Influence of detonation conditions on the characteristics of gas powder two-phase detonation in pipe

In order to investigate the variation law of the blasting characteristics of the gas-powder two-phase mixed system, the blasting experiments with different static operating pressure (Pst) at the blasting outlet were carried out in the self-built stainless steel flame acceleration pipeline, and the variation law of Pst on the two-phase blasting pressure, flame propagation velocity and blasting flame morphology was emphatically studied. Pst is determined by the blasting hole blocking ratio (θ) and the number of blasting film layers (n). The increase of θ and n together increased Pst. The increase of Pst strengthened the constraint of gas powder and reaction products flowing out of the pipe, increased the viscosity effect of the fluid in the pipe, promoted the reaction of gas powder in the pipe, and reduced the degree of "secondary explosion" of unfired gas outside the pipe. For the pressure time interval curve analysis, Pst increased from 2.97kPa to 14.64kPa, and the pressure time interval curve showed a "double peak" structure with a "keep" platform. The first pressure peak increased from 5.48kPa to 10.20kPa, the "keep" time extended from 6ms to 25ms, and the second pressure peak decreased from 23.03kPa to 9.71kPa. When Pst is 16.08kPa and 24.12kPa, the pressure before bursting film is superimposed and reflected for many times, resulting in the time-history curve of bursting film pressure showing a special oscillating and rising "three-peak" structure. In the analysis of flame propagation velocity, the increase of Pst decreased the average flame propagation velocity from 161.33m/s to 67.99m/s. When n=2, the increase of θ makes the flame structure change from cluster to jet. When θ=88.9%, the blasting flame shown a typical jet shape. The increase of θ and n made the flame brightness gradually decrease, the length of flame luminescence zone decreased, the time interval from breaking film to flame emergence and the flame duration increased.