With the demand of high efficiency, IC (internal combustion) engines have been pushed to their thermodynamic limits. As a result, severe knock occurs which would make a huge destruction to engine parts. Detonation is found to be the essence of such severe knock. In this research, a series of numerical simulations were conducted to prove that the detonation only occurs in the small clearance chamber while hardly occurs in the large clearance chamber, which is also validated by the detonation bomb experiments. If study the pressure profiles carefully, the shock wave intensification phenomenon can always be found before the severe knock event, which is found to be a reason for the detonation formation. Such intensification phenomenon is mainly caused by three mechanisms: separately the wave-secondary flame, wave-wave and wave-boundary wall interacting mechanism. Through the analysis of the detailed chemical reaction mechanisms of H₂/O₂, the shock wave intensification caused by the wave-secondary flame interacting mechanism is revealed, which would occur both in the small and the large clearance chamber. Therefore, the key factors to decide whether the severe knock would occur are attributed to the wave-wave and the wave-wall interaction. According to numerical study, it’s found that the chamber shape would affect both the wave-wave and the wave-wall interaction, which would decide the shock wave energy in the edge region. Once the energy of the shock wave is intensified to a critical level, the detonation as well as the severe knock would be formed.

由于对高效率的要求，IC（内燃）发动机已被推至其热力学极限。结果，发生严重的爆震，这将严重破坏发动机零件。发现爆炸是这种严重爆震的本质。在这项研究中，进行了一系列数值模拟，以证明爆炸仅在小间隙室内发生，而几乎不发生在大间隙室内，这也通过爆炸炸弹实验得到了验证。如果仔细研究压力分布，总是可以在严重爆震之前发现激波增强现象，这被认为是形成爆炸的原因。这种加剧现象主要是由三种机理引起的：波次火焰，波-波与波边界壁的相互作用机制。通过分析H的详细化学反应机理₂ / O ₂揭示了由波-次火焰相互作用机理引起的激波增强，该激波会在小间隙腔和大间隙腔中发生。因此，决定是否发生严重爆震的关键因素是波与波和波壁相互作用的结果。根据数值研究，发现腔室的形状会影响波波和波壁相互作用，从而决定边缘区域的冲击波能量。一旦冲击波的能量增强到临界水平，就会形成爆炸以及严重的爆震。