The mixing state of the powder in the constant volume bomb and the engine combustion chamber has a large impact on the powder detonation characteristics,so it is urgent to study the injection and mixing characteristics of the powder in a limited space,which helps to decide the appropriate ignition time for two-phase detonation.A constant-volume bomb system was built to observe the blending process of the flake anthracite pulverized coal in the constant-volume bomb through a high-speed photographic monitoring system,and post-process of the high-speed photographic images was carried out,and the change of pulverized coal blending in the constant-volume bomb was analyzed.A method for analyzing the curvature of the standard deviation of the gray value was established for the pulverized coal injection blending images.The initial moment when the curvature of standard deviation tends to zero is the best moment for the uniform mixing of pulverized coal,which can be selected as the best ignition time point,and the moment decided by this method coincides with the moment decided by the frame-by-frame analysis of the high-speed photographic images.The experiments were carried out at pulverized coal concentrations of 120 g/m3,210 g/m3 and 300 g/m3,and the standard deviation curvature analysis method of grayscale image was used to analyze.The experimental results show that,while keeping the pulverized coal concentration constant,the well-mixed time decreases with the increase of the powder blowing time,and thus the ignition moment should be advanced;while keeping the powder blowing time constant,the well-mixed time increases with the increase of powder supply concentration,and thus the ignition moment should be delayed.
powder detonation enginemultiphase flowtwo-phase detonationinjection and mixingpulverized coalconstant-volume bomb
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