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.

Film-Cooling From Holes With Compound Angle Orientations: Part 2—Results Downstream of a Single Row of Holes With 6d Spanwise Spacing

1994 ◽  
Vol 116 (2) ◽  
pp. 353-362 ◽  
Author(s):  
P. M. Ligrani ◽  
J. M. Wigle ◽  
S. W. Jackson
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Test Surface ◽  
Spanwise Direction ◽  
Single Row ◽  
Normal Plane ◽  
Structure Of Flow ◽  
Compound Angle ◽  
Angle Orientation ◽  
Effectiveness Data

Experimental results are presented that describe the development and structure of flow downstream of a single row of film-cooling holes with compound angle orientations. With this configuration, holes are spaced 6d 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<30 when m=0.50 and for x/d<60 when m=1.0 and 1.5. 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 20 to 39 percent higher when 6d spanwise hole spacing is employed compared to 7.8d spanwise hole spacing for the same m and x/d, for x/d<60. When plotted in η/m versus Xl/s coordinates, spanwise-averaged film effectiveness data measured downstream of one and two rows of holes from all injection configurations tested show a reasonable collapse. For m values between 1 and 3, spanwise-averaged iso-energetic Stanton number ratios measured just downstream of one row of holes are lower than results measured just downstream of two rows of holes, which evidences greater mixing and higher turbulence levels when the injectant emerges from two rows of holes.

Film Cooling From Spanwise-Oriented Holes in Two Staggered Rows

1997 ◽  
Vol 119 (3) ◽  
pp. 562-567 ◽  
Author(s):  
P. M. Ligrani ◽  
A. E. Ramsey
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Test Surface ◽  
Spanwise Direction ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Blowing Ratio ◽  
Streamwise Location ◽  
Adiabatic Effectiveness ◽  
Film Cooling Holes

Adiabatic effectiveness and iso-energetic heat transfer coefficients are presented from measurements downstream of film-cooling holes inclined at 30 deg. with respect to the test surface in spanwise/normal planes. With this configuration, holes are spaced 3d apart in the spanwise direction and 4d in the streamwise direction in two staggered rows. Results are presented for an injectant to free-stream density ratio near 1.0, and injection blowing ratios from 0.5 to 1.5. Spanwise-averaged adiabatic effectiveness values downstream of the spanwise/normal plane holes are significantly higher than values measured downstream of simple angle holes for x/d < 25–70(depending on blowing ratio) when compared for the same normalized streamwise location, blowing ratio, and spanwise and streamwise hole spacings. Spanwise-averaged iso-energetic Stanton number ratios range between 1.0 and 1.41, increase with blowing ratio at each streamwise station, and show little variation with streamwise location for each value of blowing ratio tested.

scholarly journals Film Cooling from Two Staggered Rows of Compound Angle Holes at High Blowing Ratios

1996 ◽  
Vol 2 (3) ◽  
pp. 201-208 ◽  
Author(s):  
Phillip M. Ligrani ◽  
Joon Sik Lee
Keyword(s):  
Film Cooling ◽  
Test Surface ◽  
Spanwise Direction ◽  
Mean Velocity ◽  
Blowing Ratio ◽  
Structure Of Flow ◽  
Inclination Angles ◽  
Lift Off ◽  
Film Cooling Holes ◽  
Compound Angle

Experimental results are presented which describe the development and structure of flow downstream of two staggered rows of film-cooling holes with compound angle orientations at high blowing ratios. These film cooling configurations are important because they are frequently employed on the first stage of rotating blades of operating gas turbine engines. With this configuration, holes are spaced 3d apart in the spanwise direction, with inclination angles of 24 degrees, and angles of orientation of 50.5 degrees. Blowing ratios range from 0.5 to 4.0 and the ratio of injectant to freestream density is near 1.0. Results show that spanwise averaged adiabatic effectiveness, spanwise-averaged iso-energetic Stanton number ratios, surveys of streamwise mean velocity, and surveys of injectant distributions change by important amounts as the blowing ratio increases. This is due to injectant lift-off from the test surface just downstream of the holes which becomes more pronounced as blowing ratio increases.

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.

scholarly journals Film Cooling From Spanwise Oriented Holes in Two Staggered Rows

1995 ◽  
Author(s):  
Phillip M. Ligrani ◽  
Anthony E. Ramsey
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Flux Ratio ◽  
Test Surface ◽  
Spanwise Direction ◽  
Transfer Coefficients ◽  
Blowing Ratio ◽  
Streamwise Location ◽  
Adiabatic Effectiveness ◽  
Lift Off

Adiabatic effectiveness and iso-energetic heat transfer coefficients are presented from measurements downstream of film-cooling holes inclined at 30 degrees with respect to the test surface in spanwise/normal planes. With this configuration, holes are spaced 3d apart in the spanwise direction and 4d in the streamwise direction in two staggered rows. Results are presented for an injectant to freestream density ratio near 1.0, and injection blowing ratios from 0.5 to 1.5. Spanwise-averaged adiabatic effectiveness values downstream of the spanwise/normal plane holes are significantly higher than values measured downstream of simple angle holes for x/d<25–70 (depending on blowing ratio) when compared for the same normalized streamwise location, blowing ratio, and spanwise and streamwise hole spacings. Differences are principally due to different coalescence of injectant accumulations from the two different rows of holes, as well as significantly different lift-off dependence on momentum flux ratio. Spanwise-averaged iso-energetic Stanton number ratios are somewhat higher than ones measured downstream of other simple and compound angle configurations studied. Values range between 1.0 and 1.41, increase with blowing ratio at each streamwise station, and show little variation with streamwise location for each value of blowing ratio tested.

