations were determined using statistical analysis. The relations obtained may be utilized in energy modeling and simulations, as well as technical diagnostics concerning this kind of engines.

Abstract: The paper presents concept of engine vibration monitoring system dedicated for all kind means of transport. Based on nature of vibration phenomena the scope of the possibilities of usage of vibration become very wide. The procedure of vibration measurements allow to conduct constant registration without invasion into construction into mechanism. These are non-destructive methods. Due to all these advantages and very difficult environment of engine in means of transport the application of vibration methods for engine monitoring system become very popular. The paper presents some exemplary results of vibration registration on the block of the engine.

Abstract: The crankshaft is exposed to numerous external extortions which generate bending, axial and torsional vibrations. Torsional vibrations are especially dangerous for a safe operation. They are generated by strongly dynamic loads, which come from the combustion processes of fuel-air mixture in cylinders and from the elements of drive system, and engine accessories. Until recently this problem concerned mainly the engines of high power, where dynamic effects generated the vibrations with amplitudes exceeding the limit values, which in effect led to failure of the engine. Crankshafts also significantly increased their torsional elasticity because of the common trend of reducing the engine mass. It resulted in the necessity of using the elements reducing the amplitude of torsional vibrations of the shaft. Rubber torsional vibration dampers are commonly used for this purpose. The author observed that while choosing torsional vibration dampers, the producers concentrated only on the criterion of reducing the amplitude of torsional vibrations below limit values. They forgot that the optimization criterion can be expanded in such a way so that a better effect can be obtained. What is more, safe and economical operation of the engine could be provided.

Abstract: The article provides a discussion concerning the potential for applying advanced methods of vibroacoustic signal processing for the purposes of identification of a combustion engine state. It contains example results of vibration measurements on the passenger car combustion engine in three directions. The research was conducted on stopping vehicle, for different pre-set values of the engine rotational speed. The results of preliminary tests focused on the potential use in the diagnostics of engine operation.

Abstract: The paper presents a method of transforming the time axis to the axis of the crank angle rotation based on the pressure measured in time domain and simplified model of the engine dynamics. Indicating is to register the pressure in synchronism with the engine crank angle rotation. Usually in the ad hoc measurements the crankshaft rotation angle transducer is avoided, and the measurements are performed in time domain. For further analysis time axis is transformed for crank angle axis on the base of linear transform. Pressure waveforms obtained during the research were subject of the described transform. During the research instantaneous angular speed (IAS) of the engine crankshaft has been changed by reducing fuel dosage to selected cylinders. Mean indicated pressure (MIP) was calculated. Values o pressure on the begging and the end of compression, opening and closing angles of valves were also determined.

Abstract: In the paper the first phase of a mathematical model construction of processes occurring in the cylinder during the working cycle of marine internal combustion engine is presented. The physical model of the mechanical and thermodynamic processes taking place when marine diesel engine drives a synchronous generator is described. In addition, assumptions of the mathematical model developed for marine engine diagnostics are discussed. The input parameters of the model and some simplifying assumptions have been presented. In parallel with the mathematical model, a computer program was created to facilitate carrying out the calculations. Descriptions of the mathematical model and a computer program are illustrated by means of graphs of selected parameters of combustion engine as a function of rotation angle of the crankshaft.

Abstract: The use of diesel engines as a basic power unit of electric generators in big ship crafts and as a power unit in smaller ship crafts is very common. Low fuel consumption, high resistance to overload and long life span are the basic features which made these engines so commonly used. The development of electronic control of high pressure injection systems of the engine made the service of such an engine not so simple any more. What is more, control systems are directed at reducing fumes toxicity, which does not have to go hand in hand with early detection of engine damages. It happens in the case of a particular group of mechanical damages of the engine, which are undetectable by an onboard diagnostic system in the early stage of the development. The injection system is able to choose regulation parameters in such a way so that the composition of the air fuel mixture is in optimal range, and as a result it hides the information about the damage.This paper presents the results of analysis of the usefulness of the chosen vibroacoustic signal measures in the process of detecting damages of this type.

Abstract: This article presents the results obtained with use of author's dynamic model of gears working on power circulating test stand. It was assumed, that properly defined and next identified model can be used to analyze dynamic phenomena in meshing and bearings of gears.The article includes results of simulations of gear with chipped tooth and with partial crack of the pinion. Results of analysis shown, that the occurrence of meshing deviations, makes the detection of damages in the early stages of their growth difficult and the detection may be not possible without using methods of advanced signal analysis.

Abstract: Recent years of the growing concerns over ship emissions have driven policy changes at the international level toward more stringent marine vessels emission standards, mainly SOx and NOx. This has also been a key factor for innovation in marine technologies leading to decrease these emissions. LNG as fuel is one of the solutions as this results in the elimination of SOx emissions, and significant reduction of NOx, CO₂ and particulate matter (PM) emissions, when comparing to the emissions from a typical vessel powered by marine diesel oil. This paper analyses environmental benefits of LNG-fuelled marine engines in the light of investment and operating costs, as well as the perspectives of the infrastructure development.