Numerical Predictions of Temporally Periodic Fluid Flow and Heat Transfer in Spatially Periodic Geometries

Gas turbine blade tips encounter large heat load as they are exposed to the high temperature gas. A common way to cool the blade and its tip is to design serpentine passages with 180-deg turns under the blade tip-cap inside the turbine blade. Improved internal convective cooling is therefore required to increase the blade tip life time. This paper presents numerical predictions of turbulent fluid flow and heat transfer through two-pass channels with and without guide vanes placed in the turn regions using RANS turbulence modeling. The effects of adding guide vanes on the tip-wall heat transfer enhancement and the channel pressure loss were analyzed. The guide vanes have a height identical to that of the channel. The inlet Reynolds numbers are ranging from 100,000 to 600,000. The detailed three-dimensional fluid flow and heat transfer over the tip-walls are presented. The overall performances of several two-pass channels are also evaluated and compared. It is found that the tip heat transfer coefficients of the channels with guide vanes are 10∼60% higher than that of a channel without guide vanes, while the pressure loss might be reduced when the guide vanes are properly designed and located, otherwise the pressure loss is expected to be increased severely. It is suggested that the usage of proper guide vanes is a suitable way to augment the blade tip heat transfer and improve the flow structure, but is not the most effective way compared to the augmentation by surface modifications imposed on the tip-wall directly.

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Temporally- and Spatially-Periodic Laminar Flow and Heat Transfer in Staggered-Plate Arrays

ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference, Volume 1 ◽

10.1115/ht2007-32679 ◽

2007 ◽

Cited By ~ 2

Author(s):

Alexandre Lamoureux ◽

B. Rabi Baliga

Keyword(s):

Heat Transfer ◽

Reynolds Number ◽

Fluid Flow ◽

Numerical Solutions ◽

Initial Conditions ◽

Plate Thickness ◽

Geometrical Parameters ◽

Reduced Pressure ◽

Flow And Heat Transfer ◽

Spatially Periodic

A computational investigation of temporally- and spatially-periodic laminar two-dimensional fluid flow and heat transfer in staggered-plate arrays is presented in this paper. The objective and the novel aspect of this study is the investigation of the influence (on the numerical solutions) of including single and multiple representative geometric modules in the calculation domain, with spatially-periodic boundary conditions imposed on the instantaneous velocity and temperature fields in both the streamwise and the lateral directions. The following geometrical parameters, normalized with respect to a representative module height, were studied: a dimensionless plate length equal to 1, and a dimensionless plate thickness of 0.250. This relatively high value of dimensionless plate thickness, compared to those commonly encountered in rectangular offset-fin cores of compact heat exchangers, was deliberately chosen to induce and enhance the unsteady features of the fluid flow and heat transfer phenomena. Different specified values of the time-mean modular streamwise gradient of the reduced pressure were investigated, yielding values of Reynolds number (Kays and London definition) in the range of 100 to 625. The Prandtl number was fixed at 0.7. In the multiple-module simulations, for Reynolds number values exceeding 400, it was found that multiple solutions are possible: the particular solution which is obtained in any one simulation depends on the specified initial conditions. The results presented include time-mean modular friction factors, modular Colburn factors, and Strouhal numbers.

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Numerical and Experimental Prediction of Transitional Characteristics of Flow and Heat Transfer in an Array of Heated Blocks

Journal of Electronic Packaging ◽

10.1115/1.2792685 ◽

1999 ◽

Vol 121 (3) ◽

pp. 202-208 ◽

Cited By ~ 4

Author(s):

Y. Asako ◽

Y. Yamaguchi ◽

M. Faghri

Keyword(s):

Heat Transfer ◽

Reynolds Number ◽

Fluid Flow ◽

Parallel Plate ◽

Three Dimensional ◽

Parallel Plates ◽

Number Range ◽

Flow And Heat Transfer ◽

Numerical Predictions ◽

Experimental Prediction

Three-dimensional numerical analysis, for transitional characteristics of fluid flow and heat transfer in periodic fully developed region of an array of the heated square blocks deployed along one wall of the parallel plates duct, is carried out by using Lam-Bremhorst low-Reynolds-number two equation turbulence model. Computations were performed for Prandtl number of 0.7, in the Reynolds number range of 200 to 2000 and for two sets of geometric parameters characterizing the array. The predicted transitional Reynolds number is lower than the value for the parallel plate duct and it decreases with increasing the height above the module. Experiments were also performed for pressure drop measurements and for flow visualization and the results were compared with the numerical predictions.

