The Numerical Study Of Combustion Characteristics In RQL Combustion Chamber

Due to the environment deteriorating increasingly, more and more attention are paid to the low pollution combustion, especially to low NOx emission combustion. RQL technology utilizes staged burning based on the theoretic study of formation oxides of nitrogen(NOx). The combustor is divided into Rich-burn zone, Lean-burn zone which produce less NOx. The transition, called Quick-quench zone, from fuel-rich to fuel-lean combustion is obtained through a rapid mixing of the rich mixture with dilution air jets. The aim is to combust stably and produce less amounts of NOX.In this paper, CFD numerical simulation method has been applied to study aerodynamic characteristic, combustion characteristic and pollutant emission of the RQL model combustor. Through comparative analysis of three different kinds of swirl number, medium intensity of swirl could not only ensure appropriate mixing of air and fuel, but also avoid high temperature on Rich zone wall. The reasonable distribution of flow patterns in Quench sector may be adjusted by the air jet distribution to achieve the rapid quenching and mixing through the analysis of cold flow field. When equivalence ratio varies from 1 to 1.6 with the constant flow-distribution,the study of temperature field and pollutant emissions showed that temperature rised of RQL combustor increases while output temperature-distribution coefficient decreased, and NOx emission lowered first then increased, meanwhile CO emission and soot emission increased with equivalence ratio rising. When equivalence ratio is 1.4, output temperature can reach 1620k,which meets the temperature demand of the flow to turbine. Under this circumstance, the results of temperature field and pollutant emission with 4 different flow distribution along the combustor chamber showed that output supreme temperature and temperature-distribution coefficient decreased as increasing the jet flow mass, meanwhile mass-weighted average of output NOx emission, CO emission and soot emission lowered. Tough large amount of jet flow mass can mix more effectively, the penetration depth is comparatively small. So the model combustor must be modified, getting rid of the annular impinging jet. Comparing to the run with the impinging, cooling annular jet, this run had a deeper penetration and a more effective mixing. In addition, output temperature distribution coefficient decrease along with lower emission of NOx, CO and soot, which achieved the design goal.The simulation results and analyses demonstrated that RQL model combustor could meet the requirements of both output temperature quality and reducing NOx emission. This study has considerable reference to the design and analysis of new concept combustor in aero engine.