Interactions Between Embedded Vortices and Injectant From Film Cooling Holes With Compound Angle Orientations in a Turbulent Boundary Layer

1994 ◽  
Vol 116 (1) ◽  
pp. 80-91 ◽  
Author(s):  
P. M. Ligrani ◽  
S. W. Mitchell
Keyword(s):  
Heat Transfer ◽  
Secondary Flow ◽  
Film Cooling ◽  
Hole Diameter ◽  
Test Surface ◽  
Normal Plane ◽  
Plane Projection ◽  
Flow Vectors ◽  
Film Cooling Holes ◽  
Compound Angle

Experimental results are presented that describe the effects of embedded, longitudinal vortices on heat transfer and film injectant downstream of two staggered rows of film cooling holes with compound angle orientations. Holes are oriented so that their angles with respect to the test surface are 30 deg in a spanwise/normal plane projection, and 35 deg in a streamwise/normal plane projection. A blowing ratio of 0.5, nondimensional injection temperature parameter θ of about 1.5, and free-stream velocity of 10 m/s are employed. Injection hole diameter is 0.945 cm to give a ratio of vortex core diameter to hole diameter of 1.6–1.67 just downstream of the injection holes (x/d = 10.2). At the same location, vortex circulation magnitudes range from 0.15 m2/s to 0.18 m2/s. By changing the sign of the angle of attack of the half-delta wings used to generate the vortices, vortices are produced that rotate either clockwise or counterclockwise when viewed looking downstream in spanwise/normal planes. The most important conclusion is that local heat transfer and injectant distributions are strongly affected by the longitudinal embedded vortices, including their directions of rotation and their spanwise positions with respect to film injection holes. Differences resulting from vortex rotation are due to secondary flow vectors, especially beneath vortex cores, which are in different directions with respect to the spanwise velocity components of injectant after it exits the holes. When secondary flow vectors near the wall are in the same direction as the spanwise components of the injectant velocity (clockwise rotating vortices R0–R4), the film injectant is more readily swept beneath vortex cores and into vortex upwash regions than for the opposite situation in which near-wall secondary flow vectors are opposite to the spanwise components of the injectant velocity (counter-clockwise rotating vortices L0–L4). Consequently, higher St/St0 are present over larger portions of the test surface with vortices R0–R4 than with vortices L0–L4. These disruptions to the injectant and heat transfer from the vortices are different from the disruptions that result when similar vortices interact with injectant from holes with simple angle orientations. Surveys of streamwise mean velocity, secondary flow vectors, total pressure, and streamwise mean vorticity are also presented that further substantiate these findings.

Interactions Between Embedded Vortices and Injectant From Film Cooling Holes With Compound Angle Orientations in a Turbulent Boundary Layer

1992 ◽  
Author(s):  
P. M. Ligrani ◽  
S. W. Mitchell
Keyword(s):  
Heat Transfer ◽  
Secondary Flow ◽  
Film Cooling ◽  
Hole Diameter ◽  
Test Surface ◽  
Normal Plane ◽  
Plane Projection ◽  
Flow Vectors ◽  
Film Cooling Holes ◽  
Compound Angle

Experimental results are presented which describe the effects of embedded, longitudinal vortices on heat transfer and film injectant downstream of two staggered rows of film cooling holes with compound angle orientations. Holes are oriented so that their angles with respect to the test surface are 30 degrees in a spanwise/normal plane projection, and 35 degrees in a streamwise/normal plane projection. A blowing ratio of 0.5, non-dimensional injection temperature parameter θ of about 1.5, and freestream velocity of 10 m/s are employed. Injection hole diameter is 0.945 cm to give a ratio of vortex core diameter to hole diameter of 1.6–1.67 just downstream of the injection holes (x/d=10.2). At the same location, vortex circulation magnitudes range from 0.15 m2/s to 0.18 m2/s. By changing the sign of the angle of attack of the half-delta wings used to generate the vortices, vortices are produced which rotate either clockwise or counter-clockwise when viewed looking downstream in spanwise/normal planes. The most important conclusion is that local heat transfer and injectant distributions are strongly affected by the longitudinal embedded vortices, including their directions of rotation and their spanwise positions with respect to film injection holes. Differences resulting from vortex rotation are due to secondary flow vectors, especially beneath vortex cores, which are in different directions with respect to the spanwise velocity components of injectant after it exits the holes. When secondary flow vectors near the wall are in the same direction as the spanwise components of the injectant velocity (clockwise rotating vortices R0-R4), the film injectant is more readily swept beneath vortex cores and into vortex upwash regions than for the opposite situation in which near-wall secondary flow vectors are opposite to the spanwise components of the injectant velocity (counter-clockwise rotating vortices L0-L4). Consequently, higher St/Sto are present over larger portions of the test surface with vortices R0-R4 than with vortices L0-L4. These disruptions to the injectant and heat transfer from the vortices are different from the disruptions which result when similar vortices interact with injectant from holes with simple angle orientations. Surveys of streamwise mean velocity, secondary flow vectors, total pressure, and streamwise mean vorticity are also presented which further substantiate these findings.

