Design assessment of the range of permissible operation modes of a marine two-stroke diesel engine

Abstract

In the practice of operating marine diesel engines, as a limiting characteristic for mechanical stress, a characteristic corresponding to a constant effective torque, which is proportional to the average effective pressure, is used. There is no such unambiguity regarding the restrictive characteristics of thermal intensity. Limitations on the thermal stress of a diesel engine depend on its design features and the efficiency of the cooling system of the cylinder-piston group. At the diesel engine design stage, it is important to assess in advance whether the operational characteristics correspond to the technical specifications.
 The work carried out computational and theoretical studies of the operational parameters of the main marine two-stroke diesel engine operating according to the screw characteristic, which affect its mechanical and thermal stress, and determined the expected limiting characteristics of the mechanical and thermal stress. The studies were carried out for wide ranges of changes in the weight coefficient of the screw characteristics and the relative power of the diesel engine. The estimated design ranges of diesel operating modes are given, excluding its mechanical and thermal overload, and an assessment of the permissible weighting of the screw characteristics is given. The results obtained were compared with the characteristics of a marine four-stroke diesel engine.