Experimental study of near-wall underexpanded jet impingement on a flat plate using temperature-insensitive semi-transparent pressure-sensitive paint

Shaped holes are considered as an effective solution to enhance gas turbine film-cooling performance, as they allow to increase the coolant mass-flux, while limiting the detrimental lift-off phenomena. A great amount of work has been carried out in past years on basic flat plate configurations while a reduced number of experimental works deals with a quantitative assessment of the influence of curvature and vane pressure gradient. In the present work PSP (Pressure Sensitive Paint) technique is used to detail the adiabatic effectiveness generated by axial shaped holes with high value of Area Ratio close to 7, in three different configurations with the same 1:1 scale: first of all, a flat plate configuration is examined; after that, the film-cooled pressure and suction sides of a turbine vane model are investigated. Tests were performed varying the blowing ratio and imposing a density ratio of 2.5 . The experimental results are finally compared to the predictions of two different correlations, developed for flat plate configurations.

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Film Cooling Effectiveness From Two Rows of Compound Angled Cylindrical Holes Using Pressure-Sensitive Paint Technique

Journal of Heat Transfer ◽

10.1115/1.4042777 ◽

2019 ◽

Vol 141 (4) ◽

Cited By ~ 1

Author(s):

Nian Wang ◽

Mingjie Zhang ◽

Chao-Cheng Shiau ◽

Je-Chin Han

Keyword(s):

Flat Plate ◽

Film Cooling ◽

Density Ratio ◽

Pressure Sensitive Paint ◽

Cooling Effectiveness ◽

Film Cooling Effectiveness ◽

Blowing Ratio ◽

Pressure Sensitive ◽

Staggered Arrangement ◽

Cylindrical Holes

This study investigates the effects of blowing ratio, density ratio, and spanwise pitch on the flat plate film cooling from two rows of compound angled cylindrical holes. Two arrangements of two-row compound angled cylindrical holes are tested: (a) the first row and the second row are oriented in staggered and same compound angled direction (β = +45 deg for the first row and +45 deg for the second row); (b) the first row and the second row are oriented in inline and opposite direction (β = +45 deg for the first row and −45 deg for the second row). The cooling hole is 4 mm in diameter with an inclined angle of 30 deg. The streamwise row-to-row spacing is fixed at 3d, and the spanwise hole-to-hole (p) is varying from 4d, 6d to 8d for both designs. The film cooling effectiveness measurements were performed in a low-speed wind tunnel in which the turbulence intensity is kept at 6%. There are 36 cases for each design including four blowing ratios (M = 0.5, 1.0, 1.5, and 2.0), three density ratios (DR = 1.0, 1.5, and 2.0), and three hole-to-hole spacing (p/d = 4, 6, and 8). The detailed film cooling effectiveness distributions were obtained by using the steady-state pressure-sensitive paint (PSP) technique. The spanwise-averaged cooling effectiveness are compared over the range of flow parameters. Some interesting observations are discovered including blowing ratio effect strongly depending on geometric design; staggered arrangement of the hole with same orientation does not yield better effectiveness at higher blowing ratio. Currently, film cooling effectiveness correlation of two-row compound angled cylindrical holes is not available, so this study developed the correlations for the inline arrangement of holes with opposing angles and the staggered arrangement of holes with same angles. The results and correlations are expected to provide useful information for the two-row flat plate film cooling analysis.

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An Experimental Study of Impingement Heat Transfer on the Surfaces With Micro W-Shaped Ribs

Volume 5B: Heat Transfer ◽

10.1115/gt2015-42573 ◽

2015 ◽

Author(s):

Yu Rao ◽

Peng Chen ◽

Jiaqi Zhu

Keyword(s):

Heat Transfer ◽

Experimental Study ◽

Flat Plate ◽

Pressure Loss ◽

Cooling System ◽

Cross Flow ◽

Jet Impingement ◽

Test Plate ◽

Plate Spacing ◽

Impingement Heat Transfer

The paper proposed an idea of using micro-W-shaped ribs on a test plate to improve the impingement heat transfer performance in a multiple-jet impingement cooling system. An experimental study has been conducted on the heat transfer characteristics of multiple-jet impingement onto a flat plate and a roughened plate with micro W-shaped ribs under maximum cross flow scheme. Transient liquid crystal thermography method has been used to obtain the detailed impingement heat transfer distribution for the Reynolds numbers from 15,000 to 30,000.The effects of micro W ribs on the local Nusselt number and the related pressure loss were investigated experimentally. The jet-to-plate spacing H/d=1.5 was used in the experiments for both the flat and the micro-W-rib roughened plate. The experiments showed that the micro W ribs on the plate can enhance the impingement heat transfer globally and locally, and increase the heat transfer uniformity, which are due to the facts that the micro W ribs on the test plate increase the near-wall turbulent mixing by interacting with the wall jets and cross flow. The pressure loss is negligibly increased compared to the impingement onto the flat plate.

