Abstract
The effective control of the tip-leakage flow and loss is of great significance to improve the aerodynamic performance of the turbine. In this paper, the evolution mechanism of tip-leakage flow in a transonic high pressure turbine with a squealer tip is investigated with numerical simulation methods. The impacts of squealer geometric, such as the inclined pressure side rim and squealer rim width, on the vortex structure in the gap and tip-leakage loss are discussed. The results show that the scraping vortex inside the cavity plays the role of aero-labyrinth seal, and forms interlocking sealing labyrinth structure with the rims on both sides, which has an effective sealing effect on the tip-leakage flow. The inclined pressure side squealer rim inhibits the development of the pressure side squealer corner vortex, which is beneficial to expand the influence range of the scraping vortex and enhance the sealing effect on the tip-leakage flow. The increase of the suction side squealer rim width reduces the effective flow area at the gap exit, which is conducive to reduction of the tip-leakage flow rate and tip-leakage loss. However, the increase of the pressure side squealer rim width strengthens the pressure side squealer corner vortex and limits the development space of the scraping vortex, causing the adverse effects on the control of tip-leakage flow.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
Abbreviations
- C :
-
chord/m
- H :
-
cavity height/m
- Ma :
-
Mach number
- ṁ :
-
mass flow rate/kg·s−1
- N :
-
airfoil count
- P :
-
pressure/Pa
- Re :
-
Reynolds number ((ρV)exitCμ−1)
- Ṡ‴g,local :
-
local entropy production rate/W·m−3·K−1
- s :
-
entropy/J·K−1·kg−1
- T :
-
temperature/K
- t :
-
squealer width/m
- V :
-
velocity/m·s−1
- Y :
-
leakage loss/J
- η :
-
efficiency
- μ :
-
dynamic viscosity/N·s·m−2
- ξ :
-
normalized leakage loss
- π :
-
total-to-total pressure ratio
- ρ :
-
density/kg·m−3
- τ :
-
gap height/m
- 2,exit:
-
rotor outlet
- inlet:
-
stator inlet
- inner:
-
inner of gap
- leakage:
-
tip-leakage flow
- n:
-
normal to camber
- notip:
-
condition without tip
- outer:
-
outer of gap
- p:
-
pressure side squealer
- passage:
-
rotor passage
- r:
-
relative
- s:
-
suction side squealer
- t:
-
tangential to camber
- tip:
-
condition with tip
- *:
-
stagnation parameter
References
Denton J.D., Loss mechanisms in turbomachines. Journal of Turbomachinery, 1993, 115(4): 621–656.
Yang H.K., Zhang W.H., Zou Z.P., et al., The development and applications of a loading distribution based tip leakage loss model for unshrouded gas turbines. Journal of Turbomachinery, 2020, 142(7): 1–29.
Yang H.K., Zhang W.H., Zou Z.P., Effects of loading distribution on turbine tip leakage losses. Journal of Engineering Thermophysics, 2020, 41(01): 113–121. (in Chinese)
Dey D., Camci C., Aerodynamic tip desensitization of an axial turbine rotor using tip platform extensions. ASME Turbo Expo 2001: power for land, sea, and air, New Orleans, United States of America, 2001, V001T03A069.
Zhou C., Hodson H., Tibbott I., et al., Effects of winglet geometry on the aerodynamic performance of tip leakage flow in a turbine cascade. Journal of Turbomachinery, 2013, 135(5): 051009.
Coull J.D., Atkins N.R., Hodson H.P., Winglets for improved aerothermal performance of high pressure turbines. Journal of Turbomachinery, 2014, 136(9): 091007.
Bunker R.S., Axial turbine blade tips: function, design, and durability. Journal of Propulsion and Power, 2006, 22(2): 271–285.
Key N.L., Arts T., Comparison of turbine tip leakage flow for flat tip and squealer tip geometries at high-speed conditions. Journal of Turbomachinery, 2006, 128(2): 213–220.
Jun L.I., Sun H., Wang J., et al., Numerical investigations on the steady and unsteady leakage flow and heat transfer characteristics of rotor blade squealer tip. Journal of Thermal Science, 2011, 20(4): 304–311.
Liu J.J., Li P., Zhang C., et al., Flowfield and heat transfer past an unshrouded gas turbine blade tip with different shapes. Journal of Thermal Science, 2013, 22(2): 128–134.
Li W., Jiang H., Zhang Q., et al., Squealer tip leakage flow characteristics in transonic condition. Journal of Engineering for Gas Turbines and Power, 2014, 136(4): V06AT36A029.
Ma H.W., Wang L.X., Experimental study of effects of tip geometry on the flow field in a turbine cascade passage. Journal of Thermal Science, 2015, 1(1): 1–9.
Dey D., Kavurmacioglu L., Camci C., Tip desensitization of an axial turbine rotor using partial squealer rims. Turbine blade tip design and tip clearance treatment. VKI Lecture Series, 2004, 2: 19–23.
Acharya S., Yang H., Prakash C., et al., Numerical study of flow and heat transfer on a blade tip with different leakage reduction strategies. ASME Turbo Expo 2003, collocated with the 2003 International Joint Power Generation Conference, Atlanta, United States of America, 2003, Paper No. GT2003-38617, pp. 471–480.
