Investigating flame acceleration of premixed gases and how deflagrations transition to detonations is extremely important because of two main reasons: 1) from the safety point of view, we want to avoid severe explosions from happening inside processing units and storage facilities; and 2) because there is a growing interest in controlling these phenomena for more efficient energy conversion inside combustion engines. For instance, an extensive effort has been made towards the development of detonation engines. Detonation engines are powerful devices whose fundamental principle is based on multiple explosions of energetic fluids such as hydrogen gas. This technology is still in the early development stage but has excellent potential to replace current engines present in airplanes and rockets.
In our laboratory, we conduct experiments to investigate how flame acceleration and detonation onset will occur in the presence of obstacles with different geometries. The goal of this work is to identify the main features of unequal obstruction characteristics that interfere with flame propagation and DDT, namely: blockage ratio, obstacle spacing, or obstacle shape. Provided in the figure below is a typical result of a DDT test performed in our detonation rig, where a soot foil was used to visualize the transition process and obvious detonation (notable by the presence of the cellular structure).
This work is performed in collaboration with the Mary Kay O’Connor Process Safety Center at Texas A&M University. In the past, we have generated experimental data for validation purposes of a CFD model to determine the potential for DDT and estimate run-up distances at small scales. This information can later be used to help design safer facilities.
Soot foil showing DDT process in a stoichiometric H2-O2 mixture downstream of a pair of obstacles in the TAMU detonation tube.