THE SLABAUGH GROUP
Advanced Propulsion
and Combustion Research
Advanced Propulsion and Combustion Research
From the Laboratory to the Engine.

ABOUT THE RESEARCH GROUP

We seek to understand the coupled physics and chemistry of combustion through complementary experimental and analytical approaches. Our research program covers a wide range of topics; from the fundamental exploration of turbulence-chemistry interactions to the development of advanced combustion technologies for liquid rocket engines. The group also maintains a continuous effort in the advancement of high-bandwidth (typically, laser-based) measurement techniques to non-intrusively probe the physics of these complex, reacting flows. Our work has been funded by government as well as private sources, a sample of which is represented below.

Our laboratory is housed within the Zucrow Laboratory complex. The high pressure, high flow-rate system capabilities enable experimental replication of the flame conditions (pressure, turbulence level, thermal power density) found in today's most advanced propulsion and energy systems. In addition to our academic endeavors, we also work with industrial sponsors on testing programs to characterize and advance the performance of propulsion systems such as rockets, gas turbines, (sc)ramjets, and rotating detonation engines.

  See Our Work

  See Our Labs

AFOSR AFRL SMC ARO DARPA DLA DOE FAA NASA NAWCWD NETL NNSA NSF ONR OUSD-RD USSF

THE TEAM

Slabaugh

Prof. Carson Slabaugh

Principal Investigator

Gejji

Dr. Rohan Gejji

Senior Research Engineer

Reid

Brandon Reid

Test Engineer

Meltzer

Chad Meltzer

Senior Laboratory Technician

Barnett

Nigel Barnett

PhD Student

Black

Charlie Black

PhD Candidate

Daigle

Robert Daigle Jr.

