Numerical Modeling of Fuel Droplet Vaporization in Gas Phase at Supercritical Conditions

Rajabi Matin, Zahra | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42017 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Hejranfar, Kazem
  7. Abstract:
  8. The study of evaporation of fuel droplet and determination of the rate of vaporization are important in designing combustion chambers. For achieving high performance of a combustor, the evaporation of fuel droplets takes place within a high pressure environment. At these conditions, the use of low-pressure models is not appropriate and many effects that are assumed negligible at low ambient pressures become very important. For example, the solubility of the ambient gas into the liquid phase is increased by increasing the ambient pressure. In addition, the ideal gas assumption is not valid for these conditions and one should use an appropriate equation of state (EOS) that can predict the thermo-physical properties of gas and liquid in a wide range of ambient conditions. In this study, a numerical modeling of droplet vaporization at supercritical conditions is presented. The model is based on the time-dependant conservation equations for both liquid and gas phases with pressure-dependent thermo-physical properties. The Peng-Robinson EOS is used to represent phase equilibrium at the droplet surface. For numerical solution of the governing equations (including conservation of mass, momentum and energy for gas phase and conservation of mass and energy for liquid phase), a second-order central finitedifference scheme is used and an arbitrary Eulerian-Lagrangian approach is adopted to properly define and track the liquid-vapor interface. Results are presented for the evaporation of n-Heptan and n-Hexan droplets in nitrogen environment. The effect of theambient pressure on the vaporization characteristics is also studied
  9. Keywords:
  10. Droplet Vaporization ; Numerical Transient Model ; Evaporation Rate

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