Modelling of air flows in automotive engines using Modelica
ABSTRACT
In the industry the need of simulation of complex systems, composed of subsystems from various domains, is increasing. A new standardized modelling language, called Modelica, has been developed for the purpose of efficient simulation. The language is object-oriented, non-causal, and multi-domain capable.
Automotive engines are mainly composed of thermodynamic sybsystems. In this master's thesis three different modelling principles are used to analyse the performance of Modelica in automotive engine applications. The modelling principle is determined by the connector applied, i.e. the interaction between the components. Connectors composed of various combinations of variables describing pressure, temperature, mass flow and energy flow have been applied. During the analysis, the performance of a control volume, restrictor, and sources has been studied. The purpose is to decide a standard set of connector variables for the description of engine components.
None of the tried modelling principles has proved to be completely satisfactory. The problems have been: two control volumes connected to each other, bi-directional gas flow, and complete support of independent design of components. A conclusion is that these problems can be solved by a simulation engine that supports conditional equations without else-clauses, and requires only that the relevant number of equations and variables is equal.
Alexander Stankovic
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