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Research Papers: Gas Turbines: Turbomachinery

Rotor Blade Heat Transfer of High Pressure Turbine Stage Under Inlet Hot-Streak and Swirl

[+] Author and Article Information
A. Rahim

Department of Engineering Science,
University of Oxford,
Oxford OX1 3PJ, UK

L. He

Department of Engineering Science,
University of Oxford,
Oxford OX1 3PJ, UK
e-mail: Li.He@eng.ox.ac.uk

1Corresponding author.

Contributed by the Turbomachinery Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received August 4, 2014; final manuscript received September 23, 2014; published online December 9, 2014. Editor: David Wisler.

J. Eng. Gas Turbines Power 137(6), 062601 (Jun 01, 2015) (10 pages) Paper No: GTP-14-1460; doi: 10.1115/1.4028740 History: Received August 04, 2014; Revised September 23, 2014; Online December 09, 2014

A key consideration in high pressure (HP) turbine designs is the heat load experienced by rotor blades. Impact of turbine inlet nonuniformity of combined temperature and velocity traverses, typical for a lean-burn combustor exit, has rarely been studied. For general turbine aerothermal designs, it is also of interest to understand how the behavior of lean-burn combustor traverses (with both hot-streak and swirl) might contrast with those for a rich-burn combustor (largely hot-streak only). In the present work, a computational study has been carried out on the aerothermal performance of a HP turbine stage under nonuniform temperature and velocity inlet profiles. The analyses are primarily conducted for two combined hot-streak and swirl inlets, with opposite swirl directions. In addition, comparisons are made against a hot-streak only case and a uniform inlet. The effects of three nozzle guide vane (NGV) shape configurations are investigated: straight, compound lean (CL) and reverse CL (RCL). The present results reveal a qualitative change in the roles played by heat transfer coefficient (HTC) and fluid driving (“adiabatic wall”) temperature, Taw. It has been shown that the blade heat load for a uniform inlet is dominated by HTC, whilst a hot-streak only case is largely influenced by Taw. However, in contrast to the hot-streak only case, a combined hot-streak and swirl case shows a role reversal with the HTC being a dominant factor. Additionally, it is seen that the swirling flow redistributes radially the hot fluid within the NGV passage considerably, leading to a much ‘flatter’ rotor inlet temperature profile compared to its hot-streak only counterpart. Furthermore, the rotor heat transfer characteristics for the combined traverses are shown to be strongly dependent on the NGV shaping and the inlet swirl direction, indicating a potential for further design space exploration. The present findings underline the need to clearly define relevant combustor exit temperature and velocity profiles when designing and optimizing NGVs for HP turbine aerothermal performance.

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References

Figures

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Fig. 1

Reduction in computational cost through use of a single-passage domain with the phase-shift condition

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Fig. 2

Computational meshes for different vane configurations

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Fig. 3

Combined hot-streak and swirl profiles

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Fig. 4

Mesh dependency check for distributions of isentropic Mach number (left) and Nusselt number (right) at 10%, 50%, and 90% radial height

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Fig. 5

Stage nonadiabatic efficacy as illustrated in h–s diagram

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Fig. 6

Hot-streak isosurface (T0 = 495 K), with and without swirl through NGV passage (viewed from upstream)

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Fig. 7

Absolute total temperatures at vane exit for straight vane (hot-streak case and two combined cases with different swirl directions)

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Fig. 8

Absolute total temperature at vane exit (hot-streak and positive swirl)

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Fig. 9

Absolute total temperature at vane exit (hot-streak and negative swirl)

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Fig. 10

Tip heat flux, HTC and Taw for straight and CL vanes (uniform inflow)

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Fig. 11

Tip heat flux, HTC and Taw for straight and CL vanes (hot-streak only)

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Fig. 12

Heat flux, HTC and Taw on rotor pressure surface for different vane shapes (hot-streak and positive swirl)

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Fig. 13

δHTC and δTaw plots on rotor pressure surface (hot-streak and positive swirl)

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Fig. 14

Heat flux, HTC, and Taw for different vane shapes (hot-streak and negative swirl)

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Fig. 15

Tip heat flux, HTC, and Taw for three vane cases (hot-streak and positive swirl)

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Fig. 16

Tip circumferential averaged heat flux for three NGV shapes (hot-streak and positive swirl)

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Fig. 17

δHTC and δTaw plots for three NGV shapes (hot-streak and positive swirl)

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Fig. 18

Tip heat flux, HTC, and Taw for three NGV shapes (hot-streak and negative swirl)

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Fig. 19

Tip circumferential averaged heat flux for three NGV shapes (hot-streak and negative swirl)

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