Heat Transfer Analysis of Two Pass Cooling Channel of Gas Turbine Blade With Analytical Wall Function Turbulence Approach

This paper reports experimental and computational studies of flow and heat transfer through a square duct with a sharp 180 degree turn. The main purpose of this research is to study flow and heat transfer predictions of the Analytical Wall-Function (AWF). To compare the predicting performance of the AWF, the standard Log-Law Wall-Function (LWF) and Low-Reynolds-number (LRN) k-ε model were applied. Their results were also compared with the experimental results for validation. In addition, three extended forms of the AWF were tested. Computational results showed better agreement with the experimental data, especially after the turn of the channel. It was also found that the wall-function (WF) models predicted more reasonable results as Reynolds number increased. The both wall-function models predicted similar results except for separation/reattachment regions where the LWF predicted lower Nusselt number than the other models.

Download Full-text

Effect of Reynolds Number and Property Variation on Fluid Flow and Heat Transfer in the Entrance Region of a Turbine Blade Internal-Cooling Channel

International Journal of Rotating Machinery ◽

10.1155/ijrm.2005.36 ◽

2005 ◽

Vol 2005 (1) ◽

pp. 36-44 ◽

Cited By ~ 1

Author(s):

R. Ben-Mansour ◽

L. Al-Hadhrami

Keyword(s):

Heat Transfer ◽

Reynolds Number ◽

Mass Flow Rate ◽

Heat Transfer Rate ◽

Turbine Blade ◽

Flow Rate ◽

Transfer Rate ◽

Internal Cooling ◽

Cooling Channel ◽

Flow And Heat Transfer

Internal cooling is one of the effective techniques to cool turbine blades from inside. This internal cooling is achieved by pumping a relatively cold fluid through the internal-cooling channels. These channels are fed through short channels placed at the root of the turbine blade, usually called entrance region channels. The entrance region at the root of the turbine blade usually has a different geometry than the internal-cooling channel of the blade. This study investigates numerically the fluid flow and heat transfer in one-pass smooth isothermally heated channel using the RNGk−εmodel. The effect of Reynolds number on the flow and heat transfer characteristics has been studied for two mass flow rate ratios (1/1and1/2) for the same cooling channel. The Reynolds number was varied between10 000and50 000. The study has shown that the cooling channel goes through hydrodynamic and thermal development which necessitates a detailed flow and heat transfer study to evaluate the pressure drop and heat transfer rates. For the case of unbalanced mass flow rate ratio, a maximum difference of8.9% in the heat transfer rate between the top and bottom surfaces occurs atRe=10 000while the total heat transfer rate from both surfaces is the same for the balanced mass flow rate case. The effect of temperature-dependent property variation showed a small change in the heat transfer rates when all properties were allowed to vary with temperature. However, individual effects can be significant such as the effect of density variation, which resulted in as much as9.6% reduction in the heat transfer rate.

Download Full-text

3-D Internal Flow and Conjugate Calculations of a Convective Cooled Turbine Blade With Serpentine-Shaped and Ribbed Channels

Volume 3: Heat Transfer; Electric Power; Industrial and Cogeneration ◽

10.1115/99-gt-220 ◽

1999 ◽

Cited By ~ 9

Author(s):

Dieter E. Bohn ◽

Volker J. Becker ◽

Karsten A. Kusterer ◽

Yokiu Otsuki ◽

Takao Sugimoto ◽

...

Keyword(s):

