Large-eddy simulations of film cooling flows

2006 ◽  
Vol 35 (6) ◽  
pp. 587-606 ◽  
Author(s):  
X. Guo ◽  
W. Schröder ◽  
M. Meinke
Keyword(s):  
Film Cooling ◽  
Large Eddy Simulations ◽  
Cooling Flows ◽  
Large Eddy

Large Eddy Simulations of Film-Cooling Flows With a Micro-Ramp Vortex Generator

2011 ◽  
Author(s):  
Aaron F. Shinn ◽  
S. Pratap Vanka
Keyword(s):  
Film Cooling ◽  
Cross Flow ◽  
Vortex Generator ◽  
Vortex Pair ◽  
Large Eddy Simulations ◽  
Wind Tunnel Experiments ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Flows ◽  
Large Eddy

Large Eddy Simulations were performed to study the effect of a micro-ramp on an inclined turbulent jet interacting with a cross-flow in a film-cooling configuration. The micro-ramp vortex generator is placed downstream of the film-cooling jet. Changes in vortex structure and film-cooling effectiveness are evaluated and the genesis of the counter-rotating vortex pair in the jet is discussed. Results are reported with the jet modeled using a plenum/pipe configuration. This configuration was designed based on previous wind tunnel experiments at NASA Glenn Research Center, and the present results are meant to supplement those experiments. It is found that the micro-ramp improves film-cooling effectiveness by generating near-wall counter-rotating vortices which help entrain coolant from the jet and transport it to the surface. The pair of vortices generated by the micro-ramp are of opposite sense to the vortex pair embedded in the jet.

Large-Eddy Simulations of a Cylindrical Film Cooling Hole

2013 ◽  
Vol 27 (2) ◽  
pp. 255-273 ◽  
Author(s):  
Perry L. Johnson ◽  
Jayanta S. Kapat
Keyword(s):  
Film Cooling ◽  
Large Eddy Simulations ◽  
Large Eddy ◽  
Cooling Hole

Effect of Blowing Ratio in the Near-Stagnation Region of a Three-Row Leading Edge Film Cooling Geometry Using Large Eddy Simulations

2009 ◽  
Author(s):  
Sai Shrinivas Sreedharan ◽  
Danesh K. Tafti
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Leading Edge ◽  
Large Eddy Simulations ◽  
Stagnation Region ◽  
Stagnation Line ◽  
Blowing Ratio ◽  
Large Eddy ◽  
Adiabatic Effectiveness ◽  
Compound Angle

Computational studies are carried out using Large Eddy Simulations (LES) to investigate the effect of coolant to mainstream blowing ratio in a leading edge region of a film cooled vane. The three row leading edge vane geometry is modeled as a symmetric semi-cylinder with a flat afterbody. One row of coolant holes is located along the stagnation line and the other two rows of coolant holes are located at ±21.3° from the stagnation line. The coolant is injected at 45° to the vane surface with 90° compound angle injection. The coolant to mainstream density ratio is set to unity and the freestream Reynolds number based on leading edge diameter is 32000. Blowing ratios (B.R.) of 0.5, 1.0, 1.5, and 2.0 are investigated. It is found that the stagnation cooling jets penetrate much further into the mainstream, both in the normal and lateral directions, than the off-stagnation jets for all blowing ratios. Jet dilution is characterized by turbulent diffusion and entrainment. The strength of both mechanisms increases with blowing ratio. The adiabatic effectiveness in the stagnation region initially increases with blowing ratio but then generally decreases as the blowing ratio increases further. Immediately downstream of off-stagnation injection, the adiabatic effectiveness is highest at B.R. = 0.5. However, further downstream the larger mass of coolant injected at higher blowing ratios, in spite of the larger jet penetration and dilution, increases the effectiveness with blowing ratio.