PhD Student, CALSPAN Fellow

DeVerter

William DeVerter

PhD Candidate

Forsythe

Joshua Forsythe

PhD Candidate

Geiger

Reed Geiger

PhD Candidate

Greder

Will Greder

MS Student

Potthast

Thomas Hockenberry

MS Student

Hodge

Alexander Hodge

PhD Candidate

Duck

Calle Junker

PhD Student, NSF Fellow

Keyser

Timothy Kayser

PhD Candidate

Kruer

Allen Kruer

MS Student

Duck

Ethan Labianca-Campbell

PhD Student

Macarie

Luca Macarie

PhD Candidate

Moehring

Ellouise Moehring

MS Student

Neafus

Thomas Neafus II

PhD Student, NSTGRO Fellow

Potthast

Kevin Potthast

PhD Student

Stava

Kristen Stava

PhD Student, Doctoral Fellow

Warner

Alex Warner

PhD Candidate

Young

Garon Young

PhD Student

Duck

Sophia Caudill

Undergraduate RA

Duck

Will Strutton

Undergraduate RA

ALUMNI


	<p style=text-align:left;font-size:100%> <u>Esteemed Slabaugh Group Alumni</u></p>
	<p style=text-align:left;> Dr. Tristan Shahin: Purdue University (West Lafayette, IN), 2025 </p>
	<p style=text-align:left;> Dr. Nicholas Strahan: Southwest Research Institute (San Antonio, TX), 2025 </p>
	<p style=text-align:left;> Dr. Ryan Strelau: Stoke Space (Kent, WA), 2025 </p>
	<p style=text-align:left;> Keaton Koenig: United States Air Force, 2025 </p>
	<p style=text-align:left;> Dr. William Senior: Sandia National Labs (Albuquerque, NM), 2023 </p>
	<p style=text-align:left;> Dr. Mark Frederick: John’s Hopkins University Applied Physics Laboratory (Laurel, MD), 2023 </p>
	<p style=text-align:left;> Dr. Ethan Plaehn: IN Space LLC (Lafayette, IN), 2023 </p>
	<p style=text-align:left;> Dr. Jay Evans: Naval Air Weapons Station China Lake (Ridgecrest, CA), 2023 </p>
	<p style=text-align:left;> John (Conner) Chapla: Air Force Research Laboratory (Dayton, OH), 2023 </p>
	<p style=text-align:left;> Allyson Haynes: United States Space Force, 2023 </p>
	<p style=text-align:left;> Timothy Winter: SpaceX (Hawthorne, CA), 2022 </p>
	<p style=text-align:left;> Deborah Jackson: Northrop Grumman (Chandler, AZ), 2022 </p>
	<p style=text-align:left;> Dr. John Philo: Blue Origin (Kent, WA), 2022 </p>
	<p style=text-align:left;> Dr. Kyle Schwinn: Boeing (Saint Louis, MO), 2021 </p>
	<p style=text-align:left;> Dr. Ian Walters: Pratt & Whitney (East Hartford, CT), 2021 </p>
	<p style=text-align:left;> Kyle Bodie: Blue Origin (Huntsville, AL), 2020 </p>
	<p style=text-align:left;> Dr. Timo Buschhagen: Isar Aerospace Technologies (Munich, Germany), 2020 </p>
    <p style=text-align:left;> Dr. Robert Zhang: Oak Ridge National Laboratory (Oak Ridge, TN), 2019 </p>
    <p style=text-align:left;> Christopher Journell: Arnold Engineering Development Center (Tullahoma, TN), 2019 </p> 
    <p style=text-align:left;> Andrew Pratt: Astra Space (Alameda, CA), 2018 </p>  
    <p style=text-align:left;> Ryan Griffin: Orbital ATK (Phoenix, AZ), 2017 </p>
    <p style=text-align:left;> Nicole Vaughn:  Jacobs Engineering (Huntsville, AL), 2017 </p>

FACILITIES


	<div class=w3-col l12 m12 w3-margin-bottom>
	<span class=w3-xxlarge>ZL8</span>
	<img src=research/HPLAerial_cropped.jpg style=width:100%;padding-bottom:3%;opacity:1 alt=ZL8>
	</div>
	
	
	
	<div class=w3-col l12 m12 w3-margin-bottom>
	<span class=w3-xxlarge>ZL9</span>
	<img src=research/ZL9Rendering.png style=width:100%;opacity:1 alt=ZL9>
	</div>

The Purdue University Zucrow Laboratories have a longstanding history of large-scale experimental capabilities. Originally built for rocket testing in the 1940s, the lab underwent a transformation to support air-breathing experiments in the late 1960s. The High-Pressure Combustion Laboratory (ZL8) was completed in 2017, and features five state-of-the-art 500 ft2 test cells and an adjacent 2200 ft2 diagnostics lab. The High-Speed Propulsion Laboratory (ZL9) is a newly completed $73M, 60,000 ft2 facility which adds five new test cells and significantly expanded the high-pressure, high-flow-rate fluid system infrastructure throughout the Zucrow complex. Both facilities were designed with access windows connecting the test cells to the diagnostics laboratories, allowing a full-host of advanced laser-based techniques to be applied in the most complex flows. Electronics fabrication and mechanical assembly rooms are fully-equipped with tools and equipment, as well as technical staff members to aid researchers. The laboratory has a dedicated staff of fabrication specialists for mechanical and electrical assemblies, multiple full-time engineers with expertise in both high-pressure combustion and energetic materials, secretarial assistance, a facilities manager, and business office staff. The university also provides environmental health and safety support staff. The PI, staff, and graduate students have office space at the laboratory and also access to high-performance computing in Purdue University research centers. The ZL8 and ZL9 facilities are uniquely capable of supporting this combination of experimental research with advanced diagnostic technique development.

41 MPa
Propellant Supplies (6000 psi)
53 MW
Thermal Power
110 kN
Thrust (25000 pound-force)
5 MHz
Optical Measurements

RESEARCH

Below are a few examples from our ongoing work in three principal areas: (1) High-Speed Airbreathing Propulsion, (2) Space Propulsion, and (3) Aviation Propulsion. Click on an image for a brief description and a list of selected publications. For a complete list of publications, please refer to the PI's Google Scholar page.

