Although the resonance system occurs in the combustionchamber , in the system under investigation ,it has occured
outside the Comprex. Lord Rayleigh (1878) studied thecombustion driven oscillations without proof, Keller and
Westbrook (1987) have established the use of Raylieigh'sefficiency as a measure of the pulse combustor and Keller et al.
(1989) have showed that the total delay time is one of the mostimportant factors in determining the resonant response of pulsecombustor.