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Numerical Analysis of a Supersonic Jet into a Subsonic Compressible Crossflow and the Effects on a Downstream Fin

Mohammadi, Masoud | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 39101 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Tayyebi Rahni, Mohammad
  7. Abstract:
  8. Jet into cross-flow interaction is one of the complex and fundamental problems in fluids dynamics and heat transfer, which is observed in various applications, such as pollutant discharges, film cooing of turbine blades, combustion chamber design of jet engines, trust vectoring systems, boundary layer control, and vertical short take-off and landing (VSTOL) aircrafts. One of the applications of this kind of flow is injection of supersonic jet into subsonic compressible cross-flow, which is used in trust vectoring systems of missiles. In this research, the two-dimensional interactions of supersonic jet into subsonic compressible cross-flow were investigated as two cases: "without a fin" and "with a fin" downstream of the jet. Finite Volume method, Reynolds averaged Navier-Stokes (RANS) equations with Spalart-Almaras turbulent model, AUSM flux evaluation, and multi-block grid were used. One of the effective parameters in this flow is the jet-to-cross-flow dynamic pressure ratio ( ), which is studied in details in this research as well as jet Mach number. In addition to the main vortex downstream of the jet and the fin, expansion waves at jet exit and their reflections as compression waves lead to the existence of phenomena such as barrel shock surrounding the jet plume, oblique shock, and Mach disk in the jet plume. Breaking of the main vortex due to the presence of the fin has also noticeable effects on surface pressure and moment coefficients (in addition to producing new flow structures), which are very important in trust vectoring control. Results show that the most important factor which changes the surface moment coefficient is the main vortex, which of course is affected by the jet and the fin. The results show that the effects of increasing dynamic pressure ratio on forces and moments reduce gradually in the presence of the fin. Fin location investigation indicates that having the fin close to the jet significantly increases the jet penetration and the size of the main vortex (besides the prevention of deflection of the jet towards the cross-flow)
  9. Keywords:
  10. Pressure Ratio ; Dynamic Pressure ; Spalart-Almaras Turbulence Model ; Flux Splitting ; Jet into Cross Flow Interaction ; Advection Upwind Splitting Method (AUSM)

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