| Micro power generating systems provide high energy density using hydrocarbon fuels. The present study investigates the combustion chamber of such a two stroke micro-engine using numerical simulation. The simulations were performed using commercial computational fluid dynamics (CFD) code STAR-CD. Thin rectangular "credit card" size combustion chambers with two thicknesses, 6.35 mm and 3.175 mm, were studied after validation of results by comparison with available experimental data from the literature. Effects of large surface to volume ratio, ignition timing, and equivalence ratio on combustion chamber pressure, temperature, and fuel mass fraction were studied. Different fuel types were also considered to explore their effect on indicated power.;The present study showed that delay in ignition reduces peak pressure and temperature inside the combustion chamber. Greater peak pressures were observed in the thinner combustor for same ignition timing. Increase in equivalence ratio resulted in higher peak pressure and temperature. For the thinner combustor, pressure variations were sizeable only after a few degrees in expansion stoke for different equivalence ratio. Compared to methane and propane, hydrogen provided maximum peak pressure and minimum indicated power. |
