Influence of clogged injector nozzles on the heat release characteristics

The paper presents the results of research of the influence of clogged injector nozzles in fuel injection system on the shape of heat release characteristics. The study was conducted on a laboratory four-stroke marine engine, type Sulzer 3Al 25/30, with nominal power Ne = 408 kW at nominal rotational speed n = 750 rpm. The study was carried out according to active experiment plan, during which the engine failure of the injection system was simulated. Simulation of loss of patency of injector nozzles (clogged) was to completely clog two holes of nine injection injector nozzle holes with a diameter of 0,325 mm. Measurements were made at a constant engine speed of 750 rev/min for five loads: 50, 100, 150, 200, 250 kW. Measurements of pressure of combustion were performed by means of tensometric sensors of Spice Company. Based on measured pressure curves heat release characteristics were determined. The algorithm allows the determination of net heat release rate q and the net generated heat Q characteristics. Based on the obtained results it can be concluded that significant improvement in the diagnostic use of indicator diagrams can be obtained by using heat release characteristics. These characteristics are correlated with the process of fuel injection and the injection pump operation. As demonstrated in the work of analysing the heat release rate q, it is possible to infer diagnosis on the technical condition of the fuel injection system.