Fluid Flow and Heat Transfer Characteristics of Backward-Facing Step Flow with Large Expansion Ratio

2019 ◽  
Vol 2019.25 (0) ◽  
pp. 19B13
Author(s):  
Takeshi IGARASHI ◽  
Masatoshi SANO
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Expansion Ratio ◽  
Heat Transfer Characteristics ◽  
Backward Facing Step ◽  
Step Flow ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Large Expansion

scholarly journals The effect of volume fraction of SiO2 nanoparticle on flow and heat transfer characteristics in a duct with corrugated backward-facing step

2018 ◽  
Vol 22 (Suppl. 5) ◽  
pp. 1435-1447 ◽  
Author(s):  
Recep Ekiciler ◽  
Emre Aydeniz ◽  
Kamil Arslan
Keyword(s):  
Heat Transfer ◽  
Volume Fraction ◽  
Numerical Study ◽  
Expansion Ratio ◽  
Uniform Heat Flux ◽  
Heat Transfer Characteristics ◽  
Backward Facing Step ◽  
Nanofluid Flow ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer

In this paper, flow and heat transfer characteristics of SiO2-water nanofluid flow over a corrugated backward-facing step are numerically investigated. The numerical study is performed by solving governing equations (continuity, momentum, and energy) with finite volume method. The duct inlet and step heights are 4.8 mm. The expansion ratio is 2. The upstream wall, Lu, and downstream wall, Ld, lengths are 48 cm and 96 cm, respectively. The downstream wall of the duct is subjected to a constant and uniform heat flux of 2000 W/m2. The ranges of the volume fraction of nanoparticles and Reynolds number are 0%-3.0% and 135-240, respectively. The effects of the volume fraction of nanoparticles on the average Nusselt number, average Darcy friction factor, and velocity distribution are investigated under laminar forced convective nanofluid flow condition. It is revealed that the nanoparticle volume fraction substantially influences the heat transfer and flow characteristics. The volume fraction of 3.0% shows the highest heat transfer performance.

scholarly journals Uncertainties Analysis on the Prediction of Flow and Heat Transfer of Liquid Sodium with CFD Technology

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Zhanwei Liu ◽  
Xinyu Li ◽  
Tenglong Cong ◽  
Rui Zhang ◽  
Lingyun Zheng ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Friction Coefficient ◽  
Liquid Sodium ◽  
Heat Transfer Characteristics ◽  
Backward Facing Step ◽  
Heating Wall ◽  
Transfer Characteristics ◽  
Cfd Models ◽  
Flow And Heat Transfer

The prediction of flow and heat transfer characteristics of liquid sodium with CFD technology is of significant importance for the design and safety analysis of sodium-cooled fast reactor. The accuracies and uncertainties of the CFD models should be evaluated to improve the confidence of the numerical results. In this work, the uncertainties from the turbulent model, boundary conditions, and physical properties for the flow and heat transfer of liquid sodium were evaluated against the experimental data. The results of uncertainty quantization show that the maximum uncertainties of the Nusselt number and friction coefficient occurred in the transition zone from the inlet to the fully developed region in the circular tube, while they occurred near the reattachment point in the backward-facing step. Furthermore, in backward-facing step flow, the maximum uncertainty of temperature migrated from the heating wall to the geometric center of the channel, while the maximum uncertainty of velocity occurred near the vortex zone. The results of sensitivity analysis illustrate that the Nusselt number was negatively correlated with the thermal conductivity and turbulent Prandtl number, while the friction coefficient was positively correlated with the density and Von Karman constant. This work can be a reference to evaluate the accuracy of the standard k-ε model in predicting the flow and heat transfer characteristics of liquid sodium.

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