Large eddy simulation of combustion characteristics during dual fuel switching process in gas turbine combustor

Abstract

The present study aims to investigate the combustion characteristics, fuel switching strategy, and flame stability associated with fuel switching processes in a dual-fuel gas turbine combustor. Specifically, the Large Eddy Simulation method is employed in conjunction with a skeletal chemical reaction mechanism to simulate the fuel switching process. It is revealed that the presence of a local rich combustion zone, formed by an increased accumulation of fuel in the head region, leads to the displacement of the heat release position towards the downstream inner shear layer. Additionally, this condition causes a reduction in the recirculation zone area and a deterioration in the uniformity of fuel blending. Simultaneously, the combustor experiences low-frequency, high-amplitude pressure pulsations, as well as pulsations in the heat release rate. Furthermore, a comparative analysis is conducted to assess the discrepancies among three distinct fuel supply strategies employed during fuel switching. The fast-opening strategy is found to demonstrate superior performance indicators, as it accomplishes filling the combustor performance indicators within 80% of the allocated time due to its lower initial fuel changing rate.