CHARACTERISTICS OF FUEL DISTRIBUTION IN THE VOLUME OF THE COMBUSTION CHAMBER OF TWO-STROKE DIESEL ENGINE WITH OPPOSITE MOVEMENT OF PISTONS

Abstract

The paper analyzes ways of organizing mixture formation in a two-stroke diesel engine with reciprocating piston move-ment. Issues such as heat exchange with the walls, atomization and evaporation of fuel, distribution of the fuel jet and fuel vapors in the volume of the combustion chamber are considered. It is noted that the tangential vortex, which is achieved thanks to the special profiling of the windows, has a significant impact on the processes in the two-stroke diesel cylinder. The movement of the air charge is an important and critical factor in the formation of a mixture, the intensity of the vortex is estimated by the vortex number, which is the ratio of the number of revolutions of the vortex to the engine speed. In the process of volumetric mixture formation, the basic issues are fuel atomization and uniform distribution in the air volume. Fuel spraying has such criteria as the degree of dispersion and uniformity of the ignited fuel. The degree of dispersion is estimated by the average diameter of drops in the sprayed fuel. And the uniformity of spraying in the volume of the combustion chamber depends on the fuel jet shape, range of the jet, swirling air, the type of combustion chamber. The presence of long-range jets must necessarily be accompanied by the necessary intensity of air charge movement along the wall. Otherwise, in the conditions of the hot wall, which is typical for the domestic 6ChN12/2×12, in the places of contact of the jets with the overheated wall, significant solid deposits of soot are found, and these deposits have the character of coke, obtained as a result of fuel cracking. The mentioned drawback cannot be eliminated only by changing the wall temperature, if its main cause is not eliminated simultaneously, namely, a local lack of air (for example, in the central part of the piston bottom). Development of measures for prevention of this phenomenon will improve the engine's environmental friendliness and efficiency.