Research Papers

Influence of Purge Flow Injection Angle on the Aerothermal Performance of a Rotor Blade Cascade

[+] Author and Article Information
G. Barigozzi

e-mail: giovanna.barigozzi@unibg.it

G. Franchini

e-mail: giuseppe.franchini@unibg.it

A. Perdichizzi

e-mail: antonio.perdichizzi@unibg.it
Dipartimento di Ingegneria,
Università degli Studi di Bergamo,
Viale Marconi 5,
Dalmine (BG) 24044, Italy

M. Maritano

e-mail: maritano@aen.ansaldo.it

R. Abram

e-mail: Roberto.Abram@aen.ansaldo.it
Hot Gas Path Engineering,
Ansaldo Energia S.p.A.,
Via N. Lorenzi 8,
Genova 16152, Italy

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received June 13, 2013; final manuscript received June 27, 2013; published online September 26, 2013. Editor: Ronald Bunker.

J. Turbomach 136(4), 041012 (Sep 26, 2013) (9 pages) Paper No: TURBO-13-1097; doi: 10.1115/1.4025168 History: Received June 13, 2013; Revised June 27, 2013

This paper is focused on the influence of stator-rotor purge flow injection angle on the aerodynamic and thermal performance of a rotor blade cascade. Tests were performed in a seven-blade cascade of a high-pressure gas turbine rotor at low Mach number (Ma2is = 0.3) under different blowing conditions. A number of fins were installed inside the upstream slot to simulate the effect of rotation on the seal flow exiting the gap in a linear cascade environment. The resulting coolant flow is ejected with the correct angle in the tangential direction. Purge flow injection angle and blowing conditions were changed in order to identify the best configuration in terms of end wall thermal protection and secondary flows reduction. The 3D flow field was surveyed by traversing a five-hole miniaturized pressure probe in a downstream plane. Secondary flow velocities, loss coefficient, and vorticity distributions are presented for the most significant test conditions. Film cooling effectiveness distributions on the platform were obtained by thermochromic liquid crystals (TLC) technique. Results show that purge flow injection angle has an impact on secondary flows development and, thus, on the end wall thermal protection, especially at high injection rates. Passage vortex is enhanced by a negative injection angle, which simulates the real counter rotating purge flow direction.

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Fig. 3

Blade Mach number distribution

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Fig. 4

Slot geometry and details of coolant supply system

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Fig. 5

Reference cascade local ζ (a) and Ω (b) distributions at X/cax = 108%

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Fig. 6

Local ζ distributions for variable MFR at X/cax = 108% (no fins)

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Fig. 7

Local Ω distributions with secondary velocity vectors at X/cax = 108% (no fins)

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Fig. 8

Local ζ distributions at X/cax = 108% for MFR = 1.0% with variable fins angle (–10 deg and 10 deg)

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Fig. 9

Local ζ distributions at X/cax = 108% for MFR = 2.0% with variable fins angle (–10 deg and 10 deg)

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Fig. 10

Local Ω distribution with secondary velocity vectors at X/cax = 108% for MFR = 2.0% with variable fins angle (–10 deg and 10 deg)

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Fig. 11

Local ζ and Ω distributions with secondary velocity vectors at X/cax = 108% for MFR = 2.0% with α = –10 deg

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Fig. 12

Pitch averaged ζ and Δβ distributions for variable injection angles (MFR = 1.0% and 2.0%)

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Fig. 13

Mixed out kinetic energy loss coefficients versus MFR

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Fig. 14

Film cooling effectiveness distributions for variable injection conditions

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Fig. 15

Pitch averaged film cooling effectiveness distributions

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Fig. 16

Area averaged η distributions versus MFR




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