scholarly journals Impingement Heat Transfer: Correlations and Numerical Modeling

2005 ◽  
Vol 127 (5) ◽  
pp. 544-552 ◽  
Author(s):  
Neil Zuckerman ◽  
Noam Lior
Keyword(s):  
Heat Transfer ◽  
Turbulence Models ◽  
Impinging Jet ◽  
Reynolds Stress Model ◽  
Model Errors ◽  
Simulation Techniques ◽  
Flow And Heat Transfer ◽  
Impingement Heat Transfer ◽  
Model Equations ◽  
Stress Models

Uses of impinging jet devices for heat transfer are described, with a focus on cooling applications within turbine systems. Numerical simulation techniques and results are described, and the relative strengths and drawbacks of the k-ε,k-ω, Reynolds stress model, algebraic stress models, shear stress transport, and v2f turbulence models for impinging jet flow and heat transfer are compared. Select model equations are provided as well as quantitative assessments of model errors and judgments of model suitability.

CFD Prediction for Multi-Jet Impingement Heat Transfer

2009 ◽  
Author(s):  
Y. Q. Zu ◽  
Y. Y. Yan ◽  
J. D. Maltson
Keyword(s):  
Heat Transfer ◽  
Shear Stress ◽  
Computational Cost ◽  
Turbulence Models ◽  
Jet Impingement ◽  
Reynolds Stress Model ◽  
Large Eddy Simulation Model ◽  
Flow And Heat Transfer ◽  
Shear Stress Transport ◽  
Impingement Heat Transfer

In this paper, the flow and heat transfer characteristics of two lines of staggered or inline round jets impinging on a flat plate are numerically analyzed using the CFD commercial code FLUENT. Firstly, the relative performance of seven versions of turbulence models, including the standard k-ε model, the renormalization group k-ε model, the realizable k-ε model, the standard k-ω model, the Shear-Stress Transport k-ω model, the Reynolds stress model and the Large Eddy Simulation model, for numerically predicting single jet impingement heat transfer is investigated by comparing the numerical results with available benchmark experimental data. As a result, the Shear-Stress Transport k-ω model is recommended as the best compromise between the computational cost and accuracy. Using the Shear-Stress Transport k-ω model, the impingement flow and heat transfer under multi-jets with different jet distributions and attack angles are simulated and studied. The effect of hole distribution and angle of attack, etc. on the heat transfer coefficient of the target plate are examined.

Steady RANS of Flow and Heat Transfer in a Smooth and Pin-Finned U-Duct With a Trapezoidal Cross Section

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Kenny S.-Y. Hu ◽  
Xingkai Chi ◽  
Tom I.-P. Shih ◽  
Minking Chyu ◽  
Michael Crawford
Keyword(s):  
Heat Transfer ◽  
Relative Error ◽  
Turbulence Models ◽  
Separated Flow ◽  
Reynolds Stress Model ◽  
Navier Stokes ◽  
Maximum Relative Error ◽  
Flow And Heat Transfer ◽  
Pin Fins ◽  
Turn Region

Steady Reynolds-averaged Navier--Stokes (RANS) simulations were performed to examine the ability of four turbulence models—realizable k–ε (k–ε), shear-stress transport (SST), Reynolds stress model with linear pressure strain (RSM-LPS), and stress-omega RSM (RSM-τω)—to predict the turbulent flow and heat transfer in a trapezoidal U-duct with and without a staggered array of pin fins. Results generated for the heat-transfer coefficient (HTC) were compared with experimental measurements. For the smooth U-duct, the maximum relative error in the averaged HTC in the up-leg is 2.5% for k–ε, SST, and RSM-τω and 9% for RSM-LPS. In the turn region, the maximum is 50% for k–ε and RSM-LPS, 14.5% for RSM-τω, and 29% for SST. In the down-leg, SST gave the best predictions and RSM-τω being a close second with maximum relative error less than 10%. The ability to predict the separated flow downstream of the turn dominated the performance of the models. For the U-duct with pin fins, SST and RSM-τω predicted the best, and k–ε predicted the least accurate HTCs. For k–ε, the maximum relative error is about 25%, whereas it is 15% for the SST and RSM-τω, and they occur in the turn. In the turn region, the staggered array of pin fins was found to behave like guide vanes in turning the flow. The pin fins also reduced the size of the separated region just after the turn.

