Numerical Analysis On Mild Combustion Process Of Gas Turbine Combustor

Increasing thermal energy utilization efficiency and decreasing combustionpollutant formation are the important research tasks in the current energy andenvironment situations. MILD combustion technology also known as flamelesscombustion has not only reduced pollutant emission efficiently but also improved theutilization efficiency of combustion. In recent years, the excellent combustionperformance of this technology has been successfully applied and approved inindustrial field, which achieve superior economy and environment profits.Numerical research on combustion mode and influence of combustor liner wallheat transfer enhancement were performed by heat exchanger model coupledturbulence combustion reaction model in this paper. Main researches included effectsof air jet Re based on incoming air flow temperature, and wall heat extracting rate on MILD combustion mode, liner wall temperature distribution, combustion mode andNOx emission. Both large Re and appropriate were favorable for organization ofMILD combustion and combustion performances improvement. The research resultsare consistent with experimental results, and have reference value for new typecombustor design.This paper have simulated and analyzed the effects on MILD combustion modeand combustion performances by changing the nozzle locations and angles of reverseinjection. Three typical gas turbine operating conditions of changing the fuel injectionquantity to control the equivalence ratio, and its influence on MILD combustion wassimulated. Air entrained injection conditions are controlled by on-off switch installedon the air diffuser wall. Effect of air entrained injection on MILD combustion stabilitymechanism and characteristics have been numerical researched by comparing withwhich of without air entrained injection.Both large Re and appropriate were favorable for organization of MILD combustion and combustion performances improvement. When the combustionparameters of nozzle location and angle are appropriate, MILD combustion modebased on the inlet air temperature. For the same air injet Reynolds and fuelequivalence ratio, fuel reverse injection has comparative good MILD combustioncharacteristics. Air entrained injection forms local swirling zone located away theoutlet wall of air diffuser which made the partial mixing possible of high temperatureflue gas with air and enhanced the injection flow perturbations near combustorentrance. In comparison to non-entrained injection, combustion flame left-off heightlocation increases little with good combustion stability, and has MILD characteristicsof temperature field homogeneity, nitrogen oxide emission very low.The research results are consistent with experimental results under similarconditions, and have reference value for new type combustor design.