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The methodology for analyzing the thermodynamics and heat transfer of the combustion chambers of a diesel engine is presented. The work is devoted to the modified quasi-steady method (MQM) for the analysis of a diesel engine piston coated with an aluminum alloy. The oxide-coated piston using a galvanic-plasma modification (GPM) depending on the thickness of the coating, including comparison with the results for uncoated piston temperature, to achieve higher characteristics of the Cummins KTA-50 diesel engine. In thermodynamic modeling of a diesel engine, instantaneous gas temperatures and convective heat exchanges are first predicted. The time-dependent boundary conditions are then applied to the gas-blown surfaces of two-dimensional, transitional finite element models of the components of the combustion chamber. Further, the predictions on the finite elements of the instantaneous heat flux passing through each surface of the component are used to determine when the engine goes into quasi-stationary operation. The results show that our path in methodology can identify the complex transition paths of the heat process in the engine combustion chamber and significantly improve heat conduction and convection heat models when modeling a diesel engine.

The purpose of the work is to identify complex transient heat flow paths in the combustion chamber of engine, significantly improve the models of diesel engine heat flow, and study the effect of aluminum oxide coating by the galvanic plasma method on short-term and long-term reactions of the piston head. The analysis of operation of aluminum alloy coated diesel engine piston is carried out using a modified quasi -steady method and a finite element method. A thermodynamic analysis is presented using energy and state equations with corresponding gas heat transfer. Time-dependent boundary conditions are set on the gas-blown surfaces of 2D finite element transition models of combustion chamber components. It is shown that this methodology can reveal complex transient paths of the heat flow in engine combustion chambers and distribution details of heat losses in various cooling media. Numerical simulation has shown that the maximum temperature increase relative to the uncoated piston is 64.3% for the coating thickness of 0.13 mm. Tests have shown that the coatings can endure up to 280 thermal cycles. It is found out that predictions of numerical simulation are in good agreement with the results of experiments conducted with repaired pistons. The experimental operation of Cummins КТА 38 engines at Chernogorsk and Vostochno-Beysk coal mines has shown that the engine equipped after repair with the piston coated with aluminum applied by the galvanic plasma method has been in operation for 2 years and 3 months, whereas its set overhaul period is 18,000 hours. Therefore, the proposed methodology allows to reduce temperature variations in the piston and, thereby increase the service life of engine pistons coated with the use of the thermal barrier coating technology.

Misalignment is one of the most common challenges that the normal operation of journal bearings faces. This type of problem may be the result of a wide range of reasons, such as bearing wear, shaft deformation, and errors related to the manufacturing and installation process. The main undesirable consequences of the misalignment, such as pressure rise and lubricant film reduction, are concentrated on the bearing edges. Therefore, chamfering the bearing edges reduces such misalignment-related drawbacks. This work presents a novel numerical solution to the problem of finite-length journal bearing considering edge chamfering. This solution involves the determination of the levels of lubricant layer thickness and pressure distribution in addition to the journal trajectory under impact load with the related stability limits. The finite difference method is used in this solution, and the equations of motion are also solved numerically using the Runge–Kutta method. The Results of this novel analysis show that chamfering the bearing edges increases the film thickness and reduces pressure spikes associated with the system operation under the case of 3D misalignment. Furthermore, the chamfered bearing shows a wide stability range under impact loads, where the normal bearing is unstable as the critical speed increases by 26.98%, which has positive consequences on the journal’s trajectory.