Film Cooling From a Single Row of Holes Oriented in Spanwise/Normal Planes

1997 ◽  
Vol 119 (4) ◽  
pp. 770-776 ◽  
Author(s):  
P. M. Ligrani ◽  
A. E. Ramsey
Keyword(s):  
Film Cooling ◽  
Test Surface ◽  
Spanwise Direction ◽  
Single Row ◽  
Local Maxima ◽  
Blowing Ratio ◽  
Streamwise Location ◽  
Structure Of Flow ◽  
Adiabatic Effectiveness ◽  
Lift Off

Experimental results are presented that describe the development and structure of flow downstream of a single row of film-cooling holes inclined at 30 deg from the test surface in spanwise/normal planes. With this configuration, holes are spaced 6d apart in the spanwise direction in a single row. Results are presented for a ratio of injectant density to free-stream density near 1.0, and injection blowing ratios from 0.5 to 1.5. Compared to results measured downstream of simple angle (streamwise) oriented holes, spanwise-averaged adiabatic effectiveness values are significantly higher for the same spanwise hole spacing, normalized streamwise location x/d, and blowing ratio m when m = 1.0 and 1.5 for x/d < 80. The injectant from the spanwise/normal holes is also less likely to lift off of the test surface than injectant from simple angle holes. This is because lateral components of momentum keep higher concentrations of injectant in closer proximity to the surface. As a result, local adiabatic effectiveness values show significantly greater spanwise variations and higher local maxima at locations immediately downstream of the holes. Spanwise-averaged iso-energetic Stanton number ratios range between 1.07 and 1.26, which are significantly higher than values measured downstream of two other injection configurations (one of which is simple angle, streamwise holes) when compared at the same x/d and blowing ratio.

scholarly journals Film Cooling from a Single Row of Compound Angle Holes at High Blowing Ratios

1996 ◽  
Vol 2 (4) ◽  
pp. 259-267 ◽  
Author(s):  
Phillip M. Ligrani ◽  
Joon Sik Lee
Keyword(s):  
Film Cooling ◽  
Test Surface ◽  
Spanwise Direction ◽  
Mean Velocity ◽  
Single Row ◽  
Blowing Ratio ◽  
Structure Of Flow ◽  
Inclination Angles ◽  
Lift Off ◽  
Compound Angle

Experimental results are presented which describe the development and structure of flow downstream of a single row of holes with compound angle orientations producing film cooling at high blowing ratios. This film cooling configuration is important because similar arrangements are frequently employed on the first stage of rotating blades of operating gas turbine engines. With this configuration, holes are spaced 6d apart in the spanwise direction, with inclination angles of 24 degrees, and angles of orientation of 50.5 degrees. Blowing ratios range from 1.5 to 4.0 and the ratio of injectant to freestream density is near 1.0. Results show that spanwise averaged adiabatic effectiveness, spanwise-averaged iso-energetic Stanton number ratios, surveys of streamwise mean velocity, and surveys of injectant distributions change by important amounts as the blowing ratio increases. This is due to injectant lift-off from the test surface just downstream of the holes.

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.

Effect of Density Ratio on Film-Cooling Effectiveness Distribution and Its Uniformity for Several Hole Geometries on a Flat Plate

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Jiaxu Yao ◽  
Jin Xu ◽  
Ke Zhang ◽  
Jiang Lei ◽  
Lesley M. Wright
Keyword(s):  
Flat Plate ◽  
Film Cooling ◽  
Density Ratio ◽  
Lateral Spread ◽  
Spanwise Direction ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cylindrical Holes ◽  
Density Ratios ◽  
Compound Angle

The film cooling effectiveness distribution and its uniformity downstream of a row of film cooling holes on a flat plate are investigated by pressure sensitive paint (PSP) under different density ratios. Several hole geometries are studied, including streamwise cylindrical holes, compound-angled cylindrical holes, streamwise fan-shape holes, compound-angled fan-shape holes, and double-jet film-cooling (DJFC) holes. All of them have an inclination angle (θ) of 35 deg. The compound angle (β) is 45 deg. The fan-shape holes have a 10 deg expansion in the spanwise direction. For a fair comparison, the pitch is kept as 4d for the cylindrical and the fan-shape holes, and 8d for the DJFC holes. The uniformity of effectiveness distribution is described by a new parameter (Lateral-Uniformity, LU) defined in this paper. The effects of density ratios (DR = 1.0, 1.5 and 2.5) on the film-cooling effectiveness and its uniformity are focused. Differences among geometries and effects of blowing ratios (M = 0.5, 1.0, 1.5, and 2.0) are also considered. The results show that at higher density ratios, the lateral spread of the discrete-hole geometries (i.e., the cylindrical and the fan-shape holes) is enhanced, while the DJFC holes is more advantageous in film-cooling effectiveness. Mostly, a higher lateral-uniformity is obtained at DR = 2.5 due to better coolant coverage and enhanced lateral spread, but the effects of the density ratio on the lateral-uniformity are not monotonic in some cases. Utilizing the compound angle configuration leads to an increased lateral-uniformity due to a stronger spanwise motion of the jet. Generally, with a higher blowing ratio, the lateral-uniformity of the discrete-hole geometries decreases due to narrower traces, while that of the DJFC holes increases due to a stronger spanwise movement.

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