About

Gregory S. Elliott is a Professor in the Department of Aerospace Engineering at the University of Illinois Urbana-Champaign. His research interests encompass experimental thermal and fluid sciences, including aerodynamics, supersonic and subsonic flows, turbulence, combustion, and plasma interactions, with a focus on the development and application of optical and laser-based diagnostics. Elliott has contributed significantly to the understanding of compressible mixing layers, shock wave interactions, and high-speed flow measurement techniques, utilizing advanced optical diagnostic methods such as Rayleigh scattering, Doppler velocimetry, and laser energy deposition. He holds a B.S. in Mechanical Engineering from The Ohio State University, where he graduated Cum Laude with Distinction in 1987, and both his M.S. (1989) and Ph.D. (1993) in Mechanical Engineering from the same institution. His academic career includes positions at Rutgers University and the University of Illinois Urbana-Champaign, where he has served as Associate Head for Undergraduate and Graduate Programs, as well as Interim Head of the Department. Elliott's extensive publication record and research contributions have advanced the field of aerospace engineering, particularly in experimental fluid mechanics and flow diagnostics.

Research topics

• Engineering
• Aerospace engineering
• Artificial Intelligence
• Physics
• Mechanics
• Computer Science
• Materials science
• Environmental science
• Optics
• World Wide Web
• Engineering management
• Thermodynamics
• Chemistry

Selected publications

• On Board Optical Emission Spectra Collection in Plasmatron X Facility for Hycube Missions

  2026-01-08

  article

  Time-resolved optical emission spectroscopy measurements were performed at the Plasmatron X facility under 110-455 W/cm$^2$ heat flux conditions through a sapphire window embedded in TPS material planned for use on a hypersonic flight vehicle known as HyCUBE. These measurements were conducted in synthetic air at 70 mbar and coupled with two-color pyrometer surface temperature measurements, as well as thermocouple-based internal temperature measurements. For samples fabricated of AETB with RCG-coating, our results demonstrate (1) negligible contamination of the observation window by potential ablation products; (2) survivability of the test articles for the anticipated HyCUBE descent trajectories, (3) capability of simultaneous inference of the rotational and vibrational temperatures at the millisecond timescale using a miniature low-resolution spectrometer. Gas (translational) temperatures and vibrational temperatures in the ranges of 8,000 - 11,000 K and 7,400 - 9,000 K were obtained, respectively. In general, we present the benefits of the HyCUBE concept for in-situ spectroscopic diagnostics in hypersonic flight vehicles.

  PublisherDOI

• From Coils to Surface Recession: Fully Coupled Simulation of Ablation in ICP Wind Tunnels

  ArXiv.org · 2026-02-17

  articleOpen access

  This work presents a fully coupled, multiphysics computational framework for predicting the thermo-chemical material response of thermal protection systems in inductively coupled plasma (ICP) wind tunnels. The framework integrates a high-fidelity Navier-Stokes plasma solver, an electromagnetic field solver, and a discontinuous-Galerkin material response solver using a partitioned coupling strategy. This enables an ab initio, end-to-end simulation of the 350 kW Plasmatron X facility at the University of Illinois Urbana-Champaign (UIUC), including plasma generation, electromagnetic heating, near-wall thermochemistry, and time-accurate material ablation. The model captures key ICP physics such as vortex-mode recirculation, Joule-heating-driven plasma formation, and Lorentz-force-induced flow confinement, and accurately predicts the transition from subsonic to supersonic jet behavior at low pressures. Validation against cold-wall calorimetry and graphite ablation experiments shows that predicted stagnation-point heat fluxes fall well within experimental uncertainty, while fully coupled simulations accurately reproduce measured stagnation temperature histories and recession rates with errors below 12% and 10%, respectively. Remaining discrepancies during early transient heating are attributed to uncertainties in power-coupling efficiency, equilibrium ablation modeling, and material property datasets. Overall, the framework demonstrates strong predictive capability for ICP wind tunnel environments and provides a foundation for improved design, interpretation, and planning of hypersonic material testing campaigns.

