From Austria to Air Force— David Hillstrom leverages rich background in mechanical engineering
A native of Tulsa, Oklahoma, David Hillstrom didn’t wander far from home to pursue an undergraduate education in mechanical engineering. Miles away at Oklahoma State University, he quickly connected with Professor Giorgio Rizzoni, and made the move to Columbus, Ohio to chase after a master’s and PhD in mechanical engineering.
His PhD specifically focuses on the fuel injector, which is responsible for spraying fuel into the cylinder where it’s ignited and provides power from the engine to drive the car. David was able to develop a new experiment which expands on this data, meaning its use in computer software is more representative of what actually happens.
Normally a fuel injector spray is caused by electronics pulling a needle away from a sealing surface, so fuel can flow freely, and then pushing the needle back, where it seals again. This needle typically moves around 100 micrometers from fully closed to fully open. David says, “our experiment allowed us to repeat this test and decrease the fully open limit from 100 micrometers down to 0 in steps of 5 micrometers.” This step is smaller than the diameter of a red blood cell, and it’s extremely difficult to do in an injector where fuel pressure can change from 500-3000 PSI. At those variations in pressure and the required location accuracy, even stainless steel starts to act like chewed bubble gum, flexing and distorting all over.
This level of complexity is why he’s proud his group was able to get the device to work the first time they ventured to Austria. Now, the data can be used to improve simulations, specifically when the needle is moving from its closed position to its open position and vice versa.
Outside of his PhD efforts, he also served in an engineering services group at OSU-CAR which provided a variety of educational opportunities. David worked with a team to design and construct a hazardous laboratory for airborne lead particles where lead-acid battery plates could be destructively tested. He also built a variety of data acquisition and post-processing systems for battery experiments, engine and vehicle dyno experiments, and image processing for manufacturing applications. Currently, he is working on system analysis, alongside the Air Force Research Laboratory, for war-game scenario simulations in the Air Force owned software AFSIM.
Looking back on his time as a graduate student, he notes working in Graz, Austria in the engine test facility as one of his most memorable experiences. Moving forward, he’s excited to continue is research while pursuing a PhD here at The Ohio State University.
Contact David at hillstrom.4@osu.edu for projects related to fuel injection, spray experiments/simulation, gasoline and natural gas engine combustion, 1D and 3D computational fluid dynamics, and battery experimentation.