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Turbine Nozzle Endwall Film Cooling Study Using Pressure-Sensitive Paint

Journal of Turbomachinery ◽

10.1115/1.1400113 ◽

2001 ◽

Vol 123 (4) ◽

pp. 730-738 ◽

Cited By ~ 75

Author(s):

Luzeng J. Zhang ◽

Ruchira Sharma Jaiswal

Keyword(s):

Flow Field ◽

Mass Flow ◽

Film Cooling ◽

Free Stream ◽

Surface Film ◽

Secondary Flows ◽

Pressure Sensitive Paint ◽

Pressure Sensitive ◽

Wall Flow ◽

Near Wall

Endwall surface film cooling effectiveness was measured on a turbine vane endwall surface using the pressure-sensitive paint (PSP) technique. A double staggered row of holes and a single row of discrete slots were used to supply film cooling in front of the nozzle cascade leading edges. Nitrogen gas was used to simulate film cooling flow as well as a tracer gas to indicate oxygen concentration such that film effectiveness by the mass transfer analogy could be obtained. Cooling mass flow was controlled to be 0.5 to 3.0 percent of the mainstream mass flow. The free-stream Reynolds number was about 283,000 and Mach number was about 0.11. The free-stream turbulence intensity was kept at 6.0 percent for all the tests, measured by a thermal anemometer. The PSP was calibrated at various temperatures and pressures to obtain better accuracy before being applied to the endwall surface. Film effectiveness distributions were measured on a flat endwall surface for five different mass flow rates. The film effectiveness increased nonlinearly with mass flow rate, indicating a strong interference between the cooling jets and the endwall secondary flows. At lower mass flow ratios, the secondary flow dominated the near wall flow field, resulting in a low film effectiveness. At higher mass flow ratios, the cooling jet momentum dominated the near wall flow field, resulting in a higher film effectiveness. The comparison between hole injection and slot injection was also made.

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VISUALIZATION OF UNDEREXPANDED JET FLOWS OVER A PLATE BY PRESSURE - SENSITIVE PAINT TECHNIQUE

International Conference on Aerospace Sciences and Aviation Technology ◽

10.21608/asat.2007.23869 ◽

2007 ◽

Vol 12 (ASAT CONFERENCE) ◽

pp. 1-18

Author(s):

M. IBRAHIM

Keyword(s):

Jet Flows ◽

Pressure Sensitive Paint ◽

Underexpanded Jet ◽

Pressure Sensitive

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Experimental Study of Underexpanded Supersonic Jet Impingement on an Inclined Flat Plate

AIAA Journal ◽

10.2514/1.17514 ◽

2006 ◽

Vol 44 (11) ◽

pp. 2691-2699 ◽

Cited By ~ 36

Author(s):

Yusuke Nakai ◽

Nobuyuki Fujimatsu ◽

Kozo Fujii

Keyword(s):

Experimental Study ◽

Flat Plate ◽

Supersonic Jet ◽

Jet Impingement ◽

Underexpanded Supersonic Jet

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Experimental Study of Air Slot Jet Impingement Cooling From Cylinder Placed on a Flat Plate

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4045521 ◽

2019 ◽

Vol 12 (4) ◽

Author(s):

Ketan Atulkumar Ganatra ◽

Dushyant Singh

Keyword(s):

Heat Transfer ◽

Experimental Study ◽

Nusselt Number ◽

Flat Plate ◽

Local Nusselt Number ◽

Jet Impingement ◽

Maximum Error ◽

Constant Heat Flux ◽

Impingement Cooling ◽

Heated Cylinder

Abstract The experimental study for air slot jet impingement cooling from the heated cylinder is carried out. The heated cylinder is placed on a flat plate. The flat plate has an effective dimension as plate length (P) from heat transfer point of view. The heating of the cylindrical surface is done by providing a constant heat flux. The various parameters which affect the heat transfer from the cylinder are ReD, h/S, S/D, and P/D. The range of the parameters considered are ReD = 10,000–25,000, h/S = 4–12, S/D = 0.072–0.108, and P/D = 0–2. The effect of various parameters on heat transfer distribution (stagnation and local Nusselt number) from the cylinder is investigated. The local Nusselt number has a maximum value at θ = 0 deg and then it decreases upto θ = 180 deg. This trend is observed for all the parametric variations. The stagnation Nusselt number (Nustag) and local Nusselt number increases with the change of parameters as increase in ReD and S/D and decrease in h/S. However, Nustag remains independent with the change in P/D. The correlation for stagnation and mean Nusselt number is developed using regression analysis as a function of ReD, h/S, S/D, and P/D. The maximum error associated with the correlated value of Nustag and Num as compared with the experimental data is observed as ±13% and ±25%.

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