Development of the calculating procedure for the diesel CHN21/21 working process to determine non-stationary local thermal boundary conditions

One of the actual tasks facing the engine building industry is the forcing and upgrading of existing medium-speed diesel engines to meet modern requirements and environmental standards. The required upgrading leads to an increase in the maximum operating temperature, and, as a result, to an increase in the thermal stress of parts contacting with hot gases. The purpose of this paper is the calculation of the boundary conditions necessary for calculating the heat-stressed-deformed state (HSDS) of the cylinder cover. In order to obtain a reliable result, modern software systems are to be used to determine the local loads on the main engine parts. For this, a three-dimensional non-stationary calculation of the diesel working process was carried out in the AVL Fire software package in the Fire Workflow Manager module, possessing physical-chemical models of a deep level of detail. The results of calculation in the zero-dimensional program complex “Dizel’-RK” were used as the initial data for modelling. The calculations were carried out using various combustion modes: Magnussen-Khartager (here the parameter B was varied) and the three-zone extended model of a coherent flame. The verification of the obtained indicator diagram of the diesel CHN21 / 21has been carried out by comparing the calculation results with the experimental data obtained during the testing of the engine at “UDMZ” Ltd. As a result of the three-dimensional non-stationary calculation of ChN21/21 diesel workflow, the values of non-stationary thermal boundary conditions of the second kind on the part of the working piece have been obtained, which will be later used to calculate the HSDS of the main engine parts forming the combustion chamber. The resulting calculation indicator diagram had a high convergence with the experimental diagram.

AVL Fire, piston engine, diesel, mathematical model, workflow, AVL Fire, optimization, boundary conditions

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