Effect of Upstream Wake With Vortex on Turbine Blade Platform Film Cooling With Simulated Stator-Rotor Purge Flow

2007 ◽  
Author(s):  
Lesley M. Wright ◽  
Sarah A. Blake ◽  
Dong-Ho Rhee ◽  
Je-Chin Han
Keyword(s):  
Turbine Blade ◽  
Film Cooling ◽  
Labyrinth Seal ◽  
Delta Wings ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Linear Cascade ◽  
Passage Vortex ◽  
Mainstream Flow ◽  
Purge Flow

Detailed film cooling effectiveness distributions were experimentally obtained on a turbine blade platform within a linear cascade. The film cooling effectiveness distributions were obtained on the platform with upstream disturbances used to simulate the passing vanes. Cylindrical rods, placed upstream of the blades, simulated the wake created by the trailing edge of the stator vanes. The rods were placed at 4 locations to show how the film cooling effectiveness was affected relative to the vane location. In addition, delta wings were placed upstream of the blades to model the effect of the passage vortex (generated in the vane passage) on the platform film cooling effectiveness. The delta wings create a vortex similar to the passage vortex as it exits the upstream vane passage. The film cooling effectiveness was measured with the delta wings placed at 4 locations, to investigate the effect of the passing vanes. Finally, the delta wings were coupled with the cylindrical rods to examine the combined effect of the upstream wake and passage vortex on the platform film cooling effectiveness. The detailed film cooling effectiveness distributions were obtained using pressure sensitive paint (PSP) in the five blade linear cascade. An advanced labyrinth seal was placed upstream of the blades to simulate purge flow from a statorrotor seal. The coolant flow rate varied from 0.5% to 2.0% of the mainstream flow, while the Reynolds number of the mainstream flow remained constant at 3.1*105 (based on the inlet velocity and chord length of the blade). The film cooling effectiveness was not significantly affected with the upstream rod. However, the vortex generated by the delta wings had a profound impact on the film cooling effectiveness. The vortex created more turbulent mixing within the blade passage, and the result is reduced film cooling effectiveness through the entire passage. When the vane induced secondary flow is included, the need for additional platform cooling becomes very obvious.

Effect of Upstream Wake With Vortex on Turbine Blade Platform Film Cooling With Simulated Stator-Rotor Purge Flow

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Lesley M. Wright ◽  
Sarah A. Blake ◽  
Dong-Ho Rhee ◽  
Je-Chin Han
Keyword(s):  
Turbine Blade ◽  
Film Cooling ◽  
Labyrinth Seal ◽  
Delta Wings ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Linear Cascade ◽  
Passage Vortex ◽  
Mainstream Flow ◽  
Purge Flow

Detailed film cooling effectiveness distributions were experimentally obtained on a turbine blade platform within a linear cascade. The film cooling effectiveness distributions were obtained on the platform with upstream disturbances used to simulate the passing vanes. Cylindrical rods, placed upstream of the blades, simulated the wake created by the trailing edge of the stator vanes. The rods were placed at four locations to show how the film cooling effectiveness was affected relative to the vane location. In addition, delta wings were placed upstream of the blades to model the effect of the passage vortex (generated in the vane passage) on the platform film cooling effectiveness. The delta wings create a vortex similar to the passage vortex as it exits the upstream vane passage. The film cooling effectiveness was measured with the delta wings placed at four location, to investigate the effect of the passing vanes. Finally, the delta wings were coupled with the cylindrical rods to examine the combined effect of the upstream wake and passage vortex on the platform film cooling effectiveness. The detailed film cooling effectiveness distributions were obtained using pressure sensitive paint in the five blade linear cascade. An advanced labyrinth seal was placed upstream of the blades to simulate purge flow from a stator-rotor seal. The coolant flow rate varied from 0.5% to 2.0% of the mainstream flow, while the Reynolds number of the mainstream flow remained constant at 3.1×105 (based on the inlet velocity and chord length of the blade). The film cooling effectiveness was not significantly affected with the upstream rod. However, the vortex generated by the delta wings had a profound impact on the film cooling effectiveness. The vortex created more turbulent mixing within the blade passage, and the result is reduced film cooling effectiveness through the entire passage. When the vane induced secondary flow is included, the need for additional platform cooling becomes very obvious.

