I am currently pursuing the Ph.D. degree with State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan, China. My current research interests include combustion diagnostics (regularized reconstruction of soot volume fraction and temperature, measurement of atomic ratios based on LIBS) and soot formation (the effect of flame structure/stoichiometric mixture fraction on soot formation and oxidation, the relationship between soot formation and chemiluminescence).
Microscopic mechanism on viscosity of carbon monoxide Junzhuo ZHANG, Yanqin LI, Zhicong LI, Shuibao YAN, and Wuli Xuebao Acta Physica Sinica, 2025 Viscosity is an essential transport property in gas dynamics, especially the bulk viscosity, which exhibits more complex behavior. Carbon monoxide (CO) is a molecule of weak polarity, which exists in many important fields such as combustion and coke metallurgy. In order to effectively uncover the mechanism of the CO viscosity, this study dealt with it from a microscopic view. A transcale model is built which integrates density functional theory (DFT, first-principles) calculations with equilibrium molecular dynamics (EMD) simulations to establish a microscale foundation. Based on that, a fitted high-precision potential function is formed, then by using the Green-Kubo linear response theory, the shear and bulk viscosities of CO are achieved in a medium temperature range of 100–800 K. The MD simulation is implemented with C programming language, and an adaptive time-step algorithm is applied so that the computational efficiency is significantly enhanced. The resulting bulk viscosity exhibits quite obvious sensitivity to the potential function of the molecule system, while the shear viscosity shows little. Unlike the shear viscosity, which appears more linear, the bulk viscosity shows clear nonlinear behavior that changes with temperature. Correspondingly, traditional theoretic models and experimental results from different literature indicate that the bulk viscosity at medium temperatures is overestimated to various degrees. Fitting functions on the shear and bulk viscosities in the defined temperature range are established, respectively. Additionally, the lower system pressure and larger system size in the model effectively reduce statistical pressure fluctuations and improve the convergence of relevant laws. This work elucidates the microscopic mechanism of CO viscosity and provides a high-fidelity theoretical tool for modeling the viscosity of high-temperature nonequilibrium gas flows (e.g. hypersonic boundary layers, and plasma transport).
Numerical Study on Chemiluminescence Characteristics in Ammonia-Hydrogen-Air Counterflow Diffusion Flames Shijia Liu, Shusen Wang, Zhicong Li Combustion Science and Technology, 2025 This numerical study presents a kinetic analysis of chemiluminescence characteristics in NH3-H2-air counterflow diffusion flames, focusing on the effects of the NH3 blending ratio (XNH3, 0–40%) and strain rate (α, 60–180 s−1). A reaction mechanism containing OH*/NO*/NH*/NH2* radicals for NH3-H2 flames is validated. The results show that the temperature gradually decreases with increasing XNH3 and α. The mole fraction of OH* radical decreases with increasing XNH3 and vice versa with α, which is primarily governed by the formation reaction R254: H + O + M = OH* + M. R255: N2O + H = OH* + N2 is significantly enhanced by NH3 blending, leading to an additional OH* peak on the fuel side of NH3-blended flames. All nitrogen-containing radicals increase with XNH3, but only NO* radical shows an increase when α increases. R280: N2A + NO = N2 + NO* dominates the formation of NO* radical, with the key pathway being NH3 → NH2 → NH → N2A → NO*. NH2* radical has the highest mole fraction of all radicals and is formed through NH3 → (NH2 → NH) → NH2*, in which R302: NH* + H2 = NH2* + H is an important conversion reaction between NH* and NH2* radicals. This study facilitates further understanding and engineering applications of NH3-H2 combustion technology.
Experimental investigation of soot formation in inverse diffusion flames of CO2 and N2 addition: Isolation of dilution and thermal effects Zhicong Li, Chun Lou Combustion Science and Technology, 2024 This experimental study compares the flame structure, temperature, and soot formation characteristics of normal (NDFs) and inverse diffusion flames (IDFs), evaluates the effect of CO2 addition, and isolates the thermal and dilution effects of CO2 and N2 addition on soot formation in IDFs. A hyperspectral imager using the TR-GSVD algorithm measures IDFs with different CO2 addition (XD) in the oxidant, with N2 addition as the comparison. In contrast to NDFs, IDFs have an opened tip, and the visible flame height and flame width decrease as XD grows. IDFs have a higher peak temperature than NDFs, but their peak soot volume fraction is substantially lower. Compared with N2 addition at the same XD, CO2 addition narrows IDFs and makes the reaction zone visible, and the peak temperature of CO2 addition is 350 K lower than that of N2 addition. The suppression effect of CO2 on soot formation is more potent than N2, with a soot formation rate of 30% that of N2 addition and a soot loading of 20–60%. The activation energy of soot formation reaction with CO2 addition is higher than N2 addition. The isolating results reveal that the thermal effect contributes to the main suppression effect of CO2 addition on soot formation, while the dilution effect of N2 addition is stronger than its thermal effect.