Theses and Dissertations

Date of Award


Document Type


Degree Name

Master of Science (MS)


Mechanical Engineering

First Advisor

Dr. Isaac Choutapalli

Second Advisor

Dr. Robert Freeman

Third Advisor

Dr. Horacio Vasquez


With the emergence of V/STOL vehicles and unmanned aircrafts has come the resurgence of thrust augmentation through an ejector. The use of an ejector has many benefits such as being lightweight and simple design to manufacture. In this study a hot steady jet and a cold steady/unsteady jet was tested. The hot steady jet was produced by a JetCAT PX-180 rxi with a two-inch diameter nozzle exit. The hot steady jet was compared to the cold free steady and unsteady cases. The cold jet was tested under free steady and unsteady condition, as well as steady and unsteady ejector conditions. The unsteady cold jet was produced by pulsing compressed air with a flow chopper. A direct measurement system was used to measure thrust values with and without the ejector. Four asymmetric nozzles of circular, diamond, elliptic, and rectangular were used during experimentation. Findings included that the circular, diamond, ellipse, and rectangular nozzle all performed better when under a pulsed ejector case in comparison to a steady ejector case due to the vortex ring entraining addition secondary air. It was also found that as Mach number increases thrust decreases because with higher speeds the vortex ring is no longer as organized and therefore no longer entrains as much air.


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