Time-resolved particle image velocimetry measurements were made in the turbulent flow environment below a hovering rotor near a ground plane that was covered with mobile sediment particles. The results were compared to the near-wall flow produced by a nominally equivalent two-dimensional wall jet. The objective was to understand the fluid dynamic mechanisms of how the mean flow, stochastic turbulence, and concentrated vorticity produced by the rotor affected the mobilization and pickup of particles from the bed. Another objective was to better understand the assumptions that would be required for the development of models that are applicable to rotor-induced particle mobilization. The mean flow in the boundary layer at the ground below the rotor was found to be similar to a wall jet. However, the instantaneous flowfield and turbulence characteristics between the two flows were significantly different. Measurements of the heterogeneous dual-phase flow environment using particle image and particle tracking velocimetry exposed the complex interplay between the carrier and dispersed phases of the flow. The turbulence characteristics were clearly modified by the presence of particles in the near-wall region. The processes of particle mobilization and pickup from the bed were found to correlate with the Reynolds stresses and discrete turbulence events, respectively.
Flow Environment and Organized Turbulence Structures Near a Plane Below a Rotor
AIAA Journal ; 52 , 1 ; 146-161
01.01.2014
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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