The paper presents algorithms for marine diesel engines’ working process monitoring designed by analyzing data obtained with IMES pressure sensors. Main features and properties of IMES sensors, used for 2- and 4-stroke modern marine diesel engines, are presented here. The pressure-time diagrams were taken as a basis for creating algorithms for marine diesel engines’ working process monitoring. The task of preliminary calculation of top dead center position (TDC) of a cylinder was solved using polytropic compression equation. TDC position was calculated using the equation P' = 0. Then algorithm for calculating the average indicator pressure and the indicator power of the cylinder has been determined. The CFD methods show how indicator valve channel influences the results of marine diesel engines’ working process monitoring. With the example of compression curves in a cylinder, it’s shown amplitude and phase distortions introduced into pressure measurements by the indicator valve channel. Such research work is important and actual in time due to the use of marine diesel portable performance analysis systems.
Although direct measurements of the fuel injection pressure and the travel of the injector needle in conjunction with measurements of the valve train mechanism timing can provide complete diagnostic information about the technical conditions of the fuel injection and valve train systems, this requires the installation of sensors and other equipment directly into the systems, which is possible within research laboratories but is generally forbidden during operation of the ship. Malfunctions in the fuel injection and valve train systems can also be identified from the indicator diagrams of an engine operating cycle, expressed as P(V) and P(deg) diagrams. The basic parameters of the engine operating cycle, such as the maximum combustion pressure Pmax, compression pressure Pcompr, and indicated mean effective pressure IMEP, can also be used to indicate deviations from proper engine operation. Using a combination of a vibration sensor with an in-cylinder gas pressure sensor widens the capabilities of diagnostics for marine diesel engines under operational conditions. A vibration sensor with a magnetic base can help in determining the timings of the lifting and landing of the injector needle, fuel delivery by the fuel injection pump, opening and closing of the circulation of heated heavy fuel oil, and opening and closing of the gas distribution valves. This also offers a promising solution for diagnostics of the cylinder lubrication oil injectors. The proposed approach allows valuable information to be received during engine operation in accordance with the principle of non-destructive control, and can help in early detection of possible engine malfunctions.
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