Research Areas

Our research is driven by applications in propulsion and energy, with extensions to health and environment. Lab activities are united by a core focus in experimental thermofluids and applied spectroscopy. Projects commonly span fundamental spectroscopy science to the design and deployment of prototype sensors to investigate dynamic flow-fields.


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Propulsion and Hypersonic Flow

Reacting internal flows in chemical propulsion and reacting external flows around high-speed vehicles represent uniquely challenging environments to understand due to the complex combination of competing fundamental mechanisms of heat transfer, chemical kinetics, and fluid mechanics. Due to the high cost, and higher cost of failure, associated with air and space travel, propulsion and entry systems must be engineered to operate near physical limits with a precision driven by intolerance for error. Advanced propulsion technologies and thermal protection systems are hindered in their development and optimization by a lack of understanding and control to minimize risk of failure at performance limits. These constraints drive the need for advanced diagnostic capability for in-situ characterization of propulsion and high-speed flows to accelerate technology development for various propulsion and planetary entry applications. Optical sensors uniquely solve this challenge.

Laser absorption spectroscopy can be used to measure temperature, species, pressure, and velocity in harsh, high-temperature flows that typify such systems. Integration of this sensing method enables quantitative determination of performance (e.g. combustion efficiency, enthalpy flux) and the identification of high-speed events / anomolous factors (e.g. instability). Such sensors further enable the investigation of alternative fuels and operating conditions (T,P) and the corresponding effects on performance and reliability. Example applications from recent research efforts include multi-parameter sensing in rotating detonation rocket systems, time-resolved measurements during simulated Martian entry conditions, and analysis of a supersonic combustor for hypersonic flight.




Energy and Environment

Chemical bond energy (in the form of solid, liquid, and gaseous fuels) accounts for more than 80% of the world's energy resource demand. Due to the high density (on both mass and volume basis) of energy stored in chemical bonds, fuels will remain carriers of energy for efficient transport and many on-board end-uses long after fossilized sources have been exhausted as a result of poor economics or regulatory constraints. Bio-fuels and cleaner synthetic fuels must be efficiently processed and integrated into existing and new energy conversion systems. These conversion processes (spanning from artificial photosynthesis to flex-fuel engines) uniformly involve reacting flows with transient species and thermodynamic properties. Laser diagnostics provide a non-intrusive means to investigate and optimize these energy conversion processes with potential for in-situ analysis and real-time control. In recent works, advanced multi-species sensor systems were used to investigate solar-driven production of hydrogen and graphitic carbon from natural gas, pollutant formation and biofuel combustion in a shock tube, and real-world power-generation systems (poly-fuel engines).

Beyond energy systems, laser spectroscopy can be used for robust and quantitative environmental monitoring in harsh environments. As such, spectrometers provide a way of tracking and understanding how the sources of various emissions influence the environment. Ongoing miniaturization of photonics equipment and reductions in size, weight, and power enable new portable, on-board or even wearable sensors. Our group is working to develop miniaturized sensors for measuring toxic wildfire emissions (including on-board versions suitable for light-duty UAVs or firefighters), as well as similarly lightweight sensors for analysis of isotopic abundance of various species on the Moon.




Health and Medicine

From a thermo-fluid engineering perspective, the human body can be depicted as a low-temperature engine with a complex inner-network of reacting flows. Like most engines, carbon-based fuel (i.e. food) and oxygen (air) are intakes, while carbon dioxide and water are the primary exhaust products. The trace composition of exhaled breath provides a window into the body's internal biochemistry, with much of the information in blood transferred across the alveolar barrier (lungs) to the breath. As such, matabolic dysfunction and disease states yield gaseous biomarkers, which can be detected by various methods ranging from mass-spectroscopy to trained animals. Breath analysis provides clear advantages to blood diagnostics due to inherent non-invasiveness and continuous monitoring potential, and yet has found little clinical traction, attributable in part to insufficient or impractical instrumentation.Laser absorption spectroscopy, particulary in the mid-infrared, provides a means for rapid-response, point-of-care clinical breath analysis of numerous volatile biomarkers. By leveraging sensing techniques developed for high time-resolution measurements in harsh propulsion flows, novel calibration-free on-line breath diagnostics can be utilized for clinical and translational research, with particular suitability to emergent conditions that require time-senstivie information.

In connection with environmental monitoring, laser absorption spectroscopy can be employed as a preventative medical diagnostic tool and for tracking exposures that impact human health. By measuring concentrations of toxicant gases in various emergency response scenarios (such as fires), first-responders can make decisions that mitigate the potential for harm or unnecessary exposure. Many toxicants can be harmful even at extremely low concentrations (on the order of ppm or ppb) that are difficult or impossible to measure with current commerical sensing methods, particularly in harsh environments. From industrial accidents to wildfires, novel spectroscopic sensors can identify when concentrations of toxic gases reach levels that are potentially lethally hazardous or could cause long term chronic health issues.