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Technical Briefs

Thermomechanical Stress Distributions in a Gas Turbine Blade Under the Effect of Cooling Flow Variations

[+] Author and Article Information
Candelario Bolaina

e-mail: cbolaina@prodigy.net.mx

Julio Teloxa

e-mail: j_teloxa@hotmail.com

Cesar Varela

e-mail: cvboydo@hotmail.com

Fernando Z. Sierra

e-mail: fse@uaem.mx
Centro de Investigación en Ingeniería y
Ciencias Aplicadas, CIICAp,
Universidad Autónoma del Estado de
Morelos, UAEM,
Av. Universidad 1001, Col. Chamilpa,
C. P. 62209, Cuernavaca, Morelos, Mexico

1Present address: Dep. de Ing. Mec. Universidad Juárez Autónoma de Tabasco.

2Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received December 16, 2010; final manuscript received August 8, 2012; published online September 13, 2013. Assoc. Editor: Matthew Montgomery.

J. Turbomach 135(6), 064501 (Sep 13, 2013) (9 pages) Paper No: TURBO-10-1229; doi: 10.1115/1.4023465 History: Received December 16, 2010; Revised August 08, 2012

Thermomechanical stresses in gas turbine blades are investigated. Attention is focused on effects caused by varying the cooling airflow that runs through the blade interior, keeping constant a mainstream condition around the blade surface. Stress concentration was predicted numerically under engine real operating conditions. Temperature distributions in the metal blade surface produced by convective boundary conditions were linked with heat conduction within the blade using a conjugate solution. Results of stress concentration in the blade material for reduced cooling flow rate, blocked cooling ducts, and rotation rate were obtained. It is shown that temperature and stress distributions are a strong function of position in blade interior material and surface. Thermomechanical stress concentration was observed in the leading edge, with the endwall region affected by large stress concentration. Stress magnitude increments were found for combined cyclic thermal heating and sustained mechanical loads on specific planes of airfoil span for reduced cooling flow. Also, large stress gradients between leading and trailing regions of the blade were observed. The study reveals that blocking channels increase stresses in the central region of blade transversal cross section.

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References

Figures

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Fig. 1

Computational domain of group blade-rotor

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Fig. 2

Computational grid of the blade used in the simulation; (a) finite volume; (b) finite element; (c) plan view of the blade with cooling channels: nine channels blocked and six channels blocked

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Fig. 3

Cascade of blades in a Perspex wind channel

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Fig. 4

Comparison of numerical to experimental results for leading edge suction side: (a) experimental contours of temperature; (b) numerical contours of temperature; (c) numerical against measurements of cooling effectiveness. Scale units are K.

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Fig. 5

Comparison of numerical prediction to experimental data for pressure side in leading edge: (a) schematic drawing of blade tip configuration and PIV velocity vectors; (b) CFD velocity vectors; (c) CFD against PIV velocity profile from the blade wall

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Fig. 6

Numerical results of temperature distributions for run 1 of Table 1 with no rotation in: (a) plane a, 0.0 L; (b) plane b, 0.2 L; (c) plane c, 0.4 L; (d) plane d, 0.6 L; (e) plane e, 0.8 L; (f) plane f, L; and (g) planes location

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Fig. 11

Numerical results of temperature distributions for plane d, run 1 of Tables 1 and 2, and rotation rate ϖ = 3600 rpm, in: (a) no blocked channels; (b) six blocked channels; (c) nine blocked channels; plane location as in Fig. 6(g). Blocking according to Fig. 2(c).

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Fig. 12

Thermomechanical stress distributions in plane d, as a function cooling Reynolds number, Rec, runs 1 to 6 of Tables 1 and 2, and blocking conditions

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Fig. 10

Numerical results of temperature distributions for no blocked channels and rotation rate ϖ = 3600 rpm in: (a) plane d; (b) plane e; (c) plane f; location as in Fig. 6(g)

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Fig. 8

Numerical results of mechanical stress distributions for rotation rate ϖ = 3600 rpm in: (a) plane a; (b) plane b; (c) plane c; (d) plane d; (e) plane e; (f) plane f; planes location as in Fig. 6(g)

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Fig. 7

Numerical results of thermal stress distributions for run 1 of Table 1 with no rotation in: (a) plane a; (b) plane b; (c) plane c; (d) plane d; (e) plane e; (f) plane f; Planes location as in Fig. 6(g)

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Fig. 9

Numerical results of thermomechanical stress distributions for run 1 of Tables 1 and 2 in: (a) plane a; (b) plane b; (c) plane c; (d) plane d; (e) plane e; (f) plane f; planes location as in Fig. 6(g)

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Fig. 13

Numerical results of thermomechanical stress distributions in the blade as a function cooling Reynolds number, Rec, runs 1 to 6 of Tables 1 and 2, and blocking conditions: (a) planes a, b, and c; (b) planes d, e and f

Tables

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