AE Brown Bag Seminar
Friday, November 7
11:00 a.m. - 12:20 p.m.
Guggenheim 442
Tyler Breaux
Amelia Hoffs
Nishka Mirkhelkar
Vanessa Montgomery
Melanie Sciammetta
Tyler Breaux
Title:
T-140 Rebuild Campaign
Abstract:
Ongoing effort to redesign, assemble, and test our lab standard platform for hall effect thruster testing. Redesign has been completed and assembly begins next week, with testing beginning as soon as the thruster is assembled. Project is focused on redesigning for manufacturability and converting a flight grade thruster to a lab grade thruster.
Faculty Advisor:
Professor Mitchell Walker
Amelia Hoffs
Title:
Solid Rocket Motor Modeling with the Development of Solid Motor Analysis Code (SMAC)
Abstract:
Solid rocket motors (SRMs) are propulsion devices that generate thrust by burning a solid propellant grain that contains fuel and oxidizer within a rigid casing. SRMs are widely used for defense and space applications because they have the capacity to produce a large amount of thrust from a small package, are considered highly stable, and offer a long storage life. Due to their practical applicability, the Aerospace Systems Design Laboratory (ASDL) is working to develop the Solid Motor Analysis Code (SMAC), a Python based code to facilitate robust comparison between SRMs used in industry. The prediction code works by taking in geometry and propellant properties of known SRMs and outputting thrust predictions. Key advancement on SMAC includes observing sensitivities between propellant parameters and thrust outputs; analyzing the effects of grain shapes and grain configurations on thrust curves; and investigating the impact of motor geometry. Long term application of this software would streamline the comparative analysis and selection of the SRM for a designed system.
Faculty Advisor:
Dr. Adam Cox
Nishka Mirkhelkar
Title:
Maximizing the Loosening of Bolted Joints Through Targeted External Forcing
Abstract:
he loosening of bolts is a universal issue that affects many industries both in and outside of engineering. The failure of a joint due to the loosening of a bolt is often associated with catastrophic failure of the system, resulting in environmental disasters as well as injuries and loss of life. Previous research on self-loosening bolts in rotational vibration has found that forcing a bolted structure at a certain rotational vibration frequency may not necessarily increase the rate of loosening of the bolts. This study concluded that bolt self-loosening is more likely to occur under larger rotational vibration amplitude and lower initial preload levels, but is not dependent on vibration frequency. However, this work did not examine the specific impact of exciting the system at its resonance frequency. As a result, it remains unclear which excitation frequencies most effectively accelerate bolt loosening in a given system. This research focuses on maximizing the loosening of bolted joints by maximizing the relative motion across the joint through harmonic excitation. A system composed of two linear oscillators coupled by a single bolted lap joint is considered and studied in this work. The equations of motion are transformed into center-of-mass and relative-motion coordinates, then the frequency-response functions (FRFs) are used to determine the frequencies that maximize and minimize the relative motion. The results from the FRFs are verified using simulations of the response of the system with an additional differential equation that models the net loss of tension. An experimental version of the system is also considered and used to update the theoretical model and verify the theoretical findings. The results demonstrate that it is possible to both maximize and minimize loosening by forcing the system at appropriate frequencies.
Faculty Advisor:
Professor Keegan Moore
Vanessa Montgomery
Title:
Single Step Reacting CFD for Determining Flow Conditioning in a Premixed Micromixer Combustor
Abstract:
Rising performance and efficiency targets for jet engines and gas turbines, combined with tighter Nitrogen Oxide (NOx) emission limits, are driving renewed interest in staged combustion. While higher pressure ratios improve efficiency, they also lead to higher inlet temperatures, which in turn promotes more NOx formation. Staged combustion addresses this by allowing for burning in segments at different equivalence ratios to better manage NOx emissions while also maintaining engine efficiency. One widely used approach is called Rich-Quench-Lean (RQL) combustion, which is when fuel burns rich initially, then is rapidly diluted with air in a quench region and finally burns lean. This sequence is beneficial in lowering NOx emissions by restricting oxygen at peak temperatures when it initially burns rich, quickly cooling the mixture during quench, and then ensuring complete burnout downstream in lean conditions. Because emissions depend strongly on the injected fuel and air mixing in the quench zone, this work aims to characterize the flow field of a reacting jet in crossflow subjected to acoustic forcing at the natural frequencies of the jet. The analysis examines how the imposed oscillations affect formation and frequency of vortices, which can lead to designs that reduce hot spot formations, lowering overall NOx emissions.
Faculty Advisor:
Professor Tim Lieuwen
Melanie Sciammetta
Title:
Numerical Analysis of Liquid Sloshing in a Cylindrical Tank
Abstract:
Liquid sloshing, or the oscillatory motion of the surface wave when a tank partially
filled with liquid is laterally excited, can significantly affect the center of gravity and dynamic
stability of vehicles such as liquid rocket engines. At the Low-Gravity Science and Technology
(LGST) Lab, an experimental study was conducted to investigate sloshing in a cylindrical tank
under high-gravity conditions. Measured natural frequencies and damping ratios were compared
with mechanical analogies generated by SLOSH-ML, an open-source, MATLAB-based
graphical user interface (GUI) tool to obtain the mechanical analogy parameters representing
lateral sloshing for axisymmetric tanks. While the frequencies showed good agreement, the
damping ratios differed, motivating a detailed numerical analysis to better understand the
expected behavior. Numerical simulations were performed in ANSYS Fluent using a Multiphase
Volume of Fluid (VOF) model assuming laminar, viscous, incompressible flow. The tank was
subjected to a sinusoidal lateral acceleration with a frequency sweep around the expected modal
frequencies, and pressure-based monitoring was used to compute liquid height variations and
extract the damping ratios.
Faculty Advisor:
Professor Álvaro Romero-Calvo