Combustible Dust Cloud Characterization Using Multiple Laser Diagnostic Methods

Abstract

Understanding dust cloud formation, ignition, and flame propagation processes is an important area of safety research with the goals of dust explosion prevention and mitigation. To expand the efforts in this active research area, our group has previously implemented high-speed digital in-line holography (HS-DIH) to characterize dust clouds inside a Kühner MIKE3 minimum ignition energy (MIE) device. This previous effort showcased a new measurement capability for dust explosion studies but also revealed limitations on the range of cloud characteristics, such as the gas velocity and turbulent flow dynamics, that can be probed with HS-DIH alone. Particle image velocimetry (PIV) was identified as a complementary laser diagnostic method for such studies. Thus, in the interest of building broader and more flexible measurement capabilities for dust cloud dynamics, we report the construction of a multiple laser diagnostic test facility for dust cloud characterization studies using HS-DIH and PIV. The new test facility closely reproduces the test geometry of the standard MIKE3 device while also enabling precisely timed optical measurements. The test facility design is described first, followed by the results from a validation experiment to characterize aluminum powder dispersions using HS-DIH and PIV. This work demonstrates the wide range of dispersion conditions that can be explored by implementing these two laser-based particle diagnostic methods. The data generated from these experiments will be valuable not only for practical safety considerations but also for validating complex dust dispersion and ignition models.