Theses and Dissertations

Date of Award


Document Type


Degree Name

Master of Science (MS)


Mechanical Engineering

First Advisor

Dr. Isaac M. Choutapalli

Second Advisor

Dr. Robert Freeman

Third Advisor

Dr. Horacio Vasquez


The resurgence of pulsejet engines has renewed the interest of the flow characteristics responsible for the high levels of thrust augmentation that are necessary for Vertical/Short Take-Off and Landing (V/STOL) aircraft. It is well known that pulsation of the engine plays an important role on the thrust performance, but many of the characteristics that are primarily responsible for these enhancements are not well understood. This study is carried out to elucidate the effect of nozzle exit Mach number and the nozzle exit geometry on the characteristics of a high Reynolds number (~105), turbulent free pulsed jet.

Direct thrust measurements are conducted using a pulsed jet as the driving source with different nozzle geometries (circular, diamond, elliptic, and rectangular) over a range of exit Mach numbers (Mj) from 0.10 to 0.30. The data show that for a given geometry, the jet strongly depends on the pulsing frequency. Further increase in pulsation will decrease thrust and eventually perform similar to an equivalent steady jet.


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