Can one- and two-equation turbulence models be modified to calculate turbulent heat transfer with variable properties?

1992 ◽  
Vol 31 (3) ◽  
pp. 756-759 ◽  
Author(s):  
Shang Woo Chyou ◽  
Charles A. Sleicher
Keyword(s):  
Heat Transfer ◽  
Turbulence Models ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Variable Properties

Determination of Flow Characteristics and Turbulent Heat Transfer in a Ribbed Roughened Square Duct, Part 2: Numerical Simulations

2011 ◽  
Vol 110-116 ◽  
pp. 2364-2369
Author(s):  
Amin Etminan ◽  
H. Jafarizadeh ◽  
M. Moosavi ◽  
K. Akramian
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Flow Characteristics ◽  
Turbulence Models ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Square Duct ◽  
Optimized Model ◽  
Rsm Model

In the part 1 of this research, some useful turbulence models presented. In that part advantages of those turbulence models has been gathered. In the next, numerical details and procedure of solution are presented in details. By use of different turbulence models, it has been found that Spallart-Allmaras predicted the lowest value of heat transfer coefficient; in contrast, RSM1 has projected the more considerable results compared with other models; besides, it has been proven that the two-equation models prominently taken lesser time than RSM model. Eventually, the RNG2 model has been introduced as the optimized model of this research; moreover.

Turbulent Heat Transfer Computations for Rearward-Facing Steps and Sudden Pipe Expansions

1985 ◽  
Vol 107 (1) ◽  
pp. 70-76 ◽  
Author(s):  
A. M. Gooray ◽  
C. B. Watkins ◽  
Win Aung
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Fluid Dynamic ◽  
Turbulence Models ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Streamline Curvature ◽  
Recirculating Flow ◽  
Moderate Reynolds Number ◽  
Entire Flow

Results of numerical calculations for heat transfer in turbulent recirculating flow over two-dimensional, rearward-facing steps and sudden pipe expansions are presented. The turbulence models used in the calculation are the standard k – ε model and the low-Reynolds number version of this model. The k – ε models have been improved to account for the effects of streamline curvature and pressure-strain (scalar) interactions including wall damping. A sequence of two computational passes is performed to obtain optimal results over the entire flow field. The presented results consist of computed distributions of heat transfer coefficents for several Reynolds numbers, emphasizing the low-to-moderate Reynolds number regime. The heat transfer results also include correlations of Nusselt numnber for both side and bottom walls. The computed heat transfer results and typical computed fluid dynamic results are compared with available experimental data.

A New Heat Transfer Correlation for Turbulent Flow of Air With Variable Properties in Noncircular Ducts

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
Peng Wang ◽  
Mo Yang ◽  
Zhiyun Wang ◽  
Yuwen Zhang
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Circular Tube ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Hydraulic Diameter ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Variable Properties ◽  
Corner Region

Turbulent flow and heat transfer of air with variable properties in a set of regular polygonal ducts and circular tube have been numerically simulated. All the ducts have the same hydraulic diameter as their characteristic lengths in the Reynolds number. The flow is modeled as three-dimensional (3D) and fully elliptic by using the finite volume method and the standard k-ε turbulence model. The results showed that the relatively strong secondary flow could be observed with variable properties fluid. For the regular polygonal ducts, the local heat transfer coefficient along circumferential direction is not uniform; there is an appreciable reduction in the corner region and the smaller the angle of the corner region, the more appreciable deterioration the corner region causes. The use of hydraulic diameter for regular polygonal ducts leads to unacceptably large errors in turbulent heat transfer determined from the circular tube correlations. Based on the simulation results, a correction factor is proposed to predict turbulent heat transfer in regular polygonal ducts.

