Numerical study of combustion flow field characteristics of industrial gas turbine under different fuel blending conditions

Abstract

Numerous studies have shown that the mixture of fuel and oxidant significantly influences the flow characteristics and pollutant emissions within the combustion flow field. This study investigates the effects of various methane fuel blending ratios (0.19–0.41) on combustion flow, emission characteristics, performance parameters, and field synergies through numerical simulation. Combustion simulation employs the SST k-ω and flame-generated manifold models. The findings indicate that as the fuel blending ratio increases from 0.19 to 0.41, the temperature at the front end of the cyclone gradually rises, resulting in an average outlet temperature increase of 165 K. The outlet temperature uniformity index (γT) shows minimal variation, while the Pattern Factor (PF) and NO emissions at the outlet gradually increase. Additionally, the fuel blending ratio (α) exhibit a limited impact on CO emissions at the outlet. When α ≥ 0.39, the peak temperature is located in the cyclonic region, resulting in an extremely heterogeneous outlet temperature distribution. Under various operational conditions, NO is primarily concentrated in the high-temperature region near the wall, and the pollutant emission merit function (fe) gradually increase with α. The optimum field synergy and overall performance for the low-resistance heat transfer are attained at α = 0.37. Significant velocity shocks are observed in the near-wall regions on both sides of the combustion chamber, when α ≥ 0.35, based on DMD analysis. To achieve low NO emission, uniform outlet temperature, and ensure safe, long-term operation of the gas turbine, the fuel blending ratio of 0.3 to 0.35 is advised.