Analysis of Radial Migration of Hot-Streak in Swirling Flow Through High-Pressure Turbine Stage

The high pressure (HP) turbine is subject to inlet flow nonuniformities resulting from the combustor. A lean-burn combustor tends to combine temperature variations with strong swirl and, although considerable research efforts have been made to study the effects of a circumferential temperature nonuniformity (hot-streak), there is relatively little known about the interaction between the two. This paper presents a numerical investigation of the transonic test HP stage MT1 behavior under the combined influence of the swirl and hot-streak. The in house Rolls-Royce HYDRA numerical computational fluid dynamics (CFD) suite is used for all the simulations of the present study. Baseline configurations with either hot-streak or swirl at the stage inlet are analyzed to assess the methodology and to identify reference performance parameters through comparisons with the experimental data. Extensive computational analyses are then carried out for the cases with hot-streak and swirl combined, including both the effects of the combustor-nozzle guide vane (NGV) clocking and the direction of the swirl. The present results for the combined hot-streak and swirl cases reveal distinctive radial migrations of hot fluid in the NGV and rotor passages with considerable impact on the aerothermal performance. It is illustrated that the blade heat transfer characteristics and their dependence on the clocking position can be strongly affected by the swirl direction. A further computational examination is carried out on the validity of a superposition of the influences of swirl and hot-streak. It shows that the blade heat transfer in a combined swirl and hot-streak case cannot be predicted by the superposition of each in isolation.