SHOCK-WAVE IGNITION OF A HYDROGEN-AIR MIXTURE IN A CONICAL CHAMBER

Processes taking place in hydrogen-air mixtures filling a semiclosed h ollow conical chamber and induced by a shock wave and gasdynamic pertu rbations generated by weak explosion and deflagration after the pertur bations enter the cone are studied experimentally. Investigations are conducted in a tightly closed chamber formed by a rigid metal cone, wi th a divergence angle of 60 degrees and the generatrix length of 0.6 m , and thin rubber diaphragm closing it. The chamber is filled with a m ixture containing 20-40 % hydrogen. Monitored were propagation of shoc k waves and flame front, and the pressure at the inner cone surface wa s also measured. The effect of initial conditions of combustion initia tion outside the cone on wave focusing near the cone vertex is explore d. The data furnish evidence of the governing influence of deflagratio n at the initiation stage on the intensity of shock waves recorded wit hin the cone. Different modes of ignition hydrogen-air mixtures near t he cone vertex are revealed. The initial intensity of shock waves capa ble of igniting a mixture within the cone is lower than the appropriat e wave intensities initiating combustion in a hemispherical chamber or upon normal reflection from a plane wall. The maximum pressure near t he cone vertex is P-max = (1.5-2)P-CI under normal conditions (P-0 and T-0 = 300 K).