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CFD simulation of vortex flashing flows in convergent-divergent nozzles.

Number: pap. 2147

Author(s) : ZHU J., ELBEL S.

Summary

Vortex control is a novel two-phase convergent-divergent nozzle restrictiveness control mechanism by adjustable nozzle inlet vortex. It requires no change to the physical dimensions of the nozzle geometry. The control range of inlet pressures and mass flow rates that can be achieved by vortex control appears to be large enough to be suitable for numerous technical applications. This novel mechanism can potentially provide flow control with less sacrifice of nozzle efficiency, which is important in applications such as ejector cycles. It is also less vulnerable to clogging since the flow control is achieved without changing the flow area. However, the underlying mechanism behind the vortex control is still unclear. In this study, 3D CFD simulation of vortex flashing flows in convergent-divergent nozzles has been conducted in order to understand the vortex control effect. The simulation results show increase of nozzle restrictiveness after the application of inlet vortex and the predicted mass flow rates agree well with the experimental results under the same inlet and outlet conditions. More vapor has been generated in the divergent part of the nozzle after the inlet vortex is applied. Due to the much lower density of vapor compared to the liquid, when vortex is applied vapor bubbles are driven towards the nozzle center. Sensible heat of the liquid closer to the nozzle center can now be more utilized for bubble growth. It is believed that due to the more available liquid sensible heat, after the introduction of inlet vortex, vapor generation in the nozzle divergent part has thus been increased and flow control can be achieved.

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Pages: 9

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Details

  • Original title: CFD simulation of vortex flashing flows in convergent-divergent nozzles.
  • Record ID : 30024416
  • Languages: English
  • Source: 2018 Purdue Conferences. 17th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2018/07/09

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