Airfoil Heat Transfer Calculation Using a Low Reynolds Number Version of a Two-Equation Turbulence Model

1985 ◽  
Vol 107 (1) ◽  
pp. 60-67 ◽  
Author(s):  
J. H. Wang ◽  
H. F. Jen ◽  
E. O. Hartel
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Reynolds Number ◽  
Turbulence Model ◽  
Low Reynolds Number ◽  
Transitional Flow ◽  
Zone Model ◽  
Suction Surface ◽  
Free Stream Turbulence ◽  
Low Reynolds

A two-dimensional, boundary-layer program, STAN5, was modified to incorporate a low-Reynolds number version of the K-ε, two-equation turbulence model for the predictions of flow and heat transfer around turbine airfoils. The K-ε, two-equation model with optimized empirical correlations was used to account for the effects of free-stream turbulence and transitional flow. The model was compared with experimental flat plate data and then applied to turbine airfoil heat transfer prediction. A two-zone model was proposed for handling the turbulent kinetic energy and dissipation rate empirically at the airfoil leading edge region. The result showed that the predicted heat transfer coefficient on the airfoil agreed favorably with experimental data, especially for the pressure side. The discrepancy between predictions and experimental data of the suction surface normally occurred at transitional and fully turbulent flow regions.

scholarly journals Prediction of Heat Transfer For Turbulent Flow in Rotating Radial Duct

1995 ◽  
Vol 2 (1) ◽  
pp. 51-58
Author(s):  
P. Tekriwal
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Reynolds Number ◽  
Turbulence Model ◽  
High Reynolds Number ◽  
Low Reynolds Number ◽  
Rotating Flows ◽  
Wall Function ◽  
Model Predictions ◽  
High Reynolds

The objective of the current modeling effort is to validate the numerical model and improve upon the prediction of heat transfer in rotating systems. Low-Reynolds number turbulence model (without the wall function) has been employed for three-dimensional heat transfer predictions for radially outward flow in a square cooling duct rotating about an axis perpendicular to its length. Computations are also made using the standard and extended high-Reynolds number kturbulence models (in conjunction with the wall function) for the same flow configuration. The results from all these models are compared with experimental data for flows at different rotation numbers and Reynolds number equal to 25,000. The results show that the low-Reynolds number model predictions are not as good as the high-Re model predictions with the wall function. The wall function formulation predicts the right trend of heat transfer profile and the agreement with the data is within 30% or so for flows at high rotation number. Since the Navier-Stokes equations are integrated all the way to wall in the case of low-Re model, the computation time is relatively high and the convergence is rather slow, thus rendering the low-Re model as an unattractive choice for rotating flows at high Reynolds number.The extended k-ε turbulence model is also employed to compute heat transfer for rotating flows with uneven wall temperatures and uniform wall heat flux conditions. The comparison with the experimental data available in literature shows that the predictions on both the leading wall and the trailing wall are satisfactory and within 5-25% agreement.

A Numerical Investigation of Transonic Axial Compressor Rotor Flow Using a Low-Reynolds-Number k–ε Turbulence Model

1999 ◽  
Vol 121 (1) ◽  
pp. 44-58 ◽  
Author(s):  
T. Arima ◽  
T. Sonoda ◽  
M. Shirotori ◽  
A. Tamura ◽  
K. Kikuchi
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Turbulence Model ◽  
Low Reynolds Number ◽  
Axial Compressor ◽  
Numerical Results ◽  
Speed Condition ◽  
Transonic Axial Compressor ◽  
Low Reynolds ◽  
Design Speed

We have developed a computer simulation code for three-dimensional viscous flow in turbomachinery based on the time-averaged compressible Navier–Stokes equations and a low-Reynolds-number k–ε turbulence model. It is described in detail in this paper. The code is used to compute the flow fields for two types of rotor (a transonic fan NASA Rotor 67 and a transonic axial compressor NASA rotor 37), and numerical results are compared to experimental data based on aerodynamic probe and laser anemometer measurements. In the case of Rotor 67, calculated and experimental results are compared under the design speed to validate the code. The calculated results show good agreement with the experimental data, such as the rotor performance map and the spanwise distribution of total pressure, total temperature, and flow angle downstream of the rotor. In the case of Rotor 37, detailed comparisons between the numerical results and the experimental data are made under the design speed condition to assess the overall quality of the numerical solution. Furthermore, comparisons under the part-speed condition are used to investigate a flow field without passage shock. The results are well predicted qualitatively. However, considerable quantitative discrepancies remain in predicting the flow near the tip. In order to assess the predictive capabilities of the developed code, computed flow structures are presented with the experimental data for each rotor and the cause of the discrepancies is discussed.

scholarly journals A Numerical Investigation of Transonic Axial Compressor Rotor Flow Using a Low Reynolds Number k-ε Turbulence Model

1997 ◽  
Author(s):  
Toshiyuki Arima ◽  
Toyotaka Sonoda ◽  
Masatoshi Shirotori ◽  
Atsuhiro Tamura ◽  
Kazuo Kikuchi
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Turbulence Model ◽  
Low Reynolds Number ◽  
Axial Compressor ◽  
Numerical Results ◽  
Speed Condition ◽  
Transonic Axial Compressor ◽  
Low Reynolds ◽  
Design Speed

