STUDY OF THE IMPACT OF OPERATING MODES OF MARINE LOW-SPEED DIESELS ON THE DYNAMIC CHARACTERISTICS OF THE CRANK-SHAFT MECHANISM

The study of the performance of the bearings of the crank-shaft mechanism of ship low-speed engines is aimed at increasing the operational reliability and reducing the operating costs of the ship's power plant. Modern economic requirements and environmental restrictions on the emission of harmful substances with exhaust gases from ship diesel engines have led to changes in the conditions of the working process in the cylinders of diesel engines, which, in combination with the use of economic vessel speeds, create new conditions for loading the bearing assemblies of the crank-shaft mechanism of low-speed engines. To create modern systems for monitoring and diagnosing the performance of the crosshead bearings and predicting their resource, it is necessary to develop appropriate criteria for their evaluation. To determine the indicators that characterize the loading conditions of the crankshaft bearings, it is necessary to collect data for modeling the working process in the engine cylinders and the dynamic characteristics of the crankshaft. This will provide an opportunity to analyze the current loading conditions of the bearing assembly and, if possible, avoid long operating times. The paper studies the influence of the working processes of the low-speed diesel engine 8K90MC-C manufactured by MAN B&W, operating at the nominal propeller characteristic, on the loading conditions of the crosshead bearings. An analysis of the limiting characteristics of the main engine was performed taking into account the selected mode of the design maximum continuous power (SMCR). A method for conducting dynamic calculations using solid-state modeling of the mass characteristics of the connecting rod is presented. As criteria for assessing the performance, the characteristics of the total force acting on the crosshead bearing, the average load and the bearing characteristic pm∙vb are selected. An assessment of the effectiveness of the application of the above indicators and the pm∙vb criterion is provided. The feasibility of using the pm∙vb criterion is indicated for indirect assessment of the thermal load regime of bearings. Directions for further research are given in the direction of developing methods and criteria for assessing and predicting the performance of the bearing assemblies of the low-speed engines.