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Research Papers

Full Coverage Shaped-Hole Film Cooling in an Accelerating Boundary Layer With High Freestream Turbulence

[+] Author and Article Information
J. E. Kingery

Raytheon Missile Systems,
1151 E. Hermans Road,
Tucson, AZ 85756
e-mail: kingery.joseph@gmail.com

F. E. Ames

Mechanical Engineering Department,
University of North Dakota,
Grand Forks, ND 58202
e-mail: forrest.ames@engr.und.edu

1Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received September 21, 2015; final manuscript received October 2, 2015; published online February 17, 2016. Editor: Kenneth C. Hall.The United States Government retains, and by accepting the article for publication, the publisher acknowledges that the United States Government retains, a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for United States government purposes.

J. Turbomach 138(7), 071002 (Feb 17, 2016) (12 pages) Paper No: TURBO-15-1208; doi: 10.1115/1.4031867 History: Received September 21, 2015; Revised October 02, 2015

Full coverage shaped-hole film cooling and downstream heat transfer measurements have been acquired in the accelerating flows over a large cylindrical leading edge test surface. The shaped holes had an 8 deg lateral expansion angled at 30 deg to the surface with spanwise and streamwise spacings of 3 diameters. Measurements were conducted at four blowing ratios, two Reynolds numbers, and six well documented turbulence conditions. Film cooling measurements were acquired over a four to one range in blowing ratio at the lower Reynolds number and at the two lower blowing ratios for the higher Reynolds number. The film cooling measurements were acquired at a coolant to free-stream density ratio of approximately 1.04. The flows were subjected to a low turbulence (LT) condition (Tu = 0.7%), two levels of turbulence for a smaller sized grid (Tu = 3.5% and 7.9%), one turbulence level for a larger grid (8.1%), and two levels of turbulence generated using a mock aerocombustor (AC) (Tu = 9.3% and 13.7%). Turbulence level is shown to have a significant influence in mixing away film cooling coverage progressively as the flow develops in the streamwise direction. Effectiveness levels for the AC turbulence condition are reduced to as low as 20% of LT values by the furthest downstream region. The film cooling discharge is located close to the leading edge with very thin and accelerating upstream boundary layers. Film cooling data at the lower Reynolds number show that transitional flows have significantly improved effectiveness levels compared with turbulent flows. Downstream effectiveness levels are very similar to slot film cooling data taken at the same coolant flow rates over the same cylindrical test surface. However, slots perform significantly better in the near discharge region. These data are expected to be very useful in grounding computational predictions of full coverage shaped-hole film cooling with elevated turbulence levels and acceleration. Infrared (IR) measurements were performed for the two lowest turbulence levels to document the spanwise variation in film cooling effectiveness and heat transfer.

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References

Figures

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Fig. 1

Schematic of UND's large-scale cascade wind tunnel with cylindrical leading edge test section

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Fig. 2

Schematic of shaped-hole film cooling insert for large cylindrical leading edge test surface

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Fig. 3

Schematic of shaped-hole array and shaped holes as configured for the leading edge film cooling insert

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Fig. 4

Photo of shaped-hole insert showing full coverage staggered array with intrahole thermocouples

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Fig. 5

Photo of shaped-hole insert installed onto cylinder upstream of bracket instrumentation and heat transfer foil

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Fig. 6

Schematic of large cylindrical leading edge test surface profile

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Fig. 7

Predicted velocity distribution over larger cylindrical leading edge test surface

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Fig. 8

Adiabatic film cooling, LT, variable blowing ratios, and larger diameter

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Fig. 9

Adiabatic film cooling, small grid far turbulence (SG2), variable blowing ratios, and larger diameter

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Fig. 10

Adiabatic film cooling, grid turbulence (GR), variable blowing ratios, and larger diameter

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Fig. 11

Adiabatic film cooling, AC turbulence, variable blowing ratios, and larger diameter

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Fig. 12

Adiabatic film cooling effectiveness, M = 0.54, variable turbulence condition, and ReD = 250,000

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Fig. 13

Adiabatic film cooling effectiveness, M = 0.97, variable turbulence conditions, and ReD = 250,000

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Fig. 14

Adiabatic film cooling effectiveness, M = 0.54 comparing turbulence conditions and Reynolds numbers

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Fig. 15

Adiabatic film cooling effectiveness, M = 0.96 comparing turbulence conditions and Reynolds numbers

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Fig. 16

Adiabatic film cooling effectiveness, M = 0.54 comparing shaped holes and slot [2] at same mass flow rate, ReD = 250,000

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Fig. 17

Adiabatic film cooling effectiveness, M = 0.95 comparing shaped holes and slot [2] at same mass flow rate, ReD = 250,000

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Fig. 18

Stanton number distributions without blowing for six turbulence conditions, ReD = 250,000

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Fig. 19

Stanton number distributions for leading edge test surface, M = 0.97, and ReD = 250,000, for six turbulence conditions

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Fig. 20

Stanton number distributions for leading edge test surface, M = 0.53, and ReD = 500,000, for six turbulence conditions

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Fig. 21

Full surface, IR, film cooling visualization, and M = 0.54 LT showing spanwise variation of film cooling effectiveness

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Fig. 22

Full surface, IR, film cooling visualization, and M = 0.97 LT showing spanwise variation of film cooling effectiveness

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Fig. 23

Full surface, IR, film cooling visualization, and M = 0.97 small grid near (SG2) showing spanwise variation of film cooling effectiveness

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Fig. 24

Adiabatic film cooling effectiveness, shaped holes, and ReD = 250,000, comparing thermocouple data with span-averaged full surface data

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Fig. 25

Comparison of IR camera data with thermocouple data at fixed X/d locations, LT, M = 0.95, and ReD = 250,000

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Fig. 26

Comparison of IR camera data with thermocouple data at fixed X/d locations, small grid far (SG2), M = 0.97, and ReD = 250,000

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Fig. 27

Full surface, IR, heat transfer visualization, and M = 0.97 LT showing spanwise variation of Stanton number, ReD = 250,000

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