Effects of Embedded Vortices on Injectant From Film Cooling Holes With Large Spanwise Spacing and Compound Angle Orientations in a Turbulent Boundary Layer

1994 ◽  
Vol 116 (4) ◽  
pp. 709-720 ◽  
Author(s):  
P. M. Ligrani ◽  
S. W. Mitchell
Keyword(s):  
Heat Transfer ◽  
Secondary Flow ◽  
Vortex Core ◽  
Film Cooling ◽  
Test Surface ◽  
Injection Hole ◽  
Plane Projection ◽  
Flow Vectors ◽  
Film Cooling Holes ◽  
Compound Angle

Experimental results are presented that describe the effects of embedded, longitudinal vortices on heat transfer and film injectant downstream of a single row of film cooling holes with compound angle orientations. Holes are spaced 7.8 hole diameters apart in the spanwise direction so that information is obtained on the interactions between the vortices and the injectant from a single hole. The compound angle holes are oriented so that their angles with respect to the test surface are 30 deg in a spanwise/normal plane projection, and 35 deg in a streamwise/normal plane projection. A blowing ratio of 0.5 is employed and the ratio of vortex core diameter to hole diameter is 1.6–1.67 just downstream of the injection holes (x/d=10.2). At the same location, vortex circulation magnitudes range from 0.15 m2/s to 0.18 m2/s. The most important conclusion is that local heat transfer and injectant distributions are strongly affected by the longitudinal embedded vortices, including their directions of rotation and their spanwise positions with respect to film injection holes. To obtain information on the latter, clockwise rotating vortices R0–R4 and counterclockwise rotating vortices L0–L4 are placed at different spanwise locations with respect to the central injection hole located on the spanwise centerline. With vortices R0–R4, the greatest disruption to the film is produced by the vortex whose downwash passes over the central hole (R0). With vortices L0–L4, the greatest disruption is produced by the vortices whose cores pass over the central hole (L1 and L2). To minimize such disruptions, vortex centers must pass at least 1.5 vortex core diameters away from an injection hole on the upwash sides of the vortices and 2.9 vortex core diameters away on the downwash sides of the vortices. Differences resulting from vortex rotation are due to secondary flow vectors, especially beneath vortex cores, which are in different directions with respect to the spanwise velocity components of injectant after it exits the holes. When secondary flow vectors near the wall are in the same direction as the spanwise components of the injectant velocity (vortices R0–R4), the film injectant is more readily swept beneath vortex cores and into vortex upwash regions than for the opposite situation in which near-wall secondary flow vectors are opposite to the spanwise components of the injectant velocity (vortices L0–L4). Consequently, higher Stanton numbers are generally present over larger portions of the test surface with vortices R0–R4 than with vortices L0–L4.

Effects of Embedded Vortices on Injectant From Film Cooling Holes With Large Spanwise Spacing and Compound Angle Orientations in a Turbulent Boundary Layer

1993 ◽  
Author(s):  
Phillip M. Ligrani ◽  
Stephen W. Mitchell
Keyword(s):  
Heat Transfer ◽  
Secondary Flow ◽  
Vortex Core ◽  
Film Cooling ◽  
Test Surface ◽  
Injection Hole ◽  
Plane Projection ◽  
Flow Vectors ◽  
Film Cooling Holes ◽  
Compound Angle

