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Improving the Performance of a Hybrid Hot/Cold Laboratory Microthruster Using CFD Analysis

Karimi, Sepideh | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48720 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Darbandi, Masoud
  7. Abstract:
  8. Micro/Nano science has obtained enormous applications in aerospace engineering especially in the propulsion system of micro/nano satellites. The satellite attitude control is a vital part of every space mission. Different thruster systems have been already suggested and utilized to achieve this important mission correctly. Considering the future perspectives of space missions for small satellites, the development of micro/nano thrusters has been attracted more attention since the last decades. The scope of this research is to analyze hybrid hot/cold laboratory supersonic micro-thrusters especially for the micro-satellite implementations. The ultimate goal of the current research is to achieve the possible maximum thrust force fixing the mass flow rate. This research and its outcome can be treated as an innovation in our country. To arrive to an optimal micro-thruster, the available nozzles and pertinent operational constraints are reviewed first. Next, a sample micro-thruster is chosen to validate the numerical tools, i.e. the FLUENT. Then, the geometry is modeled and the flow is simulated. Next is to design the required geometries of the supersonic nozzles via the well-known characteristic method, which is coded in this work. The inputs to this code are the exit Mach number and the ratio of specific heats (gamma) of the operating fluid and the output is to obtain the proposed geometry. In this regards different nozzle configurations are tested and the best ones are selected according to their generated thrust values. In this study, the independencies of the numerical solutions from the mesh size and the external domain sizes are ensured as well. The current results show that as the divergence length scale increases at viscous cold gas flow case, the achieved thrust first increases and decreases then. Alternatively, the same area ratios for the inviscid cold gas flow. As the exit Mach number (and proportionally area ratio) increases for the viscous cold gas flow case, the effect of divergence length scale increases. A lower divergence length scale would increase the thrust. However, the trust decreases at higher divergence length scales. For the hot gas flow case, the thrust always increases as the inlet temperature increases. However, as the divergence length scale increases the sensitivity of thrust to Mach number decreases. At viscous hot gas flow case, the thrust-exit Mach number always reinforces the same trend. Considering the achieved results for implementing different geometry cases and two hot and cold gas conditions with each other, it is found thrust will be attainable at specific divergence length scale value, which can be considered as the optimum nozzle configuration for the proposed two-purposes applications
  9. Keywords:
  10. Simulation ; Modeling ; Microsatellite ; Micronozzle ; Micropropulsion ; Computational Fluid Dynamics (CFD) ; Hot Gas ; Cold Gas

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