| In this study the effects of angular momentum (tumble and swirl) on flammable mixture formation between chamber air and transient gaseous jets of hydrogen and methane have been numerically investigated in fixed volume cubic and cylindrical chambers, and in a variable volume cylindrical chamber with moving piston. The magnitude of the angular momentum, injection duration, and injection velocity are the main parameters whose effects have been studied on flammable mixture formation and mixing rate. The numerical simulations were carried out with the use of KIVA3V. the code is modified for gaseous injection with standard k-epsilon model for turbulence. It was found that hydrogen and air mixing, under application of angular momentum, leads to faster formation of flammable mixture, with mixing rates several times larger than those of methane. Also dynamics of the hydrogen mixing is markedly different from that for methane with the same magnitude of angular momentum. Dissipation of bulk vortex, and angular momentum decay during compression were also studied. The results for the cylinder with moving piston show the disappearance of tumbling motion at the end of compression while the swirling motion is preserved until the expansion stroke. |