Large Eddy Simulations of Film Cooling Flow Fields From Cylindrical and Shaped Holes

2008 ◽  
Author(s):  
D. H. Leedom ◽  
S. Acharya
Keyword(s):  
Film Cooling ◽  
Flow Characteristics ◽  
Flow Fields ◽  
Large Eddy Simulations ◽  
Delivery Tube ◽  
Asymmetric Flow ◽  
Specific Mass ◽  
Cooling Flow ◽  
Large Eddy ◽  
Coolant Delivery

Large Eddy Simulations (LES) of cylindrical, laterally diffused, and console holes are performed, and the resulting flow field data is presented. The motivation for performing LES is to enable more accurate simulations and to obtain a better understanding of the flow physics associated with complex hole shapes. The simulations include the coolant delivery tube and the feeding plenum chamber, and are performed for a specific mass flow rate of coolant per unit width of blade. A crossflow inlet is used on the plenum, and the resulting asymmetric flow characteristics are investigated. Coolant delivery tube flow fields are investigated in detail. Results show qualitative agreement with reported trends of improved film coverage with diffused and console holes.

Large Eddy Simulations on Fan Shaped Film Cooling Hole with Upstream Boundary Layer Turbulence Effect Generated by Trip Strip

2021 ◽  
pp. 1-37
Author(s):  
Young Seok Kang ◽  
Sangook Jun ◽  
Dong-Ho Rhee
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Film Cooling ◽  
Main Flow ◽  
Large Eddy Simulations ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Flow ◽  
Large Eddy ◽  
Cooling Hole

Abstract Large eddy simulations on the well-known 7-7-7 fan shaped cooling hole were carried out. Like using a trip strip to create turbulent boundary layer in practical experiments, trip strips with different configurations were placed upstream of the cooling hole to investigate incoming turbulent boundary layer effect on the film cooling flow behavior. Without the trip, horseshoe vortex generated by laminar boundary layer induced laterally discharging cooling flow in the lateral direction. Meanwhile, the induced cooling flow formed high film cooling effectiveness region around the film cooling hole. When the incoming boundary flow was turbulent, laterally discharged cooling flow was influenced by the turbulent boundary layer to dissipate to the main flow and resultant high effectiveness region disappeared. Depending on the trip configuration, quantitative characteristics of boundary layer such as turbulent intensity, momentum thickness and shape factor were strongly affected. Some trip configurations resulted in fully developed turbulent boundary layer just before leading edge of the film cooling hole. In such cases, distribution of the film cooling effectiveness showed a reasonable agreement with available experimental data where the quantitative properties of the turbulent boundary layer were similar. However, when the trip was located too close to the film cooling hole, the separated and reattached flow did not develop into the stabilized turbulent boundary layer. Then strong turbulence intensity in the main flow boundary layer stimulated break down of the cooling flow vortex structure and early dissipation to the main flow. It resulted in restricted film cooling flow coverage.

Large Eddy Simulations on Fan Shaped Film Cooling Hole With Various Inlet Turbulence Generation Methods

2020 ◽  
Author(s):  
Young Seok Kang ◽  
Sangook Jun ◽  
Dong-Ho Rhee
Keyword(s):  
Vortex Structure ◽  
Film Cooling ◽  
Main Flow ◽  
Large Eddy Simulations ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Flow ◽  
Large Eddy ◽  
Cooling Hole ◽  
Turbulence Generation

Abstract Large eddy simulations on well-known 7-7-7 fan shaped cooling hole have been carried out. Film cooling methods are generally applied to high pressure turbine, of which flow condition is extremely turbulent because high pressure turbines are generally located downstream combustor in gas turbines. However, different to RANS simulations, implementing turbulence at the main flow inlet is not simple in LES. For this reason, several numerical techniques have been devised to give turbulence information at the inlet boundary condition in LES. In this study, rectangular turbulator was located in front of the cooling hole to generate turbulent boundary flow in the main flow. Another method used in this study is transient table method to simulate turbulent flow at the main flow inlet. Without turbulent velocity components in approaching flow, laterally discharged cooling flow touches wall while it forms a vortex structure. Then high film cooling effectiveness region around the cooling hole appears. In the meanwhile, when approaching flow is turbulent, the laterally discharged cooling flow no more forms vortex structure and dissipated to the main flow and resultant high effectiveness region disappears. Both turbulence generation methods showed that turbulent intensity of the main flow affects effective range of the cooling flow and resultant film cooling effectiveness distributions. Also high turbulence intensity of the main flow stimulates early break down of the vortex structure coming out of the cooling hole and its dissipation to the main flow. It means high turbulent intensity restricts film cooling flow coverage. Another lesson from the study is that vortex generated from the cooling hole, its development and dissipation to the main flow, have an important role to understand film cooling effectiveness distributions around the cooling hole.

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