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| Author(s): |
Edvaldo Angelo
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Escola Politécnica (EP/BC) |
| Defense date: | 2004-06-25 |
| Examining board members: |
José Roberto Simões Moreira;
Nisio de Carvalho Lobo Brum;
Eduardo Lobo Lustosa Cabral;
Míriam Tvrzská de Gouvêa;
Marcos de Mattos Pimenta
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| Advisor: | José R. Simões Moreira |
| Abstract | |
A high pressure and temperature fluid jet injected into a low-pressure chamber, whose pressure is lower than the corresponding saturation temperature, may remain in the liquid phase, which means that the liquid has reached the superheated or metastable state without any phase change within the injecting nozzle. Next, this superheated liquid undergoes a sudden phase change through a front or an evaporation wave process. This phase change takes the superheated liquid to a high-speed two-phase flow expanding in all directions. The present work solves the jump equations across the interface where the phase change is taking place, as well as the two-phase expansion region, which reaches increasing velocities and, usually, it involves the formation of a shock structure, as it has been observed in laboratory experiments. The problem solution is divided in two parts: (a) In the first part, it is considered that the superheated liquid exiting the nozzle comes to form a liquid core and the phase change process takes place on the surface of this core through an oblique evaporation wave. This approach is in accordance with experimental observations and it can explain some compressible phenomena present in experiments, such as shock waves and as well as flow choking; (b) In the second part, the classical numerical method of MacCormack is applied to solve the two-phase region along with a shock wave capturing scheme. It is assumed an axis-symmetric expansion (2-D)with a realistic equation-of-state to obtain the flow and properties region down the evaporation wave. There has been an excellent agreement between model and experiment results, whose data were compared to the ones obtained in the laboratory SISEA, as well as from other researchers. (AU) | |