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Generalized Richardson extrapolation procedures for estimating grid-independent numerical solutions

International Journal of Numerical Methods for Heat &amp Fluid Flow ◽

10.1108/hff-10-2015-0445 ◽

2016 ◽

Vol 26 (3/4) ◽

pp. 1121-1144 ◽

Cited By ~ 6

Author(s):

Bantwal R. (Rabi) Baliga ◽

Iurii Yuri Lokhmanets

Keyword(s):

Heat Transfer ◽

Fluid Flow ◽

Numerical Solutions ◽

Richardson Extrapolation ◽

Grid Refinement ◽

Content Type ◽

Extrapolation Procedure ◽

Flow And Heat Transfer ◽

Numerical Predictions ◽

Hexahedral Elements

Purpose – The purpose of this paper is to present outcomes of efforts made over the last 20 years to extend the applicability of the Richardson extrapolation procedure to numerical predictions of multidimensional, steady and unsteady, fluid flow and heat transfer phenomena in regular and irregular calculation domains. Design/methodology/approach – Pattern-preserving grid-refinement strategies are proposed for mathematically rigorous generalizations of the Richardson extrapolation procedure for numerical predictions of steady fluid flow and heat transfer, using finite volume methods and structured multidimensional Cartesian grids; and control-volume finite element methods and unstructured two-dimensional planar grids, consisting of three-node triangular elements. Mathematically sound extrapolation procedures are also proposed for numerical solutions of unsteady and boundary-layer-type problems. The applicability of such procedures to numerical solutions of problems with curved boundaries and internal interfaces, and also those based on unstructured grids of general quadrilateral, tetrahedral, or hexahedral elements, is discussed. Findings – Applications to three demonstration problems, with discretizations in the asymptotic regime, showed the following: the apparent orders of accuracy were the same as those of the numerical methods used; and the extrapolated results, measures of error, and a grid convergence index, could be obtained in a smooth and non-oscillatory manner. Originality/value – Strict or approximate pattern-preserving grid-refinement strategies are used to propose generalized Richardson extrapolation procedures for estimating grid-independent numerical solutions. Such extrapolation procedures play an indispensable role in the verification and validation techniques that are employed to assess the accuracy of numerical predictions which are used for designing, optimizing, virtual prototyping, and certification of thermofluid systems.

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Numerical Predictions of Fluid Flow and Heat Transfer in Corrugated Channels Using Time-Dependent and Time-Independent Flow Models

Journal of Enhanced Heat Transfer ◽

10.1615/jenhheattransf.v11.i4.130 ◽

2004 ◽

Vol 11 (4) ◽

pp. 347-358 ◽

Cited By ~ 3

Author(s):

Wei Xu ◽

Jingchun Min

Keyword(s):

Heat Transfer ◽

Fluid Flow ◽

Time Dependent ◽

Flow Models ◽

Flow And Heat Transfer ◽

Numerical Predictions

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Numerical Predictions of the Effect of Rotation on Fluid Flow and Heat Transfer in an Engine-Similar Two-Pass Internal Cooling Channel With Smooth and Ribbed Walls

Volume 4: Heat Transfer, Parts A and B ◽

10.1115/gt2010-22870 ◽

2010 ◽

Cited By ~ 3

Author(s):

M. Schu¨ler ◽

H.-M. Dreher ◽

S. O. Neumann ◽

B. Weigand ◽

M. Elfert

Keyword(s):

