Abstract
To study the effect of the ethanol concentration gradient on knocking in n-heptane/air homogeneous mixture, we carried out the compression and auto-ignition experiment by using rapid compression machine (RCM). The luminescence of flame was captured by High speed camera. Experimental results were that the luminescence progressed from top (lean) to bottom (rich) in cylinder with the ethanol concentration gradient and when the ethanol concentration gradient was over 0.1, the knock intensity was smaller than that of homogeneously mixed ethanol.
