FUEL INJECTION PROCESS AT SPEED CHARACTERISTICS OF MEDIUM-SPEED DIESEL ENGINE AT VARIABLE MODES

Abstract

The results of an experimental study of the features of the fuel injection process on the speed response of a medium-speed marine diesel engine under variable conditions are presented. The study of hydrodynamic processes for these characteristics expands the possibilities for improving the operation of a diesel engine, and also allows to clarify the methods for calculating the processes associated with fuel injection. Experimental studies have been performed on an engineless test bench under various initial conditions with the refinement of the measuring complex. The first option - before starting the high-pressure fuel system was unloaded. The second option - the engineless test bench was started after a short stop. At the same time, the residual pressure remains in the system after the first start option. The generalized results of the experimental study allowed to evaluate the process of fuel supply development during the whole experiment. At the same time, in the first option, the essential feature is the absence of a noticeable increase in pressure in the nozzles during the first three injection cycles in the acceleration process, despite the rather high rotational speed of the camshaft. Only in the fourth cycle, a pressure increase of up to 40 bar was obtained, which is not enough to lift the nozzle needle. The first injection conditions are formed in the fifth cycle (stepwise injection phase). In the second option, with an initial pressure in the fuel system of 27 bar, during acceleration already on the first revolution with a relatively low rotational speed, the pressure value corresponds to the injection conditions and reaches 166 bar. Thus, the initial pressure in the fuel system during acceleration has a significant impact on the development of the injection characteristics, which is a specific feature of the diesel engine operation in variable modes. The peculiarity of the formation of injection parameters during coasting in both options does not depend on the initial conditions in the fuel system. Consideration of the injection process features at a continuously varying rotation speed will improve the reliability of marine diesel engines during maneuvering and will ensure the improvement of diesel engine working processes at variable modes.