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Modeling of Micro Combustion Applying Electrohydrodynamics Effects

Behroozinia, Pooya | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43380 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Saeedi, Mohammad Hassan; Mozafari, Ali Asghar
  7. Abstract:
  8. In this project, one-dimensional and two-dimensional numerical approaches are used to study the effect of applying electrohydrodynamics on the temperature and species mass fraction profiles along the micro-combustor. A premixed mixture of H2-Air with a multi-step chemistry (9 species and 19 reactions) is used and thermal conductivity of the mixture is considered as a function of species thermal conductivity and temperature by using a set of new relations. Both thermal and radical quenching mechanisms are important in the micro-scale combustion due to increasing of area-to-volume ratio and significant heat loss from the combustor walls. By inserting a number of electrodes into the micro-combustor and applying voltage to them corona discharge occurs. This yields to induced ions that move to natural molecules accident with them. So this phenomenon causes the movement of the molecules that reattaches the flow to the walls and so increases the velocity near the walls that reduces the boundary layer on it. Consequently, applying electrohydrodynamics mechanism can enhance the temperature profile in the micro-combustor. Thus, this way, prevent the flame quenching in the micro-combustor. The transient gas phase energy and species conservation equations result in an Advection-Diffusion-Reaction system (A-D-R) that leads to two stiff systems of PDEs, which cannot be solved by conventional Computational Fluid Dynamics (CFD) methods. In the present work, Strang splitting method, which is suitable for nonlinear stiff system of PDEs, is used. The results show that this innovative method enhances the temperature profile along the micro- combustor. Interestingly, maximum temperature that located in the flame zone increases about 70 K by corona effect. Furthermore, uniform temperature that occurs in the middle of combustor along to the end of it increases about 200 K. In addition, increasing the convective heat transfer coefficient decreases the temperature and active radicals along the micro combustor. Increasing the inlet flow’s velocity also increases the temperature profile
  9. Keywords:
  10. Combustion ; Temperature Profile ; Electrohydrodynamic ; Wall Quenching

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