Numerical Simulation On Diluted Partially Premixed/ Oxygen Enriched Supplemental Of Swirl Combustion

In this paper, based on the FLUENT of CFD software, the establishment of reasonable mathematical and physical models was established for the numerical simulation of oxygen diluted partially premixed /oxygen enriched supplemental of swirl combustion(ODPP/OESC). And the same time comparision with partially premixed combustion(PPC) is also described. The influence of equivalent ratio and oxygen concentration on the flame structure and emission production of pollutants is analyzed through adjusting the parameters such as the concentration of components in the process of combustion.Compared with PPC, oxygen-diluted and oxygen-enriched were used to modulate the C/O concentration distribution with ODPP/OESC,the stability of flame was improved,aslo the emission of gas pollutants such as CO and NO got lower than the former.Detailed studies of the effect of changing parameters such as :total equivalent ratio, partially premixed equivalent ratio and diluted, enriched oxygen concentration on ODPP/OESC flames, We can get the following conclusions :(1)In general case, the total equivalent ratio got lower, the temperature of flames and the emission of NO and CO were reduced effectively;(2) the structure of flames was improved, the combustion temperature distribution got more uniform, and the emission of gas pollutants of CO and NO was monotonically decreased as the partially premixed equivalent ratio was reduced;(3)the emission of NO and CO was decreased significantly as the oxygen diluted concentration reduced;(4)the variation of the oxygen concentration in the annular oxygen-enriched side mainly effected the production of NO.And the decreased of oxygen-enriched concentration, the production of NO is reduced, but do not reduce CO emissions.Integrated in good working conditions, change the structure parameter,shrunk the entrance size which located in the annular oxygen-enriched side plays an important role that reduced the gradient of velocity between the annular enriched oxygen and the fuel at the center. Furthermore, the temperature distribution in the combustion chamber got more uniform.The emission of the thermal NO was reduced,and effectively with subtle increment of CO. Obviously, shrinking the size of the annular oxygen-enriched side has the advantage of reducing pollutant emission. At last, in order to capture the wrinkles on the flame surface and observe shattering process of the large eddy, further refining on the local grid of the combustion chamber is necessary.In conclusion, the optimum condition scopes based on adjusting the distribution of the fuel and oxidizer in the ODPP/OESC swirl combustion process were: the partially premixed equivalent ratio was equal to 1.2; the range of tatal equivalent ratio was 0.7- 0.8; 17%-18%in the oxygen-diluted concentration partially premixed. If the annular oxygen-enriched side needs given oxygen-enriched concentration value,the low oxygen-enriched concentration value of 22% should be selected.