Tonghun Lee

All Publications

• Numerical Simulation of Oxygen-Enhanced Combustion in an Arc-Heated Scramjet Facility AIAA JOURNAL Richardson, S., Edwards, J. R., Gessman, I., Lim, J., Paganini, A., Lee, T. 2026

  View details for DOI 10.2514/1.J066099

  View details for Web of Science ID 001669419600001

• Mixing enhancement and flame stabilization via mesh insert for supersonic cavity flameholder AEROSPACE SCIENCE AND TECHNOLOGY Kang, K., Kato, N., Gessman, I., Beck, A. D., D'agostino, M., Mayhew, E., Lee, T. 2026; 171

  View details for DOI 10.1016/j.ast.2026.111636

  View details for Web of Science ID 001667997300001

• 3D Evaluation of Porous Zeolite Absorbents Using FIB-SEM Tomography INTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND MANUFACTURING-GREEN TECHNOLOGY Bae, K., Kim, J., Son, J., Lee, T., Kang, S., Prinz, F. B., Shim, J. 2018; 5 (2): 195–99

  View details for DOI 10.1007/s40684-018-0019-4

  View details for Web of Science ID 000432458600001

• Fuel effects on lean blow-out in a realistic gas turbine combustor COMBUSTION AND FLAME Esclapez, L., Ma, P. C., Mayhew, E., Xu, R., Stouffer, S., Lee, T., Wang, H., Ihme, M. 2017; 181: 82–99

  View details for DOI 10.1016/j.combustflame.2017.02.035

  View details for Web of Science ID 000403525500007

• Bimetallic Nickel/Ruthenium Catalysts Synthesized by Atomic Layer Deposition for Low-Temperature Direct Methanol Solid Oxide Fuel Cells ACS APPLIED MATERIALS & INTERFACES Jeong, H., Kim, J. W., Park, J., An, J., Lee, T., Prinz, F. B., Shim, J. H. 2016; 8 (44): 30090-30098

  Abstract

  Nickel and ruthenium bimetallic catalysts were heterogeneously synthesized via atomic layer deposition (ALD) for use as the anode of direct methanol solid oxide fuel cells (DMSOFCs) operating in a low-temperature range. The presence of highly dispersed ALD Ru islands over a porous Ni mesh was confirmed, and the Ni/ALD Ru anode microstructure was observed. Fuel cell tests were conducted using Ni-only and Ni/ALD Ru anodes with approximately 350 μm thick gadolinium-doped ceria electrolytes and platinum cathodes. The performance of fuel cells was assessed using pure methanol at operating temperatures of 300-400 °C. Micromorphological changes of the anode after cell operation were investigated, and the content of adsorbed carbon on the anode side of the operated samples was measured. The difference in the maximum power density between samples utilizing Ni/ALD Ru and Pt/ALD Ru, the latter being the best catalyst for direct methanol fuel cells, was observed to be less than 7% at 300 °C and 30% at 350 °C. The improved electrochemical activity of the Ni/ALD Ru anode compared to that of the Ni-only anode, along with the reduction of the number of catalytically active sites due to agglomeration of Ni and carbon formation on the Ni surface as compared to Pt, explains this decent performance.

  View details for DOI 10.1021/acsami.6b08972

  View details for Web of Science ID 000387737200029

  View details for PubMedID 27739300

• Experimental evaluation of strategies for quantitative laser-induced-fluorescence imaging of nitric oxide in high-pressure flames (1-60 bar) PROCEEDINGS OF THE COMBUSTION INSTITUTE Lee, T., Jeffries, J. B., Hanson, R. K. 2007; 31: 757-764

  View details for DOI 10.1016/j.proci.2006.07.090

  View details for Web of Science ID 000252858000075

• Quantitative temperature measurements in high-pressure flames with multiline NO-LIF thermometry APPLIED OPTICS Lee, T., Bessler, W. G., Kronemayer, H., Schulz, C., Jeffries, J. B. 2005; 44 (31): 6718-6728

