| The value of combustion models cannot be overstated. As a major component of engine models they are widely used as research tools in the continuing effort to improve existing combustion systems and to develop completely new concepts. Models also find use in the classroom where they allow students to manipulate control parameters and study the effect on performance, efficiency and pollutant formation without ever visiting an engine test cell. Models of varying complexity are available for premixed combustion but there is a lack of published work on simplified modeling of the more complex case of stratified-charge combustion. In this investigation, such a model is developed and validated against experimental data for stratified combustion in a constant volume chamber. This first iteration is intended as an oversimplified foundation to which additional complexity can be added in subsequent iterations after weaknesses are identified. Data are obtained for a range of test cases from a purpose-built test stand. Each of the experimental cases is simulated and the results compared. Simulation results for pressure and flame radius match well with the experimental data. The timing of key events is also predicted with relative accuracy. Significant errors are observed only in the period where the model is predicted to break down. The overall positive result shows that it should be possible to capture the essential characteristics of stratified-charge combustion in a simple model, given adequate development time. |
