Анотація. Наведено результати експериментального дослідження механічних втрат мікролітражного чотиритактного двигуна HONDA GX25 методом прокручування електродвигуном постійного струму ЕД-25. Наведено методику експериментального дослідження та описання моторного стенда. Запропоновано емпіричну залежність для визначення середнього тиску механічних втрат. Ключові слова: мікролітражний двигун, механічні втрати, чотиритактний двигун, експериментальне дослідження.
Results are given for the comparative numerical simulation of heat-and-mass transfer processes in the cooling passages of a cylinder head in diesel locomotive engine 16 FN 26/27 running under rated power conditions at different engine boost levels. The advanced numerical methods used are shown to ensure a high degree of accuracy and information content when simulating heat-and-mass transfer processes, and enable evaluating the local values of flow parameters with account of the complex configuration of the flow parts in the cooling passages and the impact of operating parameters. The results show that an increasing boost level of a diesel engine and, respectively, a growing thermal load degrade drastically the conditions of heat rejection from the most thermally stressed zones of the cylinder head – the central part of the bottom face in the area of the injector bore and of the bridge between the bores of exhaust valve seats. The paper assesses the impact of the boost level on the effectiveness of heat rejection from the most thermally stressed areas of the cylinder head of a diesel locomotive engine. Conclusions and recommendations for improving the operating conditions of the cylinder head are given.
The results of comparative design research in the thermal stress and strain state of the piston in transport diesel engine 2 F 10.5/12 are given for its rated power operation. The standard piston is made of an aluminium alloy, and the modernized one, of steel. Piston thermal profiling and indicator test results were used for identifying the mathematical models and refining the boundary conditions for mechanics and heat conduction problems. To ensure reliable heat rejection from the piston, the paper considered the case of oil jet cooling. This was taken into account when describing the boundary conditions of the heat conduction problem. The thin-wall steel piston with oil jet cooling was shown to function reliably under the study conditions. The temperature in the first compression ring groove does not exceed 200 °С, and the radial deformation of the piston crown is less than half of that of an aluminium alloy standard piston.
Purpose. A computational valuation of the parameters of the process of commercial grade and blended fuel flow in the injector nozzle of a locomotive diesel engine, and its impact on spraying conditions in the combustion chamber. Methodology. The scientific investigation is based on using the technique of a comparative numerical experiment. Modern numerical methods in computational fluid dynamics are used for simulating fuel flow and spraying processes in the injector nozzle and combustion chamber. Findings. It was found that when working with commercial grade fuel with maximum pressure in the area of the injector well of 85MPa, the fuel flow velocity in the fuel injection nozzle hole reaches 434 m/s, whereas when working with fuel blended with alcohol the velocity decreases to 429 m/s (at a 25% alcohol concentration). Due to the lower pressure of saturated vapours of the blended fuel, as compared to that of commercial grade fuel, the fuel-air mixing conditions degrade at the operating duty being investigated. Originality. The investigation helped to study the impact of blended fuel composition on changes in the processes of its flow in the injector nozzle, and on the injection into the combustion chamber and the fuel-air mixing conditions. The study results helped to develop recommendations on ensuring effective ICE operation with blended fuel. Practical value. A change in the conditions of blended fuel spraying and fuel-air mixing should be taken into account when choosing effective fuel injection advance angles and fueling principles in order to ensure high ICE economic and ecological performance.
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