Developing Turbulent Flow and Heat Transfer in Concentric Annuli

The problem of the simultaneously developing turbulent flow and heat transfer in concentric annuli was studied from an integral viewpoint, based on a modified model for the eddy diffusivity of momentum together with a new ratio of eddy diffusivities obtained from experiment. Solutions were obtained for one surface uniformly heated and the other insulated. The analytical results were then compared with the measurement of local flow and thermal conditions for air flow through four concentric annuli for a Reynolds number range of about 20,000 to 110,000. The analysis assumed the flow was turbulent everywhere. In the experimental work the flow was tripped at the starting position of both the velocity and thermal boundary layers. Air was chosen in the experiment as it represents gas flows in general.

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Local Flow and Heat Transfer Behavior in Convex-Louver Fin Arrays

Journal of Heat Transfer ◽

10.1115/1.2825926 ◽

1999 ◽

Vol 121 (1) ◽

pp. 136-141 ◽

Cited By ~ 2

Author(s):

N. C. DeJong ◽

A. M. Jacobi

Keyword(s):

Heat Transfer ◽

Boundary Layer ◽

Reynolds Number ◽

Pressure Drop ◽

Shear Layer ◽

Local Flow ◽

Number Range ◽

Flow And Heat Transfer ◽

Transfer Behavior ◽

Strip Geometry

Local and surface-averaged measurements of convection coefficients and core pressure-drop data are provided for an array of convex-louver fins. For a Reynolds number range from 200 to 5400, these data are complemented with a flow visualization study and contrasted with new measurements from a similar offset-strip geometry. The results clarify the effects of boundary layer restarting, shear-layer unsteadiness, spanwise vortices, and separation, reattachment, and recirculation on heat transfer in the convex-louver geometry.

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Experimental and Numerical Study of the Turbulent Flow and Heat Transfer in a Wedge-shaped Channel with Guiding Pin Fin Arrays under Rotating Conditions

Journal of Turbomachinery ◽

10.1115/1.4053488 ◽

2022 ◽

pp. 1-28

Author(s):

Ce Liang ◽

Yu Rao ◽

Jianian Chen ◽

Peng Zhang

Keyword(s):

Heat Transfer ◽

Reynolds Number ◽

Turbulent Flow ◽

Numerical Simulations ◽

Rotation Number ◽

Internal Cooling ◽

Number Range ◽

Pin Fin ◽

Flow And Heat Transfer ◽

Pin Fin Arrays

Abstract Experiments and numerical simulations under stationary and rotating conditions have been conducted to investigate turbulent flow and heat transfer characteristics of innovative guiding pin fin arrays in a wedge-shaped channel, which models the internal cooling passages for gas turbine blade trailing edge. The Reynolds number range is 10,000-80,000, and the inlet rotation number range is 0-0.46. With the increase of Reynolds numbers, the enhancement of heat transfer performance with guiding pin fin arrays is significantly higher than that with conventional circular pin fin arrays. At the highest Reynolds number of Re=80,000, the overall Nusselt number of the channel with guiding pin fin arrays is about 33.7% higher than that of the channel with circular pin fin arrays under the stationary condition, and is about 23.0% higher than the latter under the rotating conditions. At the highest inlet rotation number of Ro=0.46, the heat transfer difference between the trailing side and leading side of the channel is significantly lower with the guiding pin fin arrays. Both the experiments and numerical simulations indicate that the heat transfer uniformity and enhancement of the channel endwall is significantly improved by the guiding pin fin arrays under stationary and rotating conditions, which provide more reasonable flow distribution in the wedge-shaped channel, and can further produce obviously improved heat transfer in the tip region for the trailing edge internal cooling channel.

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A Two-Temperature Model for Turbulent Flow and Heat Transfer in a Porous Layer

Journal of Fluids Engineering ◽

10.1115/1.2816810 ◽

1995 ◽

Vol 117 (1) ◽

pp. 181-188 ◽

Cited By ~ 38

Author(s):

V. Travkin ◽

I. Catton

Keyword(s):

Heat Transfer ◽

Turbulent Flow ◽

Regular Structure ◽

Momentum Equation ◽

Temperature Model ◽

Number Range ◽

Flow And Heat Transfer ◽

Effective Coefficients ◽

High Reynolds ◽

Two Temperature

A new model of turbulent flow and of two-temperature heat transfer in a highly porous medium is evaluated numerically for a layer of regular packed particles. The layer can have heat exchange from the defining surfaces. The commonly used models of variable morphology functions for porosity and specific surface were used to obtain comparisons with other works in a relatively high Reynolds number range. A few outstanding features of the closure models for additional integral terms in equations of flow and heat transfer are advanced. Closures were developed for capillary and globular medium morphology models. It is shown that the approach taken to close the integral resistance terms in the momentum equation for a regular structure can be obtained in a way that allows the second order terms for laminar and turbulent regimes to naturally occur. These terms are taken to be close to the Darcy term or Forchheimer terms for different flow velocities. The two-temperature model was compared with a one-temperature model using thermal diffusivity coefficients and effective coefficients from various authors. Calculated pressure drop along a layer showed very good agreement with experiment for a porous structure of spherical beads. A simplified model with constant coefficients was compared with analytical solutions.

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