DOI: 10.1615/ICHMT.2017.CHT-7
ISBN Print: 9781-56700-4618
ISSN: 2578-5486
NUMERICAL INVESTIGATION OF FLASH BOILING FLOW INSIDE NOZZLE: SENSITIVITY ANALYSIS ON TURBULENCE MODELING APPROACHES
ABSTRAKT
This paper studies flash boiling flow inside convergent-divergent nozzle with non-equilibrium effects via Computational Multiphase Fluid Dynamics (CMFD) approach. In particular, a convergent-divergent nozzle considering initial sub-cooled water enters nozzle at temperature around 422K and flashing in range of pressure drop from 74 to 332.3 kPa, has been used as benchmark for numerical validation.
In this study the modeling of flash boiling flow with thermal and mechanical non-equilibrium effects in the convergent-divergent nozzle is proposed. Numerical results are compared with experimental data in terms of average global and local quantities (static pressure and vapor fraction).
A 2D axisymmetric domain and the mixture model for the multiphase modeling is used in the commercial finite-volume solver ANSYS Fluent rel.16.2.
Besides, different two-equation RANS turbulence models, with different near-wall treatments are studied to give a guideline of turbulence model effects on numerical results.
A sensitivity analysis of turbulence intensity at the inlet is carried out and its effects are analyzed in details.
Numerical results are in agreement with experimental data showing a relative error in term of mass flow rate of 1.1 - 6.4% and similar trend of global and local quantities such as static pressure and vapor fraction. Only Standard k − ε model shows higher errors in mass flow rate prediction.