Heat Transfer ◽

Fluid Flow ◽

Turbine Blade ◽

Solid Body ◽

Gas Turbines ◽

Heat Transfer Analysis ◽

Numerical Code ◽

Cooling Channel ◽

Flow And Heat Transfer ◽

Body Regions

Modern cooling configurations for turbine blades include complex serpentine-shaped cooling channel geometries for internal-forced convective cooling. The channels are ribbed in order to enhance the convective beat transfer. The design of such cooling configurations is within the power of modem CFD-codes with combined heat transfer analysis in solid body regions. One approach is the conjugate fluid flow and heat transfer solver, CHT-Flow, developed at the Institute of Steam and Gas Turbines, Aachen University of Technology. It takes into account of the mutual influences of internal and external fluid flow and heat transfer. The strategy of the procedure is based on a multi-block-technique and a direct coupling module for fluid flow regions and solid body regions. The configuration under investigation in the present paper is based on a test design of a convective cooled turbine blade with serpentine-shaped cooling passages and cooling gas ejection at the blade tip and the trailing edge. The numerical investigations focus on secondary flow phenomena in the ducts and on the heat transfer analysis at the cooling channel walls. In the first part, the cooling channels are investigated with adiabatic smooth & ribbed walls. The calculations are carried out for the stationary and rotating configuration. Concerning the heat transfer analysis, the results of the ribbed configuration with a fixed thermal boundary condition at the walls in the stationary case are presented. Furthermore, in order to demonstrate the capability of the conjugate method to work without thermal boundary conditions, the cooling configuration is calculated including the external blade flow and the blade walls with internal and external heat transfer under typical operation conditions of gas turbines. The numerical code is used to determine the blade surface temperatures.

Download Full-text

Optimization of Rib Shape and Inclination in a Square Duct with Response Surface Methodology

Journal of Turbomachinery ◽

10.1115/1.4052988 ◽

2021 ◽

pp. 1-34

Author(s):

Yigang Luan ◽

Lanyi Yan ◽

Yue Yin ◽

Hao Fu

Keyword(s):

Heat Transfer ◽

Reynolds Number ◽

Response Surface ◽

Navier Stokes ◽

Internal Cooling ◽

Square Duct ◽

Flow And Heat Transfer ◽

Surface Method ◽

Geometric Factors ◽

Parameter Ranges

Abstract The paper conducts numerical investigation coupled with Reynolds-averaged Navier Stokes method on detailed flow field and heat transfer characteristics of ribbed channel with symmetric ribs mounted on two walls. The physical domain is modeled by reference to a practical turbine blade internal cooling channel. The effects of three selected geometric factors of ribs, i.e. rib inclination angle, dimensionless rib height and dimensionless rib pitch, on the flow and heat transfer are investigated by variable-controlled simulations with the Reynolds number ranges from 5,000 to 90,000. The parameter ranges are 30°≤a≤90°, 0.5≤e/w≤1.5 and 5≤P/w≤15 with the rib width w fixed at 1mm. It is newly found that the friction factor does not follow a monotonical trend with respect to the Reynolds number under certain rib configurations. In addition, three-level numerical calculations about three geometric factors as well as the Reynolds number are conducted with the response surface method (RSM). Quadratic regression model for the targeted response, TPF, is obtained. The optimal rib shape for the goal of maximizing the channel overall thermal performance turns out to be e/w=0.5, P/w=15, a=30° as Re is fixed at 30,000.

Download Full-text

Flow and Heat Transfer Analysis in Diverse Microchannel Geometries

Volume 4: Fatigue and Fracture, Heat Transfer, Internal Combustion Engines, Manufacturing, and Technology and Society ◽

10.1115/esda2006-95821 ◽

2006 ◽

Author(s):

J. Garci´a-Gonza´lez ◽

A. Herna´ndez-Guerrero ◽

C. Rubio-Arana ◽

F. Solorio-Ordaz

Keyword(s):

Heat Transfer ◽

Reynolds Number ◽

Electronic Devices ◽

Constant Heat Flux ◽

Heat Sinks ◽

Work Flow ◽

Heat Transfer Analysis ◽

Working Fluid ◽

Flow And Heat Transfer ◽

Current Contact

In this paper an analysis of the fluid flow and the heat transfer in the next generation micro-sized heat sinks is presented. The analysis includes three different geometries for the channels of the heat sinks: rectangular, triangular and trapezoidal, with water as the cooling work flow. A constant heat flux typical of the current high-intensive computational chips (such as the current Pentium chips) is applied at the bottom of the heat sink in a small 1 cm × 1 cm area, an area also typical of the current contact area between electronic devices and the heat dissipaters. The analysis aims to determine the effect of geometry at microscopic scales. It is found that the temperature at the bottom of the dissipater increases approximately in a linear fashion and that by increasing the Reynolds number this temperature decreases. On the contrary, by having a decay in the Reynolds number the temperature of the working fluid increases, bringing a decrease in the viscosity allowing in turn a decrease in the friction losses since the friction coefficient decreases.

