Title page for ETD etd-01302012-154202


Type of Document Master's Thesis
Author Song, Keun Min
Author's Email Address kmsong@vt.edu
URN etd-01302012-154202
Title Wall Modeled Large-Eddy Simulations in Rotating Systems for Applications to Turbine Blade Internal Cooling
Degree Master of Science
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Tafti, Danesh K. Committee Chair
Ekkad, Srinath V. Committee Member
Paul, Mark R. Committee Member
Keywords
  • Heat transfer
  • Large Eddy Simulation
  • Rotation
  • Turbine blade internal cooling
  • Wall layer modeling
Date of Defense 2012-01-20
Availability unrestricted
Abstract
Large-Eddy Simulations (LES or wall-resolved LES, WRLES) has been used extensively in capturing the physics of anisotropic turbulent flows. However, near wall turbulent scales in the inner layer in wall bounded flows makes it unfeasible for large Reynolds numbers due to grid requirements. This study evaluates the use of a wall model for LES (WMLES) on a channel with rotation at 〖Re〗_b = 34,000 from 〖Ro〗_b = 0 to 0.38, non-staggered 90° ribbed duct with rotation at 〖Re〗_b = 20,000 from 〖Ro〗_b = 0 to 0.70, stationary 45° staggered ribbed duct at 〖Re〗_b = 49,000, and two-pass smooth duct with a U-bend at 〖Re〗_b = 25,000 for 〖Ro〗_b = 0 to 0.238 against WRLES and experimental data. In addition, for the two-pass smooth duct with a U-bend simulations, the synthetic eddy method (SEM) is used to artificially generate eddies at the inlet based on given flow characteristics.

It is presented that WMLES captures the effects of Coriolis forces and predicts mean heat transfer augmentation ratios reasonably well for all simulations. The alleviated grid resolution for these simulations indicates significant reductions in resources, specifically, by a factor of 10-20 in non-staggered 90° ribbed duct simulations. The combined effects of density ratio, Coriolis forces, with SEM for the inlet turbulence, capture the general trends in heat transfer in and after the bend.

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