Turbulent Clustering of Particles and Radiation Induced Ignition of Dust Explosions

TL;DR

This paper proposes a new mechanism for dust explosion severity, suggesting that turbulent clustering of particles enhances radiation absorption, leading to secondary ignition and rapid combustion without detonation.

Contribution

It introduces a theoretical model showing how particle clustering in turbulence causes increased radiation absorption, resulting in secondary ignition in dust explosions.

Findings

Particle clustering increases radiation absorption length.

Clusters act as multi-point ignition kernels.

This mechanism explains high overpressures without detonation.

Abstract

Since detonation is the only established theory that allows rapid burning producing a high pressure that can be sustained in open areas, the generally accepted opinion was that the mechanism explaining the high rate of combustion in dust explosions is deflagration-to-detonation transition. We propose a theoretical substantiation of an alternative mechanism explaining the origin of the secondary explosion producing high speeds of combustion and high overpressures in unconfined dust explosions. We show that the clustering of dust particles in a turbulent flow ahead of the advancing flame gives rise to a significant increase of the radiation absorption length. This effect ensures that clusters of dust particles are exposed to and heated by radiation from hot combustion products of the primary ignited flame for a sufficiently long time to become multi-point ignition kernels in a large volume ahead of the advancing flame.