Abstract
Knocking characteristics for various flame propagation velocity was investigated by changing turbulence in the combustion chamber. The use of the super rapid compression machine (SRCM) provides an opportunity to investigate the behavior of intense knocking. The behavior of flame propagation and spontaneous ignition of end gas were observed and flame propagation velocity and the volume fraction for flame propagation could be estimated through the experiments using a high-speed direct and schlieren photography. As a result, it was found that knocking intensity takes peak value in the cases where the volume fraction for flame propagation is 60-70%, when the volume fraction was changed by changing flame propagation velocity. In the highest flame propagation velocity case, compression and combustion time corresponded to engine speed of about 6000 rpm. The wrinkles in schlieren images of end gas and pressure oscillation caused by heat release of low temperature reaction appeared before knocking occurrence. On the other hand, they did not appeared in high flame propagation velocity cases.
