20-EPN2-123: Controls on the Resuspension of Dusts of Different Mineral Composition in Air Flows

Visit by Merren Jones and Steve Covey-Crump of the University of Manchester (UK), to TA2.4 Planetary Environment Facilities (PEF), AU (Denmark)
Dates of visit: 11-15 September 2023

Report summary: Mineral dusts in the atmosphere cause a wide variety of damage to aircraft engines resulting in significant economic cost to the engine manufacturers and airline operators. The nature of damage is dependent on the mineralogy of the dust, and so there is currently a major drive to understand the controls on the composition of atmospheric dusts. We are currently planning a field campaign in central Australia to sample airborne sands and dusts together with surficial deposits, and the present study was designed to inform our sampling strategy and to help constrain the interpretation of our anticipated findings.

We performed wind tunnel experiments to examine detachment thresholds of seven minerals with different density, grain shape, and surface properties. The particle size variation (50-500 μm) of the detachment threshold is well-described by existing semi-empirical models but highlights the need to incorporate shape and adhesion properties into these models. In a further set of experiments, we used a new suction sampler to collect sand and dust particles in transport through the full depth of the flow (175 mm) to examine dust emission from the surface of a sand bed under conditions where the sand particles are saltating, and vertical particle size and compositional sorting developed within and above the saltating layer of a polymineralic sand. Provisional results show a good correlation between collected sample mass and mass-flux estimated from a laser opacity system throughout the depth of flow, and show strong vertical particle size and compositional sorting.

---