Numerical and experimental studies on separated boundary layers over ultra-high lift low-pressure turbine cascade airfoils with variable solidity: Effects of free-stream turbulence

Ken Ichi Funazaki, Kazutoyo Yamada, Yasuhiro Chiba, Nozomi Tanaka

Research output: Chapter in Book/Report/Conference proceedingConference contribution

7 Citations (Scopus)

Abstract

This paper deals with LES investigation, along with measurements, on the interaction between inlet freestream turbulence and boundary layers with separation bubble over ultra-high lift low-pressure turbine airfoils. The cross section of the test airfoils is typical for highly-loaded LP turbines for civil aeroengines. The solidity of the cascade can be reduced by increasing the airfoil pitch by at least 25%, while maintaining the throat in the blade-to-blade passage. Reynolds number examined is 57,000, based on chord length and averaged exit velocity. Free-stream turbulence is about 0.85% (no grid condition) and 2.1% (with grid condition). Hot-wire probe measurements of the boundary layer are carried out to obtain time-averaged and time-resolved characteristics of the boundary layers under the influence of the freestream turbulence. A newly developed probe positioning tool, which is installed downstream of the cascade with minimal blockage, enables precise probe positioning along lines normal to the airfoil surface. Numerical analysis based on high-resolution LES (Large-Eddy Simulation) is executed to enhance the understanding of the flow field around the Ultra-High Lift and High Lift LP turbine airfoils. Emphasis is placed on the relationship of inherent instability of the shear layer of the separation bubble and the free-stream turbulence. Standard Smagorinsky model is employed for subgrid scale modeling. The flow solver used is an in-house code that was originally developed by one of the authors as FVM (Finite Volume Method)-based fully implicit and time-accurate Reynolds-Averaged Navier-Stokes code. Homogeneous isotropic turbulence created with SNGR (Stochastic Noise Generation and Radiation) method using von Karman-Pao turbulent energy spectrum is applied in the present study for the emulation of inlet turbulence.

Original languageEnglish
Title of host publication2008 Proceedings of the ASME Turbo Expo
Subtitle of host publicationPower for Land, Sea, and Air
EditionPART B
DOIs
Publication statusPublished - Dec 1 2008
Event2008 ASME Turbo Expo - Berlin, Germany
Duration: Jun 9 2008Jun 13 2008

Publication series

NameProceedings of the ASME Turbo Expo
NumberPART B
Volume6

Other

Other2008 ASME Turbo Expo
CountryGermany
CityBerlin
Period6/9/086/13/08

All Science Journal Classification (ASJC) codes

  • Engineering(all)

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  • Cite this

    Funazaki, K. I., Yamada, K., Chiba, Y., & Tanaka, N. (2008). Numerical and experimental studies on separated boundary layers over ultra-high lift low-pressure turbine cascade airfoils with variable solidity: Effects of free-stream turbulence. In 2008 Proceedings of the ASME Turbo Expo: Power for Land, Sea, and Air (PART B ed.). (Proceedings of the ASME Turbo Expo; Vol. 6, No. PART B). https://doi.org/10.1115/GT2008-50718