The detonation research started just at the beginning of 1880, but its generation mechanism is still a mystery and has not been well explained in details for certain cases even at the beginning of 2014. Many experimental researchers in the early 1900s reported that the detonation is generated by the transition from deflagration, later known as deflagration-to-detonation transition (DDT). However, high performance laser allowing to see a detailed phenomenon was developed much later.
The present paper explains about several problems on DDT. These are difficult to study in detail experimentally and are also studied here numerically to get some insight of DDT.
The main cause for DDT in the present system is found that an auto-ignition occurs between the precursor shock wave and the flame near smooth walls (inside or at the edge of a boundary layer); a bow shock wave is formed in front of flame front; and further local explosion occurs between the precursor shock wave and flame. Then what we find out is that the compression waves are formed from the flame front, especially that of convexly curved flame front. Shock waves which travels behind the precursor shock heats up the boundary layer are triggers the auti-ignition and laten on DDT.
The aim of proposed research is also to create a full packet of new results explaining how does shock wave – boundary layer interaction triggers an auto-ignition, and what comes next, DDT.
With the experimental system we can clarify the details of DDT using a laser system and high speed Schlieren movie system. A development of three-dimensional numerical simulation system opens detailed DDT phenomena. So far we showed very good results with two-dimentional numerical code. We aim to develop new safety standard for H2/O2 and H2/Air DDT.
The expected results for the research clarify the details of DDT using a laser system and high speed Schlieren movie system, the OH or other molecular distribution and unsteady compression wave profiles from before to after DDT are visualized how they make their dynamics. This time the shock wave and boundary layer interaction plays an important role for DDT. We are able to see it through experiments. This LIF and Schlieren movie system provide us a strong impact for DDT researchers.
