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Numerical Study of Unsteady Swirl Injector Spray

Khodaverdian, Roozbeh | 2019

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52419 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Morad, Mohammad Reza; Kebriaee, Azadeh; Jahan Nama, Mohammad Reza
  7. Abstract:
  8. Iin this thesis, evaporation of droplets of a spray from a pressure-swirl injector in a sub-atmospheric combustion chamber is studied. The liquid used in this sudy is a hypergolic oxidizer, Dinitrogen Tetroxide, also known as NTO. The significance of this thesis is its application during the cold startup of a satellite thruster when only oxidizer is injected into the combustion chamber. The most important phenomemon in this stage which is also the focal point for this study, is the ‘Flashing’. In this phenomenon a liquid having a temperature above the boiling point of its own species (for the surrounding gas pressure) is present in the solution field. This state is a non-equilibrium state. Thus triggers a fast kind of evaporation in order to lower the temperature of the droplet and the surrounding gas, known as ‘Flash Evaporation’. In this study a computational method for analyzing this evaporation and the resulting circumstances is presented. The method further is validated using a study with liquid oxygen as its working fluid. This particular model then is applied to a special case with pre-determined conditions and the results are presented and discussed. In the results it is shown that a 20 ms gap before injecting the fuel is necessary for reaching a stable continuous phase. Maximum pressure calculated for the solution field is 7100 pag. It is also shown that the flashing is a very swift kind of evaporation occurring only on a quarter of the combustion chamber length
  9. Keywords:
  10. Flash Evaporation ; Flash Atomization ; Pressure-Swirl Injectors ; Transient Solution ; Discrete Particle Swarm Optimization (PSO)Algorithm ; Thruster

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