AE Brown Bag Presents: Ajinkya Sawant and Alistair Sequeira

Fri Apr 09 2021 12:30 PM to 01:30 PM

The Daniel Guggenheim School of Aerospace Engineering

is proud to present the

Brown Bag Lecture Series



Ajinkya Sawant

(Advisor: Dr. Vishal Acharya)




Alistair Sequeira

(Advisor: Prof. Kyriakos Vamvoudakis)


Friday, April 9
12:30 - 1:30 p.m. (EST)

Ajinkya Sawant will present

"A Study of Flow Dynamics on A Ballistic Bluff Body Combustor"

The objective of this research is to develop computer models of a reacting flow over a ballistic bluff body at low Reynold’s Numbers. Ballistic bluff bodies are present in a wide spectrum of applications, from industrial boilers to turbojet and ramjet afterburners, and are known for their flame stabilization characteristics. These simulations will be used to inform experimental results conducted in the Ben T. Zinn Combustion Lab and potentially provide more insight on flow fields. Several simulations were run in ANSYS Fluent, each with increasing complexity to achieve this goal. Firstly, Reynolds Averaged Navier Stokes (RANS) laminar and turbulent k-E viscous models were solved to determine the validity of the geometry and resultant solution. With these test-cases validated, unsteady RANS (URANS), k-w SST models were run for a sweep of Reynolds Numbers from 80 to 250. The results from this sweep showed that the Strouhal number, which is associated with the Von Kármán shedding off the bluff body, corresponded closely with that of the well-studied cylinder profile. As the Reynolds number increases, this vortex street grows in magnitude and frequency which can have serious implications for the flame stability. Future study would involve a Large Eddy Simulation (LES) in reacting flow. This additional investigation will be planned to gain insight on the breakdown of local vortices near the flame and irregular oscillations in the flow near lean blowoff conditions. By understanding when and how blowoff occurs with this geometry, the operating ranges of many combustion systems could be expanded and improved.

Alistair Sequeira will present

"Human-Integrated Tool for Proactive and Reactive Security in Cyber-Physical Systems"

As Unmanned Aerial Vehicles (UAVs) and Autonomous Systems (AS) become more prominent, it becomes increasingly important for a security network as well as effective collaboration between human operators and AS. To combat this issue, this presentation provides a comprehensive defense software for cyber-physical systems, comprising both proactive and reactive mechanisms to handle cyber-attacks. Specifically, the demonstrated tool allows a human operator to remain aware of the system’s health and operation, while an autonomous subsystem applies a switching rule based on the principles of Moving Target Defense (MTD). Furthermore, the man-machine interaction implements a trust metric, that allows either the autonomous mechanism or the human agent to have more control over the system based on attack detection and mitigation history. Finally, to demonstrate the tool’s security and collaboration capability, it is simulated using an ADMIRE aircraft.