Film Cooling From Two Rows of Holes Inclined in the Streamwise and Spanwise Directions

Jubran, B. A.; Brown, Andy

doi:10.1115/1.3239701

Cited by 60 publications

(29 citation statements)

References 2 publications

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“…They also found that the jets from the downstream row extended further from the wall and penetrated deeper into the mainstream than their first row because the jets from the second row were diverted less by the approaching flow due to the greater momentum deficit of the approaching flow at the second row. Jubran and Brown [17] suggested that effectiveness downstream of a second row of jets was dependent on the state of the development of the film from the first row, and its development length increased with increasing row spacing, which subsequently resulted in a near two-dimensionality when the downstream row was encountered.…”

Section: Introductionmentioning

confidence: 98%

Film cooling characteristics of rows of round holes at various streamwise angles in a crossflow: Part I. Effectiveness

Yuen

Martinez-Botas

2005

International Journal of Heat and Mass Transfer

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Film cooling effectiveness were studied experimentally on rows of cylindrical holes with streamwise angles of 30°, 60°a nd 90°, in a flat plate test facility with a zero pressure gradient. Detailed effectiveness and heat transfer results for a single cylindrical hole at the same inclinations have been presented in Yuen and Martinez-Botas [C.H.N. Yuen, R.F. Martinez-Botas, Film cooling characteristics of a single hole at various streamwise angles: Part I. Effectiveness, Int. J. Heat Mass Transfer 46 (2003) 221-235; C.H.N. Yuen, R.F. Martinez-Botas, Film cooling characteristics of a single hole at various streamwise angles: Part II. Heat transfer coefficient, Int. J. Heat Mass Transfer 46 (2003) 237-249] with the same test facility and measurement technique. This present investigation commenced with a single row of holes with two pitch-to-diameter ratios (p/D) of 3 and 6. It then presents and discusses the effects of introducing inline and staggered rows for each streamwise angle and pitch-to-diameter ratio. The row spacing in the inline and staggered rows is 12.5 diameters in the streamwise direction. The short but engine representative hole length (L/D = 4) is constant for all geometries. The blowing ratio ranges from 0.33 to 2, and the freestream Reynolds number based on the freestream velocity and hole diameter (Re D ) was 8563. Both local values and laterally averaged ones are presented, the latter refers to the averaged value across the central hole. The current results are compared with the experimental results obtained by other researchers, the effects of the additional inline and staggered rows, and of the variations in injection angle, pitch-to-diameter ratio are described.The objectives of the present study are to provide a consistent set of measurements in terms of effectiveness and heat transfer coefficients presented in the companion paper [C.H.N. Yuen, R.F. Martinez-Botas, Film cooling characteristics of rows of round holes at various streamwise angles: Part II. Heat transfer coefficient, Int. J. Heat Mass Transfer, in press], obtained systematically with the same test facility, and to deliver a better understanding of film cooling performance. The present results also serve as a database with 105 test cases, in addition to the 21 cases presented in [C.H.N. Yuen, R.F. Martinez-Botas, Film cooling characteristics of a single hole at various streamwise angles: Part I. Effectiveness, Int. J. Heat Mass Transfer 46 (2003) 221-235], for future numerical modelling.

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Section: Introductionmentioning

confidence: 98%

Film cooling characteristics of rows of round holes at various streamwise angles in a crossflow: Part I. Effectiveness

Yuen

Martinez-Botas

2005

International Journal of Heat and Mass Transfer

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“…They documented (1) skewing of the velocity towards the downstream edge of the hole exit and (2) flow disturbances created by the jet-crossflow interaction upstream of the hole exit and within the jet supply. Inclined jets were studied by Launder and York (1974), Kadotani and Goldstein (1979), Yoshida and Goldstein (1984), and Jubran and Brown (1985). Lee et al (1992) presented three-dimensional mean velocity and vorticity distributions, accompanied by flow visualization, for 35O-inclined streamwise injection with m = 5 0 and freestream turbulence intensity (FSTl) of 0.2%.…”

