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Modeling of the burning process in the piston engines with various concepts of the working proces

100%

Natriashvili T. , Kavtaradze R. , Glonti M.

Transport Problems

2020

tom T. 15, z. 1

39--48

In this paper, the results of modeling of the burning process in the piston engines whose working process is realized on the basis of various conceptual approaches are presented: in diesel with direct injection of the fuel; in a gas engine with spark ignition; and in a two-fuel engine (in the gas-diesel), where the mixture of natural gas and air ignites with the help of the fuse dose of the diesel fuel. The models of burning based on the different in-principle approaches are analyzed and used. Verification of the models is performed by a comparison of the results of modeling with the experimental diagrams. The specific values of the empirical coefficients, used in modeling of the burning proces in the engines under study, are determined. The practical recommendations on the choice of the burning model depending on the working process conception are given.

Flame propagation in a narrow gap between the piston and cylinder of a hydrogen engine

75%

Kavtaradze R. , Natriashvili T. , Glonti M. , Chilasvili G. , Gelashvili O. , Iosebidze J.

Transport Problems

2023

tom T. 18, z. 3

189--197

The processes of flame penetration and propagation in a narrow annular gap between the piston and cylinder of a hydrogen piston engine are investigated by the method of 3D mathematical modeling. The model is verified by comparing the changes in pressure and heat release rate in the cylinder obtained from an experimental hydrogen engine, considering the data collected during numerical experiments. The movement of the flame front into the gap is analyzed by changes in the instantaneous local values of the hydrogen fractions in the mixture and the local temperatures of the cold gas (unburned mixture) and combustion products. A comparative analysis of the spread of gasoline and hydrogen flames is carried out. The phenomenon of increasing heat losses in the combustion chamber of a hydrogen engine compared to a gasoline engine, previously confirmed experimentally by different authors and not yet having an acceptable theoretical interpretation, is explained by neglecting the role of heat transfer in the indicated gap.