Thesis (M.S., Mechanical Engineering)--University of Idaho, June 2014 | Single and two-zone heat release models were developed in MATLAB to expose students to the physical phenomena associated with spark-ignition, four-stroke engines. This model employed temperature dependent specific heat ratios, valve effects, exhaust gas recirculation, and speed-dependent friction losses. Upon creating a baseline MATLAB model, the simulated results were validated through back-of-the-envelope calculations. After validating the baseline model, a 2005 Yamaha YZ250F was tested, and BSFC and emissions data were gathered to further refine and validate the heat release model.
With experimental results backing the model, a set of learning activities was created for students. Students were directed in creating optimized spark-timing plots, and BSFC and emissions formation maps on an engine of their choosing. In completing these activities, students were exposed to the effect of laminar flame speed and engine speed on burn duration, the change in combustion and volumetric efficiencies relative to engine operating points, and the mathematics that govern heat release models.