mentioning

confidence: 99%

Measurements in Film Cooling Flows: Hole L/D and Turbulence Intensity Effects

Burd

Kaszeta

Simon

1998

Journal of Turbomachinery

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Hot-wire anemometry measurements of simulated film cooling are presented to document the influence of the free-stream turbulence intensity and film cooling hole length-to-diameter ratio on mean velocity and on turbulence intensity. Measurements are taken in the zone where the coolant and free-stream flows mix. Flow from one row of film cooling holes with a streamwise injection of 35 deg and no lateral injection and with a coolant-to-free-stream flow velocity ratio of 1.0 is investigated under free-stream turbulence levels of 0.5 and 12 percent. The coolant-to-free-stream density ratio is unity. Two length-to-diameter ratios for the film cooling holes, 2.3 and 7.0, are tested. The Measurements document that under low free-stream turbulence conditions pronounced differences exist in the flowfield between L/D= 7.0 and 2.3. The difference between L/D cases are less prominent at high free-stream turbulence intensities. Generally, Short-L/D injection results in “jetting” of the coolant farther into the free-stream flow and enhanced mixing. Other changes in the flowfield attributable to a rise in free-stream turbulence intensity to engine-representative conditions are documented.

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“…The works of Goldstein et al [2], Foster and Lempard [3], and Jubran and Brown [4] to name a few, are representative of this type of work. Data specific to turbine film cooling problems were reported by Mehendale and Han [5], who investigated the effects of mainstream turbulence on the film cooling effectiveness and heat transfer coefficient for a turbine airfoil leading edge.…”

Section: Imentioning

confidence: 98%

Aerodynamic/heat transfer analysis of discrete site film-cooled turbine airfoils

Hall¹,

Topp²,

Delaney³

1994

30th Joint Propulsion Conference and Exhibit

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goal is the use of film-cooling, wherein a layer of relatively The overall objective of this study was to examine cool gas is iqjected near the metal surfaces to provide a the aerodynamics and heat transfer characteristics of dis-buffer layer between the hot gas and the protected sursite film-cooled turbine &rf0&. The ob-faces. As operational temperature lev& rise in modern jective was to attempt to predict the three-dimensional gas turbine engines, accurately controlling turbine coolflow about the C3X turbine -e m a d e with a lading ing flows presents one of the more difficult engineering edge showerhead film cooling arrangement. The moti-challenges in the overall turbomaehinery d e s b process. vation behind this work was to validate and assess the Turbine airfoil blade row flows are characterized by accuracy of present 3-D Navier-Stokes predictions for re-large temperature gradients, Ma& numbers ranging from ticf film-cooled airfoil heat transfer predictions through low subsonic (< 0.15) to the transonic range (> LO), and comparisons with experimental data. high levels of freestream turbulence with strong, small Calculations were performed using a Cartesian COOP scale interactions between surface boundary layer convecdinate system and taking advantage of the spanwise p e tive flows, diffusive transport, and turbulent shear transriodicity of the C3X geometry. The film cooling flow was port. Aerodynamic and thermal design techniques curmodeled as injection at discrete holes and was introduced rently available to turbine airfoil designers have deficieninto the blade passage through the use of separate mesh cies which do not permit a priori designs which meet systems and transpiration/iection boundary conditions. desired design goals without expensive experimental deThe grid generation for the C3X m a d e involved mod-velopment iterations. As such, the airfoil/eoolant flow eling the film cooling holes as discrete objects in a 3-D injection design (hole size, placement, shaping, etc) is ofmesh. Calculations were performed for the C3X at multi-ten based on experience and/or empirical databases. Inple operating points, both with and without coolhg holes c r d utilieationof computational fluid dynamics (CFD) activated. Predicted results were compared with experi-techniques in the design process for turbmomachinery airmental data.foils and flowpaths has naturally led to the use of these tools for predicting airfoil surface heat transfer and film + . , cooling effectiveness. Unfortunately, our lack of comprchensive turbulence models capable of accurately predict ing heat transfer in high Reynolds number turbulent flows The trend in thermodynamic design Of gas turbine en-has prevented widespread acceptance of CFD techdques in the heat design arena. The of CFD for details ofthe gas path/coolant flow interaction can be very useful for determining trends a better of

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Film Cooling From Two Rows of Holes Inclined in the Streamwise and Spanwise Directions

Cited by 60 publications

References 2 publications

Film cooling characteristics of rows of round holes at various streamwise angles in a crossflow: Part I. Effectiveness

Film cooling characteristics of rows of round holes at various streamwise angles in a crossflow: Part I. Effectiveness

Measurements in Film Cooling Flows: Hole L/D and Turbulence Intensity Effects

Aerodynamic/heat transfer analysis of discrete site film-cooled turbine airfoils

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