At the 2022 ASEE Midwest Section Conference presenting my paper “Introducing LabVIEW and Arduino as Data Acquisition System Alternatives”
Author: Jackson Marsh | Major: Mechanical Engineering | Semester: Fall 2022
When I describe to my family my research from the Fall 2022 semester, I simply stated I was listening to water boil. However, this oversimplification of my work sensing the acoustic emissions of bubbles in fluid in Dr. Han Hu’s lab only scratches the surface of the key focus of my work. More accurately, I have been studying the bubble dynamics of bubbles in water, using non-intrusive acoustic sensing. The work drives forward the understanding of bubble regimes relating to boiling, which is a key component when dealing with two-phase cooling. All of this meaning, one day this research could be used to help monitor two-phase cooling systems.
My introduction to this work started before the fall semester when I joined Dr. Hu’s lab. I wanted to do something on my own that could contribute to something larger. My interest in fluid dynamics, and my goal of doing research into fluids at the graduate level led me to this research. Along with this, I have always been interested in music, and sound in general. The combination of these two led me to choose this topic. Dr. Hu gave me the tools to learn more about this and run my own experiments. He also helped pair me with a graduate student who knew a little about acoustic emissions due to their research. I soon learned that this student could help me with the technical side of things, but I wanted to understand the root of the acoustic emissions. I took some steps back and started learning on my own.
The first thing I learned from this research was the importance of a literature review. I started by just trying to create an experiment, but I had no clue what the data meant. Because of this, I started reading more and more papers. I learned that the acoustic emissions released from a bubble occurred what the bubble broke away from a surface. This means that when water is boiling, the sound is from all of the bubbles leaving the bottom of the pot, or when they break away from each other while rising. To verify this, I designed an experiment with the help of the graduate student. My experiment pushed air through a syringe tube into water until a single bubble was formed and released. I could monitor this bubble growth and departure using a high-speed camera and use acoustic sensors to monitor for sound. What I noticed was that there was no correlation between the sound and when the bubble released from the tube, which was different from the literature. I knew there had to be something wrong with the experiment. After running more tests, I realized that there was about 0.9 seconds plus or minus half a second between when the acoustic signal was and when the bubble release occurred. To fix this, I tried synchronizing acoustic sensors with the camera through software which improved this, but ultimately it was a hardware linkage that synchronized the two. Once I had done this, I reliably measured an acoustic emission milliseconds after the bubble departed. This synchronization work was with LabVIEW and I also tried using Arduino for data acquisition. The things I learned using these two allowed me to present at the American Society for Engineering Educators Midwest Section Conference.
My work synchronizing helped Dr. Hu and the graduate student run their tests, and it also allowed me to continue working on tests for myself. The tests I ran studied how different bubble sizes affect the speed at which bubbles rise and the frequency with which the acoustic emission occurs. While studying this, other data has been collected to look for other trends. So far, only two bubble sizes have been studied, not leading to enough results to make any conclusions. However, the supplies have been ordered and starting in the Spring 2023 semester, tests will be run with other sized bubbles. Once these tests have been run, I am going to see if the fluid the bubbles are created in cause any difference. Due to other experiments in the lab, engineering fluid is available for me to use. With results from all of these experiments, I hope to publish to a journal. Doing this research in my junior year, I hope to continue to elevate my work for my Honors Thesis in my senior year.