  PublisherOA PDF

• From Coils to Surface Recession: Fully Coupled Simulation of Ablation in ICP Wind Tunnels

  arXiv (Cornell University) · 2026-02-17

  preprintOpen access

  This work presents a fully coupled, multiphysics computational framework for predicting the thermo-chemical material response of thermal protection systems in inductively coupled plasma (ICP) wind tunnels. The framework integrates a high-fidelity Navier-Stokes plasma solver, an electromagnetic field solver, and a discontinuous-Galerkin material response solver using a partitioned coupling strategy. This enables an ab initio, end-to-end simulation of the 350 kW Plasmatron X facility at the University of Illinois Urbana-Champaign (UIUC), including plasma generation, electromagnetic heating, near-wall thermochemistry, and time-accurate material ablation. The model captures key ICP physics such as vortex-mode recirculation, Joule-heating-driven plasma formation, and Lorentz-force-induced flow confinement, and accurately predicts the transition from subsonic to supersonic jet behavior at low pressures. Validation against cold-wall calorimetry and graphite ablation experiments shows that predicted stagnation-point heat fluxes fall well within experimental uncertainty, while fully coupled simulations accurately reproduce measured stagnation temperature histories and recession rates with errors below 12% and 10%, respectively. Remaining discrepancies during early transient heating are attributed to uncertainties in power-coupling efficiency, equilibrium ablation modeling, and material property datasets. Overall, the framework demonstrates strong predictive capability for ICP wind tunnel environments and provides a foundation for improved design, interpretation, and planning of hypersonic material testing campaigns.

  PublisherDOI

• PlasFlowSolver: An Aerothermodynamic Data Reduction Model for Inductively Coupled Plasma Wind Tunnel Facilities

  2025-01-03 · 1 citations

  article

  Aerothermodynamic data reduction models are useful tools for analyzing experiments in high-enthalpy plasma wind tunnels, which are essential for evaluating materials used in hypersonic and reentry applications. This study introduces PlasFlowSolver, a data reduction model developed to estimate flow properties such as temperature, enthalpy, and velocity from experimental data, including pressure, stagnation pressure, and stagnation-point cold-wall heat flux. The model is based on boundary layer theory and assumes thermochemical equilibrium, providing an engineering framework for efficient analysis. The model assumptions and the computation of the stagnation-point cold-wall heat flux are thoroughly discussed. Sensitivity analyses of input parameters, such as wall temperature and jet radius, explore the applicability of the model. Results are presented, including the generation of a high-altitude partial operational map for the Plasmatron X wind tunnel at the University of Illinois at Urbana-Champaign. Limitations are discussed, and verification against an existing model is provided.

  PublisherDOI

• Evaluating major curriculum changes: Ensuring a psychologically safe learning environment is achieved for graduate students

  Anatomical Sciences Education · 2025-10-21

  articleOpen access1st authorCorresponding

  A graduate-level master's gross anatomy course was recently rewritten to enhance delivery of its content in a manner that supports student learning. End-of-course evaluations from all 88 students showed highly favorable ratings for the curricular change, but a more detailed analysis is critical to determine whether a safe learning environment had been established. A safe learning environment is established where the curriculum is appropriately challenging, faculty are supportive, and students feel they belong. A measure of the success of a new course is typically the overall performance of the cohort, in addition to the student evaluations. One limitation of this is the use of Likert scores in student evaluations, which are universally devoid of nuanced information. In most instances, students are offered an opportunity to provide written feedback, and beyond a superficial read-through of these comments, they are not typically analyzed for more information or with purpose. An AI-based text analysis tool was used to undertake the underutilized technique of scoring the comments (sentiment data) to further investigate; the data were incorporated in this instance and highlighted several important categories that students deemed necessary to comment on, including: faculty availability, humor and knowledge, effective group dynamics, and a sense of belonging, among others. Based on the assessments of categories in the student-written feedback, a safe learning environment was achieved.