Krishnababu S.K., Newton P.J., Dawes W.N., et al., Aerothermal investigations of tip leakage flow in axial flow turbines—Part I: effect of tip geometry and tip clearance gap. Journal of Turbomachinery, 2009, 131(1): 011006.
Zhou C., The tip leakage flow of an unshrouded high pressure turbine blade with tip cooling. Journal of Turbomachinery, 2011, 133(4): 929–942.
Yang D.L., Feng Z.P., Tip leakage flow and heat transfer predictions for turbine blades. ASME Turbo Expo 2007: Power for Land, Sea, and Air, Montreal, Canada, 2007, Paper No. GT2007-27728, pp. 589–596.
Yang D., Yu X., Feng Z., Investigation of leakage flow and heat transfer in a gas turbine blade tip with emphasis on the effect of rotation. Journal of Turbomachinery, 2010, 132(4): 041010.
Virdi A.S., Zhang Q., He L., et al., Aerothermal performance of shroudless turbine blade tips with relative casing movement effects. Journal of Propulsion and Power, 2015, 31(2): 527–536.
Mischo B., Behr T., Abhari R.S., Flow physics and profiling of recessed blade tips: impact on performance and heat load. Journal of Turbomachinery, 2008, 130(2): 021008.
Zhou C., Effects of endwall motion on thermal performance of cavity tips with different squealer width and height. International Journal of Heat and Mass Transfer, 2015, 91: 1248–1258.
Zou Z., Shao F., Li Y., et al., Dominant flow structure in the squealer tip gap and its impact on turbine aerodynamic performance. Energy, 2017, 138: 167–184.
Paty M., Lavagnoli S., A novel vortex identification technique applied to the 3D flow field of a high-pressure turbine. Journal of Turbomachinery, 2020, 142(3): 031004.
Gao J., Zheng Q., Effect of squealer tip geometry on rotor blade aerodynamic performance. Acta Aeronautica et Astronautica Sinica, 2013, 34(2): 218–226.
Lomakin N., Granovskiy A., Belkanov V., et al., Effect of common blade tip squealer designs in terms of tip clearance loss control. ASME 2013 Turbine Blade Tip Symposium, Hamburg, Germany, 2014, V001T03A005.
Lomakin N., Granovskiy A., Shchaulov V., et al., Effect of various tip clearance squealer design on turbine stage efficiency. ASME Turbo Expo 2015: Turbine Technical Conference and Exposition, Montreal, Canada, 2015, V02AT38A017.
Zhou C., Hodson H., Squealer geometry effects on aerothermal performance of tip-leakage flow of cavity tips. Journal of Propulsion and Power, 2012, 28(3): 556–567.
Senel C.B., Maral H., Kavurmacioglu L.A., et al., An aerothermal study of the influence of squealer width and height near a HP turbine blade. International Journal of Heat and Mass Transfer, 2018, 120: 18–32.
Prakash C., Lee C.P., Cherry D.G., et al., Analysis of some improved blade tip concepts. Journal of Turbomachinery, 2006, 128(4): 639–642.
De Maesschalck C., Lavagnoli S., Paniagua G., et al., Heterogeneous optimization strategies for carved and squealer-like turbine blade tips. Journal of Turbomachinery, 2016, 138(12): 121011.
Cernat B.C., Pátý M., De Maesschalck C., et al., Experimental and numerical investigation of optimized blade tip shapes—Part I: Turbine rainbow rotor testing and numerical methods. Journal of Turbomachinery, 2019, 141(1): 011006.
Pátý M., Cernat B.C., De Maesschalck C., et al., Experimental and numerical investigation of optimized blade tip shapes—Part II: tip flow analysis and loss mechanisms. Journal of Turbomachinery, 2019, 141(1): 011007.
Qi L., Zou Z., Liu H., et al., Upstream wake-secondary flow interactions in the endwall region of high-loaded turbines. Computers & Fluids, 2010, 39(9): 1575–1584.
Wang Y., Zhang W., Cao X., et al., The applicability of vortex identification methods for complex vortex structures in axial turbine rotor passages. Journal of Hydrodynamics, 2019, 31(4): 700–707.
Liu C.Q., Wang Y.Q., Yang Y., et al., New omega vortex identification method. Science China Physics, Mechanics and Astronomy, 2016, 59(8): 684711.
Zhang Q., Du J., Li Z., et al., Entropy generation analysis in a mixed-flow compressor with casing treatment. Journal of Thermal Science, 2019, 28(5): 915–928.
Acknowledgements
The authors would like to acknowledge the support of the National Science Foundation of China (No. 51406003) and the National Science and Technology Major Project (J2019-II-0019-040).
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Zeng, F., Zhang, W., Wang, Y. et al. Effects of Squealer Geometry of Turbine Blade Tip on the Tip-Leakage Flow and Loss. J. Therm. Sci. 30, 1376–1387 (2021). https://doi.org/10.1007/s11630-021-1488-2
Received:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11630-021-1488-2