Evaluation of different nucleation models and droplet radius averaging methods and their combination on condensing steam flow

Authors

1 Master of Science Student/ Hakim Sabzevari University

2 Assistant Professor of Mechanics/Hakim Sabzevari University

3 Professor of Mechanics/Ferdowsi University of Mashhad

Abstract

During the course of expansion of steam in LP steam turbines, the vapor becomes supersaturated, and subsequently nucleates. Then condensation occurs, that causes some damages. Exact prediction of wetness terms, and formed droplets radius has extensive effects on accurate estimation of the flow properties, and damages due to vapor condensation. Nucleation rate is one of the governing equations of liquid phase which finally determines number of generated droplets. Considering exchange of mass and energy between two phases, different models of radius averaging at each cross-section of nozzle have been used. In the present investigation, various nucleation models have been combined with different droplet radius averaging methods in a semi-analytical Eulerian-Lagrangian model. The pressure distribution and droplets radius, in several cases, have been compared with experimental data. According to the results, using Girshik-Chiu’s refinement on Hale’s nucleation model with simultaneous application of Sauter averaging approach, provide the best prediction of the flow properties. In addition, classical nucleation equation with Girshick-Chiu’s refinement and without any refinement in combination with Sauter averaging approach; are standing on the second and third ranks and specially focusing on the pressure distributions.

Keywords

Main Subjects

References

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Journal of Solid and Fluid Mechanics
Volume 5, Issue 1 - Serial Number 1
March and April 2015
Pages 193-209

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