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University of Missouri - St. Louis: Students and Teachers As Research Scientists [UMSL STARS]
My first taste of the research process.
My first taste of the research process.
Over the Summer of 2022, I participated in my first college-level research project as part of the UMSL STARS program. In this program, I was assigned a mentor in a field of STEM that aligned with my interests. For me, my mentor was Dr. Mark McQuilling, a professor of Aerospace Engineering at Saint Louis University. Under his guidance, I had my first experience with computational fluid dynamics, marking my initial steps toward understanding aerodynamics long before I entered college. This program eventually led to me writing a research paper on my work and delivering a scientific presentation to a panel of distinguished professors, allowing me to explain my findings. The slideshow for that final scientific presentation is attached at the bottom of this webpage.
My Work
My Work
The UMSL STARS program consists of two main components: your primary research under your assigned mentor, and weekly sessions with distinguished speakers from various neighboring universities. These speakers would present their work, inspiring us students to pursue significant advancements in research.
At one of these sessions, a marine biologist shared his experiences working on topics ranging from the effects of microgravity on the human eye to catfish populations in the Mississippi River. While his research was fascinating, he ended his talk with some inspiring words: "Always go for it," he said (paraphrased). "It doesn’t matter if you feel unfit for the role. Don’t let your lack of confidence stop you from achieving something great. No matter how big the task, go for it. Put your mind to it, and always pursue it if that’s what you want to do, if that’s what you’re passionate about." These words have stayed with me and are something I hold close to my heart as I conduct research and progress in my education here at Purdue University.
My own research, however, was much more technical. During my first meeting with Dr. McQuilling, I was introduced to a whiteboard filled with the procedures for running CFD and the goals of the project. I was paired with another student for the research. My project was titled "The Effect of the Magnitude of Shockwaves on Air Velocity in a Supersonic Air Stream." My task was to recreate previous computational research conducted by one of Dr. McQuilling's Ph.D. students, examining how shockwaves generated by various geometries in a supersonic air stream would slow down the airflow before it exited the geometry.
The general application of this research is related to the deceleration of air as it passes through a supersonic jet engine. As air flows into a supersonic jet's engine, it must be slowed and properly directed before reaching the internal machinery that propels the aircraft. To achieve this, jet engine inlets are designed to produce shockwaves that decelerate and direct the airflow to the turbine. However, these shockwaves can create significant pressure and velocity differences within the inlet. Due to air viscosity, the air closer to the walls of the inlet moves slower than the rest of the airstream. In extreme cases, this can cause the entire airstream to reverse direction, which is problematic for the aircraft. Additionally, the boundary layer of air can interact with the shockwaves, known as shockwave-boundary layer interactions (SBLI), causing vortices that block airflow to the turbine. This is why research is focused on how to properly generate shockwaves while preventing backflow.
For this research, I used Cradle SC/Tetra, a CFD software that follows the same general process as mainstream CFD tools. My research partner and I were provided with engine geometries by Dr. McQuilling and tasked with running simulations to visualize how shockwaves would behave when passed through these geometries. We were given five models to analyze, and the graphics below show how the shockwaves appeared when the supersonic air stream passed through these designs.
Geometry 1
Geometry 2
Geometry 3
Geometry 4
Geometry 5
The setup for all simulations run on these models was generally the same. First, the model would be imported into the preprocessor window of the software. In this step, various regions within the model would be registered with specific labels, such as "wall" or "shock-holding plate" (shp). Below is Geometry 4 with the registered regions clearly marked.
Geometry 4 with Registered Regions
Once all the regions had been registered, I set the initial and analysis conditions for the inlets and outlets of each geometry. The next step involved generating a detailed mesh for each geometry. The mesh was refined near the shock-holding plate, the region of most interest for the analysis. This mesh consisted of prism layers near the walls and edges, with the remaining regions using a tetrahedral mesh. Below is Geometry 1 with its mesh (referred to as an "octree" in this software).
Geometry 1 "Octree" Mesh
After reaching this point, I ran simulations on these geometries and extracted the results. The first goal of my research was to set the initial conditions correctly to produce a Mach 1.6 airstream velocity, which I achieved on my 11th run with Geometry 2. The second goal was to produce a shockwave in the airstream, which I accomplished on the first simulation of Geometry 5. The resulting graphic from this simulation is shown below.
Geometry 5 Simulation 1 Velocity Results
The two goals of this research were achieved by tweaking the geometries, adjusting the initial conditions, boundary conditions, and registered regions of the models. From this fundamental research, I learned that a significant pressure difference between the inlet and outlet increased the pressure of the airstream, which helped define the shockwave more clearly. Additionally, a blunt (referred to here as 'rounded') shock-holding plate proved to be more effective in producing a sharper shockwave.
Though my research was very basic, tedious, and did not directly align with the PhD student’s original research, it marked my first hands-on research experience. This project sparked my passion for research. Engaging in research, especially in aerospace engineering, fuels my curiosity and desire to explore the unknown. From a young age, I’ve been fascinated by space and have always wondered why certain things work the way they do. Conducting research allows me to seek out tangible answers to these questions.
What excites me the most about the research process is that it aligns with my long-term career goals of advancing humanity’s knowledge of space exploration. The thought that my work, no matter how small, could contribute to the development of space and propulsion technologies is truly inspiring. Each new research project presents an opportunity to push the boundaries of what we know and solve real-world challenges. This drives my passion for astronautical engineering.
After this experience, I was eager to continue my research career. It inspired me to look beyond and dive deeper into academia. I aspire to one day be at the forefront of propulsion research, witnessing the growth and impact of my work.
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