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A Study on Factors Affecting Combustion Characteristics of GCSC Injector
Yuangang Wang(왕위엔강),Jinwoo Son(손진우),Chae Hoon Sohn(손채훈) 한국연소학회 2019 한국연소학회지 Vol.24 No.1
Factors affecting the combustion characteristics of gas-centered swirl coaxial (GCSC) injectors are investigated numerically and experimentally. The factors are fuel volume flow rate (Qf), momentum flux ratio (MFR) and oxidizer/fuel (O/F) ratio. Firstly, the flame pattern becomes asymmetric as the fuel volume flow rate increases with a fixed momentum flux ratio. Then, the suitable fuel volume flow rate is selected according to the results. Next, the momentum flux ratio is increased by increasing the oxidizer volume flow rate (Qo) with a fixed fuel volume flow rate. Results show that the spreading angle decreases as momentum flux ratio increases, which agrees with our previous results. Finally, in order to check effects of oxidizer/fuel ratio, the Qf, Qo, and MFR are kept the same but the O₂ mole fraction of oxidizer is changed. From numerical and experimental results, it is found that flame pattern depends on oxidizer/fuel ratio and spreading angle increases as the O₂ mole fraction decreases.
Combustion Instability Analysis of a Model Gas Turbine by Application of Dynamic Mode Decomposition
Yuangang Wang(왕위엔강),Jinwoo Son(손진우),Chae Hoon Sohn(손채훈),Jisu Yoon(윤지수),Jinhyun Bae(배진현),Youngbin Yoon(윤영빈) 한국연소학회 2019 한국연소학회지 Vol.24 No.1
Dynamic mode decomposition (DMD) technique is applied to analyze combustion instabilities in a model gas turbine combustor. The flame transfer function (FTF) obtained by the DMD method agrees with the experimental results qualitatively. However, FTF results show that the perturbation frequency with the largest gain is 100Hz, which contradicts the 1000Hz with the largest amplitude in the fast Fourier transform (FFT) results. In order to figure out this, gains and damping coefficients of all resonance frequencies are calculated by DMD technique. Results show the possibility that the model combustor has high-frequency instabilities as a results of coupling between flame and chamber responses. Another finding is that to obtain a pure FTF, the combustor must be removed to exclude coupling of chamber response with flame response.
A Comparative Study of Chemical-Kinetic Mechanisms for Combustion of Methane/Hydrogen/Air Mixtures
Yuangang Wang,한희선,손채훈 한국항공우주학회 2024 International Journal of Aeronautical and Space Sc Vol.25 No.2
Eighteen chemical kinetic mechanisms for combustion of methane/hydrogen mixtures are compared for various burning conditions. The 18 mechanisms include eight detailed mechanisms, nine reduced mechanisms, and one global mechanism. Six of the reduced mechanisms are derived in this study. In the methane/hydrogen mixture, the blending ratio of hydrogen increases from 0 to 100% by 20% point in mole fraction. Calculated ignition delay times and laminar burning velocities are compared with available experimental data over the wide ranges of pressure and equivalence ratio as variables, respectively. Ignition delay times with NO2 are also evaluated by several mechanisms to compare their prediction accuracy for NOx emission. The aim of this study is to provide information for the purpose of choice of particular kinetic mechanism to obtain accurate results at a reasonable computational cost. The results show that although the reduced reaction mechanisms developed in this study have a narrower applicable range for predicting ignition delay times with hydrogen blending, they present higher accuracy in calculating laminar burning velocities and NOx emissions.
A Numerical Study on Gas Mixing Time in a Low-Pressure (Driven) Section of a Shock Tube
YuanGang Wang(왕위엔강),Cheon Hyeon Cho(조천현),Chae Hoon Sohn(손채훈),Youngbin Yoon(윤영빈) 한국연소학회 2017 한국연소학회지 Vol.22 No.3
The fuel and oxidizer mixing process in the shock tube driven section is simulated numerically. The boundary condition is set based on an shock tube experimental condition. The objective is to predict the gas mixing time for experiments. In the experiment, the amount of fuel to be injected is determined in advance. Then, according to duration of fuel injection, 5 cases with the same fuel mass but different fuel mass flow rate are simulated. After fuel is injected into the driven section, the fuel and air will be mixed with each other through convection and diffusion processes. The mixing time is predicted numerically for experiments.
YuanGang Wang(왕위엔강),Chul Jin Kim(김철진),Chae Hoon Sohn(손채훈),In-Seuck Jeung(정인석) 한국연소학회 2016 한국연소학회지 Vol.21 No.4
Pressure and temperature variations in a shock tube have been studied numerically by changing the diameter ratio of a driven part to a driver part . There are five cases where the adopted diameter ratios are 40%, 50%, 60%, 80%, and 100% respectively. The diameter of the driver part remains unchanged meanwhile the shock tube driven part diameter increases from 40% to 100% of the driver part. In the 100% ratio case, the driver part and driven parts have the same diameter of 66.9 mm. As the diameter ratio decreases, the pressure in the shock tube and available test time are increased.