Numerical Calculations of the Turbulent Flow Through a Controlled Diffusion Compressor Cascade

1995 ◽  
Vol 117 (2) ◽  
pp. 223-230 ◽  
Author(s):  
Shin-Hyoung Kang ◽  
Joon Sik Lee ◽  
Myung-Ryul Choi ◽  
Kyung-Yup Kim
Keyword(s):  
Reynolds Number ◽  
Control Volume ◽  
Low Reynolds Number ◽  
Turbulence Models ◽  
Compressor Cascade ◽  
Mean Velocity ◽  
Flow Angle ◽  
Controlled Diffusion ◽  
Flow Through ◽  
Low Reynolds

The viscous flow through a controlled diffusion (CD) compressor cascade was calculated and compared with the measured data for two different test conditions. A control volume method was used, which has been developed for a generalized nonorthogonal coordinate system. The discretized equations for the physical covariant velocity components were obtained by an algebraic manipulation of the discretized equations for the Cartesian velocity components. Low Reynolds number k–ε turbulence models were used to obtain the eddy viscosity. The numerical scheme using the low Reynolds number k–ε turbulence model reasonably predicted the general performance, i.e, mean outlet flow angle and loss coefficients. The development of the shear layer along the pressure and suction sides was well estimated, and the physical features found in the experiment were reasonably well confirmed in the simulation. However, the calculated profiles of mean velocity and turbulent kinetic energy in the near wake show considerable disagreement with the measured values.

Numerical Simulation of Turbine Blade Boundary Layer and Heat Transfer and Assessment of Turbulence Models

1997 ◽  
Vol 119 (4) ◽  
pp. 794-801 ◽  
Author(s):  
J. Luo ◽  
B. Lakshminarayana
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Reynolds Number ◽  
Low Reynolds Number ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Bypass Transition ◽  
Boundary Layer Development ◽  
Low Reynolds ◽  
Layer Development

The boundary layer development and convective heat transfer on transonic turbine nozzle vanes are investigated using a compressible Navier–Stokes code with three low-Reynolds-number k–ε models. The mean-flow and turbulence transport equations are integrated by a four-stage Runge–Kutta scheme. Numerical predictions are compared with the experimental data acquired at Allison Engine Company. An assessment of the performance of various turbulence models is carried out. The two modes of transition, bypass transition and separation-induced transition, are studied comparatively. Effects of blade surface pressure gradients, free-stream turbulence level, and Reynolds number on the blade boundary layer development, particularly transition onset, are examined. Predictions from a parabolic boundary layer code are included for comparison with those from the elliptic Navier–Stokes code. The present study indicates that the turbine external heat transfer, under real engine conditions, can be predicted well by the Navier–Stokes procedure with the low-Reynolds-number k–ε models employed.

Numerical Study of Deteriorated Convection Heat Transfer of Supercritical Fluid Flowing Through Vertical Mini Tube at Relatively Low Reynolds Numbers

2018 ◽  
Author(s):  
Chen-Ru Zhao ◽  
Zhen Zhang ◽  
Qian-Feng Liu ◽  
Han-Liang Bo ◽  
Pei-Xue Jiang
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Reynolds Number ◽  
Low Reynolds Number ◽  
Convection Heat Transfer ◽  
Turbulence Models ◽  
Convection Heat ◽  
Flow Acceleration ◽  
Heat Transfer Deterioration ◽  
Low Reynolds

Numerical investigations are performed on the convection heat transfer of supercritical pressure fluid flowing through vertical mini tube with inner diameter of 0.27 mm and inlet Reynolds number of 1900 under various heat fluxes conditions using low Reynolds number k-ε turbulence models due to LB (Lam and Bremhorst), LS (Launder and Sharma) and V2F (v2-f). The predictions are compared with the corresponding experimentally measured values. The prediction ability of various low Reynolds number k-ε turbulence models under deteriorated heat transfer conditions induced by combinations of buoyancy and flow acceleration effects are evaluated. Results show that all the three models give fairly good predictions of local wall temperature variations in conditions with relatively high inlet Reynolds number. For cases with relatively low inlet Reynolds number, V2F model is able to capture the general trends of deteriorated heat transfer when the heat flux is relatively low. However, the LS and V2F models exaggerate the flow acceleration effect when the heat flux increases, while the LB model produces qualitative predictions, but further improvements are still needed for quantitative prediction. Based on the detailed flow and heat transfer information generated by simulation, a better understanding of the mechanism of heat transfer deterioration is obtained. Results show that the redistribution of flow field induced by the buoyancy and flow acceleration effects are main factors leading to the heat transfer deterioration.

An Investigation Into the Potential of Low-Reynolds Number Eddy Viscosity Turbulent Flow Models to Predict Electronic Component Operational Temperature

2005 ◽  
Vol 127 (1) ◽  
pp. 67-75 ◽  
Author(s):  
Peter Rodgers ◽  
Vale´rie Eveloy ◽  
M. S. J. Hashmi
Keyword(s):  
Thermal Analysis ◽  
Reynolds Number ◽  
Eddy Viscosity ◽  
Predictive Accuracy ◽  
Low Reynolds Number ◽  
Turbulence Models ◽  
Thermal Design ◽  
Junction Temperature ◽  
Temperature Prediction ◽  
Low Reynolds

The flow modeling approaches employed in computational fluid dynamics (CFD) codes dedicated to the thermal analysis of electronic equipment are generally not specific for the analysis of forced airflows over populated electronic boards. This limitation has been previously highlighted (Eveloy, V. et al., 2004, IEEE Trans. Compon., Packag., Technol. 27, pp. 268–282), with component junction temperature prediction errors of up to 35% reported. This study evaluates the potential of three candidate low-Reynolds number eddy viscosity turbulence models to improve predictive accuracy. An array of fifteen board-mounted PQFPs is analyzed in a 4 m/s airflow. Using the shear stress transport k-ω model, significant improvements in component junction temperature prediction accuracy are obtained relative to the standard high-Reynolds number k-ε model, which are attributed to better prediction of both board leading edge heat transfer and component thermal interaction. Such improvements would enable parametric analysis of product thermal performance to be undertaken with greater confidence in the thermal design process, and the generation of more accurate temperature boundary conditions for use in Physics-of-Failure based reliability prediction methods. The case is made for vendors of CFD codes dedicated to the thermal analysis of electronics to consider the adoption of eddy viscosity turbulence models more suited to board-level analysis.

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