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Numerical Study of Ignition Transient in Solid Fuel Ramjets

Tahsini, Amir Mahdi | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40045 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Farshchi, Mohammad
  7. Abstract:
  8. Solid fuel ignition transient in dump combustor geometry is numerically studied. The objective of this work is to gain insight into the ignition of the fuel and its controlling parameters in back-step turbulent flow. The system of governing equations is solved with a finite volume approach using a structured grid in which the AUSM+ scheme is used to calculate the gas phase convective fluxes. The Spalart-Allmaras turbulence model is used in these simulations. First, the auto-ignition of solid fuel subject to an inlet oxidizer flow at elevated temperatures is considered and distinct intervals in ignition delay time are studied. We have demonstrated that for inlet oxidizer streams with high initial oxygen concentration levels and high enough inlet temperatures a diffusion-controlled ignition mechanism controls the ignition delay but at lower inlet temperatures, chemical kinetics has substantial effect on ignition delay time. Afterward the igniter jet exit location in solid fuel ramjet is analyzed. The results show that the step-top igniter can provide proper conditions for ignition transient. Finally, the piloted ignition of solid fuel subject to an igniter jet plume is investigated. The ignition delay time and the flame spreading speed are estimated. The results show that the flowfield behavior after igniter cutoff should be considered in the ignition transient studies.
  9. Keywords:
  10. Numerical Simulation ; Solid Fuel Ramjet ; Turbulent Reactive Flow ; Finite Rate Chemistry ; Ignition Transient

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