
COMBUSTION CHAMBERS AND PROCESSES 71
vances across the chamber, but about ten times faster,
and before it can complete its journey the unburnt
gases ahead of it - or end gases as they are usually
termed - become heated to such an extent by the
overall pressure rise in the chamber that their
self-
ignition temperature is exceeded (Figure 3.2). When
this occurs a condition of spontaneous combustion is
created, resulting in a high-pressure detonation wave
travelling through the chamber at a speed comparable
to that of sound. Quite understandably, this produces a
shock loading on the engine structure and components
sufficient to generate a clearl ...