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Numerical Investigation of Cavitation Phenomenon in the Turbopump Inducer of Cryogenic Engines

Sedaghi, Reza | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52269 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Farshchi, Mohammad; Ebrahimi Chamgardani, Abbas
  7. Abstract:
  8. Simulation of the flow inside a turbopump inducer of a cryogenic engine, can help to reduce the number of experimental tests in the design phase. In cryogenic engines, high speed of the turbo pump, engine working at off-design conditions, startup and shutdown of the engine, can cause the pressure to drop below the vapor pressure at the inducer blades. In such circumstances, cavitation bubbles start to grow and collapse as they are washed by the flow to the regions with higher pressure. Cavitation is the rapid formation and collapse of vapour cavities in a liquid.The energy required for evaporation is received from the surrounding liquid which causes the temperature to drop in the cavitational area. In cryogenic engines, the operating point of the fluid is close to the critical point in which the ratio of the liquid phase density to the vapor density is very low. On the other hand the slope of vapor pressure against temperature is very steep. These conditions introduce thermodynamic effects of cryogenic cavitation. Owning a frothy and smaller cavitational region compared to the cavitation of water at 20oC as well as performance improvement of a cavitating inducer (due to the delay of NPSH breakdown) in cryogenic fluids are known as the thermodynamic effects. In the present thesis, the ability to capture the thermodynamic effects is added to the “Schnerr & Sauer” cavitation model by using UDF in ANSYS FLUENT. To validate the model, cavitational flow around axisymmetric body with hemispherical head in liquid water was simulated. To validate the UDF code simulation of cryogenic cavitational flow around a 2D hydrofoil was performed. Finally, cavitational and noncavitational flow was investigated in two cryogenic inducers. The numerical method is finite volume and the turbulence model is k ω SST. The results were compared with the experimental results at each step
  9. Keywords:
  10. Cavitation ; Thermodynamic Effects ; Turbopump Inducer ; Cryogenic Engines ; Numerical Investigation ; Flow Simulation

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