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Analysis of Turbine Rotor Tip Clearance Losses and Parametric Optimization of Shroud

Banks, William V, III

Abstract Details

2019, Master of Science, Ohio State University, Mechanical Engineering.
Aerodynamic losses due to tip leakage in a High Pressure Turbine (HPT) rotor setting are analyzed using the commercial CFD software Star-CCM+. The compressible RANS equations were solved over unstructured polyhedral grids of 11 to 17 million cells, with turbulence resolved using the k-w SST model. A study of 3 blade tip/casing confi gurations at tip clearances between 0% and 4% of blade span is performed, with resulting mass-flow Reynolds #'s of 2.4-2.7 million and levels of reaction of 0.13-0.17. A flat-tip blade experienced a linear correlation between tip clearance and efficiency. The same blade with recessed casing was more efficient for small clearances, but large shear losses were seen to nullify this advantage at high clearances. A shrouded blade was more efficient than both at all clearances, displaying asymptotic behavior at high clearances. Various pressure and velocity monitoring techniques are employed to evaluate leakage flow and loss. Location and strength of leakage vortices are discussed, as these are closely tied with efficiency. A parametric study was performed on the shroud geometry, examining seal angle, number of seals, seal wear, and shroud axial gap. Efficiencies were compared between each study point at clearances of 2% and 4% of blade span. Total pressure loss was tracked across the blade and split between the main flow path and tip gap to distinguish between Profi le and Internal Gap Shear losses. Axial gap was seen to have the greatest impact on efficiency, as a narrower gap acts as additional tip flow blockage and increases efficiency. At lower clearances, seal wear produced a negative impact as well.
Jeffrey Bons, Dr. (Advisor)
Randall Mathison, Dr. (Committee Member)
Ali Ameri, Dr. (Committee Member)
Robert Boyle (Committee Member)
107 p.

Recommended Citations

Citations

  • Banks, III, W. V. (2019). Analysis of Turbine Rotor Tip Clearance Losses and Parametric Optimization of Shroud [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu155718636896448

    APA Style (7th edition)

  • Banks, III, William. Analysis of Turbine Rotor Tip Clearance Losses and Parametric Optimization of Shroud. 2019. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu155718636896448.

    MLA Style (8th edition)

  • Banks, III, William. "Analysis of Turbine Rotor Tip Clearance Losses and Parametric Optimization of Shroud." Master's thesis, Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu155718636896448

    Chicago Manual of Style (17th edition)