Flow and Heat Transfer Predictions for a Flat-Tip Turbine Blade

2002 ◽  
Author(s):  
Huitao Yang ◽  
Sumanta Acharya ◽  
Srinath V. Ekkad ◽  
Chander Prakash ◽  
Ron Bunker
Keyword(s):  
Heat Transfer ◽  
Reynolds Stress ◽  
Turbulence Models ◽  
Reynolds Stress Model ◽  
Computational Effort ◽  
Stress Model ◽  
Tip Leakage Flow ◽  
Flow And Heat Transfer ◽  
Pitch Direction ◽  
Blade Tip

Numerical calculations are performed to simulate the tip leakage flow and heat transfer on the GE-E3 High-Pressure-Turbine (HPT) rotor blade. The calculations are performed for a single blade with periodic conditions imposed along the two boundaries in the circumferential-pitch direction. Cases considered are a flat blade tip at three different tip gap clearances of 1%, 1.5% and 2.5% of the blade span. The numerical results are obtained for two different pressure ratios (ratio of inlet total pressure to exit static pressure) of 1.2 and 1.32 and an inlet turbulence level of 6.1%. To explore the effect of turbulence models on the heat transfer results, three different models of increasing complexity and computational effort (standard high Re k-ε model, RNG k-ε and Reynolds Stress Model) are investigated. The predicted tip heat transfer results are compared with the experimental data of Azad [1], and show satisfactory agreement with the data. Hear transfer predictions for all three turbulence models are comparable, and no significant improvements are obtained with the Reynolds-stress model.

Stagnation Point and Surface Heat Transfer for a Turbine Stage: Prediction and Comparison With Data

1989 ◽  
Vol 111 (1) ◽  
pp. 28-35 ◽  
Author(s):  
D. B. Taulbee ◽  
L. Tran ◽  
M. G. Dunn
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Stagnation Point ◽  
Initial Conditions ◽  
Turbulence Models ◽  
Reynolds Stress Model ◽  
Surface Heat ◽  
Mean Velocity ◽  
Surface Heat Transfer ◽  
Model Equations

Predictions using turbulence models are reported for the time-averaged heat-flux distributions on the vane and blade surfaces of the Garrett TFE 731-2 HP and Teledyne CAE 702 HP turbines. To provide the proper initial conditions for the boundary layer solution, the stagnation point process starting from the far free stream is considered. The mean velocity and temperature and the turbulence variation along the stagnation streamline are predicted with a Reynolds stress model so as to resolve accurately the turbulent normal stresses that govern the production of turbulence in the stagnating flow. Using the results from the stagnation solution as initial conditions, the k–ε model equations in boundary layer form are solved at midspan for the pressure and suction sides of the vane and the blade, using a pressure distribution obtained from inviscid codes. The predicted surface heat transfer distributions are compared with measurements from short-duration full-stage rotating turbine measurements.

Two-Equation Versus Reynolds-Stress Modeling in Predicting Flow and Heat Transfer in a Smooth U-Duct With and Without Rotation

2002 ◽  
Author(s):  
X. Gu ◽  
H.-W. Wu ◽  
H. J. Schock ◽  
T. I.-P. Shih
Keyword(s):  
Heat Transfer ◽  
Reynolds Stress ◽  
Turbulence Models ◽  
Reynolds Stress Model ◽  
Surface Heat ◽  
Small Radius ◽  
Stress Model ◽  
Surface Heat Transfer ◽  
Flow And Heat Transfer ◽  
Significant Difference

Computations were performed by using Version 5.5 of the Fluent-UNS code to compare two turbulence models in predicting the three-dimensional flow and heat transfer in a smooth duct of square cross section with a small radius of curvature 180-degree bend under rotating and non-rotating conditions (Re = 25,000; Ro = 0.0 and 0.24). The two turbulence models investigated are the standard k-ε model and a Reynolds stress model. For both models, the two-layer low-Reynolds model of Chen and Patel was used in the near-wall region. Results obtained show that though the k-ε model predicts turbulence quantities incorrectly, the predicted velocity and temperature fields and the surface heat transfer are similar to those from the Reynolds stress model when there is no rotation. When there is rotation, there is significant difference in the predicted surface heat transfer on the leading surface. But, the predicted flow field is still qualitatively similar.

