| Combustion of fossil fuels provides around 88% of total energy supply for modern society, and meanwhile causes many environmental problems and social problems such as air pollution and energy crisis. Ethylene itself is major components of fossil fuels, and is an important intermediate product in the oxidation of higher-order hydrocarbons. Therefore investigation on the chemical kinetics of ethylene will help us understand the combustion behaviors of higher-order hydrocarbons and predict key parameters of practical combustion processes. On the other hand, ethylene has greater sooting tendencies than other low-order hydrocarbons, making its combustion an ideal system to study soot formation mechanism. Soot is the main particulate matter produced by burned fossil fuel, and it represents unrealized chemical energy of fuel. The emission of soot by combustion processes can reduce utilization rate of heat output of fuel, and tiny particulate matter (PM2.5) can cause serious harm to human health. Otherwise, soot formation process is a complicate physicochemical process, which involves an exchange of mass energy, such as thermodynamics, fluid dynamics, heat and mass transfer and chemical reaction kinetics. It is an interesting topic in understanding soot formation in detail and effective simulation. So, based on study of simulation for chemical reaction kinetics, the effort is to simplify detail mechanism for a specific combustion system of hydrocarbons. Another goal is to develop computational combustion for practical ways to numerically simulate flame environments, such as chemical kinetics coupled with CFD, radiant heat transfer and soot kinetics.In this dissertation, the present situation of investigations about soot formation and oxidation at home and abroad was systematically summarized. The mechanism models of soot formation and influences in soot formation process were emphatically elaborated. The simplification methods for chemical reaction kinetics models of hydrocarbons and characteristics for different reaction models were presented in detail. The fairly mature mechanisms of ethylene oxidation were were emphatically elaborated. On this basis, the characteristics of soot formation and intermediates for ethylene oxidation were systemly investigated by simulation. Firstly, bssed on CHEMKIN-PRO and advanced functions (AIP), the formations of soot precursors for ethylene flame is investigated by kinetics modeling. In the kinetic modeling work, different pressure laminar premixed ethylene/oxygen/argon flames at broad ranged of equivalence ratio (stoichiometric and rich flames) were computational studied using different gas mechanisms for formation of soot precursors, and regularly results are given. Otherwise, a reaction system for jet stired ractor/plug flow reactor (JSR/PFR) was modeled by using one perfectly stirred reactor (PSR) and two PFR and investigated by simulation. In the simulation, the gas model (Wang-Frenklach mechanism), which is used by this paper, was optimized to satisfiedly predict intermediates and soot volume fractions for ethylene oxidation using Particle Tracking Feature. The results show that modeling is reasonable in this paper, and the growth process from benzene to PAHs is caused by H-abstraction-C2H2-addition (HACA) mechanism combining PAH-PAH radical recombination and addition reactions.Nevertheless, detailed chemical kinetics simulation of hydrocarbon combustion within multidimensional turbulent reacting flows is computationally prohibitive. Therefore, it is necessary to develop a reduced mechanism with a minimum number of species and reactions. The reduced mechanism (19 species and 20 reactions) is obtained from the full ethylene mechanism (GRI-Mech 3.0) by using sensitivity and reaction path diagram analysises (RPA), quasi steady state assumption (QSSA) and Computer Assisted Reduction Mechanism (CARM) software in this paper. And the calculation results are in good agreement with the existing detail mechanism and literatures.For investigation of two-dimension diffusion flame, a combined computational and experimental investigation that examines temperature and soot volume fraction in coflow ethylene-air diffusion flames was presented. A numerical simulation was conducted by using a reduced gas-phase chemistry and complex thermal and transport properties coupled with a semi-empirical two-equation soot model. Thermal radiation was calculated using the discrete ordinates method. The results show that it saves 52.5 percent calculation time by comparing the computation time using reduced mechanism and detail menchanism. Otherwise, an image processing technique and decoupled reconstruction method were used to simultaneously measure the distributions of temperature and soot volume fraction. The results show that the simulation results are identical to the measurement results.As an application attempt, the reduced mechanism coupled with 2-D flame code by using CHEMKIN II to investigate the effects of coflow velocity and gravity on flame structure and soot formation in diffusion flames. The results show that the coflow velocities produce little influence on the distribution of temperature and average velocity in normal gravity. However, the enhancement soot formation is observed when the coflow air velocity is decreased. The gravity has a rather significant effect on the flame structure and soot formation such as flame shape, mixture velocity, temperature, species fraction and soot. The visible flame height in general increase with the gravity from 1g decreased to Og. The peak flame temperature decreases with decreasing gravity level. The peak soot volume fraction increases with decreasing the gravity level. Comparing the calculated results from 1g to Og, the flame becomes wider along radial direction, the high temperature zone becomes shorter, the mixture velocity has a sharp decrease, the soot volume fraction has a sharp increase, CO and unprovided species mole fraction distribution becomes wider along radial direction. At normal and half gravity, the flame is buoyancy controlled and the axial velocity is largely independent of the coflow air velocity. At microgravity (0g), the flame is momentum controlled. The temperature and soot volume fraction in each case occur in the annular region.
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