Experimental results are presented which describe the effects of embedded, longitudinal vortices on heat transfer and film injectant downstream of a single row of film cooling holes with compound angle orientations. Holes are spaced 7.8 hole diameters apart in the spanwise direction so that information is obtained on the interactions between the vortices and the injectant from a single hole. The compound angle holes are oriented so that their angles with respect to the test surface are 30 degrees in a spanwise/normal plane projection, and 35 degrees in a streamwise/normal plane projection. A blowing ratio of 0.5 is employed and the ratio of vortex core diameter to hole diameter is 1.6–1.67 just downstream of the injection holes (x/d=10.2). At the same location, vortex circulation magnitudes range from 0.15 m2/s to 0.18 m2/s. The most important conclusion is that local heat transfer and injectant distributions are strongly affected by the longitudinal embedded vortices, including their directions of rotation and their spanwise positions with respect to film injection holes. To obtain information on the latter, clockwise rotating vortices R0-R4 and counter-clockwise rotating vortices L0-L4 are placed at different spanwise locations with respect to the central injection hole located on the spanwise centerline. With vortices R0-R4, the greatest disruption to the film is produced by the vortex whose downwash passes over the central hole (R0). With vortices L0-L4, the greatest disruption is produced by the vortices whose cores pass over the central hole (L1 and L2). To minimize such disruptions, vortex centers must pass at least 1.5 vortex core diameters away from an injection hole on the upwash sides of the vortices and 2.9 vortex core diameters away on the downwash sides of the vortices. Differences resulting from vortex rotation are due to secondary flow vectors, especially beneath vortex cores, which are in different directions with respect to the spanwise velocity components of injectant after it exits the holes. When secondary flow vectors near the wail are in the same direction as the spanwise components of the injectant velocity (vortices R0-R4), the film injectant is more readily swept beneath vortex cores and into vortex upwash regions than for the opposite situation in which near-wall secondary flow vectors are opposite to the spanwise components of the injectant velocity (vortices L0-L4). Consequently, higher Stanton numbers are generally present over larger portions of the test surface with vortices R0-R4 than with vortices L0-L4.

Film-Cooling From Holes With Compound Angle Orientations: Part 1—Results Downstream of Two Staggered Rows of Holes With 3d Spanwise Spacing

1994 ◽  
Vol 116 (2) ◽  
pp. 341-352 ◽  
Author(s):  
P. M. Ligrani ◽  
J. M. Wigle ◽  
S. Ciriello ◽  
S. M. Jackson
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Test Surface ◽  
Spanwise Direction ◽  
Normal Plane ◽  
Streamwise Location ◽  
Structure Of Flow ◽  
Film Cooling Holes ◽  
Compound Angle ◽  
Angle Orientation

Experimental results are presented that describe the development and structure of flow downstream of two staggered rows of film-cooling holes with compound angle orientations. With this configuration, holes are spaced 3d apart in the spanwise direction, inclined at 35 deg with respect to the test surface when projected into the streamwise/normal plane, and inclined at 30 deg with respect to the test surface when projected into the spanwise/normal plane. Results are presented for an injectant to free-stream density ratio near 1.0, and injection blowing ratios from 0.5 to 1.50. Comparisons are made with measurements from two other configurations to determine: (1) the effects of hole angle orientation for constant spanwise hole spacing, and (2) the effects of spanwise hole spacing when the hole angle orientation is maintained constant. Results from the first comparison show that the compound angle injection configuration provides significantly improved film-cooling protection compared to a simple angle configuration for the same spanwise hole spacing, normalized streamwise location x/d, and blowing ratio m, for x/d<60. At x/d>60, spanwise-averaged adiabatic effectiveness data downstream of the two configurations generally cover about the same range. Results from the second comparison show that spanwise-averaged effectiveness values are 25 to 40 percent higher when 3d spanwise hole spacing is employed compared to 3.9d spanwise hole spacing for the same m and x/d, for x/d<40. At x/d>40, differences between the two configurations range from 12 to 30 percent. Results from all configurations studied show that spanwise-averaged iso-energetic Stanton number ratios cover approximately the same range of values and show roughly the same trends, ranging between 1.0 and 1.25. In particular, Stf/St0 values increase with m at each x/d, and show little variation with x/d for each value of m tested.

