Modeling of solid-liquid flow inside conical diverging sections using computational fluid dynamics approach

•Flow separation is observed in short diverging sections.•The separation length is found to be a strong inverse function of Reynold's number.•The flow reattaches on slight increase in the section length.•Increasing section length experiences decreasing velocity gradient and increasing skin fric...

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Bibliographic Details
Published in:International journal of mechanical sciences Vol. 186; p. 105909
Main Authors: Singh, Harmanpreet, Kumar, Satish, Mohapatra, Saroj Kumar
Format: Journal Article
Language:English
Published: Elsevier Ltd 15.11.2020
Subjects:
3D computational fluid dynamics modelling
Coal water slurries
Conical diverging section
Flow separation
Flow visualization
Head-loss characteristics
Flow visualization
Conical diverging section
Head-loss characteristics
Coal water slurries
Flow separation
3D computational fluid dynamics modelling
ISSN:0020-7403, 1879-2162
Online Access:Get full text
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Summary:•Flow separation is observed in short diverging sections.•The separation length is found to be a strong inverse function of Reynold's number.•The flow reattaches on slight increase in the section length.•Increasing section length experiences decreasing velocity gradient and increasing skin friction.•The section that balanced velocity gradient and skin friction yielded minimum pressure loss and maximum pressure recovery. In a slurry pipeline, the diverging sections are an important pipe fitting and also a cause of major pressure loss and sometimes flow separation. To address this potential issue, the complex solid-liquid flow of coal water slurry through conical diverging sections is simulated using the computational fluid dynamics approach. Nine different geometries of the diverging sections are analyzed in the present study. The length of the diverging section is the key variable in the geometric variations and ranges from 0.05 m to 0.6 m. The influx velocity at the entrance of all the diverging sections is varied in the range of 0.5 m/s to 5 m/s. The mass concentration of the solids dispersed inside the liquid phase is varied from 10 to 60%. The results generated by the computational fluid dynamics tool are in good agreement with the experimental data. The design of the diverging section is evaluated based on results obtained for three characterization parameters viz. pressure recovery coefficient, head-loss across the diverging section and volumetric efficiency. The 0.3 m long diverging section is found to be the optimum design for best pressure recovery, maximum volumetric efficiency and lowest head-loss. [Display omitted]
ISSN:0020-7403
1879-2162
DOI:10.1016/j.ijmecsci.2020.105909