Relationship between gas-dynamic parameters of a deflagration explosion and explosion loading in cleanrooms

Introduction. Accidental explosions of gas-air mixtures in confined spaces pose a serious hazard to personnel, building structures, and production facilities. A key factor determining the nature of damage is not only the peak overpressure, but also the time history of its development governed by gas-dynamic and deformation processes within the enclosed space.

Goals and objectives. The aim of this work is to analyze the relationship between the stages of deflagration explosion development identified using the video recording data and changes in overpressure inside the experimental cleanroom.

Materials and methods. The experiment was carried out using a laboratory unit (2,230 × 2,230 × 2,360 mm, effective volume 11.74 m3) with enclosing structures made of AMS-MZMO sandwich panels. A doorway covered with polyethylene film served as the relief structure. Propane-butane (525 l, stoichiometric mixture, 4.5 %) was supplied into the experimental cleanroom; overpressure was recorded by two APZ 3420 sensors; the process was filmed by a high-speed camera at 239 fps.

Results and their discussion. The main process stages were identified using the video recording. They included tightness loss (0.735 s), first structural deflection (0.747 s), maximum deflection (0.865 s), and opening formation (0.885 s). Maximum overpressure values were 654 Pa (sensor  1) and 520 Pa (sensor  2). Comparison between the video data and the pressure oscillogram was employed to identify a staged pattern of overpressure development associated with sequential gas-dynamic and deformation development changes in the enclosing structures.

Conclusions. A combined analysis of the video recording and the pressure oscillogram data enables a more exhaustive description of explosion loading patterns for an indoor deflagration explosion in a cleanroom; this methodology can be applied to analyze other enclosing structures.

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