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The analysis of the ECFM-3Z combustion model in the marine 4-stroke engine for the exhaust gas composition

Kowalski J.

Journal of Polish CIMAC

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2014

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Vol. 9, no 1

95--102

EN

The paper presents ECFM-3Z combustion model analysis in the marine, 4-stroke diesel engine. The purpose of the modeling was to determine the composition of the exhaust gas. This composition depends on the composition of the combustible mixture, combustion time and thermodynamic conditions prevailing in the engine cylinder during the working process. Mentioned parameters are variable in time and space, and therefore require the use of 3-dimensional model based on the finite volume method, taking into account the fuel injection, brake-up and evaporation, mixing with air, auto-ignition and combustion. All models presented in the literature are adapted to the parameters of relatively small engines. Different marine engine parameters require significant modifications taking into account the heat exchange with the structural elements of the engine, leakage through piston rings and energy losses by riction. It should also be noted that dimensions of the marine engine require careful optimization of spatial moving meshes according to computation time and quality of results. Paper presents influence of mixing time, start of injection and autoignition delay on modeling results of the exhaust gas composition.

2

Assessment of the 3-D combustion model in the marine 4-stroke engine

Kowalski J.

Journal of Polish CIMAC

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2014

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Vol. 9, no 1

79--86

EN

The aim of this research is to formation of the model of combustion process in the marine, 4 -stroke, diesel engine. The chosen object of research is a laboratory AL25/30 engine. For achievement of the aim, laboratory measurements are made and the results are used to determine the boundary and initial conditions. In addition, measurements of the fuel injection shape are made on the test bench and are made a faithful geometric model of structural components of the engine cylinder. The obtained data has been implemented in the three - dimensional model comprising the fuel injection phenomena, the brake - up and the evaporation of fuel, auto - ignition, flame propagation and heat exchange with the structural elements of the engine cylinder. As a result of activities succeeded in creating a model of the combustion process in the cylinder, which has been positively validated due to the maximum combustion pressure and the temperature of the exhaust gases. Obtained results of calculations also allowed verifying the assumption of negligible auto-ignition delay. The adopted ECFM - 3Z model of the ignition and combustion, used for modeling of combustion in diesel engines, showed the calculated size of the auto - ignition delay of 7 - 8 ° CA.

3

3d mesh model for rans numerical research on marine 4-stroke engine

Kowalski J., Jaworski P.

Journal of Polish CIMAC

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2014

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Vol. 9, no 1

87--94

EN

The article consist the 3d mesh analysis prepared for simulation of the processes in combustion chamber of marine compression ignition engine. The three moving meshes models where prepared: A–mesh for engine cycle work simulation; B –mesh of combustion chamber volume for work stroke simulations, no valves included; C-mesh of combustion chamber including mountings screw whole for work stroke simulations , no valves including. Prepared mesh where used for numerical simulations of injection and combustion processes in engine combustion chamber. Type C model, even if the total number of cells is lower in comparison to B model, result in calculation time increase. B and C models are solution for fast and robust validation of injection and auto ignition model parameters. Type A model is only one suitable for full cycle simulation. Only with accurate initial and boundary conditions the qualitative results of the injection, mixing and combustion process can be obtain on mesh type B and C.