ORCID Number

0009-0003-3310-1676

Date of Award

Summer 7-20-2026

Access Type

Thesis - Open Access

Degree Name

Master of Science in Aerospace Engineering

Department

Aerospace Engineering

Committee Chair

Ebenezer Gnanamanickam

Committee Chair Email

gnanamae@erau.edu

First Committee Member

Michael P. Kinzel

First Committee Member Email

Kinzelm@erau.edu

Second Committee Member

Luke Hill

Second Committee Member Email

Hillj37@erau.edu

College Dean

James W. Gregory

Abstract

Wind-blown sand and other instances of solid particles mobilized and suspended in gaseous turbulent boundary layers (TBLs) are seen in a wide variety of engineering contexts. An experimental framework was developed to study the incipient particle motion driven by external forcing within a turbulent boundary layer, which is provided by an airfoil section oscillating in the free-steam flow, resulting in a periodic disturbance in the near-wall region through production of synthetic large-scale structures at a fixed frequency. The incoming unsteady carrier-phase eddies were measured with a hot-film sensor upstream of a particle bed, and the particle motion was captured by a high-speed camera where motion was characterized using a PIV-based approach. Nominally spherical Soda Lime particles of different size ranges for large (355 - 500 micrometers), medium (300 - 425 micrometers), and small (180 - 250 micrometers) particles are considered with a common density ratio (~2500). Barium Titanate particles were also considered for greater density ratios (185-260 micrometers, density ratio ~4500). The incipient motion of solid particles was evaluated under forced conditions, where the airfoil mechanism was accelerated from rest to a terminal frequency, and natural conditions, where a higher free-stream velocity was set to produce sustained particle transport. Medium and large sized particle groups were found to be mobilized by the initial impulsive motions of the airfoil, where the small particles were found to mobilize towards the end of the oscillation cycle with reduced magnitude. In the case of naturally driven mobilization, small particles were found to mobilize with a significantly greater magnitude and frequency compared to larger particle sizes. A band-pass analysis of the conditional flow structure surrounding significant particle motion events showed increased activity in a large-scale band in both flow conditions, indicating that smaller particles are more responsive to the naturally-occurring turbulent scales present in the boundary layer, and larger particles are preferentially mobilized by larger-scale artificial motions when the free-stream velocity is lower. Particles with a greater density ratio were found to have their motion limited to rocking in place, and greatly inhibited when compared to particles of a similar size.

Download

Share

COinS