Simple Modeling of Combustion for Natural Gas Engines

Computer models of engine processes are valuable tools for predicting and analyzing engine performance and allow exploration of many engine design alternatives in an inexpensive fashion. Knowledge of the flame initiation period and subsequent propagation periods are the most important parameters of the combustion modeling. At the present work, a simple experimentally based model for flame propagation period was developed for a natural gas engine. This model does not require any knowledge of the flame shape and propagation speed to calculate the burning rate. The model was used along with the mass and energy conversation equations to calculate cylinder pressure traces for various engine operating conditions. In all cases the model's results and the experimental data agree well in trends and magnitudes.