Visualisations of autoignition of the end gas due to flame propagation and intense oscillations caused by Shockwaves that occur during engine knocking were carried out in a hydrogen spark-ignition engine using a high speed video camera. Our results demonstrated that autoignition in an end-gas region that was compressed by the propagating flame front could be visualised using the high-speed colour camera. A large amount of unburned mixture caused by the autoignited kernel explosion generated strong pressure waves. Strong pressure wave oscillations induced by the initial autoignition inside the end-gas region could be visualised using a video camera with a speed of 125 thousand frames per second. The autoignition and pressure waves caused the thermal boundary layer to break down near the cylinder wall and piston head, which may result in damage to the cylinder wall and piston head during engine knocking.
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