Comparative Numerical Study of Two Turbulence Models for Airfoil Static and Dynamic Stall

Abstract The transfer of particles in laminar and turbulent flows has many applications in combustion systems, biological, environmental, nanotechnology. In the present study, a Combined Baffles Quick-Separation Device (CBQSD) is simulated numerically using the Eulerian-Lagrangian method and different turbulence models of RNG k-ε, k-ω, and RSM for 1–140 μm particles. A two-way coupling technique is employed to solve the particles’ flow. The effect of inlet flow velocity, the diameter of the splitter plane, and solid particles’ flow rate on the separation efficiency of the device is examined. The results demonstrate that the RSM turbulence model provides more appropriate results compared to RNG k-ε and k-ω models. Four thousand two hundred particles with the size distribution of 1–140 µm enter the device and 3820 particles are trapped and 380 particles leave the device. The efficiency for particles with a diameter greater than 28 µm is 100%. The complete separation of 22–28 μm particles occurs for flow rates of 10–23.5 g/s, respectively. The results reveal that the separation efficiency increases by increasing the inlet velocity, the device diameter, and the diameter of the particles.

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Computational Fluid Dynamics Evaluation of Heat Transfer Correlations for Sodium Flows in a Heat Exchanger

Journal of Heat Transfer ◽

10.1115/1.4000707 ◽

2010 ◽

Vol 132 (5) ◽

Cited By ~ 3

Author(s):

Seok-Ki Choi ◽

Seong-O Kim ◽

Hoon-Ki Choi

Keyword(s):

Heat Transfer ◽

Heat Exchanger ◽

Turbulence Model ◽

Numerical Solutions ◽

Numerical Study ◽

Cross Flow ◽

Turbulence Models ◽

Parallel Flow ◽

Sst Model ◽

Heat Transfer Correlations

A numerical study for the evaluation of heat transfer correlations for sodium flows in a heat exchanger of a fast breeder nuclear reactor is performed. Three different types of flows such as parallel flow, cross flow, and two inclined flows are considered. Calculations are performed for these three typical flows in a heat exchanger changing turbulence models. The tested turbulence models are the shear stress transport (SST) model and the SSG-Reynolds stress turbulence model by Speziale, Sarkar, and Gaski (1991, “Modelling the Pressure-Strain Correlation of Turbulence: An Invariant Dynamical System Approach,” J. Fluid Mech., 227, pp. 245–272). The computational model for parallel flow is a flow past tubes inside a circular cylinder and those for the cross flow and inclined flows are flows past the perpendicular and inclined tube banks enclosed by a rectangular duct. The computational results show that the SST model produces the most reliable results that can distinguish the best heat transfer correlation from other correlations for the three different flows. It was also shown that the SSG-RSTM high-Reynolds number turbulence model does not deal with the low-Prandtl number effect properly when the Peclet number is small. According to the present calculations for a parallel flow, all the old correlations do not match with the present numerical solutions and a new correlation is proposed. The correlations by Dwyer (1966, “Recent Developments in Liquid-Metal Heat Transfer,” At. Energy Rev., 4, pp. 3–92) for a cross flow and its modified correlation that takes into account of flow inclination for inclined flows work best and are accurate enough to be used for the design of the heat exchanger.

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Numerical Simulations of Heat Transfer and Fluid Flow for a Rotating High-Pressure Turbine

Volume 6: Turbomachinery, Parts A and B ◽

10.1115/gt2006-90016 ◽

2006 ◽

Cited By ~ 1

Author(s):

F. Mumic ◽

L. Ljungkruna ◽

B. Sunden

Keyword(s):

Heat Transfer ◽

High Pressure ◽

Fluid Flow ◽

Numerical Study ◽

Three Dimensional ◽

Turbulence Models ◽

High Pressure Turbine ◽

Experimental Heat ◽

Commercial Code ◽

Stator Vane

In this work, a numerical study has been performed to simulate the heat transfer and fluid flow in a transonic high-pressure turbine stator vane passage. Four turbulence models (the Spalart-Allmaras model, the low-Reynolds-number realizable k-ε model, the shear-stress transport (SST) k-ω model and the v2-f model) are used in order to assess the capability of the models to predict the heat transfer and pressure distributions. The simulations are performed using the FLUENT commercial software package, but also two other codes, the in-house code VolSol and the commercial code CFX are used for comparison with FLUENT results. The results of the three-dimensional simulations are compared with experimental heat transfer and aerodynamic results available for the so-called MT1 turbine stage. It is observed that the predictions of the vane pressure field agree well with experimental data, and that the pressure distribution along the profile is not strongly affected by choice of turbulence model. It is also shown that the v2-f model yields the best agreement with the measurements. None of the tested models are able to predict transition correctly.

