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Numerical Analysis and Optimization of Anti-vortex Holes for Film Cooling

Chaharlang Kiani, Kiarash | 2020

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 53903 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Mazaheri, Karim; Karimi, Mohsen
  7. Abstract:
  8. The present thesis is devoted to deeply reconsider the anti-vortex film cooling method and its undiscovered features using numerical optimization and advanced turbulence models. In this regards, a modified turbulent heat-flux model was developed to enhance the predictions in complex flow fields with highly anisotropy and non-equilibrium flow/thermal features. Next, the model was introduced to ANSYS FLUENT 16.0 package to prepare a more accurate flow solver. Then, the solver was coupled with an in-house Differential-Evolution (DE) optimization algorithm to find the optimum configurations of anti-vortex holes for several flow and geometric conditions such as flat-plate, convex/concave surfaces and gas turbine NGV. Finally, two optimum configurations which were more attractive to study in more details were chosen for time-dependent study and resolving the coherent structures using Open-FOAM 4.0 and WMLES approach. Using numerical optimization, it was revealed that at least four effective types of anti-vortex interactions exist and each one was deeply explored in the present thesis. The results show that the optimum configurations enhances the adiabatic film cooling effectiveness up to 40 percent while it is possible to cut the coolant flow consumption up to 30 percent. Moreover, it was found that the optimum anti-vortex holes are still effective for blowing-ratios higher than 2.0 that most of the shaped holes are not efficient. The time dependent simulations revealed several coherent vortex structures such as horseshoe, spiral, hairpin, and etc. Moreover, two new types of vortex structures i.e., long vortex tubes and long hairpins are identified. Finally, several practical guidelines with regard to the design and decision-making phases were provided along with the range of design variables including injection angle, length-to-diameter ratio, side-hole diameter, horizontal and lateral position of the side hole and the intersection location of the side and the main hole
  9. Keywords:
  10. Film Cooling ; Large Eddy Simulation (LES) ; Optimization ; Antivortex Holes ; Heat Flux ; Turbulence Simulation

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