Practical Method for Burner Staging Turbine Forced Response Evaluation

Abstract

Decarbonization and sustainability efforts challenge gas turbine engineers to come up with creative strategies for reduction of emissions and efficiency increase over the whole operating range. Burner staging at part loads presents a flexible solution to achieve these goals through selective burner deactivation. Shutting off burners could also be required for combustion of increased H2 content at some conditions. Burner staging will create circumferential unevenness with patterns of hot and cold streaks that could excite blade rows through the entire turbine. This paper presents a parametric method for annular combustor staging patterns' profile generation intended for use for forced response predictions from a limited number of combustor computational fluid dynamics (CFD) calculations while keeping the key phenomenological features. Two cases with burner staging turbine inlet temperature (TIT) distributions are considered and compared to a base case with uniform temperature distribution. The unsteady aerodynamic forcing was obtained from full wheel time marching unsteady CFD calculations. The results show that the hot streaks generate important and noticeable excitation sources. Additionally, the results show that the pattern generator could be used extensively before and after the unsteady calculations' phase to minimize the excitation levels and the computational load.