"quench" is one of many terms used to describe the "chemical dynamics" of a combustion wave/zone. In this case, the combustion wave is stabilized by allowing the "flame" to stabilize through the process of "attaching" to a stationary (or at least nearly stationary; referring to the time it takes to combust) boundary layer and dissipate some heat into that boundary layer/wall. This feature, of one possible combustion process, aids the compression process prior to combustion by absorbing "compression heat" and by establishing a stabil "flame holder" for propogation of the deflagration wave front (rather than a detonation wave forming; i.e. supersonic combustion waves, pinging, ect.) This is also why additives are used in fuels to raise "OCTANE" numbers; the avoidance of detonation, pre-ignition, pinging, etc. These unwanted combustion processes reduced power generation. If they become severe, they can also damage/ruin an engine.