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 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.

A Stochastic Lagrangian Model for Near-Wall Turbulent Heat Transfer

1997 ◽  
Vol 119 (1) ◽  
pp. 46-52 ◽  
Author(s):  
S. Mazumder ◽  
M. F. Modest
Keyword(s):  
Heat Transfer ◽  
Joint Probability ◽  
Molecular Transport ◽  
Temperature Fluctuations ◽  
Reynolds Stress Model ◽  
Constant Heat Flux ◽  
Lagrangian Model ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Near Wall

The modeling of near-wall turbulent heat transfer necessitates appropriate description of near-wall effects, namely, molecular transport, production of turbulence by inhomogeneities, and dissipation of the temperature fluctuations by viscosity. A stochastic Lagrangian model, based on the velocity-composition joint probability density function (PDF) method, has been proposed. The proposed model, when compared with experimental and direct numerical simulation (DNS) data, overdamps the dissipation of the temperature fluctuations in the inertial sublayer, but reaches the correct limit at the wall. The performance of the model has also been compared to the standard k-ε and the algebraic Reynolds stress model (ARSM) for both constant heat flux and constant temperature boundary conditions at large Reynolds numbers. The Lagrangian nature of the model helps eliminate numerical diffusion completely.

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 in Corrugated-Wall Channels With and Without Fins

1987 ◽  
Vol 109 (1) ◽  
pp. 62-67 ◽  
Author(s):  
R. S. Amano ◽  
A. Bagherlee ◽  
R. J. Smith ◽  
T. G. Niess
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Reynolds Stress Model ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Reynolds Stresses ◽  
Flow Recirculation ◽  
Nusselt Numbers ◽  
Visible Effect ◽  
Corrugated Wall

A numerical study is performed examining flow and heat transfer characteristics in a channel with periodically corrugated walls. The complexity of the flow in this type of channel is demonstrated by such phenomena as flow impingement on the walls, separation at the bend corners, flow reattachment, and flow recirculation. Because of the strong nonisotropic nature of the turbulent flow in the channel, the full Reynolds-stress model was employed for the evaluation of turbulence quantities. Computations are made for several different corrugation periods and for different Reynolds numbers. The results computed by using the present model show excellent agreement with experimental data for mean velocities, the Reynolds stresses, and average Nusselt numbers. The study was further extended to a channel flow where fins are inserted at bends in the channel. It was observed that the insertion of fins in the flow passage has a visible effect on flow patterns and skin friction along the channel wall.

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