Heat Transfer to a Fluid Flowing Inside a Pipe Rotating About Its Longitudinal Axis

1969 ◽  
Vol 91 (1) ◽  
pp. 135-139 ◽  
Author(s):  
J. N. Cannon ◽  
W. M. Kays
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Turbulent Flow ◽  
Flow Region ◽  
Longitudinal Axis ◽  
Reynolds Numbers ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Through Flow ◽  
Wide Range

In this paper the effects of tube rotation on heat transfer to a fluid flowing inside a tube are examined. The most pronounced influence is noted to be on the transition from laminar to turbulent flow region with lesser effects in the laminar region, and no measurable effects once the flow has become fully turbulent. Heat transfer data are presented for a wide range of through-flow and rotational Reynolds numbers. A brief examination of the flow by visual means revealed that tube rotation tends to stabilise laminar flow, and in fact can cause an already turbulent flow to revert back to a laminar flow. When the tube is rotating, the transition from laminar to turbulent flow as through-flow Reynolds number is sufficiently increased is characterized by a very distinct “burst of turbulence” phenomenon, photographs of which are presented in this paper.

A Numerical and Experimental Investigation of Turbulent Heat Transport Downstream From an Abrupt Pipe Expansion

1983 ◽  
Vol 105 (4) ◽  
pp. 862-869 ◽  
Author(s):  
R. S. Amano ◽  
M. K. Jensen ◽  
P. Goel
Keyword(s):  
Heat Transfer ◽  
Numerical Solutions ◽  
Numerical Study ◽  
Separated Flow ◽  
Flow Region ◽  
Reynolds Numbers ◽  
Turbulent Heat ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Pipe Expansion

An experimental and numerical study is reported on heat transfer in the separated flow region created by an abrupt circular pipe expansion. Heat transfer coefficients were measured along the pipe wall downstream from an expansion for three different expansion ratios of d/D = 0.195, 0.391, and 0.586 for Reynolds numbers ranging from 104 to 1.5 × 105. The results are compared with the numerical solutions obtained with the k ∼ ε turbulence model. In this computation a new finite difference scheme is developed which shows several advantages over the ordinary hybrid scheme. The study also covers the derivation of a new wall function model. Generally good agreement between the measured and the computed results is shown.

Turbulent Heat Transfer Between a Series of Parallel Plates With Surface-Mounted Discrete Heat Sources

1994 ◽  
Vol 116 (3) ◽  
pp. 577-587 ◽  
Author(s):  
S. H. Kim ◽  
N. K. Anand
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Electronic Equipment ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Computational Domain ◽  
Heat Sources ◽  
Parallel Plates ◽  
Wide Range ◽  
Independent Parameters

Two-dimensional turbulent heat transfer between a series of parallel plates with surface mounted discrete block heat sources was studied numerically. The computational domain was subjected to periodic conditions in the streamwise direction and repeated conditions in the cross-stream direction (Double Cyclic). The second source term was included in the energy equation to facilitate the correct prediction of a periodically fully developed temperature field. These channels resemble cooling passages in electronic equipment. The k–ε model was used for turbulent closure and calculations were made for a wide range of independent parameters (Re, Ks/Kf, s/w, d/w, and h/w). The governing equations were solved by using a finite volume technique. The numerical procedure and implementation of the k–ε model was validated by comparing numerical predictions with published experimental data (Wirtz and Chen, 1991; Sparrow et al., 1982) for a single channel with several surface mounted blocks. Computations were performed for a wide range of Reynolds numbers (5 × 104–4 × 105) and geometric parameters and for Pr = 0.7. Substrate conduction was found to reduce the block temperature by redistributing the heat flux and to reduce the overall thermal resistance of the module. It was also found that the increase in the Reynolds number decreased the thermal resistance. The study showed that the substrate conduction can be an important parameter in the design and analysis of cooling channels of electronic equipment. Finally, correlations for the friction factor (f) and average thermal resistance (R) in terms of independent parameters were developed.

