Effect of coriolis and centrifugal forces at high rotation and density ratios

    Authors

    A. Sleiti;J. S. Kapat

    Comments

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    Abbreviated Journal Title

    J. Thermophys. Heat Transf.

    Keywords

    HEAT-TRANSFER; TURBULENT-FLOW; SERPENTINE PASSAGES; 2ND-MOMENT CLOSURE; SMOOTH WALLS; SQUARE DUCT; COMPUTATION; PREDICTION; CHANNELS; MODEL; Thermodynamics; Engineering, Mechanical

    Abstract

    Numerical simulation of fluid flow and heat transfer of high rotation and density ratio flow in internal cooling channels of turbine blades with smooth walls is the main focus of this study. The flow in these channels is affected by rotation, buoyancy, bends, and boundary conditions. On the basis of comparison between two-equation (k-epsilon and k-omega) and Reynolds-stress (RSM) turbulence models, it is concluded that the two-equation turbulence models cannot predict heat transfer correctly, whereas RSM showed improved prediction. Thus RSM model was validated against available experimental data (which are primarily at low rotation and buoyancy numbers). The model was then used for cases with high rotation numbers (as much as 1.29) and high-density ratios (up to 0.4) not studied previously. Particular attention was given to how Reynolds stresses, turbulence intensity, and transport are affected by coriolis and buoyancy/centrifugal forces caused by high levels of rotation and density ratio. The results obtained are explained in view of physical interpretation of Coriolis and centrifugal forces. It has been concluded that the heat-transfer rate can be enhanced rapidly by increasing rotation number to values that are comparable to the enhancement caused by introduction of ribs inside internal cooling channels. It is possible to derive linear correlation for the increase in Nusselt number as a function of rotation number. Increasing density ratios at high rotation number does not necessarily cause an increase in Nusselt number. The increasing thermal boundary-layer thickness near walls is the possible reason for this behavior of Nusselt number.

    Journal Title

    Journal of Thermophysics and Heat Transfer

    Volume

    20

    Issue/Number

    1

    Publication Date

    1-1-2006

    Document Type

    Article; Proceedings Paper

    Language

    English

    First Page

    67

    Last Page

    79

    WOS Identifier

    WOS:000234900300007

    ISSN

    0887-8722

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