Comparison Between EVM and RSM Turbulence Models in Predicting Flow and Heat Transfer in Rib-Roughened Channels

2004 ◽  
Author(s):  
A. K. Sleiti ◽  
J. S. Kapat
Keyword(s):  
Heat Transfer ◽  
Reynolds Stress ◽  
Turbulence Models ◽  
Reynolds Stress Model ◽  
Wall Region ◽  
Internal Cooling ◽  
Wall Functions ◽  
Flow And Heat Transfer ◽  
Near Wall ◽  
Rib Roughened

A 3-D analysis of two-equation eddy-viscosity (EVMs) and Reynolds stress (RSM) turbulence models and their application to solving flow and heat transfer in rotating rib-roughened internal cooling channels is the main focus of this study. The flow in theses channels is affected by ribs, rotation, buoyancy, bends and boundary conditions. The EVMs considered are: The standard k–ε Model: of Launder and Spalding Launder and Spalding [1], the Renormalization Group k-ε model: Yakhot and Orszag [2], the Realizable k-ε model Shur et al. [3], the standard k-ω Model, Wilcox Wilcox [4], and the Shear-Stress Transport (SST) k-ω Model, Menter [5]. The viscosity affected near wall region is resolved by enhanced near wall treatment using combined two-layer model with enhanced wall functions. The results for both stationary and rotating channels showed the advantages of Reynolds Stress Model (RSM), Gibson and Launder [6], Launder [7], Launder [8] in predicting the flow field and heat transfer compared to the isotropic EVMs that need corrections to account for streamline curvature, buoyancy and rotation.

Effects of alternating elliptical chamber on jet impingement heat transfer in vane leading edge under different cross-flow conditions

2021 ◽  
pp. 1-17
Author(s):  
K. Xiao ◽  
J. He ◽  
Z. Feng
Keyword(s):  
Heat Transfer ◽  
Velocity Ratio ◽  
Cross Flow ◽  
Leading Edge ◽  
Longitudinal Vortices ◽  
Impingement Jet ◽  
Flow And Heat Transfer ◽  
Impingement Heat Transfer ◽  
Cross Flow Velocity ◽  
The Cross

ABSTRACT This paper proposes an alternating elliptical impingement chamber in the leading edge of a gas turbine to restrain the cross flow and enhance the heat transfer, and investigates the detailed flow and heat transfer characteristics. The chamber consists of straight sections and transition sections. Numerical simulations are performed by solving the three-dimensional (3D) steady Reynolds-Averaged Navier–Stokes (RANS) equations with the Shear Stress Transport (SST) k– $\omega$ turbulence model. The influences of alternating the cross section on the impingement flow and heat transfer of the chamber are studied by comparison with a smooth semi-elliptical impingement chamber at a cross-flow Velocity Ratio (VR) of 0.2 and Temperature Ratio (TR) of 1.00 in the primary study. Then, the effects of the cross-flow VR and TR are further investigated. The results reveal that, in the semi-elliptical impingement chamber, the impingement jet is deflected by the cross flow and the heat transfer performance is degraded. However, in the alternating elliptical chamber, the cross flow is transformed to a pair of longitudinal vortices, and the flow direction at the centre of the cross section is parallel to the impingement jet, thus improving the jet penetration ability and enhancing the impingement heat transfer. In addition, the heat transfer in the semi-elliptical chamber degrades rapidly away from the stagnation region, while the longitudinal vortices enhance the heat transfer further, making the heat transfer coefficient distribution more uniform. The Nusselt number decreases with increase of VR and TR for both the semi-elliptical chamber and the alternating elliptical chamber. The alternating elliptical chamber enhances the heat transfer and moves the stagnation point up for all VR and TR, and the heat transfer enhancement is more obvious at high cross-flow velocity ratio.

Investigation of Leakage Flow and Heat Transfer in a Gas Turbine Blade Tip With Emphasis on the Effect of Rotation

2008 ◽  
Author(s):  
Dianliang Yang ◽  
Xiaobing Yu ◽  
Zhenping Feng
Keyword(s):  
Heat Transfer ◽  
Relative Motion ◽  
Turbulence Models ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Blade Height ◽  
Tip Leakage ◽  
Flow And Heat Transfer ◽  
Blade Rotation ◽  
Blade Tip

In this paper, numerical methods have been applied to the investigation of the effect of rotation on the blade tip leakage flow and heat transfer. Using the first stage rotor blade of GE-E3 engine high pressure turbine, both flat tip and squealer tip have been studied. The tip gap height is 1% of the blade height, and the groove depth of the squealer tip is 2% of the blade height. Heat transfer coefficient on tip surface obtained by using different turbulence models was compared with experimental results. And the grid independence study was carried out by using the Richardson extrapolation method. The effect of the blade rotation was studied in the following cases: 1) blade domain is rotating and shroud is stationary; 2) blade domain is stationary and shroud is rotating; and 3) both blade domain and shroud are stationary. In this approach, the effects of the relative motion of the endwall, the centrifugal force and the Coriolis force can be investigated respectively. By comparing the results of the three cases discussed, the effects of the blade rotation on tip leakage flow and heat transfer are revealed. It indicated that the main effect of the rotation on the tip leakage flow and heat transfer is resulted from the relative motion of the shroud, especially for the squealer tip blade.

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