Research

Turbine-integrated High-pressure Optical RDE (THOR) Test Rig

Rotating detonation engines (RDEs) offer the potential to significantly improve thermodynamic efficiency and/or enable efficient combustion in a compact and lightweight architecture.
Ongoing research with a highly modular RDE test rig is used to evaluate the effects of chamber geometry, operating conditions, and coupling with post-combustion devices on detonation wave characteristics.
Detailed experiments and simulations in a collaboration with Prof. Guillermo Paniagua, James Braun, Spectral Energies, LLC, and others are revealing complex dynamics that are critical for RDE stability and performance.
Diagnostics include kHz-MHz laser-based imaging and spectroscopy of combustion species, velocity, temperature, and liquid spray evolution.

The video to the left shows simultaneous hydroxyl planar laser-induced fluorescence (OH PLIF) and excited-state OH* chemiluminescence of a passing detonation wave within a rotating detonation combustor, each collected at 1 MHz from two different viewing directions.

This reveals the detailed three-dimensional structure of the detonation wave as it consumes the hydrogen-air mixture. The two views are shown in the diagram above.

More information can be found at V. Athmanathan, J. Braun, Z.M. Ayers, C.A. Fugger, A.M. Webb, M.N. Slipchenko, G. Paniagua, S. Roy, and T.R. Meyer, “On the effects of reactant stratification and wall curvature in non-premixed rotating detonation combustors,” Combust. Flame 240, 112013, 2022; doi.org/10.1016/j.combustflame.2022.112013.

Alternative/Green Fuels for Aviation

A key goal of future aviation is to reduce pollutant and greenhouse gas emissions.
New research involves the combustion of ammonia (NH3) as a carbon-free fuel. NH3 is more easily stored as a liquid and contains 45% more H2 per volume than pure H2.
A key goal in this work is to develop a multistage combustion system that can burn ammonia with near-zero emissions of pollutant or greenhouse gases at relevant aviation conditions. This will employ the High-Enthalpy Aerothermal (HEAT) Rig at Purdue's Zucrow Laboratories.

High-Pressure Combustion Physics and Chemistry of Alternative Fuels

Full-scale combustor test rigs are complex and cannot be used to isolate the physics and chemistry governing the behavior of alternative propulsion fuels.
New research involves experiments in the High-Pressure Experimental Laser-Based Imaging and Optical Spectroscopy (HELIOS) test rig designed to achieve well-controlled conditions up to pressures of 100 bar.
Laminar premixed, diffusion, and counterflow flame configurations can be used to evaluate combustion physics and chemistry of new alternative fuels.

High-Speed 3D Laser-Based Tomography of Turbulent Flames

Turbulent combustion is characterized by chemical reactions within highly-transient, 3D flowfields. The dynamics of these flows affect combustion efficiency, performance, emissions, and stability in propulsion and energy systems. This requires diagnostics that can track the spatially and temporally evolving physico-chemical behavior.
Through burst mode laser based volume illumination and wide-angle plenoptic imaging, it is possible to measure high-speed 3D combustion species, such as the soot volume fractions shown to the right, using tomographic reconstruction.
This approach has potential for application in many spatio-temporally evolving flows.

Ultrashort-Pulse Laser Spectroscopy for High-Pressure Combustion

The pressure scaling laws for chemical kinetics in combustion systems require diagnostics that can extract quantitative information such as temperature and concentrations of combustion intermediates.
Recent work has demonstrated the first hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering thermometry (right) and two-photon laser-induced fluorescence of species such as CO and O atoms (not shown) at high pressures.
Potential applications of ultrashort-pulse laser spectroscopy include measurements in plasmas and hypersonic flows.

High-Speed 3D Tomographic Imaging of Energetic Reactions

Energetic reactions within post-detonation fireballs are highly dynamic, shock-laden flows that carry multiphase (particulates and droplets) that are evolving and reacting at very short time scales.
Recent work has investigated the use of wide-angle relay plenoptic imaging to capture 3D time-evolving images of energetic reactions using tomographic reconstruction. The demonstration shown to the right was conduced in an e-match used for igniting energetic materials.
Ongoing work includes application to 3D measurements in multiphase blast fields.

High-Speed 3D X-ray Tomographic Imaging of Liquid Volume Fractions

X-ray imaging can readily penetrate optically dense regions of sprays and multiphase flows but has typically been limited to low repetition rates.
In recent work, an x-ray system with three lines of sight were used to collect multiple views simultaneously, followed by tomographic reconstruction. The 3D images from a spray (right) show quantitative liquid mass fraction during jet impingement and breakup into ligaments and droplets at a rate of 10 kHz.
Other applications include in-situ evaluation within alternative propellant formulations.