A Combustion Model for Homogeneous Charge Natural Gas Rotary Engines 890328
In previous papers a complete simulation model of the combustion in a gasoline rotary engine has been described. This combustion model, developed at the University of Gent and UMIST (University of Manchester Institute of Science and Technology), is based on a turbulence enhancement factor for the flame in various zones of the combustion chamber.
The purpose of this paper is to give a description of the modifications of the model for a homogeneous natural gas rotary engine.
The real geometry of the combustion chamber is incorporated In the model. Calculations are executed for different geometries of rotary engines (especially different positions and shapes of the recess in the rotor).
Different formulas of the laminar flame speed for natural gas are examined. The turbulent flame speed is calculated with a turbulence factor or with a turbulence intensity factor. A correlation between the engine conditions and the turbulence intensity is proposed.
The model is validated by experimental results (pressure measurements) for different load conditions of a particular engine.
A parametric study is carried out to examine the influence of equivalence ratio, turbulence, ignition timing, and so on.
The experimental data is also used to obtain the heat release curves and the Wiebe parameters for a natural gas, rotary engine. The recalculated pressure diagrams, based on the Wiebe parameters, are in very close agreement with the measured diagrams.