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Numerical Simulation of Reacting Flow with Chemical Kinetics using a Modified Dual-Algorithm

Ebrahimi Kebria, Hamid Reza | 2017

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 51064 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Darbandi, Masoud; Ghafourian, Akbar
  7. Abstract:
  8. An important issue in aerospace propulsion systems is the reacting flow analyses, which involve many different concepts and physics including various chemical reactions mechanisms and radiation and convection heat transfer physics. As known, the computer simulation is a powerful tool to analyze the reacting flow physics in various combusting environments. It can suitably provide details of both chemical reaction occurrences and heat transfer physics. In combustion environments, the temperature gradient is noticeably affected by the density gradient. On the other hand, the accurate modeling of density gradients highly affects the computational results. In practice, the density-based methods are seriously limited by instabilities if one uses them to treat low Mach number flows because of little density gradients in the flow field. In contrast, the pressure-based methods have sufficient capability to treat such flow fields. In this work, a dual pressure-based algorithm is suitably modified to analyze low Mach combustion flow fields. The current modified algorithm has the capability to treat very accurately the density gradients due to either the pressure or temperature field changes. This dual algorithm basically benefits from the analogy between the compressible and incompressible governing equations. This algorithm implements the equation of state to relate the density field to either pressure or temperature fields in both compressible and quasi-compressible flow domains. Contrary to the past classic pressure-based methods, the current developed analogy helps to avoid employing the Bousinesque estimation to relate the density field to the temperature field. Contrary to the past compressible algorithms, the current modified algorithm can readily solve the low Mach number flow fields without enouncing any instability. This is due to suitable link between the density and the temperature fields as well as the pressure field. The current improved algorithm and modified method are then used to simulate the low Mach flows with and without chemical reactions. In the low Mach reacting flow cases, the density is affected considerably not only by the pressure but also the temperature field gradients. The current work shows that the current developed method can smoothly solve the reacting flows fields assuming either compressible or incompressible flows. This is shown by testing various test cases regarding steady and unsteady conditions. The current results are validated with other numerical methods as well as the CFD software. The performed validations indicate that the current modified method is highly accurate, comparing with the past classical pressure-based methods
  9. Keywords:
  10. Numerical Simulation ; Reacting Flow ; Chemical Kinetic ; Simple Algorithm ; Laminar Premixed Flamel ; Mixed Flow ; Dual Purpose Algorithm ; Hydrogen-Air Mixting

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