SIMULATION OF CRANKPIN BEARINGS OPERATING PARAMETERS OF A LOW-SPEED MARINE DIESEL ENGINE WARTSILA RT-FLEX82C

Introduction. Systematic modeling and analysis of the crankshaft bearings condition can significantly improve the understanding of the mechanism of contact interaction of the bearing surfaces and the crankshaft, related to dynamic characteristics and is an effective method for determining performance limits for crankshaft bearings. Purpose. This article is devoted to modeling the performance of the crank bearing of a diesel engine Wartsila RT-flex82C in the software environment GT-Suite at different values of operating clearances, which will help improve the theory of lubrication of engine bearings and can provide a more complete reference base for constructional design of connecting rods and bearings. The simulation was performed using SAE 30 viscosity engine oil values supplied at a temperature of 318 К and a pressure of 0,5 MPa. Results. The results of operating parameters for four variants of radial clearance 0.3, 0.4, 0.5 and 0.6 mm in the bearing are obtained. The increase in wear is accompanied by an increase in the maximum hydrodynamic pressure in the oil layer, namely from 9.44 MPa to 13.02 MPa (40%), a decrease in the thickness of the lubricating layer from 65.3 μm to 63.0 μm (3.5%). In addition, the increase of the clearance naturally leads to a decrease in the average friction moment of -625.6 N m to -468.1 N m and reduces power losses from 7.8 kW to 6.3 kW. Accordingly, the oil temperature in the bearing decreases from 323.4 to 318 К. Conclusions. In this paper, we show that increasing the radial clearance leads to an increase in oil flow through the bearing, which in turn leads to a drop in pressure. Since the mathematical model is based on the condition of constant pressure of circulating oil, the calculated average flow is 21.3, 28.6, 64.8 and 102.8 l/min for the studied variants of radial clearances. We can say that the performance of a bearing with a radial clearance of 0.6 mm will be difficult to ensure due to the pressure drop in it.