My name is Mario Medina and I am a Ph.D. candidate in the Mechanical Engineering Department. I currently work on understanding the physical mechanisms that govern spray behavior of fuel injectors as it pertains to atomization, under non-reactive and reactive conditions. I also look at a phenomenon known as injector tip wetting, which is responsible for high particulate emissions during certain engine operating conditions. I am in my 5th year of graduate school and I’m planning to present my dissertation by early-mid March 2020. During my time at the University of Michigan (UM) I have been involved in many programs, organizations, workshops, and research projects. I want to share my experiences that have left a lasting impression during my time at UM as a graduate mechanical engineering student. First, I will focus on my research experiences at three separate institutions: UM, Robert Bosch LLC (Bosch), and the Universitat Politecnica de Valencia (UPV). Second, I will go over my involvement with the Society of Hispanic Professional Engineers – Graduate Committee (SHPE-GC).
Being a part of the U-M research environment has been one of the most rewarding experiences. There are a lot of factors that one must consider but everything up to this point has always ended on a positive note. I am part of a combustion lab with ME Prof. Margaret Wooldridge where we study chemical kinetics, fuel synthesis, combustion applications, internal combustion engines, and fuel injectors. My work has been focused on the latter, where I isolated the injection process of novel fuels at high pressure to understand the spray development for atomization and mixing under non-reactive conditions. The first project I was involved in characterized macroscopic behavior of the spray development to create a reference case for high-pressure gasoline. Applications for this type of work are centered around internal combustion engines. There are two interesting areas that can benefit from utilizing high-pressure gasoline injection; the first being current gasoline direction injection (GDI) engines and the second being low-temperature combustion concept known as gasoline compression ignition (GCI). The work resulted in a publication titled, “High-Speed Imaging Studies of Gasoline Fuel Sprays at Fuel Injection Pressures from 300 to 1500 bar” published in the Society of Automotive Engineers Technical Paper.
During the summer of 2018, Bosch was looking for an intern to work on a project related to particulate emissions in GDI engines. The project I worked with focused on understanding particulate emissions that are caused by injector deposits by a phenomenon known as injector tip wetting. The study was very expansive, consisting of engine test from three different engine architectures, a total of 34 injectors, and various operating conditions. The conclusion of the study was that tip wetting causes significant particulate emissions under certain conditions and we proposed a conceptual understanding of the mechanisms that cause tip wetting and drying. The work is in preparation for submission to the International Journal of Engine Research.
The most recent experience happened during the winter and spring/summer term of 2019. I was awarded the Rackham International Research Award (RIRA) to visit the department of Centro Motores Termicos (CMT) within the Universitat Politecnica de Valencia (UPV) as a visiting research assistant. While abroad in Valencia, Spain, I had the chance to continue my work with fuel injectors but with a slightly different focus. Rather than injector tip wetting, my work abroad focused on the hydraulic characterization and spray development of novel fuels at high pressure under reactive conditions. The objective of this study was similar to the first project but expanded the study to reactive conditions. Under reactive conditions, the fuel and air not only mix due to instabilities, but chemical reactions begin to take place. This can cause the dynamics of the mixing to change. The work from this study is still under the analysis but will be prepared for submission to another journal. During this experience, I had to pleasure to work with experts in fuel injectors and injection processes that have demonstrated high caliber research. The faculty at CMT provided great guidance and support to allow me to conduct the research of my interest. The graduate students and technicians were a tremendous help not only from their moral support and joint experiences but because of their technical expertise and intellectual input. I made great relationships with some of these people to which I have maintained communication with them.
Coming to UM for graduate school was a huge step forward in my academic career and one that has helped shaped many aspects of my personal life as well. Finding a community is very important to many individuals. That community was partially provided by the Society of Hispanic Professional Engineers – Graduate Committee (SHPE-GC). This student-ran organization helped me create a community amongst other Latinx students from many disciplines. I’ve had the opportunity to foster relationships with students from various STEM fields, students from different organizations outside of STEM and other graduate student organizations such as Grad – Society Women Engineering (GradSWE) and Graduate Society of Black Engineers and Scientist (GSBES, formerly SMES-G). Sustained communication between students from different backgrounds is important because it allows each organization to learn multiple perspectives so that they we can all better serve our communities. Particularly, SHPE focuses on three main pillars which are outreach, professional development, and community building. Some of the previous events that highlight each pillar are Scarlett Middle School Science day company visits, alumni visits, and our annual Whirlyball event. However, my involvement with SHPE-GC has had continuous support from many faculty and staff across the College of Engineering. Particular individuals that I would like to highlight for their help and support are Prof. Susan Montgomery, Dr. Mauro Rodriguez (UM Ph.D. 2019), Rachel Casanova, the staff at Office of Student Affairs (OSA) and past and current members of SHPE-GC.
The experiences I have shared are not comprehensive in any way. As I mentioned from the beginning, there have been many events, projects, people, funding, etc. that were shared with me. U-M has plenty of great opportunities to offer and I believe I have extracted all I could from its resources to my benefit. I have also used my platform to volunteer, mentor, and serve as a leader in my community. Do your homework regarding what opportunities are on tap and foster relationships with Michigan folks. That is the main message I want to share: take advantage of all resources available to you and do something positively impactful.