The article presents the results of a study aimed at creating a mathematical model of thermodynamic processes in the intake manifold of a forced diesel engine, taking into account the features of simultaneous injection of fuel and water into the collector. In the course of the study, the tasks of developing a mathematical model were solved, it was implemented in the existing software for component simulation “Internal combustion engine research and development” (ICE RnD), created using the Modelica language, and verification was undertaken using the results of bench tests of diesel engines with injection fuel and water into the intake manifold. The mathematical model is based on a system of equations for the energy and mass balances of gases and includes detailed mathematical submodels of the processes of simultaneous evaporation of fuel and water in the intake manifold; it takes into account the effect of the evaporation of fuel and water on the parameters of the gas state in the intake manifold; it takes into account the influence of the state parameters of the working fluid in the intake manifold on the physical characteristics of fuel and water; it meets the principles of component modeling, since it does not contain parameters that are not related to the simulated component; it describes the process of simultaneous transfer of vapors and non-evaporated liquids between components; and it does not include empirical relationships requiring data on the dynamics of fuel evaporation under reference conditions. According to the results of a full-scale experiment, the adequacy of the mathematical model developed was confirmed. This model can be used to determine the rational design parameters of the fuel and water injection system, the adjusting parameters of the forced diesel engine that provide the required power, and economic indicators, taking into account the limitations on the magnitude of the mechanical and thermal loads of its parts.

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The article presents the results of software development, using the Modelica language, designed to create and use simulation models as part of reciprocating internal combustion engines digital twins. The software was created on the basis of component, system and declarative approaches, the theory of a casual bond graphs. The software includes submodels for determining the main engine parts wear rate and allows to predict engine parts life time, to simulate normal and accelerated engine reliability and durability tests. In the course of the study, the well-known model for determining mechanical frictional losses SLM (Shayler, Leong, Murphy, 2005) was adapted to calculate the relative change in the wear rate of engine parts. Universal equations are obtained to determine the friction forces as applied to rotationally and reciprocally moving engine parts. A method is proposed for calculating the relative change in the wear rate of parts and the time of failure due to wear, taking into account the physical properties (hardness), geometric dimensions and the speed of the relative movement of parts in the conjunction.

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