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The Role of Turbulence Models for Predicting a Thermal Stratification

Journal of Pressure Vessel Technology ◽

10.1115/1.2371078 ◽

2006 ◽

Vol 128 (4) ◽

pp. 656-662 ◽

Cited By ~ 1

Author(s):

Seok-Ki Choi ◽

Seong-O Kim

Keyword(s):

Liquid Metal ◽

Thermal Stratification ◽

Transport Model ◽

Numerical Study ◽

Turbulence Models ◽

Liquid Metal Reactor ◽

Temporal Oscillation ◽

Elliptic Relaxation ◽

Shear Stress Transport Model

A numerical study of the evaluation of turbulence models for predicting the thermal stratification phenomenon is presented. The tested models are the elliptic blending turbulence model (EBM), the two-layer model, the shear stress transport model (SST), and the elliptic relaxation model (V2-f). These four turbulence models are applied to the prediction of a thermal stratification in an upper plenum of a liquid metal reactor experimented at the Japan Nuclear Cooperation (JNC). The EBM and V2-f models predict properly the steep gradient of the temperature at the interface of the cold and hot regions that is observed in the experimental data, and the EBM and V2-f models have the capability of predicting the temporal oscillation of the temperature. The two-layer and SST models predict the diffusive temperature gradient at the interface of a thermal stratification and fail to predict a temporal oscillation of the temperature. In general, the EBM predicts best the thermal stratification phenomenon in the upper plenum of the liquid metal reactor.

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Numerical Study of Turbulence Models in heat Transfer of a Confined and Submerged Jet Impingement using AL2O3 - water Nano Fluid

International Journal of Mechanical Engineering ◽

10.14445/23488360/ijme-v2i5p118 ◽

2015 ◽

Vol 2 (5) ◽

pp. 47-55

Author(s):

Amir H Ghahremani ◽

Reza Saleh

Keyword(s):

Heat Transfer ◽

Numerical Study ◽

Turbulence Models ◽

Jet Impingement ◽

Submerged Jet ◽

Nano Fluid

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Assessment of Different Turbulence Models for Predicting Laminar Separation Bubble Over Thick Airfoils

ASME 2015 Gas Turbine India Conference ◽

10.1115/gtindia2015-1277 ◽

2015 ◽

Cited By ~ 1

Author(s):

Saravana Kumar Lakshmanan ◽

Alok Mishra ◽

Ashoke De

Keyword(s):

Reynolds Number ◽

Numerical Study ◽

Separation Bubble ◽

Turbulence Models ◽

Laminar Separation Bubble ◽

Laminar Separation ◽

Performance Variables ◽

Rans Models ◽

High Angles Of Attack ◽

Aerodynamic Lift

Accurate laminar-turbulent prediction is very much important to understand the complete performance characteristics of any airfoil which operates at low and medium Reynolds number. In this article, a numerical study has been performed over two different thick airfoils operating at low Reynolds number using k-ω SST, k-kl-ω and Spalart-Allmaras (SA) RANS models. The unsteady two dimensional (2D) simulations are performed over NACA 0021 and NACA 65-021 at Re 120,000 for a range of angle of attacks. The performances of these models are assessed through aerodynamic lift, drag and pressure coefficients. To obtain better comparison, the simulated results are compared with the experimental measurements and XFOIL results as well. In this present study, it is found that the k-kl-ω transition model is capable of predicting correct lift, drag coefficient and separation bubble as reported in experiments. At high angles of attack, this model fails to predict performance variables accurately. The SA and SST models are fail to predict laminar separation bubble. However, At high angle of attack, SA model shows better predictions compared to k-kl-ω and k-ω SST models.

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