Pressure Oscillations Generated by Knocking Combustion of C_2H_2 in a Constant Volume Vessel

摘要

Onset of super-knock in highly intensified spark ignition engines poses a great threat to the reliability. In this context, An approaching attempt was exerted on the initial condition of C_2H_2-O_2-N_2 mixtures ignited within a constant volume vessel, in order to determine the critical condition of knock and response to oxygen ratio, acetylene ratio and mixture density. Results show that with a low acetylene content, sole elevation of oxygen doesn't necessarily lead to knock onset. On the other hand, with oxygen content fixed to a sufficient value, elevation of acetylene content results in louder combustion noise and when it approaches the stoichiometry ratio, auto-ignition happens in the unburnt far end and strong oscillation appears on the combustion pressure curve. Surprisingly, elevation of mixture density has no significant effect on knock propensity.