Aspects of Vane Film Cooling With High Turbulence: Part II—Adiabatic Effectiveness

Ames, F. E.

doi:10.1115/1.2841789

Cited by 42 publications

(20 citation statements)

References 13 publications

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“…The improvement was most pronounced over mass flux ratios ranging from 0.4 to 1.0. Ames [10] also found improved film cooling effectiveness levels for a single row of holes on the pressure surface of a vane with strong favorable acceleration compared with the suction surface where the local pressure was mildly adverse for his LT case. Ito et al [11] investigated the influence of curvature on laterally averaged effectiveness.…”

Section: Introductionmentioning

confidence: 92%

“…They initially found the mixing between the freestream and jet was largely due to jet to freestream shear layer structures, while at high turbulence, flow field turbulence structures quickly dominated the mixing process. Ames [10,21] investigated vane film cooling at low (Tu ¼ 0.9%) and high (Tu ¼ 12.4% and Lu/d ¼ 25) turbulence levels for single and double row film cooling. On the pressure surface of the vane where turbulence levels were highest, he noted the incremental dissipation of film cooling effectiveness levels by nearly 60% at an X/d of 68.…”

Section: Effects Of Turbulence On Discrete Hole Film Coolingmentioning

confidence: 99%

“…Jabbari and Goldstein [13] compared two staggered rows of holes with a single row at the same blowing ratio (0.5) and density ratio (0.84) and found improved film cooling effectiveness over a single row of holes superposed. Ames [10] looked at one and two rows of holes on the pressure surface of a vane and at velocity ratios of 1.0 and 1.5 found significantly improved effectiveness levels compared with one row of holes superposed. A double staggered row causes more flow blockage with the freestream than a single row, and this blockage is believed to result in the enhanced laydown of the jets.…”

Section: Introductionmentioning

confidence: 99%

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

Kingery

Ames

2016

Journal of Turbomachinery

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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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Section: Introductionmentioning

confidence: 92%

Section: Effects Of Turbulence On Discrete Hole Film Coolingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Kingery

Ames

2016

Journal of Turbomachinery

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“…The spanwise-averagedheat-ux ratio for all of the three kinds of injection is about 1 after X=D D 15. The last three lines (4,5,6) in Fig. 8 compare the hole-shape effects under unsteady ow condition.…”

Section: Effect Of Unsteady Wakementioning

confidence: 98%

Evaluation of Real-Gas Phenomena in High-Enthalpy Aerothermal Test Facilities: A Review

2001

Journal of Thermophysics and Heat Transfer

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Detailed coolant jet temperature pro les and lm effectiveness distributions on the suction side of a gas turbine blade are measured using a thermocouple probe and a transient liquid crystal image method, respectively. The blade has only one row of lm holes near the gill-hole portion on the suction side of the blade. The hole geometries studied include standard cylindrical holes and holes with diffuser-shaped exit portion (i.e., fan-shaped holes and laidback fan-shaped holes). Tests are performed on a ve-blade linear cascade in a low-speed wind tunnel. The mainstream Reynolds number based on cascade exit velocity is 5:3 £ £ 10 5 . Upstream unsteady wakes are simulated using a spoke-wheel-type wake generator. The wake Strouhal number is kept at 0 or 0.1. Coolant blowing ratio is varied from 0.4 to 1.2. Results show that both expanded holes have signi cantly improved thermal protection over the surface downstream of the ejection location, particularly at high blowing ratios. In general, the unsteady wake tends to reduce lm-cooling effectiveness. Nomenclatureconductivity of mainstream air L = lm-cooling hole length M = coolant-to-mainstreammass ux ratio or blowing ratio, ½ c V c =½ m V N = speed of rotating rods Nu = local Nusselt number based on axial chord, hC x =k air Nu = spanwise-averagedNusselt number n= number of rods on wake generator P = lm-hole pitch q 00 = local forced convection heat ux with lm injection q 00 0 = local forced convection heat ux for the no lm-hole case N q 00 = spanwise-averagedforced convection heat ux with lm injection N q 00 0 = spanwise-averagedforced convection heat ux for the no lm-hole case Re = Reynolds number based on exit velocity and axial chord, V 2 C x =º S = wake Strouhal number, 2¼ N dn=.60V 1 / SL = streamwise length on the suction surface (33.1 cm) T c = coolant temperature T f = lm temperature T i = initial temperature of blade surface T m = mainstream temperature T w = liquid crystal color change from green to red t = liquid crystal color change time V = local mainstream velocity along the blade suction surface at the lm-hole location V c = coolant hole exit velocity V 1 = cascade inlet velocity V 2 = cascade exit velocity X = streamwise distance starting from lm-hole centerline; streamwise distance measured from leading edge to lm-hole centerline Y = perpendicular distance from blade surface Z = spanwise distance from centerline of lm-cooling holes ® = thermal diffusivity of blade material .0:135 £ 10 6 m 2 /s) ± 2 = local momentum thicknesś = local lm-cooling effectiveness Ń = spanwise-averaged lm-cooling effectiveness µ = nondimensional coolant jet temperature .T T m /=.T c T m / º = kinematic viscosity of cascade inlet mainstream air ½ c = coolant density ½ m = mainstream ow density Á = overall cooling effectiveness given by Á D .T m T w /=.T m T c /

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“…This study also determined that the turbulent length scale in their flowfield was on the order of magnitude of the dilution hole diameter. These high freestream turbulence levels are well-known to augment heat transfer and disperse film cooling, particularly at the stagnation point on a vane (Ames [9], Gandavarapu and Ames [10], Ames [11], Nasir et al [12], Radomsky and Thole [13]).…”

Section: Relevant Literaturementioning

confidence: 99%

Combustor Dilution Hole Placement and Its Effect on the Turbine Inlet Flowfield

Leonetti

Lynch

O’Connor

et al. 2017

Journal of Propulsion and Power

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Dilution jets in a gas turbine combustor are used to oxidize remaining fuel from the main flame zone in the combustor and to homogenize the temperature field upstream of the turbine section through highly turbulent mixing. The high-momentum injection generates high levels of turbulence and very effective turbulent mixing. However, mean flow distortions and large-scale turbulence can persist into the turbine section. In this study, a dilution hole configuration was scaled from a rich-burn-quench-lean-burn combustor and used in conjunction with a linear vane cascade in a large-scale, low-speed wind tunnel. Mean and turbulent flowfield data were obtained at the vane leading edge with the use of high-speed particle image velocimetry to help quantify the effect of the dilution jets in the turbine section. The dilution hole pattern was shifted (clocked) for two positions such that a large dilution jet was located directly upstream of a vane or in between vanes. Time-averaged results show that the large dilution jets have a significant impact on the magnitude and orientation of the flow entering the turbine. Turbulence levels of 40% or greater were observed approaching the vane leading edge, with integral length scales of approximately 40% of the dilution jet diameter. Incidence angle and turbulence level were dependent on the position of the dilution jets relative to the vane.

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Aspects of Vane Film Cooling With High Turbulence: Part II—Adiabatic Effectiveness

Cited by 42 publications

References 13 publications

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

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

Evaluation of Real-Gas Phenomena in High-Enthalpy Aerothermal Test Facilities: A Review

Combustor Dilution Hole Placement and Its Effect on the Turbine Inlet Flowfield

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