ANALYSIS OF THE PERFORMANCE OF CONNECTING ROD BEARINGS IN THE MEDIUM-SPEED ENGINE HIMSEN H25/33 DURING OPERATION WITH PERMISSIBLE CLEARANCES WITHOUT REPAIR

Abstract

This article is devoted to determining the influence of loading conditions and working clearances on the performance of main and backup bearings on the example of a medium-speed marine diesel engine Hyundai HiMSEN H25/33. Another important aspect of this study is the analysis of the safety of the studied bearings at the assembly and limit values of working clearances. The sequence of modeling of work processes in connecting rod bearings using the specialized software package GT-Suite is presented. The characteristics of the operating parameters of the studied bearings during diesel engine operation at the most commonly used load mode of 75 % Nₑ and overload mode of 110 % Nₑ at assembly and allowable working clearances without repair were determined. The obtained results of computer modeling of the working processes in the motive power bearings indicate the presence of a stable hydrodynamic lubrication regime at all loadings and working clearances. It has been established that under the most unfavorable operating conditions, the minimum thickness of the lubricating layer is 10.2 microns. This value is the limit for this type of bearing and is therefore reasonable. The maximum value of the lubricating layer pressure is 226.4 MPa, which does not exceed the tensile strength for aluminum bearing materials. In the main bearings, the boundary lubrication regime occurs over a long area relative to the crankshaft rotation angle, which is approximately 300º - from the beginning of the stroke to almost the end of the release stroke. The boundary lubrication mode in this bearing is caused by high loads and low sliding speed with a change in the direction of rotation with each revolution of the crankshaft. The increase in the working clearance also contributes to an increase in the maximum pressure in the lubricating layer by 45% (75% Nₑ mode) and 48% (110% Nₑ mode). The maximum value of the lubricating layer pressure is 507 MPa, which indicates a possible overload of the bearing assembly material.