An experimental study on flame acceleration and deflagration-to-detonation transition in narrow tubes

In this study we investigate and discuss the phenomenon of flame acceleration and deflagration to detonation transition (DDT) in small tubes of mm in diameter with experimental measurements and based on study we further propose the design of a pre-chamber at the head end of the small tube to promote flame acceleration and to stabilize the onset of detonation. Experimental parameters include tube sizes, pre-chamber dimensions, and initial pressure of the mixtures. Results show that the pre-chamber set-up is definitely helpful for flame acceleration, and occurrence of DDT in the stoichiometric hydrogen-oxygen mixture in the 1mm-diameter to 2mm-diameter tubes at atmospheric pressure. Besides, DDT induction distance can be reduced depending on increase of the initial pressure. For cases of fixed tube size, effects of pre-chamber are not pronounced in the smaller tube, whereas this influence become significant in the larger 2mm-diameter tube cases. In this study, the shortest detonation induction distance of 116mm is reached for the conditions of 1mm-diameter tube with 9mm-diameter pre-chamber at 34.5 psia.