Experimental and Numerical Investigation of a Prototype Low NOx Gas Turbine Burner

Clean gas turbine combustion research has gained popularity in power generation and propulsion industry in recent days. Present days, advanced efficient emission (NOx, CO and UHC) reduction combustion technologies are acknowledged for using the lean premixed combustion system. To support continuous development of eco-friendly combustion system, a 4^th generation dry low NOx prototype downscaled burner (designed and manufactured by Siemens Industrial Turbomachinery AB) has been researched experimentally and numerically. The research burner has multiple stages, which includes a central Pilot (named as RPL/Rich-Premixed Lean) stages, Pilot stage and Main stage. The RPL combustion chamber holds the primary flame, which produces the temperature and high concentration of radicals. The radicals and hot product is reached to the forward stagnation point of the Main flame anchoring point. Swirled reactant mixture is delivered to the Main combustion zone and a strong recirculation zone is developed. The recirculated product is moved to the Main flame root and ignites the fresh mixture. The Main flame was visualized by applying Chemiluminescence and 2D OH-PLIF imaging techniques. Emission measurement was performed to quantify the burner operability and emission competency. Burner stage fuel splits are varied and their effects on flame stability was monitored thoroughly. Computational fluid dynamic (CFD) analysis was performed to understand the flow field and compare the experimental results with numerical analysis. CFD simulation can help to identify the approximate NOx formation region and flame locations inside the burner. RPL flow and Pilot fuel split shows significant contribution towards flame stabilization as experienced from experiment and CFD. A high temperature B-type thermocouple was positioned at the liner exit to measure the exhaust gas temperature. Numerical calculation prediction and measured temperatures showed good qualitative agreement. From the present experimental and numerical research, it is evident that the downscaled prototype gas turbine burner demonstrates a wide flame stability for various operating condition. The fundamental physics behind the flame stabilization and flame dynamics were explored using numerical and experimental research.