Effect of a Combined Hot-Streak and Swirl Profile on Cooled 1.5-Stage Turbine Aerodynamics: An Experimental and Computational Study

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.

Transport of Swirling Entropy Waves through an Axial Turbine Stator

“…However, previous experimental campaigns in a wind tunnel have shown that the wake is completely reabsorbed at stator leading edge [20]. As such, the aforementioned flow features of the generated swirl make the generated vortex comparable to what documented in literature [16,17,25,26].…”

“…Although there are several works that presented and discussed the effect of injecting swirl profile [10], hot-streak [11,12] and entropy waves [13,14], to authors knowledge there are no published experimental studies that combine the effects of a swirl profile and unsteady temperature perturbation (EW) in an annular turbine cascade. The only experimental campaign getting close to the present one has been carried out at Oxford university and it is based on the combustor simulator developed in Adams et al [15]: this campaign combines the generation of a swirl profile with a steady temperature perturbation [16]. According to Khanal et al [17] computational study, a superimposition of the isolate cases considering either a swirl profile or a temperature perturbation leads to misleading results, hence they should be considered together, their effects being strongly non-linear.…”

Heat transfer characteristics of a high-pressure turbine under combined distorted hot-streak and residual swirl: an unsteady computational study

“…The time-averaged film cooling effectiveness on the rotor blade SS and PS was reduced by 10% and 6%, respectively with respect to the uniform case. Very recently Adams et al [31] conducted the first joined experimental and CFD investigation on the impact of combined realistic hot-streak and swirl on a 1.5 stage film-cooled turbine. They conducted the experimental measurements on the new research turbine called LEMCOTEC in the OTRF, which has been designed to represent new generation aero-engine operating conditions and architectures.…”

Generation of Realistic Boundary Conditions at the Combustion Chamber/Turbine Interface Using Large-Eddy Simulation

“…The interaction of the combustion chamber with a turbine located downstream is a very important subject for engine manufacturers. Thus, several studies have already been made on various configurations, in particular in order to understand the effects of a hot spot migration in the turbine [12][13][14]. For the FACTOR configuration, many LES of the isolated or integrated chamber with the downstream turbine are already available in the literature [15][16][17][18][19][20][21].…”