  PublisherOA PDFDOI

• Spectrally Resolved ns TALIF Imaging of O atoms Near a Reacting Copper Surface in the UIUC Plasmatron X Facility

  2025-01-03 · 2 citations

  article

  In this work, we report progress on spectrally resolved nanosecond two-photon absorption laser-induced fluorescence (nsTALIF) measurements of O atoms to probe radial property distributions within the reacting boundary layer above a water-cooled copper sample in the 350 kW Plasmatron X Facility. Radial beam images from spectral nsTALIF scans were acquired at various locations, spanning from the boundary layer edge to the sample surface, with sufficient spatial resolution to capture critical sub-millimeter temperature and species density gradients near the material surface. Preliminary rotational temperature measurements have shown encouraging agreement with nitrogen (N2) rotational temperatures obtained through not yet reported efforts using coherent anti-Stokes Raman spectroscopy (CARS). Additionally, relative number density measurements along the stagnation line and across radial profiles exhibit promising trends. Efforts are ongoing to fully calibrate the system for determining absolute species concentrations.

  PublisherDOI

• In-Depth Ablation of Charring Ablators for Titan and Earth Atmospheric Entries

  SSRN Electronic Journal · 2025-01-01

  preprintOpen access
  PublisherDOI

• Characterization of O Atoms in the Plasmatron X Facility Free Jet via Spectrally Resolved Two Photon Laser Induced Fluorescence Imaging

  2025-01-03 · 2 citations

  article

  In this work, we report progress on using non-intrusive, spectrally resolved nanosecond two-photon absorption laser-induced fluorescence (nsTALIF) strategies to probe oxygen (O) atoms in the University of Illinois Urbana-Champaign Plasmatron X Facility operating with an air plasma, aiming to better assess flow enthalpy. Measurements were conducted using an ICCD camera to take radial profile images of a tuned laser beam across the jet under various pressure and power conditions. The data presented here reveal encouraging trends in temperature, relative number density, and velocity, which are expected to complement future measurements of other species, such as nitric oxide (NO) and nitrogen (N) atoms. Comparisons with the latest numerical simulations are also provided, highlighting areas of agreement between the model and experiment, as well as identifying discrepancies that offer valuable guidance for future improvements. Near-term advancements, including improved energy normalization, better understanding of laser energy fluence limits, and refined laser linewidth estimates, are expected to help reduce uncertainties in the preliminary temperature and density results reported here.

  PublisherDOI

• Coherent Anti-Stokes Raman Scattering Thermometry and CO Concentration Measurements in Plasmatron X

  2025-01-03 · 3 citations

  articleSenior author

  We present coherent anti-Stokes Raman scattering thermometry and relative carbon monoxide concentration measurements acquired under low-pressure conditions in the Plasamtron X plasma wind-tunnel facility. Free-stream nitrogen CARS thermometry indicates a consistent mean free-stream temperature of T = 4973 +/- 133 K, for pressures of 100-200 mbar at 55 kW plasma power. Wall-normal profiles of temperature and CO concentration are demonstrated within the boundary layer of an ablating graphite sample at the same 55 kW power at 200 mbar pressure and near-wall CARS spectra are successfully recorded at pressure as low as 100 mbar. The CARS instrument enables spatially precise measurements of mean temperature and CO to within ~50-100 microns of the graphite surface.

  PublisherDOI

• Coherent anti-Stokes Raman scattering thermometry and concentration measurements in Plasmatron X

  2025-01-01

  report
  PublisherDOI

Frequent coauthors

• J. C. Dutton

  University of Illinois Urbana-Champaign

  45 shared

• Mo Samimy

  The Ohio State University

  29 shared

• Stephen Arnette

  Jacobs (United States)

  27 shared

• Nick Glumac

  University of Illinois Urbana-Champaign

  24 shared

• Jonathan B. Freund

  23 shared

• Andrew Mosedale

  Boeing (Australia)

  15 shared

• Campbell D. Carter

  United States Air Force Research Laboratory

  14 shared

• Russell Adelgren

  Edwards Air Force Base

  12 shared

Labs

• Combustion, Flow, and Plasma Interaction LaboratoryPI

Education

• Ph.D., Aerospace Engineering

  University of Illinois at Urbana-Champaign

  1990

• M.S., Aerospace Engineering

  University of Illinois at Urbana-Champaign

  1986

• B.S., Aerospace Engineering

  University of Illinois at Urbana-Champaign

  1984