<p style=text-align:left;> Investigating high-speed flows produces a variety of research questions due to physical phenomena which are either not present or minor at low speeds but become consequential in supersonic and hypersonic regimes. In combustion experiments, chief among these is the assumption that chemical reactions occur much more quickly than the flow timescale. Therefore, a thorough understanding of mixing, flameholding, and the interactions between flames, shocks, and expansion waves is critical for optimal combustor design. Additionally, the flow experienced by high-speed vehicles has a significantly higher enthalpy than low-speed flows, and air must be heated to high temperatures in order to simulate these conditions. The Slabaugh Group has developed facilities specifically designed for producing the conditions necessary for studying high-speed flows, and our expertise in high-repetition rate optical diagnostics allows us to investigate and understand the flow physics required for solving high-speed combustion problems.</p> 
	  <p style=text-align:left;font-size:85%> <u>Select Publications:</u></p>
		   	<p style=text-align:left;font-size:75%> Tristan T. Shahin, Alexander J. Hodge, Benjamin K. Murdock, Thomas N. McLean, Keaton C. Koenig, Rohan M. Gejji, Robert P. Lucht, and Carson D. Slabaugh. Dynamics of hydrogen–ammonia–natural gas lean-premixed high-pressure flames. Fuel, Volume 385, 134016, ISSN 0016-2361. 2025. doi: 10.1016/j.fuel.2024.134016.</p>
		   		   	<p style=text-align:left;font-size:75%> Alexander J. Hodge, Tristan T. Shahin, Rohan M. Gejji, John J. Philo, Robert P. Lucht, and Carson D. Slabaugh. Fuel temperature effects on combustion stability of a high-pressure liquid-fueled swirl flame. Journal of Propulsion and Power 41(1), 53-63. 2025. doi: 10.2514/1.B39592.</p>
	<p style=text-align:left;font-size:75%> John J. Philo, Tristan T. Shahin, Colin T. McDonald, Rohan M. Gejji, Robert P. Lucht, and Carson D. Slabaugh. Effect of fuel temperature on the structure of a high-pressure liquid-fueled swirl flame. Fuel, Volume 354, 129142, ISSN 0016-2361. 2023. doi: 10.1016/j.fuel.2023.129142.</p>
	  <p style=text-align:left;font-size:75%> Jay V. Evans, Brandon T. Reid, Rohan M. Gejji, and Carson D. Slabaugh. Solid-fuel ramjet regression rate measurements using X-ray radiography and ultrasonic transducers.
Journal of Propulsion and Power, 39(6) 905-919, 2023. doi: 10.2514/1.B39210.</p>
	  <p style=text-align:left;font-size:75%> John J. Philo, Rohan Gejji, and Carson D. Slabaugh. Injector-coupled transverse instabilities in a multi-element premixed combustor. International Journal of Spray and Combustion Dynamics (12), 2020. doi: 10.1177/1756827720932832.</p>
      <p style=text-align:left;font-size:75%> Robert Zhang, Andrew C. Pratt, Robert P. Lucht, and Carson D. Slabaugh. Structure conditioned velocity statistics in a high pressure swirl flame. Proceedings of the Combustion Institute, 37(4):5031–5038, 2019. doi: 10.1016/j.proci.2018.06.146.</p>
      <p style=text-align:left;font-size:75%> Timo Buschhagen, Rohan Gejji, John Philo, Lucky Tran, Enrique Portillo-Bilbao, and Carson D. Slabaugh. Self-excited transverse combustion instabilities in a high pressure lean premixed jet flame. Proceedings of the Combustion Institute, 37(4):5181–5188, 2019. doi: 10.1016/j.proci.2018.07.086.</p>
      <p style=text-align:left;font-size:75%> Carson D. Slabaugh, Isaac Boxx, Stephanie Werner, Wolfgang Meier, and Robert P. Lucht. The Structure and Dynamics of Premixed Swirl Flames at Elevated Power Density. AIAA Journal, 54(3):946–961, 2016. doi: 10.2514/1.J054294.</p>