  Abstract

  An accurate temperature measurement technique for steady, high-pressure flames is investigated using excitation wavelength-scanned laser-induced fluorescence (LIF) within the nitric oxide (NO) A-X(0, 0) band, and demonstration experiments are performed in premixed methane/air flames at pressures between 1 and 60 bars with a fuel/air ratio of 0.9. Excitation spectra are simulated with a computational spectral simulation program (LIFSim) and fit to the experimental data to extract gas temperature. The LIF scan range was chosen to provide sensitivity over a wide temperature range and to minimize LIF interference from oxygen. The fitting method is robust against elastic scattering and broadband LIF interference from other species, and yields absolute, calibration-free temperature measurements. Because of loss of structure in the excitation spectra at high pressures, background signal intensities were determined using a NO addition method that simultaneously yields nascent NO concentrations in the postflame gases. In addition, fluorescence emission spectra were also analyzed to quantify the contribution of background signal and to investigate interference in the detection band-width. The NO-LIF temperatures are in good agreement with intrusive single-color pyrometry. The proposed thermometry method could provide a useful tool for studing high-pressure flame chemistry as well as provide a standard to evaluate and validate fast-imaging thermometry techniques for practical diagnostics of high-pressure combustion systems.

  View details for Web of Science ID 000232938000022

  View details for PubMedID 16270561

• Strategies for laser-induced fluorescence detection of nitric oxide in high-pressure flames. III. Comparison of A-X excitation schemes APPLIED OPTICS Bessler, W. G., Schulz, C., Lee, T., Jeffries, J. B., Hanson, R. K. 2003; 42 (24): 4922-4936

  Abstract

  Laser-induced fluorescence (LIF) has proven a reliable technique for nitric oxide (NO) diagnostics in practical combustion systems. However, a wide variety of different excitation and detection strategies are proposed in the literature without giving clear guidelines of which strategies to use for a particular diagnostic situation. We give a brief review of the high-pressure NO LIF diagnostics literature and compare strategies for exciting selected transitions in the A-X(0, 0), (0, 1), and (0, 2) bands using a different detection bandpass. The strategies are compared in terms of NO LIF signal strength, attenuation of laser and signal light in the hot combustion gases, signal selectivity against LIF interference from O2 and CO2, and temperature and pressure sensitivity of the LIF signal. The discussion is based on spectroscopic measurements in laminar premixed methane-air flames at pressures between 1 and 60 bars and on NO and O2 LIF spectral simulations.

  View details for Web of Science ID 000184940000019

  View details for PubMedID 12952340

• Strategies for laser-induced fluorescence detection of nitric oxide in high-pressure flames. II. A-X(0,1) excitation 8th Topical Meeting on Laser Applications to Chemical and Environmental Analysis (8th LACEA) Bessler, W. G., Schulz, C., Lee, T., Jeffries, J. B., Hanson, R. K. OPTICAL SOC AMER. 2003: 2031–42

  Abstract

  A-X(0,1) excitation is a promising new approach for NO laser-induced fluorescence (LIF) diagnostics at elevated pressures and temperatures. We present what to our knowledge are the first detailed spectroscopic investigations within this excitation band using wavelength-resolved LIF measurements in premixed methane/air flames at pressures between 1 and 60 bar and a range of fuel/air ratios. Interference from O2 LIF is a significant problem in lean flames for NO LIF measurements, and pressure broadening and quenching lead to increased interference with increased pressure. Three different excitation schemes are identified that maximize NO/O2 LIF signal ratios, thereby minimizing the O2 interference. The NO LIF signal strength, interference by hot molecular oxygen, and temperature dependence of the three schemes are investigated.

  View details for Web of Science ID 000182386600003

  View details for PubMedID 12716143

• Strategies for laser-induced fluorescence detection of nitric oxide in high-pressure flames. I. A-X(0,0) excitation APPLIED OPTICS Bessler, W. G., Schulz, C., Lee, T., Jeffries, J. B., Hanson, R. K. 2002; 41 (18): 3547-3557

  Abstract

  Three different high-pressure flame measurement strategies for NO laser-induced fluorescence (LIF) with A-X(0,0) excitation have been studied previously with computational simulations and experiments in flames up to 15 bars. Interference from O2 LIF is a significant problem in lean flames for NO LIF measurements, and pressure broadening and quenching lead to increased interference with increased pressure. We investigate the NO LIF signal strength, interference by hot molecular oxygen, and temperature dependence of the three previous schemes and for two newly chosen excitation schemes with wavelength-resolved LIF measurements in premixed methane and air flames at pressures between 1 and 60 bars and a range of fuel/air ratios. In slightly lean flames with an equivalence ratio of 0.83 at 60 bars, the contribution of O2 LIF to the NO LIF signal varies between 8% and 29% for the previous schemes. The O2 interference is best suppressed with excitation at 226.03 nm.

  View details for Web of Science ID 000176274200009

  View details for PubMedID 12078680