Direct Numerical Simuiation Of Gas/Coal Particles Gas-Solid Two-Phase Round Jet Combustion Flow

The research is divided into two main parts, first, a comprehensive procedure which can be used to compute three-dimensional compressible coal particles gas-solid two-phase combustion flow based on direct numerical method has been developed, namely DNS-TPCRF procedure; second, four combustion cases based on DNS-TPCRF procedure have been carried out successfully, namely, a laminar round diffusion jet flame, a turbulent round lifted jet flame based on an experiment, a still carbon particle combustion in a flowing air environment with different velocity magnitude and temperature; coal particles gas-solid two-phase turbulent round jet flame, respectively.DNS-TPCRF program developed by our research group has several characteristics compared with other similar international procedures:the solution format is stability, high precision, and easy to large-scale parallel computing; the boundary condition is quite stable, which is very important in compressible combustion simulation; the reduced acoustic method is employed in the procedure, which can increase time step as needed; a coal combustion model is embedded in the procedure, and we also put forward two new algorithms used to solve oxygen and carbon dioxide concentration of coal particles’surface in single-film model.The first case is mainly used to study the influence of two ignition methods on the ultimate laminar flame configuration. These two ignition methods form an attached flame and a lifted flame respectively. The paper also analyzes the formation mechanism of the attached flame as well as lifted flame in a further way. The second case is mainly used to study a turbulent flame phenomenon based on an experiment. The comparation between the DNS results and experimental data coincides very well, which indicates that we have applied DNS to such flame successfully. The paper also studies the autoignition phenomenon, the instantaneous turbulent flame configuration and the turbulent stabilization mechanism using the DNS results. Novel results are emerged among them. The third case quantitatively studies a still carbon particle combustion in a flowing air environment with different velocity magnitude and temperature. According to the results in the paper, people can almost quantitatively determine the relationship between the carbon diameter, the velocity magnitude, the temperature of the air and the three carbon combustion regimes (kinetic-controlled, diffusion-controlled, and kinetic-diffusion-controlled). To determine the carbon combustion regime has another important effect which can afford a carbon combustion model selective method. The paper also provides this selective method. The fourth case is used to calculate a coal gas-solid two-phase turbulent round jet flame. Although boundary conditions are artificially settled, it also possesses a possibility to conduct a similar experiment. The paper mainly studies the instantaneous evolution of coal particles fom the inflow to the outflow of the computational domain as well as the statistical field of the solid phase and the gas phase.