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Computational Simulation of a Pre-swirl Incompressible Turbulent Jet-into-Cross-Flow Problem, Using LES Approach

Banyassady, Rayhaneh | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40355 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Taeibi Rahni, Mohammad; Ramezanizadeh, Mahdi
  7. Abstract:
  8. Injection of jet into cross-flow has various applications, such as film cooling of gas turbine blades, reaction control jets for missiles and aircrafts, and mixing of air and fuel in combustion chambers. Velocity ratio (blowing ratio), momentum ratio, and streamwise jet inclination angle are important correlation parameters which have been studied extensively. However, not much work has been done on the jet swirling effects. The present work investigates computational simulation of a row of swirling square jets injected normally into a cross-flow. The swirl is introduced using two injectors discharged normally into the jet. Computational simulations were performed using LES approach with Smagorinsky Model. The jet Reynols number was 4700 while jet to cross-flow velocity ratio was 1.5 and injector to jet velocity ratios were 0.5, 0.75, 1.0, 1.25, and 1.5. In addition, four different injector positions were studied (0.5D, 1.0D, 1.5D, and 2D). For code validation purposes, the results of the simulation without swirl were compared with available experimentl data. Our results show that by adding swirl to the jet, clear asymmetry appears in all quantities. However, counter rotating vortex pair (CRVP) is still the basic mechanism for entrainment of cross-flow into the jet. Swirling has effects on the position of the CRVP such that they get more apart (in wall normal direction). Also as the injectors gets further from the main jet exit and as the injector to jet velocity ratio increases, the jet penetration into the cross-flow is increased.
  9. Keywords:
  10. Jet into Cross Flow Interaction ; Turbulent Flow ; Large Eddy Simulation (LES) ; Subgrid Scales ; Smagorinsky Model ; Swirl Jet

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