Control of Turbulent Transport: Less Friction and More Heat Transfer

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Nobuhide Kasagi ◽  
Yosuke Hasegawa ◽  
Koji Fukagata ◽  
Kaoru Iwamoto
Keyword(s):  
Heat Transfer ◽  
Heat Transport ◽  
Turbulent Transport ◽  
Scalar Fields ◽  
Wall Friction ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Control Input ◽  
Divergence Free Vector ◽  
Wide Range

Because of the importance of fundamental knowledge on turbulent heat transfer for further decreasing entropy production and improving efficiency in various thermofluid systems, we revisit a classical issue whether enhancing heat transfer is possible with skin friction reduced or at least not increased as much as heat transfer. The answer that numerous previous studies suggest is quite pessimistic because the analogy concept of momentum and heat transport holds well in a wide range of flows. Nevertheless, the recent progress in analyzing turbulence mechanics and designing turbulence control offers a chance to develop a scheme for dissimilar momentum and heat transport. By reexamining the governing equations and boundary conditions for convective heat transfer, the basic strategies for achieving dissimilar control in turbulent flow are generally classified into two groups, i.e., one for the averaged quantities and the other for the fluctuating turbulent components. As a result, two different approaches are discussed presently. First, under three typical heating conditions, the contribution of turbulent transport to wall friction and heat transfer is mathematically formulated, and it is shown that the difference in how the local turbulent transport of momentum and that of heat contribute to the friction and heat transfer coefficients is a key to answer whether the dissimilar control is feasible. Such control is likely to be achieved when the weight distributions for the stress and flux in the derived relationships are different. Second, we introduce a more general methodology, i.e., the optimal control theory. The Fréchet differentials obtained clearly show that the responses of velocity and scalar fields to a given control input are quite different due to the fact that the velocity is a divergence-free vector, while the temperature is a conservative scalar. By exploiting this inherent difference, the dissimilar control can be achieved even in flows where the averaged momentum and heat transport equations have the same form.

Theoretical Model of Wall Heat Transfer in Turbulent Flow

2011 ◽  
Vol 201-203 ◽  
pp. 171-175
Author(s):  
Wei Zheng Zhang ◽  
Xiao Liu ◽  
Chang Hu Xiang
Keyword(s):  
Heat Transfer ◽  
Theoretical Model ◽  
Turbulent Flow ◽  
Local Heat ◽  
Turbulent Heat Transfer ◽  
Wall Region ◽  
Turbulent Heat ◽  
Wall Heat Transfer ◽  
Local Heat Flux ◽  
Turbulent Wall

The turbulent flow in the near-wall region affects the wall heat transfer dominantly. The farther it is from the wall, the less effect it has. So a two-step mechanism of the turbulent wall heat transfer is released: first, the energy is transferred to the outside of the viscous sub-layer by the rolling of the micro-eddy; secondly, the energy gets to the wall by conduction. Then, a theoretical model of wall heat transfer is developed with this concept. The constant in the model is confirmed by experiment and simulation of the transient turbulent heat transfer in pipe flow. Finally, the model is used to predict the local heat flux under different conditions, and the results agree well with the experimental results as well as the simulation results.

Modified Algebraical Cebeci --- Smith Turbulent Viscosity Model for the Entire Surface of a Blunted Cone

2020 ◽  
pp. 28-41
Author(s):  
V.V. Gorskiy ◽  
A.G. Loktionova
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Experimental Studies ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Entire Surface ◽  
Wide Range ◽  
Semi Empirical ◽  
Transfer Properties ◽  
Turbulent Pulsations

In order to compute the intensity of laminar-turbulent heat transfer, algebraic or differential models are commonly used, which are designed to compute the contribution of turbulent pulsations to the transfer properties of the gas. This, in turn, dictates the necessity of validating these semi-empirical models against experimental data obtained under conditions simulating the gas dynamics inherent to the phenomenon as observed in practice. The gas dynamic patterns observed during gradient flow around fragments of aircraft structure (such as a sphere or a cylinder) differs qualitatively from the patterns revealed by the flow around the lateral surfaces of these fragments, which necessitates using various semi-empirical approaches in this case, followed by mandatory validation against the results of respective experimental studies. In recent years, there appeared scientific publications dealing with modifying one of the algebraic models designed to compute the contribution of turbulent pulsations in the boundary layer to the transfer properties of the gas; this was accomplished by making use of experimental data obtained for a hemisphere at extremely high Reynolds numbers. The paper proposes a similar modification of the same turbulence model, based on fitting a wide range of experimental data obtained for lateral surfaces of spherically blunted cones. As a result of the investigations conducted, we stated a method for computing laminar-to-turbulent heat transfer over the entire surface of a blunted cone; the accuracy of the method is acceptable in terms of most practical applications. We show that the computational method presented is characterised by minimum error as compared to the most widely spread methods for solving this problem

