Engineering Commons^™

Helical Models Of The Bidirectional Vortex In A Conical Geometry, Timothy Andrew Barber

Doctoral Dissertations

This dissertation represents the descriptive and analytical breakdown of two new fluid dynamics solutions for vortex motion. Both solutions model the bidirectional vortex within a conical geometry. The first explored solution satisfies a simple Beltramian characteristic, where the Lamb vector is identically zero. The second solution is of the generalized Beltramian type, which fulfills the condition that the curl of the Lamb vector is equal to zero. The two Beltramian solutions describe the axisymmetric, double helical motion often found in industrial cyclone separators. Other applications include cone-shaped, vortex-driven combustion chambers and the swirling flow through conical devices. Both solutions are …

Stability Of Particle-Mean Flow Interactions In Solid And Hybrid Rockets, Trevor Sterling Elliott

Doctoral Dissertations

Combustion instabilities associated with rocket motors as a result of unsteady components in the combustion chamber flow have been known to cause pressure oscillations. These pressure oscillations can result in changes to flight characteristics and vibrations translated to the rocket or payload. The unsteady components are comprised of two subcomponents, the vortico-acoustic fluctuations and the hydrodynamic fluctuations. As the vortico-acoustic fluctuations have been investigated in an exhaustive manner this work will focus on the hydrodynamic fluctuations. It has been known that the addition of particles increases specific impulse due to the resulting increase in combustion temperature and mass flow. They …

Hybrid Rocket Design Study Utilizing Nozzle Cooling And Aft-End Vortex Oxidizer Injection, John Nicholas Quigley

Masters Theses

The current study focused on two innovations intended to reduce the cost and enhance the performance of hybrid rockets. The majority of the emphasis was placed on the design, fabrication and testing of a 3-D printed, water cooled nozzle. This work was done as proof of concept to show that complex, high temperature components could be manufactured using these new techniques, thereby substantially bringing down fabrication costs and allowing configurations that are not feasible using traditional machining. A water-cooled calorimeter nozzle was made and used in thrust stand tests to verify analytic and numerical heating models used in the design …

A Qualitative Experimental Study Of Drag Reduction Devices For Tractor Trailers With Ground Effects, Nicolas Robert Reed

Masters Theses

This is an experimental qualitative study of how drag reduction devices affect air flow around a tractor trailer. A 1/32 scale detail model of a truck with its trailer was used for testing in a 20"x14" low speed wind tunnel at the University of Tennessee Space Institute. Major modifications were made to the wind tunnel so that it would include a moving bed (floor) section for ground effect simulation. This was done to accurately simulate relative ground movement with the truck being held stationary in the tunnel flow.

Drag reduction devices were designed based on aerodynamic fundamental understanding for streamlining …

Neutron Imaging Of Lithium (Li) Coolants Inside High Temperature Niobium (Nb) Heat Pipes, Brad Harrison Hight

Masters Theses

Lithium (Li) behavior inside a high temperature Nb-Li leading edge heat pipe was successfully imaged under induction heating operation via neutron imaging. Startup and cool-down operations gave visual confirmation of bulk Li movement using both gravity assisted and inverted operating orientations. The pipe was imaged during an operation cycle from ambient conditions, heated to a steady state temperature of 908.8 ⁰C, and allowed to cool below 200^°C. The experiment was performed at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland, and at the Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee.

Tomographic images …