Experimental Study of Deflagration to Detonation Transition in Hydrogen-Air Mixtures

2018-03-05T12:14:25Z (GMT) by Andre Vagner Gaathaug
This dataset contains high speed videos and pressure recordings from DDT experiments in hydrogen-air mixtures. The experimental setup and method is given in the reference below. The experimental setup is given in the excel-table. Details are given in the README.txt file.<br><br>Abstract of thesis:<br>Gas explosions in a square channel have been investigated with a main focus on the deflagration<br>to detonation transition (DDT). The gas mixtures were hydrogen and air at different concentrations.<br>This work have been motivated by issues of process safety and hydrogen infrastructure<br>development. There is a need to understand the deflagration to detonation transition from a<br>safety perspective. Recent accident have shown possibilities of DDT in premixed fuel and air.<br>At present there are no software tools capable of predicting DDT in real scenarios, and there is<br>a need to produce accurate experimental data for validation, but also a better understanding of<br>the physics related to DDT.<br>The experiments presented in this thesis were performed in a square channel with transparent<br>side walls and one obstacle. The obstacle was placed 1m from the closed ignition end, and the<br>first results chapter presents the experimental study of flame propagation from ignition up to the<br>obstacle. The ignition source was both a single spark and a distributed ignition, were the latter<br>was assumed to produce a 2 dimensional flame front. The main conclusion of this study was<br>that the 2D assumption was only valid up to the point of tulip flame formation.<br>The study of DDT was divided in two parts, one in homogeneous gas mixtures, the other<br>regarding inhomogeneous gas mixtures. The homogeneous gas mixture experiments showed<br>that transverse waves were important for the DDT, but also that these waves originated from far<br>behind the leading tip of the deflagration. This conclusion was also found in a numerical study<br>using the in-house FLIC code developed by Dr. Vaagsaether.<br>The study of inhomogeneous gas mixtures were done to investigate if inhomogeneities increased<br>the likeliness of DDT. The conclusion was that it was not the case in this particular<br>setup and method. However, other interesting results were found regarding detonation propagation<br>in layers of reactants bound by a wall and a layer of air. The propagation mechanism of<br>detonations in a reactive layer was also studied using the FLIC code, where it was observed a<br>expansion effect and a merging of triple points at the top wall. This was qualitatively similar as<br>the experimental results.<br>