Paul M. Ordin
The ignition of hydrogen-oxygen gas mixtures at a pressure of 1 atmosphere in a 2-foot-diameter duct resulted in detonation combustion. The detonation static pressure at an oxidant-fuel mole ratio of 0.82 was about 315 lb/sq in. abs (pressure-rise ratio of 21). The use of water curtain sprays distributed through a substantial section of the duct did not prevent a detonation but did reduce the peak pressure to 200 lb/sq in. abs. The detonation could be prevented by adding sufficient carbon dioxide to place the gas mixture out of the flammable range. The use of smaller quantities of carbon dioxide resulted in a reduction in the peak detonation pressures. The total pressures exerted on various designs of 90 degree steel elbows by the detonation were about 900 lb/sq in. abs (pressure-rise ratio of 60). A design stress of 38,400 psi and suitable supporting members for the exhaust duct elbow contained the detonation without any damage to the structure.
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