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Investigation of the Effects of Injector Chamber Geometry on the Characteristics of the Produced Spray Along with the Phenomenon of Flash Evaporation

Taherinezhad, Ali | 2024

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 57367 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Kebriaee, Azadeh; Morad, Mohammad Reza
  7. Abstract:
  8. One of the most used and attractive topics in engineering is the atomization of fluids, which has many applications in the fields of combustion, pharmaceuticals, perfume sprays, etc. In some spray production mechanisms, especially in spray cans that benefit from liquid propellants, a phenomenon called flash evaporation occurs. This phenomenon, along with the geometric parameters of the expansion chamber, play a significant role in the quality of the produced spray. The advantages of using this phenomenon in the spray production process include: reducing chamber pressure, reducing droplet penetration and uniform dispersion. In this research, first, the steps and rules governing each section in the spray production path will be introduced, and then it will be explained by focusing on the phenomenon of physics governing the problem. By changing the parameter of the ratio of inlet to outlet in different pressure conditions, the optimal dimensions for butane hydrocarbon propellant have been calculated and the pressure range of the flash evaporation phenomenon and the conditions of suffocation in the chamber have been checked. Considering the vapor pressure of butane as the selected propellant and ethanol as the solvent for the occurrence of the flushing phenomenon, propellant molar fractions of 0.6 and 0.7 have been considered for the mixture and by checking the injection conditions, the flow inside the chamber was not exposed to suffocation. The range of aspect ratio determined to create spray conditions with the presence of flashing phenomenon was also determined. At the end, a relationship was developed to determine the optimal volume according to the presented model to calculate the growth of the bubble inside the chamber. The advantage of this relationship is the coverage of bubble growth in the regimes of inertia and thermal diffusion
  9. Keywords:
  10. Flash Atomization ; Spray System ; Two-Phase Flow Modeling ; Atomizer Design ; Spray System Geometry ; Injector Optimization

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