Concurrent Effects of Hot Streak and Gas Species Concentration on Aerothermal Characteristics in a Turbine Stage

Hydrogen or syngas derivative turbines in IGCC power plant promise increased efficiency with exceptional low NO_x and CO₂ emission. On one hand, the working flow in hydrogen turbines will be primarily water steam mixed with nitrogen, which leads to special aero-thermal characteristics in the turbine. On the other hand, the diluting and cooling air in combustors forms a cushion around the hot combustion gas, which results in both temperature and gas species non-uniformity at the turbine inlet. The goal of this paper is to study the concurrent effect of the two non-uniform inlet conditions on aerodynamics and heat transfer characteristics of the downstream turbine. In this paper, three-dimensional unsteady Navier-Stokes simulation was performed primarily on two cases: one with both hot streak and a range of species concentrations, and the other with only hot streak at the turbine inlet. The hot streak and species concentration migration was investigated to reveal their interaction. The results indicated that the steam concentration, among the range of species concentration, have the influential impact on the streak migration. It will enhance radial hot streak migration and promote the hot gas accumulation the rotor pressure side. Also, the tip leakage flow was also increased by the species concentration. Based on the understanding of their migration behaviors, the adiabatic wall temperature distribution was discussed to reveal the inlet species concentration effects on the blade heat load. The maximum blade surface temperature increase, due to the inlet species concentration, is about 1.5% of inlet total temperature (about 25 K) on the pressure side. The research in this paper will provide a practical guideline for the cooling strategy design of hydrogen turbines in the future.