Heat Transfer, Adiabatic Effectiveness, and Injectant Distributions Downstream of a Single Row and Two Staggered Rows of Compound Angle Film-Cooling Holes

1992 ◽  
Vol 114 (4) ◽  
pp. 687-700 ◽  
Author(s):  
P. M. Ligrani ◽  
S. Ciriello ◽  
D. T. Bishop
Keyword(s):  
Film Cooling ◽  
Test Surface ◽  
Mean Velocity ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Normal Plane ◽  
Structure Of Flow ◽  
Lift Off ◽  
Film Cooling Holes ◽  
Compound Angle

Experimental results are presented that describe the development and structure of flow downstream of one row and downstream of two staggered rows of film-cooling holes with compound angle orientations. With the compound angle configuration, holes are inclined at 35 deg with respect to the test surface when projected into the streamwise/normal plane, and 30 deg with respect to the test surface when projected into the spanwise/normal plane. Within each row, holes are spaced 7.8 hole diameters apart, which gives 3.9d spacing between adjacent holes for the staggered row arrangement. Results presented include disributions of iso-energetic Stanton numbers, and adiabatic film cooling effectiveness deduced from Stanton numbers using superpositiion. Also presented are plots showing the streamwise development of injectant distributions and streamwise development of mean velocity distributions. Spanwise-averaged values of the adiabatic film cooling effectivenss, η, measured downstream of two staggered rows of holes are highest with a blowing ratio m of 0.5, and decrease with blowing ratio because of injection lift-off effects for x/d < 20. However, as the boundary layers convect farther downstream, η values for m = 0.5 are lower than values for m = 1.0, 1.5, and 1.74 since smaller amounts of injectant are spread along the test surface. These differences also result because injectant from the upstream row of holes eventually merges and coalesces with the injectant from the downstream row of holes (of the two staggered rows) at the higher m. With one row of holes, local effectivenss variations are spanwise periodic, where higher values correspond to locations where injectant is plentiful near the test surface. Local Stf/Sto data also show spanwise periodicity, with local Stf/So maxima corresponding to regions of higher mixing between streamwise velocity deficits. Spanwise-averaged iso-energetic Stanton number ratios downstream of both the one-row and two-row arrangements generally range between 1.0 and 1.25, and show little variation with x/d for each value of m tested. However, for each x/d Stf/StoValues increase with m. Additional discussion of these results is presented along with comparisons to ones obtained downstream of film cooling holes with simple angles in which holes are inclined at 35 deg with respect to the test surface in the streamwise/normal plane.

Effect of Internal Crossflow Velocity on Film Cooling Effectiveness: Part II — Compound Angle Shaped Holes

2017 ◽  
Author(s):  
John W. McClintic ◽  
Joshua B. Anderson ◽  
David G. Bogard ◽  
Thomas E. Dyson ◽  
Zachary D. Webster
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Film Cooling ◽  
Velocity Ratio ◽  
Injection Rate ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Crossflow Velocity ◽  
Film Cooling Holes ◽  
Compound Angle

In gas turbine engines, film cooling holes are commonly fed with an internal crossflow, the magnitude of which has been shown to have a notable effect on film cooling effectiveness. In Part I of this study, as well as in a few previous studies, the magnitude of internal crossflow velocity was shown to have a substantial effect on film cooling effectiveness of axial shaped holes. There is, however, almost no data available in the literature that shows how internal crossflow affects compound angle shaped film cooling holes. In Part II, film cooling effectiveness, heat transfer coefficient augmentation, and discharge coefficients were measured for a single row of compound angle shaped film cooling holes fed by internal crossflow flowing both in-line and counter to the span-wise direction of coolant injection. The crossflow-to-mainstream velocity ratio was varied from 0.2–0.6 and the injection velocity ratio was varied from 0.2–1.7. It was found that increasing the magnitude of the crossflow velocity generally caused degradation of the film cooling effectiveness, especially for in-line crossflow. An analysis of jet characteristic parameters demonstrated the importance of crossflow effects relative to the effect of varying the film cooling injection rate. Heat transfer coefficient augmentation was found to be primarily dependent on injection rate, although for in-line crossflow, increasing crossflow velocity significantly increased augmentation for certain conditions.

