Two-phase reacting flow induced by a sufficiently strong shock wave impacting on an interface of combustible dust suspension at an angle of 0 or passing over a combustible dust deposit at an angle of 90 has been investigated experimentally and numerically. The: onset and development processes of interactions have been gliscussed according to the results reported. Computed and measured results are in reasonable agreement.

The propagation of a flame is investigated experimentally and theoretically for a large, horizontal combustion tube containing a mixture of air and aluminum powder with pre-existing turbulence. One end of the tube is closed and the other is connected to a large dump-tank. Twenty dispersion systems are used on the tube to produce a uniform suspension of aluminum dust in the tube with a mean diameter of 6mm. The characteristics of a flame front from the ignitors at the closed end are measured using photodiodes and the development of pressure is monitored by transducers. Experimental results revealed the entire process of an accelerating flame and the development of shock waves. A set of conservation equations for two-phase turbulent combustion flow is derived, using the two-fluid model, k-3 model, Hinze-Tchen model and EBU-Arrhenius model for turbulent combustion. The SIMPLE scheme usually applied to the homogeneous turbulent combustion is extended to fit this two-phase, reactive behavior. The results of calculations show the positive feedback coupling among combustion, expansion and turbulence during flame propagation. Computed and measured results are generally in good agreement.

Experiments of explosion venting in different conditions were performed in a cylindrical vessel with a vent duct; the pressure-time profiles from four transducers mounted in the line-of-sight centerline outside the vessel and the clear sequential shadowgraphs of external venting flow field taken by a high-speed shadowgraph imaging system were obtained. Based on these results, the characteristics of the external pressure field during venting were discussed systematically to explain the generation mechanism of the secondary explosion. In addition, the variations of the intensity of the secondary explosion in different venting conditions, namely the failure pressure, ignition location, area blockage ratio or equivalence ratio of the fuel, were also analyzed in detail.

Self-sustaining detonation along a combustible dust deposit on a bottom wall have been investigated experimentally and theoreticall. Experiments were conducted in a square cross-section tube. Three kinds of particles with a mean dianneter of 15μm were used; AL, RDX, and HMX. Sharp-shadow photographs were taken by means of a spectial optical system and shock-wave veloeties were measured by pressore transducers. It has been shown that the steady-state ditonation velocity is independent with initial shock wave strengths. An analytical model has been developed to describe the two-dimensional structure of dust-film detonations. A set of equations for the twe-phase turbulent-reaction boundary layer considering the particle ingestion and the interphase transfers and a general Chapman-Jouguet condition were derived. The Lees-Dorodnytzin transformation usually applied to the compressibie boundary layer has been extended to fit the two-phase reacting case, and the numerical siulations have been performed by applying a Box method and an improved particle source in cell (PSIC) method. Which shows that the structure of the boundary layer behind the shock fornt consists of an inducton zone, a reaction, and a diffusion zone. Computed and measured results are in reasonable agreement.