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Feasibility Study for Employment of Tandem Airfoil in High Pressure Axial Fan and Compressors

Rezaee Ghavamabadi, Nazanin | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42769 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Ghorbanian, Kaveh
  7. Abstract:
  8. The objective of the current work is to investigate the application of tandem blade rotor for possible improvements of a transonic fan. A near term application of tandem blade rotor could be either in the last stages of a high pressure compressor or in the fan section. The present research is motivated by evaluating the tandem configuration for transonic fan of high bypass ratio turbofan engines. The main idea is to achieve higher overall blade loading and at the same time lowering the flow separation tendency by shifting the boundary layer growth to the rear rotor. A computational fluid dynamics code, solving the Navier-Stokes equations based on a flexible multiple-block grid discretization scheme with a four-stage Runge-Kutta time-marching finite volume solution technique and using k-ɛ turbulence model, is used. Code validation is performed for NASA rotor 67 with 22 blades, a design pressure ratio of 1.63, and a tip speed of 1500 ft/sec. The numerical results are compared with available experimental data from open literature as well as those from commercially available solvers. Further, the flow behavior of a tandem configuration of NASA rotor 67 is investigated where the total tandem chord length is kept equal to a single airfoil. A performance analysis is carried out for different axial distance, percent pitch, and ratio of the front blade chord length to the rear blade chord length. Results are compared with those of a single airfoil. Although initial results reveal that, at mid-span, tandem blade rotor is from fluid mechanical point of view in advantage; however, the performance of the rear rotor is strongly affected by the performance of the front rotor. Consequently, the resulting high losses due to flow non-uniformities at the hub region and tip region are of different nature and order. Results indicate that by far a higher attention should be paid to the design of the tandem configuration at the hub and tip region, in particular for transonic fan application.

  9. Keywords:
  10. Axial Compressor ; Gas Turbines ; Axial Compressor ; Tanden Airfoil

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