Heat Transfer ◽

Fluid Flow ◽

Flow Field ◽

Secondary Flow ◽

Internal Cooling ◽

Cooling Channel ◽

Flow And Heat Transfer ◽

Numerical Predictions ◽

Smooth Channel ◽

Secondary Flow Field

In the present study, a two-pass internal cooling channel with engine-similar cross-sections was investigated numerically. The channel featured a trapezoidal inlet pass, a sharp 180° bend and a nearly rectangular outlet pass. Calculations were conducted for a configuration with smooth walls and walls equipped with 45° skewed ribs (P/e = 10, e/dh = 0.1) at a Reynolds number of Re = 50,000. The present study focused on the effect of rotation on fluid flow and heat transfer. The investigated rotation numbers were Ro = 0.0 and 0.10. The computations were performed by solving the Reynolds-averaged Navier-Stokes equations (RANS method) with the commercial Finite-Volume solver FLUENT using a low-Re k-ω-SST turbulence model. The numerical grids were block-structured hexahedral meshes generated with POINTWISE. Flow field measurements were independently performed at DLR using Particle Image Velocimetry. In the smooth channel rotation had a large impact on secondary flows. Especially, rotation induced vortices completely changed the flow field. Rotation also changed flow impingement on tip and outlet pass side wall. Heat transfer in the outlet pass was strongly altered by rotation. In contrast to the smooth channel, rotation showed less influence on heat transfer in the ribbed channel. This is due to a strong secondary flow field induced by the ribs. However, in the outlet pass Coriolis force markedly affected the rib induced secondary flow field. The influence of rotation on heat transfer was visible in particular in the bend region and in the second pass directly downstream of the bend.

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Computation of Spatially Periodic Turbulent Fluid Flow and Heat Transfer in a Channel With Various Rib Shapes

Volume 4: Heat Transfer; Electric Power; Industrial and Cogeneration ◽

10.1115/95-gt-023 ◽

1995 ◽

Author(s):

Tong-Miin Liou ◽

Shih-Hui Chen

Keyword(s):

Heat Transfer ◽

Fluid Flow ◽

Cross Sections ◽

Hydraulic Diameter ◽

Wall Region ◽

Mean Velocity ◽

Turbulent Fluid Flow ◽

Turbulent Fluid ◽

Flow And Heat Transfer ◽

Spatially Periodic

Periodic fully developed turbulent fluid flow and heat transfer in a channel with four shapes, namely, triangular, semicircular, semielliptic, and square cross sections, of rib pairs periodically mounted on two opposite walls has been investigated computationally with a curvilinear nonorthogonal body-fitted coordinate system. The Reynolds number based on the channel hydraulic diameter and bulk mean velocity, the rib pitch-to-height ratio, and the rib height-to-channel hydraulic diameter ratio are 1.3×104, 10, and 0.08, respectively. The standard k-ε turbulence model together with the two-layer wall region treatment was applied to solve the accelerating, decelerating, separating, recirculating, reattaching and redeveloping flows. The predicted fluid flow and heat transfer results were tested by previous laser-Doppler and holographic interferometry data, and reasonable agreement was achieved. The two layer treatment shows a superiority to the conventional wall function in predicting near wall mean velocity and peak turbulent kinetic energy. Triangular-shaped rib is favorable for a compromise between the thermal performance and possible presence of hot spots.

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Numerical Prediction of Transitional Characteristics of Flow and Heat Transfer in a Corrugated Duct

Journal of Heat Transfer ◽

10.1115/1.2824101 ◽

1997 ◽

Vol 119 (1) ◽

pp. 62-69 ◽

Cited By ~ 39

Author(s):

L. C. Yang ◽

Y. Asako ◽

Y. Yamaguchi ◽

M. Faghri

Keyword(s):

Heat Transfer ◽

Reynolds Number ◽

Fluid Flow ◽

Pressure Drop ◽

Parallel Plate ◽

Numerical Prediction ◽

Number Range ◽

Flow And Heat Transfer ◽

Numerical Predictions ◽

Corrugated Duct

The numerical prediction of transitional characteristics of fluid flow and heat transfer in periodic fully developed corrugated duct is carried out by using a Lam-Bremhorst low Reynolds number turbulence model. Computations were performed for Prandtl number of 0.7, in the Reynolds number range of 100 to 2500, for corrugation angles of θ = 15 and 30 deg, and for three interwall spacings. The predicted transitional Reynolds number is lower than the value for the parallel plate duct and it decreases with increasing corrugation angle. Experiments were also performed for pressure drop measurements and for flow visualization and the results were compared with the numerical predictions.

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