Influence of Large Turbo-Generator Stator Ventilation Ducts Structural Changes on Stator Temperature

2012 ◽  
Vol 462 ◽  
pp. 318-326
Author(s):  
Fei Yang Huo ◽  
Jia Hui Sun ◽  
Wei Li Li ◽  
Yi Huang Zhang
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Temperature Distribution ◽  
Velocity Distribution ◽  
Fluid Velocity ◽  
Three Dimensional ◽  
Flow And Heat Transfer ◽  
Turbo Generator ◽  
Ventilation Ducts ◽  
Cooling Air

For the complex status of fluid flow in stator radial ventilation ducts of large turbo-generator, the temperature distribution of stator is dramatically affected by the flow status of cooling medium in stator ventilating ducts. In this paper, a new ventilating ducts structure in stator is investigated. According to fixing a wind deflector on the stator teeth adjacent to the ventilation ducts, the fluid flow status of cooling air is changed flowing in stator ventilation ducts. For this reason, the effect of heat transfer in stator is changed. Taking an air-cooled turbo-generator as an example, considering the characteristics of fluid flow and heat transfer in turbo-generator ventilation system, the three-dimensional fluid flow and heat transfer coupling model is established. Using finite volume method, three-dimensional fluid field and temperature field control equations are coupling solved. Based on this, the velocity distribution in ventilating ducts is obtained. Besides that, the velocity distribution is studied with the cooling air flows into radial ventilation ducts at different incident angles. The influences of wind deflector and incident angles on the fluid velocity and temperature distribution are analyzed. Based on that, some useful conclusions are obtained.

Verification of Finite Volume Computations on Steady-State Fluid Flow and Heat Transfer

2001 ◽  
Vol 124 (1) ◽  
pp. 11-21 ◽  
Author(s):  
J. Cadafalch ◽  
C. D. Pe´rez-Segarra ◽  
R. Co`nsul ◽  
A. Oliva
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Steady State ◽  
Finite Volume ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Independent Solution ◽  
Post Processing ◽  
Square Duct ◽  
Flow And Heat Transfer

This work presents a post-processing tool for the verification of steady-state fluid flow and heat transfer finite volume computations. It is based both on the generalized Richardson extrapolation and the Grid Convergence Index GCI. The observed order of accuracy and a error band where the grid independent solution is expected to be contained are estimated. The results corresponding to the following two and three-dimensional steady-state simulations are post-processed: a flow inside a cavity with moving top wall, an axisymmetric turbulent flow through a compressor valve, a premixed methane/air laminar flat flame on a perforated burner, and the heat transfer from an isothermal cylinder enclosed by a square duct. Discussion is carried out about the certainty of the estimators obtained with the post-processing procedure. They have been shown to be useful parameters in order to assess credibility and quality to the reported numerical solutions.

Fluid flow and heat transfer of a stratified system during natural convection – influence of chamfered corners

2019 ◽  
Vol 29 (2) ◽  
pp. 470-486 ◽  
Author(s):  
Alireza Rahimi ◽  
Aravindhan Surendar ◽  
Aygul Z. Ibatova ◽  
Abbas Kasaeipoor ◽  
Emad Hasani Malekshah
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Natural Convection ◽  
Entropy Generation ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Three Dimensional ◽  
Immiscible Fluids ◽  
Content Type ◽  
Flow And Heat Transfer

Purpose This paper aims to investigate the three-dimensional natural convection and entropy generation in the rectangular cuboid cavities included by chamfered triangular partition made by polypropylene. Design/methodology/approach The enclosure is filled by multi-walled carbon nanotubes (MWCNTs)-H2O nanofluid and air as two immiscible fluids. The finite volume approach is used for computation. The fluid flow and heat transfer are considered with combination of local entropy generation due to fluid friction and heat transfer. Moreover, a numerical method is developed based on three-dimensional solution of Navier–Stokes equations. Findings Effects of side ratio of triangular partitions (SR = 0.5, 1 and 2), Rayleigh number (103 < Ra < 105) and solid volume fraction (f = 0.002, 0.004 and 0.01 Vol.%) of nanofluid are investigated on both natural convection characteristic and volumetric entropy generation. The results show that the partitions can be a suitable method to control fluid flow and energy consumption, and three-dimensional solutions renders more accurate results. Originality/value The originality of this work is to study the three-dimensional natural convection and entropy generation of a stratified system.

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

1999 ◽  
Vol 121 (3) ◽  
pp. 202-208 ◽  
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.

A Numerical Study of Flow and Heat Transfer in a Smooth and Ribbed U-Duct With and Without Rotation

2000 ◽  
Vol 123 (2) ◽  
pp. 219-232 ◽  
Author(s):  
Y.-L. Lin ◽  
T. I.-P. Shih ◽  
M. A. Stephens ◽  
M. K. Chyu
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Fluid Flow ◽  
Mach Number ◽  
Vector Fields ◽  
Numerical Study ◽  
Density Ratio ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Flow And Heat Transfer

Computations were performed to study the three-dimensional flow and heat transfer in a U-shaped duct of square cross section under rotating and non-rotating conditions. The parameters investigated were two rotation numbers (0, 0.24) and smooth versus ribbed walls at a Reynolds number of 25,000, a density ratio of 0.13, and an inlet Mach number of 0.05. Results are presented for streamlines, velocity vector fields, and contours of Mach number, pressure, temperature, and Nusselt numbers. These results show how fluid flow in a U-duct evolves from a unidirectional one to one with convoluted secondary flows because of Coriolis force, centrifugal buoyancy, staggered inclined ribs, and a 180 deg bend. These results also show how the nature of the fluid flow affects surface heat transfer. The computations are based on the ensemble-averaged conservation equations of mass, momentum (compressible Navier-Stokes), and energy closed by the low Reynolds number SST turbulence model. Solutions were generated by a cell-centered finite-volume method that uses second-order flux-difference splitting and a diagonalized alternating-direction implicit scheme with local time stepping and V-cycle multigrid.

Fluid Flow and Heat Transfer Over a Three-Dimensional Spherical Object in a Pipe

1998 ◽  
Vol 120 (4) ◽  
pp. 985-990 ◽  
Author(s):  
N. Shahcheraghi ◽  
H. A. Dwyer
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Pipe Wall ◽  
Three Dimensional ◽  
Governing Equations ◽  
Sphere Surface ◽  
Spherical Object ◽  
Number Range ◽  
Flow And Heat Transfer ◽  
Grid Scheme

An incompressible viscous fluid flow with heat transfer over a spherical object inside a pipe is considered. The flow is made three-dimensional by an eccentric positioning of the sphere inside the pipe. The governing equations are solved by a numerical method which uses a finite volume formulation in a generalized body fitted coordinate system. An overset (Chimera) grid scheme is used to resolve the two geometries of the pipe and sphere. The results are compared to those of an external flow over a sphere, and the code is validated using such results in the intermediate Reynolds number range. The blockage effects are analyzed through evaluation of lift, drag, and heat transfer rate over the sphere. Also the change in the shear stress pattern is examined through evaluation of the local friction factor on a pipe wall and sphere surface.

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