This paper describes progress in the development of a 25 ppm NOx combustor that requires no diluent injection or post-combustion treatment The combustor will be retrofittable in all existing Allison Model 501-K series industrial engines. The approach undertaken is based on lean-premix combustion design incorporating an efficient fuel and air pre-mixing, fuel staging, and advanced wall cooling.
Extensive use has been made of Computational Combustor Dynamics (CCD) codes in the design of the low NOx combustor. Experimental work in support of the present effort includes atmospheric bench scale testing and high pressure rig testing. The bench tests have been performed to evaluate several candidate designs, to gain better understanding of general lean pre-mixed combustor behavior, and to verify model predictions. The bench test results have indicated good fuel/air mixing performance of the lean premixing domes. The high pressure simulated engine rig tests of the dry lean pre-mixed low emissions combustors using natural gas have demonstrated NOx levels less than 15 ppm vd (15% O2 corrected), well below the program goals.