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Research Papers

Turbine Blade Tip Film Cooling With Blade Rotation—Part I: Tip and Pressure Side Coolant Injection

[+] Author and Article Information
Onieluan Tamunobere

Turbine Innovation and Energy
Research (TIER) Center,
Louisiana State University,
Baton Rouge, LA 70803

Sumanta Acharya

Turbine Innovation and Energy
Research (TIER) Center,
Louisiana State University,
Baton Rouge, LA 70803;
Mechanical Engineering Department,
University of Memphis,
Memphis, TN 38152
e-mail: s.acharya@memphis.edu

1Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received November 23, 2015; final manuscript received January 31, 2016; published online April 5, 2016. Editor: Kenneth C. Hall.

J. Turbomach 138(9), 091002 (Apr 05, 2016) (8 pages) Paper No: TURBO-15-1273; doi: 10.1115/1.4032672 History: Received November 23, 2015; Revised January 31, 2016

An experimental study of film cooling is conducted on the tip of a turbine blade with a blade rotation speed of 1200 rpm. The coolant is injected from the blade tip and pressure side (PS) holes, and the effect of the blowing ratio on the heat transfer coefficient and film cooling effectiveness of the blade tip is investigated. The blade has a tip clearance of 1.7% of the blade span and consists of a cut back squealer rim, two cylindrical tip holes, and six shaped PS holes. The stator–rotor–stator test section is housed in a closed loop wind tunnel that allows for the performance of transient heat transfer tests. Measurements of the heat transfer coefficient and film cooling effectiveness are done on the blade tip using liquid crystal thermography. These measurements are reported for the no coolant case and for blowing ratios of 1.0, 1.5, 2.0, 3.0, and 4.0. The heat transfer result for the no coolant injection shows a region of high heat transfer on the blade tip near the blade leading edge region as the incident flow impinges on that region. This region of high heat transfer extends and stretches on the tip as more coolant is introduced through the tip holes at higher blowing ratios. The cooling results show that increasing the blowing ratio increases the film cooling effectiveness. The cooling effectiveness signatures indicate that the tip coolant is pushed toward the blade suction side thereby providing better coverage in that region. This shift in coolant flow toward the blade suction side, as opposed to the PS in stationary studies, can primarily be attributed to the effects of the blade relative motion.

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References

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Figures

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Fig. 1

Schematic of turbine facility [16]

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Fig. 2

Turbine blade model and blade profile [16]

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Fig. 3

Schematic of test section showing coolant path [16]

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Fig. 4

Data-acquisition system

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Fig. 5

Heat transfer coefficient for (a) no coolant case, (b) M = 1.0, (c) M = 1.5, (d) M = 2.0, (e) M = 3.0, and (f) M = 4.0

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Fig. 6

Film cooling effectiveness for (a) M = 1.0, (b) M = 1.5, (c) M = 2.0, (d) M = 3.0, and (e) M = 4.0

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Fig. 7

Laterally averaged h/h0 versus axial distance for the blade tip at different blowing ratios

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Fig. 8

Laterally averaged η versus axial distance for the blade tip at different blowing ratios

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Fig. 9

Heat transfer coefficient at (a) M = 1.5 and (b) M = 3.0 for the blade tip holes only

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Fig. 10

Film cooling effectiveness at (a) M = 1.5 and (b) M = 3.0 for the blade tip holes only

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Fig. 11

Heat transfer coefficient for (a) M = 1.5 and (b) M = 3.0 for the PS holes only

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Fig. 12

Film cooling effectiveness for (a) M = 1.5 and (b) M = 3.0 for the PS holes only

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Fig. 13

Laterally averaged h/h0 versus axial distance for the blade tip, blade PS and blade tip and PS holes at blowing ratios M = 1.5 and M = 3.0

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Fig. 14

Laterally averaged η versus axial distance for the blade tip, blade PS and blade tip and PS holes at blowing ratios M = 1.5 and M = 3.0

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