(286b) Cratering of a Particle Bed By a Subsonic Turbulent Jet: Effect of Particle Shape, Size and Density

Casey Q. LaMarcheand Jennifer Sinclair Curtis

Department of Chemical Engineering

University of Florida

Abstract

The interaction of dense granular beds with gas jets is prevalent in many applications such as fluidized beds, blast furnaces, scour-hole and crater formation. This presentation explores the crater formation application, in which a gas jet impinges downward from above on a stationary bed of particles.  This application is very important for lunar or Martian space missions during spacecraft takeoff and landing.  Crater formation can affect the stability of the landing, and the resulting particle erosion can cause significant damage to neighboring equipment.  Here, the effect of particle properties on the crater formation is studied experimentally.  Measurements of the dynamics of the crater growth (crater depth and width as a function of time) provide benchmark data for validation of gas-solid multiphase flow models.  About twenty different particle types are studied, and each individual particle property is isolated in turn.  For the effect of particle shape, the equivalent sphere diameter of the particle is kept constant.  It is found that the effect of particle shape on cratering dynamics is significant and complex, depending on the particle aspect ratio and surface roughness.  Increasing the particle density and size decreases the crater growth rate and the asymptotic crater size.  Finally, a scaling function, accounting for the effect of particle shape, is developed which predicts the asymptotic crater depth.