Download Full-text

Computations of Turbulent Flow and Heat Transfer in Circular Pipes Using a Low Reynolds Number Two-Equation Model of Turbulence Without Use of Wall Function

International Journal for Computational Methods in Engineering Science and Mechanics ◽

10.1080/15502287.2012.698699 ◽

2012 ◽

Vol 13 (5) ◽

pp. 350-356

Author(s):

Mohsen Abou-Ellail ◽

Ryo Amano ◽

S. H. Chan ◽

Hatem Kayed

Keyword(s):

Heat Transfer ◽

Reynolds Number ◽

Turbulent Flow ◽

Low Reynolds Number ◽

Equation Model ◽

Wall Function ◽

Flow And Heat Transfer ◽

Circular Pipes ◽

Low Reynolds

Download Full-text

NUMERICAL STUDY OF FLOW AND HEAT TRANSFER FOR PULSATING FLOW IN A SQUARE DUCT WITH RIBS

10.1615/ihtc16.hte.022757 ◽

2018 ◽

Author(s):

Wei Wang ◽

Bowen Du ◽

Yuemei Jia

Keyword(s):

Heat Transfer ◽

Numerical Study ◽

Pulsating Flow ◽

Square Duct ◽

Flow And Heat Transfer

Download Full-text

SUPERCRITICAL HEAT TRANSFER IN A HEATED TUBE: MIXED-CONVECTION CRITERIA AND PROPOSED TURBULENT WALL-FUNCTION MODELS

Equipment ◽

10.1615/ihtc13.trb.24 ◽

2006 ◽

Cited By ~ 1

Author(s):

K. W. Seo ◽

Moo Hwan Kim ◽

M. Anderson ◽

Michael L. Corradini

Keyword(s):

Heat Transfer ◽

Mixed Convection ◽

Wall Function ◽

Heated Tube ◽

Turbulent Wall ◽

Function Models

Download Full-text

Entropy generation and heat transfer analysis for ferrofluid flow between two rotating disks with variable conductivity

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406221991184 ◽

2021 ◽

pp. 095440622199118

Author(s):

Anupam Bhandari

Keyword(s):

Heat Transfer ◽

Reynolds Number ◽

Differential Equations ◽

Entropy Generation ◽

Heat Transfer Analysis ◽

Entropy Generation Rate ◽

Geometrical Parameters ◽

Rotating Disks ◽

Coupled Differential Equations ◽

Lower Disk

Present model analyze the flow and heat transfer of water-based carbon nanotubes (CNTs) [Formula: see text] ferrofluid flow between two radially stretchable rotating disks in the presence of a uniform magnetic field. A study for entropy generation analysis is carried out to measure the irreversibility of the system. Using similarity transformation, the governing equations in the model are transformed into a set of nonlinear coupled differential equations in non-dimensional form. The nonlinear coupled differential equations are solved numerically through the finite element method. Variable viscosity, variable thermal conductivity, thermal radiation, and volume concentration have a crucial role in heat transfer enhancement. The results for the entropy generation rate, velocity distributions, and temperature distribution are graphically presented in the presence of physical and geometrical parameters of the flow. Increasing the values of ferromagnetic interaction number, Reynolds number, and temperature-dependent viscosity enhances the skin friction coefficients on the surface and wall of the lower disk. The local heat transfer rate near the lower disk is reduced in the presence of Harman number, Reynolds number, and Prandtl number. The ferrohydrodynamic flow between two rotating disks might be useful to optimize the use of hybrid nanofluid for liquid seals in rotating machinery.

Download Full-text