TY - GEN
T1 - INTRODUCTION OF AXISYMMETRIC GROOVES AS A TIP SEAL TREATMENT FOR SMALL-CORE TURBINES
AU - Wiese, Connor J.
AU - Berdanier, Reid A.
AU - Thole, Karen Ann
N1 - Publisher Copyright:
Copyright © 2024 by The United States Government.
PY - 2024
Y1 - 2024
N2 - The aerodynamic penalties associated with the tip gap flow in axial turbines remains a challenging problem for turbine manufacturers. As modern gas turbines with small-core architectures are brought online, the influence of the tip gap continues to grow. While technologies to reduce the losses associated with the tip gap flow have been implemented into the blades themselves, little attention has been paid to the stationary tip seal, or casing, around the rotor wheel. In this study, an introduction to the use of axisymmetric groove enhancements for the casing of the rotor tip are examined computationally. These studies use the National Experimental Turbine (NExT) geometry, an engine-representative high-pressure turbine blade. Steady, Reynolds-Averaged Navier-Stokes simulations are used to assess the basic characteristics of axisymmetric grooves, such as depth, location, and arrangement. The objective of this introductory study was to determine the feasibility of impacting the tip leakage vortex formation and the associated losses in rotor efficiency. Furthermore, analyses were done with different tip gap heights along with both flat- and squealer-tipped blades. Tip seals with a single groove are demonstrated to improve rotor aerodynamic efficiency relative to ungrooved seals by up to 0.4 points when applied to flat-tipped rotor blades and up to 0.15 points with squealer tips. Alternating arrays of grooves show improvements for flat-tipped blade performance by up to 0.76 points, while having little additional aerodynamic effect on squealer tip compared to the best single-groove designs. Finally, grooved tip seals appear to exert greater influence on the aerodynamic performance of the turbine rotor when at larger tip gaps, indicating that grooved tip seals alter the sensitivity of rotor performance to the tip gap.
AB - The aerodynamic penalties associated with the tip gap flow in axial turbines remains a challenging problem for turbine manufacturers. As modern gas turbines with small-core architectures are brought online, the influence of the tip gap continues to grow. While technologies to reduce the losses associated with the tip gap flow have been implemented into the blades themselves, little attention has been paid to the stationary tip seal, or casing, around the rotor wheel. In this study, an introduction to the use of axisymmetric groove enhancements for the casing of the rotor tip are examined computationally. These studies use the National Experimental Turbine (NExT) geometry, an engine-representative high-pressure turbine blade. Steady, Reynolds-Averaged Navier-Stokes simulations are used to assess the basic characteristics of axisymmetric grooves, such as depth, location, and arrangement. The objective of this introductory study was to determine the feasibility of impacting the tip leakage vortex formation and the associated losses in rotor efficiency. Furthermore, analyses were done with different tip gap heights along with both flat- and squealer-tipped blades. Tip seals with a single groove are demonstrated to improve rotor aerodynamic efficiency relative to ungrooved seals by up to 0.4 points when applied to flat-tipped rotor blades and up to 0.15 points with squealer tips. Alternating arrays of grooves show improvements for flat-tipped blade performance by up to 0.76 points, while having little additional aerodynamic effect on squealer tip compared to the best single-groove designs. Finally, grooved tip seals appear to exert greater influence on the aerodynamic performance of the turbine rotor when at larger tip gaps, indicating that grooved tip seals alter the sensitivity of rotor performance to the tip gap.
UR - http://www.scopus.com/inward/record.url?scp=85204428976&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85204428976&partnerID=8YFLogxK
U2 - 10.1115/GT2024-121398
DO - 10.1115/GT2024-121398
M3 - Conference contribution
AN - SCOPUS:85204428976
T3 - Proceedings of the ASME Turbo Expo
BT - Turbomachinery - Axial Flow Turbine Aerodynamics; Deposition, Erosion, Fouling, and Icing
PB - American Society of Mechanical Engineers (ASME)
T2 - 69th ASME Turbo Expo 2024: Turbomachinery Technical Conference and Exposition, GT 2024
Y2 - 24 June 2024 through 28 June 2024
ER -