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Experimental Study of the Effect of Divergence Angle on the Efficiency of Conical Nozzle in a Laboratory Solid Rocket Motor

Karimi, Farhad | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51840 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Farahani, Mohammad; Mohammadi, Alireza
  7. Abstract:
  8. Most propulsion systems use nozzles to increase the velocity of exhaust gas. Therefore, the efficiency of nozzles is important. Losses due to geometry and physical phenomena inside the nozzle define this efficiency. The length and divergence angle of the nozzle, the throat diameter, the Reynolds number, and the specifications and the combinations of fuel have a direct impact on these losses. Solid propellant rockets are widely used and today optimization of rockets is most noticeable. On the other hand, in different phases of design and optimization, empirical experiments are necessary, which are costly in real dimensions. The use of laboratory motors with specific considerations decrease the time and cost of design and optimization. In this project first, a test platform for the scaled rocket is designed and fabricated. This platform can measure pressure and thrust. Subsequently, the effect of divergence and nozzle length on the thrust coefficient and nozzle efficiency are studied using a number of the scaled solid propellant rocket. It is observed that the efficiency in terms of the divergence angle has an optimum point. Also, with the increase in the diameter of the aluminum particles in the solid propellant, in addition to reducing the nozzle efficiency, the characteristic speed or the combustion efficiency diminishes. Due to the fuel combinations, the combustion chamber length can determine characteristic speed. In fact, when the metal particles in the fuel do not have enough time(or space) to burn for complete combustion, we will see a decrease in the efficiency of the combustion chamber. According to this point, the combustion chamber dimensions used for a specific fuel must be checked. In the next step, using the results of the experimental tests, a real solid propellant rocket is optimized that has similar dimensions to the laboratory motors. In fact, the performance parameters of this rocket are optimized by using the experimental efficiency of the nozzle in terms of the nozzle divergence angle. The design and fabrication of a test stand with this characteristic and the optimization of the length of the rocket using the divergence angle are the need of the industry. Also, the use of the experimental results to improve the specifications of a real rocket is new research and experiment in the country
  9. Keywords:
  10. Nozzle Divergence Angle ; Trust Coefficient ; Laboratory Solid Propellant Motor ; Divergence Loss ; Viscous Loss ; Two Phase Loss

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