Conjugate Heat Transfer on Full-Coverage Film Cooling With Array Impingement Jets

2015 ◽  
Author(s):  
Eui Yeop Jung ◽  
Heeyoon Chung ◽  
Seok Min Choi ◽  
Ta-kwan Woo ◽  
Hyung Hee Cho
Keyword(s):  
Heat Transfer ◽  
Stainless Steel ◽  
Film Cooling ◽  
Steel Plate ◽  
Hole Diameter ◽  
Maximum Deviation ◽  
Stainless Steel Plate ◽  
Cooling Effectiveness ◽  
Impingement Jet ◽  
Film Cooling Holes

We report an investigation of the total cooling effectiveness of a film cooled surface with staggered array impingement jet cooling using infra-red thermography. Heat transfer experiments were carried out using three film cooled test plates of different thermal conductivities: stainless steel (with a thermal conductivity, k = 13.4 W/mK), Corian® (k = 1 W/mK), and polycarbonate (k = 0.2 W/mK). The effects of conduction through the test plates and convective heat transfer due to the arrayed impingement jets were analyzed. The inclination angle of the film cooling holes was 35° and that of the impingement jet holes was 90°. The film and impingement jet holes on each plate were arranged in a staggered pattern, and the film cooling holes and impingement jet holes were also positioned in a staggered pattern. The jet Reynolds number based on the hole diameter was Rejet = 3,000 and the equivalent blowing rate was M = 0.3. The ratio of the target surface height to the hole diameter was varied in the range 1 < H/d < 5. The diameter of both the film cooling holes and impingement jet holes was 5 mm. The total cooling effectiveness was investigated with and without the impingement jets. When the impingement jets were added to the internal cooling, the averaged total cooling effectiveness was enhanced about 8.4%. The stainless steel plate was found to exhibit better cooling performance with more uniform temperature distribution. The total cooling effectiveness was increased up to 0.87 in the stainless steel plate, and the maximum deviation of total cooling effectiveness in the stainless steel was reduced to 85% from that in polycarbonate plate along the lateral direction. The total cooling effectiveness was related to the Biot number of the film cooled plate, however, the effect of the H/d ratio was not significant.

Louver Slot Cooling and Full-Coverage Film Cooling With a Combination Internal Coolant Supply

2020 ◽  
Author(s):  
Austin Click ◽  
Phillip M. Ligrani ◽  
Maggie Hockensmith ◽  
Joseph Knox ◽  
Chandler Larson ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Film Cooling ◽  
Cross Flow ◽  
Test Surface ◽  
Test Plate ◽  
Blowing Ratio ◽  
Impingement Jet ◽  
Full Coverage ◽  
Film Cooling Holes

Abstract Within the present investigation, a louver slot is employed upstream of an array full coverage film cooling holes. Cooling air is supplied using a combination arrangement, with cross-flow and impingement together. The louver consists of a row of film cooling holes, contained within a specially-designed device which concentrates, and directs the coolant from a slot, so that it then advects as a layer downstream along the test surface. This louver-supplied coolant is then supplemented by coolant which emerges from different rows of downstream film cooling holes. The same coolant supply passage is employed for the louver row of holes, as well as for the film cooling holes, such that different louver and film cooling mass flow rates are set by different hole diameters for the two different types of cooling holes. The results are different from data provided by past investigations, because of the use and arrangement of the louver slot, and because of the unique coolant supply configurations. The experimental results are given for mainstream Reynolds numbers from 107000 to 114000. Full-coverage blowing ratios are constant with streamwise location along the test surface, and range from 3.68 to 5.70. Corresponding louver slot blowing ratios then range from 1.72 to 2.65. Provided are heat transfer coefficient and adiabatic effectiveness distributions, which are measured along the mainstream side of the test plate. Both types of data show less variation with streamwise development location, relative to results obtained without a louver employed, when examined at the same approximate effective blowing ratio, mainstream Reynolds number, cross flow Reynolds number, and impingement jet Reynolds number. When compared at the same effective blowing ratio or the same impingement jet Reynolds number, spanwise-averaged heat transfer coefficients are consistently lower, especially for the downstream regions of the test plate, when the louver is utilized. With the same type of comparisons, the presence of the louver slot results in significantly higher values of adiabatic film cooling effectiveness (spanwise-averaged), particularly at and near the upstream portions of the test plate. With such characteristics, dramatic increases in thermal protection are provided by the presence of the louver slot, the magnitudes of which vary with experimental condition and test surface location.

