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Research Papers

Experimental Investigation of the Effect of Purge Flow on Film Cooling Effectiveness on a Rotating Turbine With Nonaxisymmetric End Wall Contouring

[+] Author and Article Information
M. Rezasoltani

Turbomachinery Performance
and Flow Research Laboratory,
Department of Mechanical Engineering,
Texas A&M University,
College Station, TX 77843-3123

M. T. Schobeiri

Turbomachinery Performance
and Flow Research Laboratory,
Department of Mechanical Engineering,
Texas A&M University,
College Station, TX 77843-3123
e-mail: tschobeiri@tamu.edu

J. C. Han

Department of Mechanical Engineering,
Texas A&M University,
College Station, TX 77843-3123

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received November 14, 2013; final manuscript received November 27, 2013; published online May 2, 2014. Editor: Ronald Bunker.

J. Turbomach 136(9), 091009 (May 02, 2014) (10 pages) Paper No: TURBO-13-1256; doi: 10.1115/1.4027196 History: Received November 14, 2013; Revised November 27, 2013

The impact of the purge flow injection on aerodynamics and film cooling effectiveness of a three-stage, high-pressure turbine with nonaxisymmetric end wall contouring has been experimentally investigated. As a continuation of the previously published work involving stator-rotor gap purge cooling, this study investigates film cooling effectiveness on the first-stage rotor contoured platform due to a coolant gas injection. Film cooling effectiveness measurements are performed on the rotor blade platform using a pressure-sensitive paint (PSP) technique. The present study examines, in particular, the film cooling effectiveness due to injection of coolant from the rotor cavity through the circumferential gap between the first stator followed by the first rotor. Effects of the presence of contouring, blowing ratios, rotational speeds, and coolant density ratio are studied and compared to a noncontouring platform. The experimental investigation is carried out in a three-stage turbine facility at the Turbomachinery Performance and Flow Research Laboratory (TPFL) at Texas A&M University. Its rotor includes nonaxisymmetric end wall contouring on the first and second rotor row. The turbine has two independent cooling loops. Film cooling effectiveness measurements are performed for three coolant-to-mainstream mass flow ratios of 0.5%, 1.0%, and 1.5%. Film cooling data is obtained for three rotational speeds, 3000 rpm (reference condition), 2550 rpm, and 2400 rpm, and compared with noncontoured end wall data. Effect of density ratio for coolant-to-mainstream density ratio (DR) = 1.0 and DR = 1.5 is also investigated. The comparisons of film effectiveness results show that contoured cases have a noticeable quantitative improvement compared to those of noncontoured ones.

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References

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Figures

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Fig. 1

The overall layout of TPFL research turbine facility

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Fig. 2

Section view of the modified stator-rotor turbine assembly for stator-rotor purge flow and platform film cooling

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Fig. 3

Detailed view of the stator-rotor gap design for the rotating platform

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Fig. 4

Variation of contour depth along the suction surface to obtain the best end wall contouring efficiency

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Fig. 5

Position of the circumferential gap for ejection of purge flow (left), contour geometry for first rotor

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Fig. 6

PSP calibration curve

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Fig. 7

Optical setup for PSP data acquisition

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Fig. 8

Film cooling effectiveness distribution on the contoured rotating platform for 3000 rpm

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Fig. 9

Comparison of film cooling effectiveness distribution on the contoured and noncontoured rotating platform for 3000 rpm

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Fig. 10

Film cooling effectiveness distribution on the contoured and noncontoured rotating platform for 2550 rpm

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Fig. 11

Film cooling effectiveness distribution on the contoured and noncontoured rotating platform for 2400 rpm

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Fig. 12

Velocity triangles and relative inlet and exit flow angles for design speed and off-design rotating speeds

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Fig. 13

Pitchwise average film cooling effectiveness distribution along axial chord for different rpms

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Fig. 14

Pitchwise average film cooling effectiveness distribution along axial chord for contoured platform for different MFRs

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Fig. 15

Total average film cooling effectiveness for different rpms

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Fig. 16

Film cooling effectiveness distribution at two different density ratios at 3000 rpm and MFR = 1%

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Fig. 17

Pitchwise average film cooling effectiveness distribution for two different coolants at 3000 rpm, MFR = 1%

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