<p style=text-align:left;> The fundamental mechanisms of detonation propagation and sustention involve the highly coupled and non-linear interaction of high-speed gas dynamics and complex chemical kinetics. In an ideal model, a shock wave, typically traveling five to seven time faster than the speed of sound, adiabatically compresses and ignites the reactants it processes. The combustion of this material releases energy that supports the wave and propels it forward. However, in practice, detonation propagation is far from ideal and involves the collision of three-dimensional shock structure across a wide range of length and time scales. Proper understanding of these processes is necessary to inform the design of practical devices, such as rotating detonation engines. Our work utilities high-speed imaging and laser diagnostics to uniquely quantify essential flow and flame properties and advance the state-of-the-art in detonation physics.</p>
	  <p style=text-align:left;font-size:85%> <u>Select Publications:</u></p>
		   <p style=text-align:left;font-size:75%> Mark D. Frederick, Rohan M. Gejji, Joseph E. Shepherd, Carson D. Slabaugh,
Reactive processes following transverse wave interaction,
Proceedings of the Combustion Institute 40(1–4), 2024. doi: 10.1016/j.proci.2024.105552.</p>
		   <p style=text-align:left;font-size:75%> Mark D. Frederick, Rohan M. Gejji, Joseph E. Shepherd, Carson D. Slabaugh. Statistical analysis of detonation wave structure. Proceedings of the Combustion Institute 39(3), 2023. doi: 10.1016/j.proci.2022.08.054.</p>
	  <p style=text-align:left;font-size:75%> Mark D. Frederick, Rohan M. Gejji, Joseph E. Shepherd, and Carson D. Slabaugh. Time-resolved imaging of the cellular structure of methane and natural gas detonations. Shock Waves 32, 337–351, 2022. doi: 10.1007/s00193-022-01080-8.</p>
<p style=text-align:left;> Detonation based propulsion systems represent the next technological leap in the never-ending quest for more efficient and higher performing combustion devices.  With applications in both power generation and aerospace propulsion, thermodynamic cycles utilizing detonations can exploit the advantages of combusting propellants at a higher pressure to generate more work, thrust, or heat.  In our group, we specialize in capturing and understanding the underlying chemical and hydrodynamic processes within a detonation.  We leverage that understanding into the designs of large scale experiments wherein we test rotating detonation combustors (RDCs) at engine-relevant conditions.  Using high speed optical diagnostics, we probe the reacting flow fields to measure scalar and vector fields within the combustor and provide data for physics-based modeling of the combustor operation.  From the microscale physical processes within a detonation wave to the macroscale performance and operability of RDCs, the Slabaugh group is at the forefront of detonation diagnostics and research.</p>
	  <p style=text-align:left;font-size:85%> <u>Select Publications:</u></p>
		<p style=text-align:left;font-size:75%> Ethan W. Plaehn, Rohan M. Gejji, Ian V. Walters, and Carson D. Slabaugh. Continuous injector geometry variation to augment rotating detonation combustor operation and performance. Journal of Propulsion and Power 40(3), 2024. doi: 10.2514/1.B39296.</p>
		<p style=text-align:left;font-size:75%> Ethan W. Plaehn, Ian V. Walters, Rohan M. Gejji, and Carson D. Slabaugh. Bifurcation in rotating detonation engine operation with continuously variable fuel injection location. Journal of Propulsion and Power 39(2), 2023. doi: 10.2514/1.B38801.</p>
	  <p style=text-align:left;font-size:75%> Ian V. Walters, Aaron I. Lemcherfi, Rohan M. Gejji, Stephen D. Heister, and Carson D. Slabaugh. Performance characterization of a natural gas-air rotating detonation engine. Journal of Propulsion and Power 37(2), 2020. doi: 10.2514/1.B38087.</p>
