Zbigniew Korczewski

Alternative diagnostic method applied on marine diesel engines having limited monitoring susceptibility

The paper presents a method of technical state evaluation of working spaces of a marine diesel engine at the limited control susceptibility. The method foresees making a diagnosis of the engine’s working spaces on the basis of measurements of the exhaust gas pressure in the channels connecting engine cylinders with the turbocharger’s turbine. Diagnostic measurements are carried out at representative (comparative) steady loads depending on floating conditions. In the beginning of the article, the research objects are characterized, i.e. a Zviezda marine main engine M401 type and Detroit Diesel marine auxiliary engine DDA149TI type. Then, diagnostic measures used to identify the condition of the considered engines are defined. Moreover, selected results of diagnostic tests carried out on the engines in current operation on warships in the Polish Navy are demonstrated. The tested diagnostic classifiers confirmed that the elaborated method could be successfully applied for the engines not equipped with indicator valves.

Exhaust gas temperature measurements in diagnostic examination of naval gas turbine engines

Exhaust gas temperature measurements in diagnostic examination of naval gas turbine engines The third part of the article presents a method for detecting failures of the automatic engine control system with the aid of an exhaust gas temperature setter, specially designed and machined for this purpose. It also presents a procedure of identifying the operating tolerances and determining the diagnostic tolerances for the exhaust gas temperature recorded in the naval turbine engine during the start-up and acceleration processes. The diagnostic tolerances were determined using the statistic inference, based on the hypothesis about the normal distribution of the starting exhaust gas temperature dispersion at the initial time of engine operation. The above hypothesis was verified using the non-parametric statistic test χ2 for examining the consistency of the empirical distribution with the assumed normal distribution. As a result of the examination, satisfactory convergence of the compared distributions was obtained which made the basis for assuming the three-sigma limits of the diagnostic tolerance for the analysed engine control parameter.

Entropy function application in the selection process of diagnostic parameters of marine diesel and gas turbine engines

Entropy function application in the selection process of diagnostic parameters of marine diesel and gas turbine engines The article presents the method of analysing the diagnostic informativeness of the parameters characterizing gas dynamic processes observed inside the working spaces of marine diesel and gas turbine engines. The entropy function was used as the measure of indeterminacy of the identified set of engine unserviceability states. Based on numerical simulation experiments of the analysed gasodynamic processes, the amount of introduced diagnostic information was assessed and the most adequate parameters for the technical state of the engine were selected. These parameters compose the minimised set of diagnostic parameters which make it possible to assess unmistakably the technical state of the examined working spaces.

Operational problems of large power diesel engines combusting biofuels, considered together with assessment of their operation

Operational problems of large power diesel engines combusting biofuels, considered together with assessment of their operation In this paper the problem is discussed of supplying high power diesel engines with biofuels in the aspect of consequences which occurr during their operation. Attention was paid to advantages and difficulties associated with application of biofuels to self-ignition engines. A relevant research problem was characterized and research targets were proposed to make it possible to most favourably shape energy merits of the engines. Special attention was given to wear process of such engines and their failures resulting from application of biofuels. The following problems were also considered: calcium carbonate sedimentation, closing graphite platelets in structure of cylider bearing surface and surface defects of piston rings made of aluminium bronze. It was demonstrated that to assess operation of the engines is possible under the assumption that in a valuating approach their operation can be compared to a physical quantity represented numerically and measured with the use of the joule*sec unit. Conclusions resulting from the domestic and foreign investigations on power and reliability of such engines were also presented.

Analysing the potential for application of the phase shift method in endoscopic examination of marine engines

Abstract The article presents theoretical principles of image processing in digital endoscopy which makes use of a miniaturised spectral scanner “PhaseProbe” designed by General Inspection Technologies LP, the producer of the measuring videoendoscope Everest XLG3. The technology of optoelectronic 3D mapping of the examined surface, which consists in measuring the phase shift between the emitted and reflected light waves, is briefly described. The efficiency of the “PhaseProbe” based method of endoscope measurements is compared with the earlier developed methods, such as “ShadowProbe” and “LaserDots”, which were used by the author in real conditions of diagnostic investigations of engines in operation in marine power plants. The processed results of the endoscope analysis of the broken gas turbine engine rotor blades which were earlier dimensioned using the inspection probes of “StereoProbe”, “ShadowProbe” and “LaserDots” type and now are examined by the author with the aid of the phase shift method make a valuable complement and synthesis of the discussion presented in the article.

