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Research Papers: Fundamental Issues and Canonical Flows

Experimental Flow-Field Investigations Downstream a Scaled-Up Micro-Tangential-Jet Scheme Using the Particle Image Velocimetry Technique

[+] Author and Article Information
Othman Hassan

Department of Mechanical
and Industrial Engineering,
Concordia University,
Montreal, QC H3G 1M8, Canada

Ibrahim Hassan

Department of Mechanical
and Industrial Engineering,
Concordia University,
Montreal, QC H3G 1M8, Canada
e-mail: ibrahimh@alcor.concordia.ca

1Corresponding author.

Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received April 29, 2013; final manuscript received February 12, 2014; published online May 6, 2014. Assoc. Editor: Prashanta Dutta.

J. Fluids Eng 136(7), 071204 (May 06, 2014) (14 pages) Paper No: FE-13-1275; doi: 10.1115/1.4026881 History: Received April 29, 2013; Revised February 12, 2014

This paper presents experimental investigations of the flow-field characteristics downstream a Scaled-Up Micro-Tangential-Jet (SUMTJ) film-cooling scheme using the particle image velocimetry (PIV) technique over a flat plate. The SUMTJ scheme is a shaped scheme designed so that the secondary jet is supplied tangentially to the surface. The scheme combines the thermal benefits of tangential injection and the enhanced material strength of discrete holes’ schemes compared with continuous slot schemes. The flow-field characteristics downstream one row of holes were investigated at three blowing ratios, 0.5, 1.0, and 1.5, and were calculated based on the scheme exit area. A density ratio of unity, a Reynolds number of 1.16 × 105, and an average turbulence intensity of 8% were used throughout the investigations. The performance of the SUMTJ scheme was compared to that of the circular hole scheme, base line case case, at the same test conditions and blowing ratios. From the investigations, it was noticeable that the SUMTJ scheme jet stays attached to the surface for long downstream distances at all investigated blowing ratios. Moreover, the lateral expansion angles of the scheme help perform a continuous film from adjacent jets close to the schemes’ exits; however, they have a negative impact on the uniformity of the film thickness in the lateral direction. The vorticity strength downstream the SUMTJ scheme in the y-z plane was much less than the vorticity strength downstream the circular scheme at all blowing ratios. However, the vorticity behavior in the shear layer between the secondary SUMTJ scheme jet and the main stream was changing dramatically with the blowing ratio. The latter is expected to have a significant impact on the film-cooling performance as the blowing ratio increases.

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Figures

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Fig. 3

PIV system details

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Fig. 2

Schematic diagram of the test facility

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Fig. 1

The SUMTJ scheme geometrical details

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Fig. 4

Experimental 2D and 3D velocity ratio comparison with theoretical

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Fig. 5

3D velocity distribution comparison between present work and the work of Bernsdorf et al. [16] downstream a circular scheme at x/d = 4.0

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Fig. 6

Velocity ratio distribution at x/d = 2.0 for the SUMTJ and the circular schemes at different blowing ratios

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Fig. 11

Dimensionless vorticity distribution at x/d = 8.0 for the SUMTJ and the circular schemes at different blowing ratios

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Fig. 12

Peak vorticity variation with blowing ratio increase at different x/d locations for both SUMTJ and circular schemes

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Fig. 13

Dimensionless vorticity distribution at the mid-x-y plane (z/d = 0.0) for the SUMTJ scheme at different blowing ratios and downstream locations

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Fig. 7

Velocity ratio distribution at x/d = 8.0 for the SUMTJ and the circular schemes at different blowing ratios

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Fig. 8

Midplane (z/d = 0.0) x-axis velocity ratio comparison for the SUMTJ scheme at different downstream locations and blowing ratios

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Fig. 9

Midplane (z/d = 0.0) x-axis velocity ratio comparison between the SUMTJ and the circular schemes at two downstream locations and blowing ratios

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Fig. 10

Dimensionless vorticity distribution at x/d = 2.0 for the SUMTJ and the circular schemes at different blowing ratios

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