Influence of Coolant Feed Direction and Hole Length on Film Cooling Jet Velocity Profiles

Brundage, Aaron Leon.; Plesniak, Michael W.; Ramadhyani, S.

doi:10.1115/99-gt-035

Cited by 15 publications

(6 citation statements)

References 19 publications

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“…While the reversed flow region near the smaller vortex pair has diminished by plane H-2, the reversed flow region near the leading edge has grown slightly, with the leading-edge stagnation point moving downstream slightly. This is consistent with the report by Brundage, Plesniak & Ramadhyani (1999) that the size of an in-hole separation region at the leading edge increases as the length of the hole is traversed.…”

Section: In-hole Velocity Fieldsupporting

confidence: 93%

Evolution of jets emanating from short holes into crossflow

2004

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The evolution of a short injection-hole jet issuing into a crossflow at low blowing ratios is presented. Particle image velocimetry (PIV) is used to determine structural features of the jet/crossflow interaction throughout its development from within the jet supply channel (which feeds the holes), through the injection hole, and into the crossflow. The effect of supply channel feed orientations, i.e. counter to, or in the same direction as the crossflow is emphasized. Feed orientation profoundly affects such jet characteristics as trajectory and lateral spreading, as well as its structural features. Fluid within the high-speed supply channel exhibits swirling motions similar to the flow induced by a pair of counter-rotating vortices. The sense of rotation of the swirling fluid depends upon the orientation of the supply channel flow with respect to the crossflow, and in turn impacts the in-hole velocity fields. In the coflow supply channel geometry (channel flow is in the same direction as the free stream), a pair of vortices exists within the hole with the same sense of rotation as the primary jet counter-rotating vortex pair (CRVP). In contrast, the counterflow supply channel configuration has in-hole vortices of opposite rotational sense to that of the CRVP. The in-hole vortices interact constructively or destructively with the CRVP, thus affecting the strength and coherence of the CRVP. The counterflow configuration has a weakened CRVP because of destructive interference with the in-hole vortices. The weaker CRVP has a lower trajectory and increased spanwise spreading. External to the injection hole, a pair of vortices exists immediately downstream of the jet. They are initially perpendicular to the boundary-layer plate near the wall and are outboard of the streamwise hole centreline. These vortices, denoted ‘downstream spiral separation node’ (DSSN) vortices, are affected by both the supply channel feed direction and the blowing ratio. They appear to form by free-stream fluid wrapping around the jet and interacting with the CRVP. The coflow supply channel geometry is associated with the largest and most well-defined DSSN vortices, and their size is inversely proportional to the blowing ratio. At low blowing ratio, these vortices induce a large recirculating flow region downstream of the injection hole at the wall.

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Section: In-hole Velocity Fieldsupporting

confidence: 93%

Evolution of jets emanating from short holes into crossflow

2004

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“…The longer injection hole data are investigated for the 90° counter-flow cases. The trend observed in the 90° counter flow cases could be due to the inhole vortex pairs, (as reported by Leylek and Zerlde, 1994;Kohli and Thole, 1997;and Brundage et al, 1999 ) with the opposite sense of rotation to the main counter-rotating vortex pair. The in-hole vortices may persist out of the hole and lower the trajectory of the jet through mutual induction.…”

Section: Id Effectssupporting

confidence: 72%

Film Cooling Effectiveness for Short Film Cooling Holes Fed by a Narrow Plenum

Hale

Plesniak

Ramadhyani

1999

Volume 3: Heat Transfer; Electric Power; Industrial and Cogeneration

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The adiabatic, steady-state liquid crystal technique was used to measure surface adiabatic film cooling effectiveness values in the near-hole region (X / D < 10). A parametric study was conducted for a single row of short holes (L / D ≤ 3) fed by a narrow plenum (H / D = 1). Film cooling effectiveness values are presented and compared for various L / D ratios (0.66 to 3.0), three different blowing ratios (0.5, 1.0, and 1.5), two different plenum feed configurations (co-flow and counter flow), and two different injection angles (35° and 90°). Injection hole geometery and plenum feed direction were found to significantly affect short hole film cooling performance. Under certain conditions, comparable or improved coverage was achieved with 90° holes as with 35° holes. This result has important implications for manufacturing of thin-walled film-cooled blades or vanes.

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“…The vertical and the spanwise components of the velocity show another characteristic of the velocity field in the hole: counter-rotating vortices appear in the aperture itself, in the low-momentum region. This type of organization has often been reported before, for example by Leylek & Zerkle (1994) or Brundage et al (1999). The counter-rotating vortices seem to be related to the deformation of the velocity field due to the separation at the entry of the hole.…”

Section: Flow Within the Aperturesupporting

confidence: 79%

“…They define two regions in the hole: the jetting region along the upstream wall and the low-momentum region along the downstream wall of the hole. This structure is also reported by Brundage, Plesniak & Ramadhyani (1999). When the jet issues in the upper channel, another separation zones is observed just downstream of the jet, near the wall (3).…”

Section: General Flow Descriptionsupporting

confidence: 73%

Large-eddy simulation of a bi-periodic turbulent flow with effusion

Mendez

Nicoud

2008

J. Fluid Mech.

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International audienceLarge-eddy simulations of a generic turbulent flow with discrete effusion are reported. The computational domain is periodic in both streamwise and spanwise directions and contains both the injection and the suction sides. The blowing ratio is close to 1.2 while the Reynolds number in the aperture is of order 2600. The numerical results for this fully developed bi-periodic turbulent flow with effusion are compared to available experimental data from a large-scale spatially evolving isothermal configuration. It is shown that many features are shared by the two flow configurations. The main difference is related to the mean streamwise velocity profile, which is more flat for the bi-periodic situation where the cumulative effect of an infinite number of upstream jets is accounted for. The necessity of considering both sides of the plate is also established by analysing the vortical structure of the flow and some differences with the classical jet-in-crossflow case are highlighted. Finally, the numerical results are analysed in terms of wall modelling for full-coverage film cooling. For the operating point considered, it is demonstrated that the streamwise momentum flux is dominated by non-viscous effects, although the area where only the viscous shear stress contributes is very large given the small porosity value (4%)

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Influence of Coolant Feed Direction and Hole Length on Film Cooling Jet Velocity Profiles

Cited by 15 publications

References 19 publications

Evolution of jets emanating from short holes into crossflow

Evolution of jets emanating from short holes into crossflow

Film Cooling Effectiveness for Short Film Cooling Holes Fed by a Narrow Plenum

Large-eddy simulation of a bi-periodic turbulent flow with effusion

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