Abstract

Recently developed lean-burn combustors offer reduced NOx emissions for gas turbines. The flow at exit of lean-burn combustors is dominated by hot-streaks and residual swirl, which have been shown–individually–to impact turbine aerodynamic performance. Studies have shown that residual swirl at inlet to the high-pressure (HP) stage predominantly affects the vane aerodynamics, while hot-streaks affect the rotor aerodynamics. Studies have also shown that these changes to the HP stage aerodynamics can affect the downstream intermediate-pressure (IP) vane aerodynamics. Yet, to date, there have been no published studies presenting experimental turbine test data with both swirl and hot-streaks simultaneously present at inlet. This paper presents the first experimental and computational investigation into the effects of combined hot-streaks and swirl on turbine aerodynamics.

Measurements were conducted in the Oxford Turbine Research Facility, a short-duration rotating transonic facility that matches non-dimensional engine conditions.

Two turbine inlet flows are considered. The first is uniform in total pressure, total temperature, and flow angle. The second features a non-uniform total temperature (hot-streak) profile featuring strong radial and weak circumferential variation superimposed on a swirling velocity profile. Area surveys of the flow were conducted throughout the turbine. Measurements and URANS predictions suggest that the inlet temperature non-uniformity was relatively well preserved upon being convected through the turbine, and relatively poor comparisons between URANS and experiment highlight the challenge of accurately predicting the complex IP vane flow.

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