STEADY STATE HEAT TRANSFER TO FULLY DEVELOPED TURBULENT FLOW IN A CURVED CHANNEL

1957 ◽  
Vol 35 (4) ◽  
pp. 410-434
Author(s):  
A. W. Marris
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Mean Flow ◽  
Curved Channel ◽  
Mean Velocity ◽  
Fully Developed Turbulent Flow ◽  
Angular Velocities ◽  
The Mean

A vorticity transfer analogy theory of turbulent heat transfer is developed first for the case of fully developed turbulent flow under zero transverse pressure and temperature gradients such as that in the annulus between concentric cylinders rotating with different angular velocities or in a "free vortex". The mean flow is assumed to be two-dimensional. The theory, which requires that the turbulence be statistically isotropic, yields a temperature distribution in agreement with experiment except in narrow regions immediately adjacent to the boundaries. An argument is given to show that the boundary layer thickness should be of the order of the reciprocal of the square root of the mean velocity, these boundaries are introduced, and Nusselt moduli are defined and their dependence on Reynolds and Prandtl numbers is investigated.The temperature distributions for the case of non-zero transverse temperature and pressure gradients, i.e. for the case of flow in a curved channel in which the fluid does not flow back into itself, are then obtained and the applicability of the simpler equations for zero transverse gradients to this case is investigated.

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.

scholarly journals An Experimental Study on the Relationship Between Velocity Fluctuations and Heat Transfer in a Turbulent Air Flow

1998 ◽  
Author(s):  
Michael J. Denninger ◽  
Ann M. Anderson
Keyword(s):  
Heat Transfer ◽  
Maximum Velocity ◽  
Turbulent Pipe Flow ◽  
Heated Wall ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Velocity Fluctuations ◽  
Wide Range ◽  
Reported Study ◽  
Turbulent Air Flow

The work presented here is the first reported study to test the general correlation for turbulent heat transfer proposed by Maciejewski and Anderson (1996). A turbulent pipe flow apparatus was built for heat transfer and fluid studies. Tests were performed for a range of Reynolds numbers from 27,000 to 90,000. The heated wall temperature, adiabatic temperature, the wall heat flux and the maximum velocity fluctuations were measured at each Reynolds number. The non-dimensional groups recommended by Maciejewski and Anderson were formed and compared to the correlation. The results verify the correlation with agreement to within ±7% (as per figure 11). This study has important implications for the study of heat transfer in a wide range of fields, including the gas turbine industry. The development of a geometry independent correlation will lead to faster turn around times and improved engine design.

scholarly journals Turbulent flow through a high aspect ratio cooling duct with asymmetric wall heating

2018 ◽  
Vol 860 ◽  
pp. 258-299 ◽  
Author(s):  
Thomas Kaller ◽  
Vito Pasquariello ◽  
Stefan Hickel ◽  
Nikolaus A. Adams
Keyword(s):  
Heat Transfer ◽  
Aspect Ratio ◽  
Turbulent Flow ◽  
Secondary Flow ◽  
High Aspect Ratio ◽  
Heated Wall ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Wall Heating ◽  
Flow Through

We present well-resolved large-eddy simulations of turbulent flow through a straight, high aspect ratio cooling duct operated with water at a bulk Reynolds number of $Re_{b}=110\times 10^{3}$ and an average Nusselt number of $Nu_{xz}=371$. The geometry and boundary conditions follow an experimental reference case and good agreement with the experimental results is achieved. The current investigation focuses on the influence of asymmetric wall heating on the duct flow field, specifically on the interaction of turbulence-induced secondary flow and turbulent heat transfer, and the associated spatial development of the thermal boundary layer and the inferred viscosity variation. The viscosity reduction towards the heated wall causes a decrease in turbulent mixing, turbulent length scales and turbulence anisotropy as well as a weakening of turbulent ejections. Overall, the secondary flow strength becomes increasingly less intense along the length of the spatially resolved heated duct as compared to an adiabatic duct. Furthermore, we show that the assumption of a constant turbulent Prandtl number is invalid for turbulent heat transfer in an asymmetrically heated duct.

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