Computational and theoretical analysis of changes in the thermal gaps of the "piston-sleeve" interfaces during the removal of carbon
Abstract
Computational and theoretical analysis of changes in the thermal gaps of the "piston-sleeve" interfaces during the removal of carbon
Incoming article date: 08.11.2021Carbon formation in diesel engines affects an increase in the temperature of the sleeve, a decrease in the thickness of the oil film, an increase in oil fumes, which causes more intensive wear of the piston group cylinder parts. According to the theory of heat exchange, the heat flow from the working fluid (combustion products) is directed perpendicular to the surface of the piston bottom and is proportional to the equivalent temperature to the average heat transfer coefficient per cycle. Heat can also be supplied to the side surface of the piston bottom, but since the thermal gap between the piston head and the cylinder is small, the heat flow is insignificant. The deposition of carbon deposits on the bottom of the piston and cylinder head causes a slight decrease in its temperature, but at the same time the temperature of the cylinder liner increases, which causes a change in the gaps of the "piston-sleeve" interfaces. Experimental determination of interface gaps on a running engine is associated with significant difficulties. As a result, a computational and theoretical analysis of changes in the magnitude of thermal gaps was performed with a decrease in the thickness of the carbon layer on the bottom of the piston. The deposition of carbon deposits on the bottom of the piston indicates less favorable operating conditions of the piston-sleeve conjugations due to an increase in the dynamic performance of the cycle.
Keywords: quality, surface, part, performance properties, roughness, friction, wear, research, processing, physical and mechanical properties, hardening, deformation