Exhaust gas temperature measurements in diagnostic examination of naval gas turbine engines: Part II Unsteady processes

Exhaust gas temperature measurements in diagnostic examination of naval gas turbine engines: Part II Unsteady processes The second part of the article presents the results of operating diagnostic tests of a two- and three-shaft engine with a separate power turbine during the start-up and acceleration of the rotor units. Attention was paid to key importance of the correctness of operation of the automatic engine load control system, the input for which, among other signals, is the rate of increase of the exhaust gas flow temperature. The article presents sample damages of the engine flow section which resulted from disturbed functioning of this system. The unsteady operation of the compressor during engine acceleration was the source of excessive increase of the exhaust gas temperature behind the combustion chamber and partial burning of the turbine blade tips.

Contemporary diagnostic methods for ship engines: a report on scientific research activity of Polish Naval Academy in this field

Contemporary diagnostic methods for ship engines: a report on scientific research activity of Polish Naval Academy in this field This paper devoted to ship combustion engine diagnostics, presents short characteristics of experimental test techniques applicable to state assessment of piston and gas turbine engines presently being in use in Polish Navy. Some metrological and organizational aspects of realization of necessary diagnostic tests as well as measurements of control parameters of engines of low susceptibility to control, were highlighted. Such engines are installed a.o. on board American origin frigates of Oliver Hazard Perry type as well as Norwegian origin submarines of Kobben type which have been recently incorporated into Polish Navy (i.e.General Electric turbine engines, Detroit Diesel and Mercedes Benz piston engines), as well as older engines of Russian production (Zorya turbine engines, Zvezda piston engines). Applicability of particular diagnostic methods was also assessed from the point of view of their effectiveness in identifying engine failures in conditions of its operation in ship power plant. Recently realized tests have made it possible to conduct operation of all piston and turbine engines used on board Polish Navy ships in accordance with their current technical state. On the average 120-130 diagnostic expertises are yearly issued, and the carried-out tests cover main functional systems of engines together with their control and safety subsystems.

Energy Analysis of Propulsion Shaft Fatigue Process in Rotating Mechanical System Part I Testing Significance of Influence of Shaft Material Fatigue Excitation Parameters

Abstract The article discusses the problem of mathematical modelling of energy conversion processes in a rotating mechanical system for the purpose of identifying fatigue states of propulsion shafts in this system. A simplified physical model of the analysed system, constructed in an appropriate scale, has made the basis for the experimental research. The research programme took into consideration mechanical fatigue excitation of the model propulsion shaft to find the correlation between the dynamic system load generated by a bending moment and the energy state of a specified shaft segment. A physical model of the analysed process was proposed, for which the plan of static randomised block experiment was worked out. The recorded experimental results were used for statistical analysis of the significance of influence of the quantities exciting the propeller shaft fatigue process and the adequacy of the developed mathematical model describing shaft’s durability. The analysis made use of the F-Snedecor test. The article describes the general concept of the research, the constructed laboratory test rig, and the methodology of statistical inference concerning the significance of influence of input (exciting) parameters of the physical model on the recorded output parameters. The results of the performed statistical tests confirm the absence of the significance of influence of the rotational speed of the propulsion shaft on the selected types of rotating operation of the mechanical system. As a consequence, only one exciting parameter, which is the loading mass, is going to be taken into account in the functional description of fatigue life of the propulsion shaft.

A Method to Assess Transverse Vibration Energy of Ship Propeller Shaft for Diagnostic Purposes

Abstract The article discusses a key problem of ship propulsion system vibration diagnostics, which concerns assessing this part of mechanical energy transmitted from the main engine to the ship propeller which is dissipated due to propeller shaft vibration. A simplified calculation model is proposed which allows the total energy of the generated torsional vibration to be assessed from the shaft deflection amplitude measured at the mind-span point between the supports. To verify the developed model, pilot tests were performed on the laboratory rotational mechanical system test rig. In those tests, cyclic bending moment was applied to a unified (cylindrical) material sample, which modelled, at an appropriate scale, structural and functional properties of a real propeller shaft.

Exhaust Gas Temperature Measurements in Diagnostics of Turbocharged Marine Internal Combustion Engines Part I Standard Measurements

Abstract The second part of the article describes the technology of marine engine diagnostics making use of dynamic measurements of the exhaust gas temperature. Little-known achievements of Prof. S. Rutkowski of the Naval College in Gdynia (now: Polish Naval Academy) in this area are presented. A novel approach is proposed which consists in the use of the measured exhaust gas temperature dynamics for qualitative and quantitative assessment of the enthalpy flux of successive pressure pulses of the exhaust gas supplying the marine engine turbocompressor. General design assumptions are presented for the measuring and diagnostic system which makes use of a sheathed thermocouple installed in the engine exhaust gas manifold. The corrected thermal inertia of the thermocouple enables to reproduce a real time-history of exhaust gas temperature changes.