We have developed a computer simulation code for three-dimensional viscous flow in turbomachinery based on the time-averaged compressible Navier-Stokes equations and a low Reynolds number k-ε turbulence model. It is described in detail in this paper. The code is used to compute the flow fields for two types of rotor (a transonic fan NASA Rotor 67 and a transonic axial compressor NASA rotor 37), and numerical results are compared to experimental data based on aerodynamic probe and laser anemometer measurements. In the case of Rotor 67, calculated and experimental results are compared under the design speed to validate the code. The calculated results show good agreement with the experimental data, such as the rotor performance map and the spanwise distribution of total pressure, total temperature, and flow angle downstream of the rotor. In the case of Rotor 37, detailed comparisons between the numerical results and the experimental data are made under the design speed condition to assess the overall quality of the numerical solution. Furthermore, comparisons under the part speed condition are used to investigate a flow field without passage shock. The results are well predicted qualitatively. However, considerable quantitative discrepancies remain in predicting the flow near the tip. In order to assess the predictive capabilities of the developed code, computed flow structures are presented with the experimental data for each rotor and the cause of the discrepancies is discussed.

Calculation of Transitional Boundary Layers With an Improved Low-Reynolds-Number Version of the k–ε Turbulence Model

1994 ◽  
Vol 116 (4) ◽  
pp. 765-773 ◽  
Author(s):  
D. Biswas ◽  
Y. Fukuyama
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Boundary Layers ◽  
Turbulent Flows ◽  
Free Stream ◽  
Low Reynolds Number ◽  
Turbine Rotor ◽  
Limiting Behavior ◽  
Free Stream Turbulence ◽  
Low Reynolds

Several well-known low-Reynolds-number versions of the k–ε models are analyzed critically for laminar to turbulent transitional flows as well as near-wall turbulent flows from a theoretical and numerical standpoint. After examining apparent problems associated with the modeling of low-Reynolds-number wall damping functions used in these models, an improved version of the k–ε model is proposed by defining the wall damping factors as a function of some quantity (turbulence Reynolds number Ret) that is only a rather general indicator of the degree of turbulent activity at any location in the flow rather than a specific function of the location itself, and by considering the wall limiting behavior, the free-stream asymptotic behavior, and the balance between production and destruction of turbulence. This new model is applied to the prediction of (1) transitional boundary layers influenced by the free-stream turbulence, pressure gradient, and heat transfer; (2) external heat transfer distribution on the gas turbine rotor and stator blade under different inlet Reynolds number and free-stream turbulence conditions. It is demonstrated that the present model yields improved predictions.

Analysis of transitional flow and heat transfer over turbine blades: Algebraic versus low-Reynolds-number turbulence model

2001 ◽  
Vol 215 (9) ◽  
pp. 1003-1018 ◽  
Author(s):  
S Sarkar
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Low Reynolds Number ◽  
Turbine Blades ◽  
Transitional Flow ◽  
Flow And Heat Transfer ◽  
Turbulent Transition ◽  
Wide Range ◽  
Low Reynolds ◽  
Laminar Turbulent Transition

The numerical simulation of flow and heat transfer over turbine blades involving laminar-turbulent transition is presented. The predicted results are compared with the experimental surface heat transfer and pressure distributions for two transonic turbine blades over a wide range of flow conditions. The time-dependent, mass-averaged Navier-Stokes equations are solved by an explicit four-stage Runge-Kutta scheme in the finite volume formulation. Local time stepping, variable-coefficient implicit residual smoothing and a full multigrid method have been implemented to accelerate the steady state calculation. The turbulence is simulated by the algebraic Baldwin-Lomax model together with an explicitly imposed model for transition. For comparison, the low-Reynolds-number version of the two-equation ( k-∊) model of Chien is also used. The modified Baldwin-Lomax model performs well in predicting the onset of laminar-turbulent transition, whereas the Chien model shows a tendency to mimic the transition early and over a shorter distance.

scholarly journals Calculation of Transitional Boundary Layers With an Improved Low-Reynolds Number Version of the k-ε Turbulence Model

1993 ◽  
Author(s):  
Debsish Biswas ◽  
Yoshitaka Fukuyama
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Boundary Layers ◽  
Turbulent Flows ◽  
Free Stream ◽  
Low Reynolds Number ◽  
Turbine Rotor ◽  
Limiting Behavior ◽  
Free Stream Turbulence ◽  
Low Reynolds

Several well known low-Reynolds version of the k-ε models are analyzed critically for laminar to turbulent transtional flows as well as near wall turbulent flows from theoretical and numerical standpoint. After examining apparent problems associated with the modelling of low-Reynolds number wall damping functions used in these models, an improved version of k-ε model is proposed by defining the wall damping factors as a function of some quantity (turbulence Reynolds number Rt) which is only a rather general indicator of the degree of turbulent activity at any location in the flow rather than a specific function of the location itself, and by considering the wall limiting behavior, the free-stream asyptotic behavior, and the balnce between production and destruction of turbulence. This new model is applied to the prediction of 1) transitional boundary layers influenced by the free-stream turbulence, pressure gradient and heat transfer; 2) external heat transfer distribution on the gas turbine rotor and stator blade under different inlet Reynolds number and free-stream turbulence conditions. It is demonstrated that the present model yield improved predictions.

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