Effect of orifice plate spacing on detonation propagation. (September 2017)

• Record Type: Journal Article
• Authors: Ciccarelli, G.; Wang, Z.; Lu, J.; Cross, M.
• Is Part Of: Journal of loss prevention in the process industries. Volume 49:Part B(2017)
• Page Start: 739
• Page End: 744
• Publication Date: 2017-09
• Subjects: Detonation -- DDT -- Industrial explosion; Chemical industries -- Safety measures -- Periodicals; 660.2804
• DOI: 10.1016/j.jlp.2017.03.014
• Languages: English
• ISSNs: 0950-4230

Abstract

Abstract: Experiments were carried out to measure the detonation propagation limits in a 10 cm inner-diameter tube equipped with equally spaced orifice plates. The limits were established based on the successful transmission of a detonation wave from the obstacle-free first-half into the obstacle-filled second-half of the tube. The effect of the orifice plate spacing was studied for hydrogen, ethylene and acetylene-air mixtures at atmospheric pressure and temperature. Experiments were carried out with 63.5 mm and 76.2 mm diameter orifice plates, spaced at 1.5 and 2 times the tube inner-diameter. The results were compared to previously reported data obtained at a plate spacing equal to one-tube inner-diameter. By increasing the plate spacing the quasi-steady detonation velocity, measured at the end of the orifice plate filled section, approached the theoretical Chapman-Jouguet detonation velocity. The results show that for the 76.2 mm orifice plates, with 1.5 and 2 tube diameter spacing, the detonation propagation limits correspond to the condition d/λ > 1, where d is the orifice plate diameter and λ is the detonation cell width. The same correlation was found for the larger blockage 63.5 mm orifice plates with 1.5 and 2 tube diameter spacing. This is in contrast to previous results obtained by Cross and Ciccarelli (2015) for the same 63.5 mm orifice plates at one tube inner-diameter spacing that correlated the propagation limits with d/λ > 2. Large wave velocity fluctuations were observed for the two-diameter orifice plate spacing for mixtures near the propagation limits. These velocity fluctuations, measured by ion probes spaced at a distance larger than the orifice plate spacing, are indicative of a galloping detonation wave. Highlights: The detonation propagation limits were investigated (these limits are different from the traditional DDT limits) in a round tube with orifice plates. The effect of orifice spacing on the propagation limits were reported. It was discovered that the orifice plate spacing is important for higher blockage ratio plates of 62% but not lower blockage ratio plates of 44%.