Louver Slot Cooling and Full-Coverage Film Cooling With a Combination Internal Coolant Supply

2021 ◽  
Vol 143 (3) ◽  
Author(s):  
Austin Click ◽  
Phillip M. Ligrani ◽  
Maggie Hockensmith ◽  
Joseph Knox ◽  
Chandler Larson ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Film Cooling ◽  
Cross Flow ◽  
Test Surface ◽  
Test Plate ◽  
Blowing Ratio ◽  
Impingement Jet ◽  
Full Coverage ◽  
Film Cooling Holes

Abstract Within the present investigation, a louver slot is employed upstream of an array full-coverage film cooling holes. Cooling air is supplied using a combination arrangement, with cross-flow and impingement together. The louver consists of a row of film cooling holes, contained within a specially designed device that concentrates and directs the coolant from a slot, so that it then advects as a layer downstream along the test surface. This louver-supplied coolant is then supplemented by coolant which emerges from different rows of downstream film cooling holes. The same coolant supply passage is employed for the louver row of holes, as well as for the film cooling holes, such that different louver and film cooling mass flowrates are set by different hole diameters for the two different types of cooling holes. The results are different from data provided by past investigations, because of the use and arrangement of the louver slot, and because of the unique coolant supply configurations. The experimental results are given for mainstream Reynolds numbers from 107,000 to 114,000. Full-coverage blowing ratios are constant with streamwise location along the test surface and range from 3.68 to 5.70. Corresponding louver slot blowing ratios then range from 1.72 to 2.65. Provided are heat transfer coefficient and adiabatic effectiveness distributions, which are measured along the mainstream side of the test plate. Both types of data show less variation with streamwise development location, relative to results obtained without a louver employed, when examined at the same approximate effective blowing ratio, mainstream Reynolds number, cross-flow Reynolds number, and impingement jet Reynolds number. When compared at the same effective blowing ratio or the same impingement jet Reynolds number, spanwise-averaged heat transfer coefficients are consistently lower, especially for the downstream regions of the test plate, when the louver is utilized. With the same type of comparisons, the presence of the louver slot results in significantly higher values of adiabatic film cooling effectiveness (spanwise-averaged), particularly at and near the upstream portions of the test plate. With such characteristics, dramatic increases in thermal protection are provided by the presence of the louver slot, the magnitudes of which vary with the experimental condition and test surface location.

Full-Coverage Film Cooling: Film Effectiveness and Heat Transfer Coefficients for Dense Hole Arrays at Different Hole Angles, Contraction Ratios, and Blowing Ratios

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Phil Ligrani ◽  
Matt Goodro ◽  
Mike Fox ◽  
Hee-Koo Moon
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Test Surface ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Blowing Ratio ◽  
Full Coverage ◽  
Contraction Ratio ◽  
Cooling Hole ◽  
Film Cooling Holes

Experimental results are presented for a full-coverage film cooling arrangement which simulates a portion of a gas turbine engine, with appropriate streamwise static pressure gradient. The test surface utilizes varying blowing ratio (BR) along the length of the contraction passage which contains the cooling hole arrangement. For the different experimental conditions examined, film cooling holes are sharp-edged and streamwise inclined either at 20 deg or 30 deg with respect to the liner surface. The film cooling holes in adjacent streamwise rows are staggered with respect to each other. Data are provided for turbulent film cooling, contraction ratios of 1, 3, 4, and 5, blowing ratios (at the test section entrance) of 2.0, 5.0, and 10.0, coolant Reynolds numbers Refc of 10,000–12,000, freestream temperatures from 75 °C to 115 °C, a film hole diameter of 7 mm, and density ratios from 1.15 to 1.25. Nondimensional streamwise and spanwise film cooling hole spacings, X/D and Y/D, are 6, and 5, respectively. When the streamwise hole inclination angle is 20 deg spatially averaged and line-averaged adiabatic effectiveness values at each x/D location are about the same as the contraction ratio varies between 1, 3, and 4, with slightly higher values at each x/D location when the contraction ratio Cr is 5. For each contraction ratio, there is a slight increase in effectiveness when the blowing ratio is increased from 2.0 to 5.0 but there is no further substantial improvement when the blowing ratio is increased to 10.0. Overall, line-averaged and spatially averaged-adiabatic film effectiveness data, and spatially averaged heat transfer coefficient data are described as they are affected by contraction ratio, blowing ratio, hole angle α, and streamwise location x/D. For example, when α = 20 deg, the detrimental effects of mainstream acceleration are apparent since heat transfer coefficients for contraction ratios Cr of 3 and 5 are often higher than values for Cr = 1, especially for x/D > 100.

Sign in / Sign up

Export Citation Format

Share Document