Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Department of Aeronautics and Astronautics

First Advisor

Mark F. Reeder, PhD.


A submerged inlet investigation, using flow control in the form of discrete blowing, examined proximity and jet directionality to improve compressor face uniformity. The flow control locations were at the head of the ramp and part way down the ramp, providing four configurations under examination. Laser Doppler velocimetry (LDV)measurements at the throat determined the effect of the flow control based on the statistical velocity measurements. Blowing at closer proximity to the throat and targeting the largest velocity deficit region provided the best results. The airspeed and inlet velocity simulated takeoff and landing conditions; velocities ranged from Mach 0.1-0.3 at the throat. Secondary components and turbulence measurements proved useful in determining the effect of the flow control configurations. In a complimentary study, two serpentine ducts of rectangular cross-section evaluated the LDV capability before the inlet examination. The s-shaped serpentine ducts had features comparable to those expected in the submerged inlet. The flow through two serpentine ducts, of identical hydraulic diameters but different aspect ratios, demonstrated different behaviors despite all other features being the same. Two strong counter-rotating streamwise vortices formed for the 2:1 aspect ratio while four weaker vortices formed in the 1:2 aspect ratio duct. Computational simulations, performed on the serpentine ducts using a Reynolds shear stress model on a 4 million cell grid, agreed with the results of the experimental examination. The agreement between the exit profiles provided confidence in the LDV system to make the inlet measurements possible.

AFIT Designator


DTIC Accession Number