Applied Mechanics and Materials Vol. 817

Abstract: The article presents the results of an empirical study of unrepeatability of the spark-ignition engine BMW N43 B20 AY, which uses a spray-guided gasoline direct injection system to create the fuel mixture. The values of the so-called unrepeatability index of maximum indicated pressure were analyzed for two different engine operating conditions: under maximum load (absolute throttle at 91%) and under partial load (absolute throttle at 33%). The values of the index were calculated on the basis of values of indicated pressure recorded over 100-cycles at five predefined rotational speeds of the engine crankshaft. It was found that the unrepeatability of maximum indicated pressure during operation of the test engine was lower under partial load than under maximum load.

Abstract: The results of crankshaft forced vibration calculations, including the dry friction force which can be formed in the viscous damper bearing sliding, were presented. This problem concerns the big dampers used in the marine engines. The friction force influence is presented using the function {sign}. Low values of friction coefficient, corresponding to the conditions similar to the real ones, were assumed. In the range of tested value, it was found that the vibration increases linearly, and system free vibration frequency doesn’t change practically.

Abstract: Increasing the share of renewable electrical energy in the overall energy balance is one of the major challenges of humanity. It is primarily connected with global warming and increasing environmental pollution. One of the ways to counteract this problem is to promote the importance of renewable fuels, including gaseous fuels which are relatively low in carbon.This paper presents the effects of selected parameters of a pilot dose of diesel fuel on the efficiency of a dual-fuel compression ignition engine. The dose of gaseous fuel powering the engine was a mixture of methane and carbon dioxide in varying proportions.

Abstract: This article describes selected contaminants of the fuel system which substantially affect the operation of fuel injection equipment of self-ignition engines. The authors present a simple method of identifying biological contaminants (bacteria and fungi), which can be used with no need for laboratory tests during a vessel’s voyage at sea.

Abstract: The goal of the paper is to determine a possibility to use methyl cameline esters and their mixtures with diesel oil (in ratios of 95:5, 90:10, 85:15, and 80:20) as fuels for compression-ignition engines (diesel engines). The cameline esters obtained in the result of one-step basic transesterification were characterised in respect of kinematic viscosity at 40°C, density at 15°C, acid number, solid impurities content, sulfur content, ignition temperature, temperature of cold filter clogging, and oxidation resistance at 110°C. It was shown that majority of factors of pure cameline esters analysed in the paper, excluding content of impurities and oxidation resistance, met the requirements of the PN-EN 14214, 2012 standard. Whereas, in case of mixtures of diesel oil with varied addition of esters, it was ascertained that 5, 10 and 15% addition of the biocomponent did not affect significantly the physico-chemical properties of the prepared fuel. In turn, the highest, 20% share of a cameline ester caused a slight increase in viscosity, density, content of impurities and ignition temperature of the obtained mixture. However, it is noteworthy that these factors did not exceed the acceptable values according to the standard. In general, it was also ascertained that the only parameter disqualifying use of these samples as a fuel for compression-ignition engines was too high content of impurities.

Abstract: The increase of transverse contact ratio (ε_α) value usually allows reducing general level of gear vibroactivity. Article put to the test influence of coefficient ε_α value on dynamic forces in mesh zone with use of dynamic model of toothed gear. From theoretical point of view, the optimum value of transverse contact ratio is equal 2, what mean, that in mesh are always two pair of teeth. Obtainment such value of coefficient ε_α requires another construction of toothed wheels – wheels with HCR (High Contact Ratio) profile teeth. On result of occurrence of different deviations in toothed gears, as well as the dynamic phenomena, obtainment of continuous two-pair cooperation of gear pair is impossible and when this necessary is, solutions with near or exceed optimum value of coefficient are applied.

Abstract: Improving the efficiency or work and reducing the emissions of toxic substances into the atmosphere are the two key directions of development of modern combustion engines. Improvement of engine efficiency is feasible only by increasing the precision of control thereof, which necessitates long-term operating tests. Regrettably, due to complexity of processes taking place during the combustion of fuel, these phenomena can only be tested on simulation models, based on a mathematical description of the phenomena.This paper presents the results of verification tests of the developed fuel combustion model in a multifuel compression-ignition engine for an engine running only on diesel fuel.

Abstract: Naval propulsion systems are characterized by a high degree of complexity within a single system and a large variation between the solutions applied to individual vessels. In this situation, issues relating to the comprehensive diagnostic is a serious problem. Diagnostics models are useful to made the this problem easier. It should be emphasized that it is impossible to develop a universal model correct for all types of vessels. The paper presents general guidelines for the creation of diagnostic models. The results of first stage of studies on diagnostic model covers unit equipped with a twin-engine twin-shaft drive system had been presented.Introduction Changes of technical state of the machine occur as a result of its response to changes in the energy emitted by them. If qualitative and quantitative parameters of this energy are known diagnostician after proper analysis is able to determine the technical condition of the machine. It can be concluded that the technical diagnostics is a test of object response to the impact of energy causing change of its technical condition [9]. As far as the destruction of the object model is concerned we find that the degree of wear of the machine is proportional to the energy dissipated from it.

Abstract: This paper presents the results of numerical modelling of cavitation flows in a hydrodynamic module. The simulation was performed using the SolidWorks software package. The computations were made based on the Navier-Stokes equation combined with liquid state equations and empirical dependencies which define liquid parameters. The numerical results are in good agreement with experimental data.