Prediction of Turbulent Heat Transfer and Fluid Flow in 2D Channels Roughened by Square and Deformed Ribs

2003 ◽  
Author(s):  
Rongguang Jia ◽  
Bengt Sunde´n
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Turbine Blades ◽  
Turbulence Models ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Turbine Cooling ◽  
Experimental Heat ◽  
Flow And Heat Transfer ◽  
Enhancing Heat Transfer

Introduction of roughness by ribs in flow passages is a popular method of enhancing heat transfer in the cooling passages, e.g., of turbine blades and combustors. It is essential to accurately predict the enhancement of heat transfer generated by the ribs to ensure good design decisions. In most of the studies square ribs have been considered, but in practice such ribs may appear rounded due to improper manufacturing or wear during operation. This study is focused on the effect of the rib deformations, based on computational fluid dynamics (CFD). One of the main difficulties in CFD is the reliable modeling of the underlying physics of the turbulence. This paper describes some recent efforts to validate and apply RANS-based models for predictions of turbulent flow and heat transfer in ribbed ducts, relevant to gas turbine cooling. The evaluated turbulence models include a basic low-Re k-ε model (AKN), and two promising higher order models: namely, the explicit algebraic stress model (EASM), and the V2F model. All these models are validated with available 2D experimental heat transfer and fluid flow data. Some conclusions are reached on their suitable application situations. The effect of the roundedness on heat transfer and fluid flow is presented in detail. Some possible improvements, i.e., of the deformed ribs, are proposed to suppress the hot spots, and/or to enhance the overall thermal and hydraulic performance.

scholarly journals A Logarithmic Turbulent Heat Transfer Model in Applications with Liquid Metals for PR = 0.01-0.025

2020 ◽  
Author(s):  
Roberto Da Vià ◽  
Sandro Manservisi ◽  
Valentina Giovacchini
Keyword(s):  
Heat Transfer ◽  
Turbulence Model ◽  
Liquid Metals ◽  
Turbulence Models ◽  
Turbulent Heat Flux ◽  
Turbulent Heat Transfer ◽  
Transfer Model ◽  
Turbulent Heat ◽  
Reynolds Analogy ◽  
Wide Range

The study of turbulent heat transfer in liquid metal flows has gained interest because of applications in several industrial fields. The common assumption of similarity between the dynamical and thermal turbulence, namely the Reynolds analogy, has been proven to be not valid for these fluids. Many methods have been proposed in order to overcome the difficulties encountered in a proper definition of the turbulent heat flux, such as global or local correlations for the turbulent Prandtl number or four parameter turbulence models. In this work we assess a four parameter logarithmic turbulence model for liquid metals based on RANS approach. Several simulation results considering fluids with Pr = 0.01 and Pr = 0.025 are reported in order to show the validity of this approach. The Kays turbulence model is also assessed and compared with integral heat transfer correlations for a wide range of Peclet numbers.

Numerical Study of a New Heat Transfer Correlation for Turbulent Air Flow in Noncircular Ducts With Variable Properties

2013 ◽  
Author(s):  
Mo Yang ◽  
Peng Wang ◽  
Yuwen Zhang ◽  
Zhiyun Wang
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Circular Tube ◽  
Numerical Study ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Hydraulic Diameter ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Variable Properties

Turbulent flow of air with variable properties in a set of regular polygonal ducts and circular tube have been numerically simulated. All the ducts have the same hydraulic diameter as their characteristic length dimension in the Reynolds number. The flow is modeled as three-dimensional and fully elliptic by using the finite volume method and the standard k-ε turbulence model is adopted. The performances of the flow and heat transfer have been thoroughly investigated. The results showed that comparatively strong secondary flow can be observed with variable properties fluid. For the regular polygonal duct, the local heat transfer coefficient along circumferential direction is not uniform and there is an appreciable reduction in the corner region. The use of hydraulic diameter for regular polygonal ducts to determine turbulent flow heat transfer from circular tube correlations leads to unacceptably large errors. Based on the simulation results, a correction factor Cϕ is proposed to ameliorate the previous correlations, and the error in the prediction of turbulent heat transfer with the new correlation is within 6%.

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