2015 Volume 57 Issue 181 Pages 222-231
Sub-chambers were used to initiate the detonation wave by injecting a flame-jet into the detonation tube. A configuration of the sub-chamber was divided into five types by changing the number of sub-chambers and the directions of flame injection. The detonation tube had a cross area of 50 × 50 mm, a length of 775 mm and equipped a window section for a visualization of the flowfield. The test gas was a stoichiometric premixed gas of hydrogen and oxygen and the initial pressure was constant as 80 kPa. The experimental results showed that the detonation transition distance was about 60% shorter than the case of spark ignition without flame-jet. Increasing the number of sub-chambers and colliding flame-jets emanating from counter positions resulted in decreasing the detonation transition distance. Schlieren photographs showed that the flame-jets promoted the formation of leading shock wave ahead of the turbulent flame in a short distance. Pressure measurements on the end wall of the detonation tube indicated that the shock or compression waves were reflected repeatedly in the cross-section, leading to a pressure wave and flame interaction. For the flame-jet initiation using the sub-chambers, generating turbulent flow in the premixed gas was of importance to promote the detonation transition.
