Numerical Comparison of Turbulent Heat Transfer and Flow Characteristics of SiO2/Water Nanofluid within Helically Corrugated Tubes and Plain Tube

2015 ◽  
Vol 28 (10 (A)) ◽  
Keyword(s):  
Heat Transfer ◽  
Flow Characteristics ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Numerical Comparison ◽  
Plain Tube

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.

Heat Transfer and Flow Characteristics of an Oblique Turbulent Impinging Jet Within Confined Walls

1995 ◽  
Vol 117 (2) ◽  
pp. 316-322 ◽  
Author(s):  
K. Ichimiya
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Flow Characteristics ◽  
Local Heat Transfer ◽  
Flow Region ◽  
Turbulent Heat Transfer ◽  
Working Fluid ◽  
Turbulent Heat ◽  
Transfer Coefficients ◽  
Impingement Surface

Experiments were conducted to determine the turbulent heat transfer and flow characteristics of an oblique impinging circular jet within closely confined walls using air as a working fluid. The local temperature distribution on the impingement surface was obtained in detail by a thermocamera using a liquid crystal sheet. A correction to the heat flux was evaluated by using the detailed temperature distribution and solving numerically the three-dimensional equation of heat conduction in the heated section. Two-dimensional profiles of the local Nusselt numbers and temperatures changed with jet angle and Reynolds number. These showed a peak shift toward the minor flow region and a plateau of the local heat transfer coefficients in the major flow region. The local velocity and turbulent intensity in the gap between the confined insulated wall and impingement surface were also obtained in detail by a thermal anemometer.

Turbulent Heat Transfer Enhancement in Round Tubes by Inserting Triple Twisted-Tapes

2015 ◽  
Author(s):  
S. Eiamsa-ard ◽  
P. Promthaisong ◽  
V. Chuwattanakul
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Flow Characteristics ◽  
Temperature Fields ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Round Tube ◽  
Constant Wall Temperature ◽  
Twisted Tapes ◽  
Twist Ratio

Turbulent flow characteristics and heat transfer performances in a round tube equipped with triple twisted tapes are investigated numerically. Effects of the triple twisted tapes at different twist ratios on the heat transfer and thermal performance characteristics are reported. The results of velocity and temperature fields, and the local heat transfer coefficients as well as the flow structure in tube with tape inserts are also given. A round tube wall is subjected to a constant wall temperature condition. Thermal field, heat transfer and fluid flow characteristics are studied using computational fluid dynamics (CFD) analysis. Computations, based on a finite volume method, are carried out by utilizing the Renormalized Group (RNG) k-ε turbulence model. The investigation is carried out for triple twisted tapes with y/W = 2.0, 3.0 and 4.0 in round tubes for laminar air flow with Reynolds numbers between 500 and 2000. It is found that the use of triple twisted tapes with smallest twist ratio of y/W = 2.0 results in the highest heat transfer and friction factor while the use of the tapes with the largest twist ratio (y/W = 4.0) results in the highest thermal performance. The highest thermal performances based on the constant pumping power criterion of the tubes equipped triple twisted tapes with y/W = 2.0, 3.0 and 4.0 are 2.43, 2.63 and 2.73, respectively.

scholarly journals Heat Transfer in a Square Ribbed Channel: Evaluation of Turbulent Heat Transfer Models

2019 ◽  
Vol 4 (3) ◽  
pp. 18
Author(s):  
Beate Wörz ◽  
Mark Wieler ◽  
Viola Dehe ◽  
Peter Jeschke ◽  
Michael Rabs
Keyword(s):  
Heat Transfer ◽  
Turbine Blades ◽  
Flow Characteristics ◽  
Reynolds Stress Model ◽  
Turbulent Heat Flux ◽  
Numerical Calculations ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Algebraic Models ◽  
Channel Configuration

This paper presents the results of integral heat transfer measurements taken in a square ribbed cooling channel configuration for evaluating heat transfer and turbulent flow characteristics in convective cooled gas turbine blades and draws a comparison with numerical results. The heated section of the channel is either smooth or equipped with 45 ∘ crossed ribs on two opposite walls. The first part of the paper describes the instrumentation and experimental setup in detail. The second part compares the numerical calculations with the experimentally determined results. The turbulent heat transfer is calculated using two common algebraic models and three implemented explicit algebraic models, each time in combination with an explicit algebraic Reynolds stress model. The numerical calculations show that the use of higher-order models for the turbulent heat flux provides a higher accuracy of the heat transfer prediction for both configurations. The best model is able to predict almost all results within the experimental uncertainties.

Determination of Flow Characteristics and Turbulent Heat Transfer in a Ribbed Roughened Square Duct, Part 1: Turbulence Models

2011 ◽  
Vol 110-116 ◽  
pp. 2359-2363
Author(s):  
Amin Etminan ◽  
H. Jafarizadeh ◽  
M. Moosavi ◽  
K. Akramian
Keyword(s):  
Heat Transfer ◽  
Flow Structure ◽  
Flow Characteristics ◽  
Turbulence Models ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Turbulent Model ◽  
Square Duct ◽  
Rans Models

Nowadays, many researchers works in fluid dynamics has been concentrated on determine the suitable turbulent model for better describing the flow structure and heat transfer characteristics in a specific problem, there are a lot of cases which are necessary about designation of an optimized turbulent model. In the present work, a ribbed roughened square duct has been investigated numerically. A two-dimensionally study has been done to evaluate the flow structure, heat transfer and computational efforts of seven turbulent RANS models, contemporaneously. In the Part 1 of this study turbulence models, which are used in these type of problems has been investigated. In the next, advantages of introduced turbulence models has been present and explained. The results of numerical simulations will be presented in the Part 2.

A Numerical Study of Turbulent Heat Transfer in a Spherical Annulus

1988 ◽  
Vol 110 (4a) ◽  
pp. 870-876
Author(s):  
W. Stein ◽  
H. Brandt
Keyword(s):  
Heat Transfer ◽  
Turbulence Model ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Local Heat Transfer ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Total System ◽  
Navier Stokes Equation ◽  
Spherical Annulus

A numerical study of steady, buoyant, incompressible water flow and heat transfer through a spherical annulus has been made. A two-dimensional computer code based on the TEACH code was rewritten in spherical coordinates to model the Navier–Stokes equation and to model fluid turbulence with a k–ε turbulence model. Results are given for the total system Nusselt number, local heat transfer rate, and fluid flow characteristics for both buoyant and nonbuoyant laminar and turbulence modeled flow. Incorporating both the turbulence model and buoyancy into the calculations improves the results.

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