An investigation has been carried out of the influence of the geometry and operating parameters of the rich/quench/lean (RQL) combustion concept on the NOx emissions. The RQL combustor is a three stage, variable geometry system in which fuel is burned in a carefully controlled fuel rich and fuel lean environment. The data utilized in this investigation were obtained under a wide range of operation that simulates the maximum continuous power mode, and for fuels that represent the future distillate types. An expression based on residence time, reaction rates, and mixing rates in each of the combustion zones was derived to estimate the NOx concentration. It was used also to define the range of operation that gives acceptable NOx for future applications. A 3-D combustor flow analysis was conducted to investigate the impact of various system components on the flow field and the total NOx. It was found that for further reduction of NOx modifications to the fuel nozzle and the quench mixer may be required.

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