An attempt was made to extend mild combustion to forward flow furnace, such as the refinery and petrochemical tube furnace. Three dimensional numerical simulation was carried out to study the performance of this furna...An attempt was made to extend mild combustion to forward flow furnace, such as the refinery and petrochemical tube furnace. Three dimensional numerical simulation was carried out to study the performance of this furnace. The Eddy Dissipation Concept(EDC) model coupled with the reaction mechanism DRM-19 was used. The prediction showed a good agreement with the measurement. The effect of air nozzle circle(D), air nozzle diameter(d), air nozzle number(N), and air preheating temperature(Tair) on the flow, temperature and species fields, and the CO and NO emissions was investigated. The results indicate that there are four zones in the furnace, viz.: a central jet zone, an ignition zone, a combustion reaction zone, and a flue gas zone, according to the distribution profiles of H_2 CO and OH. The central jet entrains more flue gas in the furnace upstream with an increasing D while the effect of D is negligible in the downstream. The air jet momentum increases with a decreasing d or an increasing Tair, and entrains more flue gas. The effect of N is mainly identified near the burner exit. More heat is absorbed in the radiant section and less heat is discharged to the atmosphere with a decreasing d and an increasing N as evidenced by the flue gas temperature. The CO and NO emissions are less than 50 μL/L and 10 μL/L, respectively, in most of conditions.展开更多
As a basic problem in many engineering applications, transition from laminar to turbulence still remains a difficult problem in computational fluid dynamics （CFD）. A numerical study of one transitional flow in two-d...As a basic problem in many engineering applications, transition from laminar to turbulence still remains a difficult problem in computational fluid dynamics （CFD）. A numerical study of one transitional flow in two-dimensional is conducted by Reynolds averaged numerical simulation （RANS） in this paper. Turbulence model plays a significant role in the complex flows＇ simulation, and four advanced turbulence models are evaluated. Numerical solution of frictional resistance coefficient is compared with the measured one in the transitional zone, which indicates that Wilcox （2006） k-ω model with correction is the best candidate. Comparisons of numerical and analytical solutions for dimensionless velocity show that averaged streamwise dimensionless velocity profiles correct the shape rapidly in transitional region. Furthermore, turbulence quantities such as turbulence kinetic energy, eddy viscosity, and Reynolds stress are also studied, which are helpful to learn the transition＇s behavior.展开更多
基金supported by the technology development fund of China Petroleum & Chemical Corporation (Sinopec 312016 and 314054)
文摘An attempt was made to extend mild combustion to forward flow furnace, such as the refinery and petrochemical tube furnace. Three dimensional numerical simulation was carried out to study the performance of this furnace. The Eddy Dissipation Concept(EDC) model coupled with the reaction mechanism DRM-19 was used. The prediction showed a good agreement with the measurement. The effect of air nozzle circle(D), air nozzle diameter(d), air nozzle number(N), and air preheating temperature(Tair) on the flow, temperature and species fields, and the CO and NO emissions was investigated. The results indicate that there are four zones in the furnace, viz.: a central jet zone, an ignition zone, a combustion reaction zone, and a flue gas zone, according to the distribution profiles of H_2 CO and OH. The central jet entrains more flue gas in the furnace upstream with an increasing D while the effect of D is negligible in the downstream. The air jet momentum increases with a decreasing d or an increasing Tair, and entrains more flue gas. The effect of N is mainly identified near the burner exit. More heat is absorbed in the radiant section and less heat is discharged to the atmosphere with a decreasing d and an increasing N as evidenced by the flue gas temperature. The CO and NO emissions are less than 50 μL/L and 10 μL/L, respectively, in most of conditions.
基金Foundation item： Supported by the National Natural Science Foundation of China （Nos. 51309040, 51379025）, and the Fundamental Research Funds for the Central Universities （Nos. 3132014224, 3132014318）.
文摘As a basic problem in many engineering applications, transition from laminar to turbulence still remains a difficult problem in computational fluid dynamics （CFD）. A numerical study of one transitional flow in two-dimensional is conducted by Reynolds averaged numerical simulation （RANS） in this paper. Turbulence model plays a significant role in the complex flows＇ simulation, and four advanced turbulence models are evaluated. Numerical solution of frictional resistance coefficient is compared with the measured one in the transitional zone, which indicates that Wilcox （2006） k-ω model with correction is the best candidate. Comparisons of numerical and analytical solutions for dimensionless velocity show that averaged streamwise dimensionless velocity profiles correct the shape rapidly in transitional region. Furthermore, turbulence quantities such as turbulence kinetic energy, eddy viscosity, and Reynolds stress are also studied, which are helpful to learn the transition＇s behavior.