	  <p style=text-align:left;font-size:75%> Ian V. Walters, Christopher L. Journell, Aaron I. Lemcherfi, Rohan M. Gejji, Stephen D. Heister, and Carson D. Slabaugh. Operability of a Natural Gas-Air Rotating Detonation Engine. Journal of Propulsion and Power 36(3), 2020. doi: 10.2514/1.B37735.</p>
<p style=text-align:left;> High-speed laser diagnostics can provide critical information about reacting flows. We develop and apply imaging techniques, such as schlieren, particle image velocimetry (PIV), and planar laser-induced fluorescence (PLIF), to characterize the structure of the fluid flow, the progress of chemical reactions, and the dynamics of these coupled processes. We apply spectroscopic techniques, such as coherent anti-Stokes Raman scattering (CARS), to quantitatively measure fluid properties such as temperature, pressure, and species concentration.</p>
   	  <p style=text-align:left;font-size:85%> <u>Select Publications:</u></p>
	<p style=text-align:left;font-size:75%> William C. B. Senior, Rohan M. Gejji, Tianyu Gai, Carson D. Slabaugh, and Robert P. Lucht. Background suppression for CARS thermometry in highly luminous flames using an electro-optical shutter. Opt. Lett. 48, 2010-2013. 2023. doi: 10.1364/OL.487082.</p>
	  <p style=text-align:left;font-size:75%> John J. Philo, Mark D. Frederick, and Carson D. Slabaugh. 100 kHz PIV in a liquid-fueled gas turbine swirl combustor at 1 MPa. Proceedings of the Combustion Institute, 2020. doi: 10.1016/j.proci.2020.06.066.</p>
   	  <p style=text-align:left;font-size:75%> Lucky V. Tran and Carson D. Slabaugh. On Correlated Measurements in the Transient Thermochromic Liquid Crystals Technique with Multiple Indicators. International Journal of Heat and Mass Transfer, 137:229–241, 2019. doi: 10.1016/j.ijheatmasstransfer.2019.03.077.</p>
      <p style=text-align:left;font-size:75%> Claresta N. Dennis, Carson D. Slabaugh, Isaac Boxx, Wolfgang Meier, and Robert P. Lucht. 5 kHz Thermometry in a Swirl-Stabilized Gas Turbine Model Combustor using Chirped Probe Pulse Femtosecond CARS. Part 1: Experimental Measurements. Combustion and Flame, 173:441–453, 2016. doi: 10.1016/j.combustflame.2016.02.033.</p>
      <p style=text-align:left;font-size:75%>  Carson D. Slabaugh, Andrew C. Pratt, and Robert P. Lucht. Simultaneous 5 kHz OH-PLIF/PIV for the study of turbulent combustion at engine conditions. Applied Physics B: Lasers and Optics, 118(1), 2015. doi: 10.1007/s00340-014-5960-5.</p>
<p style=text-align:left;> In-space rocket propulsion requires a reliable and repeatable method of ignition. We use focused laser pulses to deposit energy into the mixing layer of a shear co-axial rocket injector as one such ignition method. Application of Schlieren and chemiluminescence imaging, as well as the use of Coherent Anti-Stokes Raman Scattering (CARS) measurements at points of interest within the flow, to provide information about the evolution of the flame structure through the ignition process and the mixture state and composition at the point of energy deposition. Shown above is a combined Schlieren and OH* chemiluminescence video showing density gradients and emissions from OH* radicals, a product of hydrocarbon combustion, in our optically-accessible rocket combustor.</p>
   	  <p style=text-align:left;font-size:85%> <u>Select Publications:</u></p>
   	  <p style=text-align:left;font-size:75%>Ryan M. Strelau, Mark D. Frederick, Timothy R. Winter, William C.B. Senior, Rohan M. Gejji, Carson D. Slabaugh. Laser induced spark ignition of a gaseous methane–oxygen model rocket combustor. Combustion and Flame, Volume 265, 2024. doi: 10.1016/j.combustflame.2024.113463.</p>
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