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Numerical study of heat and mass transfer in underexpanded sonic free jet

Adibi, O ; Sharif University of Technology

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  1. Type of Document: Article
  2. DOI: 10.18280/ijht.350432
  3. Abstract:
  4. In case of unexpected ruptures in high pressure tanks, choking phenomenon occurs in the cracked area which fluid velocity gets sonic and its pressure exceeds atmospheric pressure. Afterward, pressure of discharged gas quickly changes by crossing through compression and expansion shock waves. The main aim of this study was numerical simulation and investigation of this flow in a 3-step process: (a) Detailed analysis of numerical method, (b) Qualitative and quantitative analysis of velocity, pressure, temperature and turbulence intensity, in order to propose safety strategies and (c) parametric studies on the effects of tank pressure and nozzle geometry on flow structure. In numerical simulations, governing equations (conservation of mass, momentum, energy and equation of state) were discretized based on the finite volume method and flow variables (velocity, pressure, temperature and density) were calculated using density-based algorithm. Validation of numerical method was achieved by comparison with experimental data. The results showed that within 4.4 mm of cracked area, fluid temperature reached to its minimum value of 86 K which would freeze nearby equipment and would make them fragile. Also, parametric studies indicated that inlet pressure had direct relation with exhausted mass flow rate and its maximum occurred in nozzle angle of 3.82
  5. Keywords:
  6. Numerical simulation ; Sonic free jets ; Atmospheric pressure ; Computer simulation ; Cracks ; Equations of state ; Finite volume method ; Mass transfer ; Nozzles ; Numerical models ; Shock waves ; Tanks (containers) ; Conservation of mass ; Density-based algorithm ; Free jets ; Gas release ; Heat and mass transfer ; High-pressure tanks ; Qualitative and quantitative analysis ; Turbulence intensity ; Numerical methods
  7. Source: International Journal of Heat and Technology ; Volume 35, Issue 4 , 2017 , Pages 959-968 ; 03928764 (ISSN)
  8. URL: http://www.iieta.org/sites/default/files/Journals/IJHT/35.04_32.pdf