Upstream Vortex Effects on Turbine Blade Platform Film Cooling With Typical Stator-Rotor Purge Flow

2007 ◽  
Author(s):  
Zhihong Gao ◽  
Diganta Narzary ◽  
Shantanu Mhetras ◽  
Je-Chin Han
Keyword(s):  
Turbine Blade ◽  
Film Cooling ◽  
Delta Wing ◽  
Delta Wings ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Pressure Sensitive ◽  
Passage Vortex ◽  
Mainstream Flow ◽  
Purge Flow

Detailed film cooling effectiveness distributions were experimentally obtained on a turbine blade platform within a five-blade linear cascade. A typical labyrinth-like seal was placed upstream of the cascade blades to simulate purge flow from a stator-rotor gap. Delta wings were periodically placed upstream of the blades to model the effect of the passage vortex generated in the vane passage on the downstream blade platform film cooling effectiveness. Typical vane passage vortex was simulated by two delta wings with height of 10% and 20% of the blade span, respectively. The strength of vane passage vortex was also modeled by varying the attack angle of mainstream to the delta wing. The film cooling effectiveness was measured with the delta wings placed at four phase locations, to investigate the effect of the passing vanes. The detailed film cooling effectiveness distributions on the platform were obtained using pressure sensitive paint (PSP) technique. The coolant mass flow rate varied from 0.25% to 1.0% of the mainstream flow. The freestream Reynolds number, based on the axial chord length and the exit velocity, was 750,000. The Mach numbers at the inlet and the exit were 0.27 and 0.44, respectively. The vortex generated by the delta wings had a profound impact on the platform film cooling effectiveness. The upstream vortex created more turbulent mixing within the blade passage and resulted in reduced film cooling effectiveness on the blade platform.

Influence of Coolant Density on Turbine Blade Platform Film-Cooling

2012 ◽  
Vol 4 (2) ◽  
Author(s):  
Diganta P. Narzary ◽  
Kuo-Chun Liu ◽  
Je-Chin Han
Keyword(s):  
Turbine Blade ◽  
Flow Rate ◽  
Turbulence Intensity ◽  
Film Cooling ◽  
Density Ratio ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Mainstream Flow ◽  
Purge Flow

Detailed parametric study of film-cooling effectiveness was carried out on a turbine blade platform of a five-blade linear cascade. The parameters chosen were freestream turbulence intensity, upstream stator-rotor purge flow rate, discrete-hole film-cooling blowing ratio, and coolant-to-mainstream density ratio. The measurement technique adopted was temperature sensitive paint (TSP) technique. Two turbulence intensities of 4.2% and 10.5%; three purge flows between the range of 0.25% and 0.75% of mainstream flow rate; three blowing ratios between 1.0 and 1.8; and three density ratios between 1.1 and 2.2 were investigated. Purge flow was supplied via a typical double-toothed stator-rotor seal, whereas the discrete-hole film-cooling was accomplished via two rows of cylindrical holes arranged along the length of the platform. The inlet and the exit Mach numbers were 0.27 and 0.44, respectively. Reynolds number of the mainstream flow was 7.5 * 105 based on the exit velocity and chord length of the blade. Results indicated that platform film-cooling effectiveness decreased with turbulence intensity, increased with purge flow rate and density ratio, and possessed an optimum blowing ratio value.

Film Cooling Effectiveness Distributions on a Turbine Blade Cascade Platform With Stator-Rotor Purge and Discrete Film Hole Flows

2006 ◽  
Author(s):  
Lesley M. Wright ◽  
Sarah A. Blake ◽  
Je-Chin Han
Keyword(s):  
Turbine Blade ◽  
Flow Rate ◽  
Film Cooling ◽  
Coolant Flow ◽  
Coolant Flow Rate ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Wide Range ◽  
Mainstream Flow ◽  
Purge Flow

An experimental investigation has been completed to obtain detailed film cooling effectiveness distributions on a cooled turbine blade platform within a linear cascade. The platform has a labyrinth-like seal upstream of the blades to model a realistic stator-rotor seal configuration. Additional coolant is supplied to the downstream half of the platform via discrete film cooling holes. The coolant flow rate through the upstream seal varies from 0.5% to 2.0% of the mainstream flow, while the blowing ratio of the coolant through the discrete holes varies from 0.5 to 2.0 (based on the mainstream velocity at the exit of the cascade). Detailed film cooling effectiveness distributions are obtained using the pressure sensitive paint (PSP) technique under a wide range of coolant flow conditions and various freestream turbulence levels (0.75% or 13.4%). The PSP technique clearly shows how adversely the coolant is affected by the passage induced flow. With only purge flow from the upstream seal, the coolant flow rate must exceed 1.5% of the mainstream flow in order to adequately cover the entire passage. However, if discrete film holes are used on the downstream half of the passage, the platform can be protected while using less coolant (i.e. the seal flow rate can be reduced).

Influence of Coolant Density on Turbine Blade Platform Film-Cooling

2009 ◽  
Author(s):  
Diganta P. Narzary ◽  
Kuo-Chun Liu ◽  
Je-Chin Han
Keyword(s):  
Turbine Blade ◽  
Flow Rate ◽  
Turbulence Intensity ◽  
Film Cooling ◽  
Density Ratio ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Mainstream Flow ◽  
Purge Flow

Detailed parametric study of film-cooling effectiveness was carried out on a turbine blade platform of a five-blade linear cascade. The parameters chosen were — freestream turbulence intensity, upstream stator-rotor purge flow rate, discrete-hole film-cooling blowing ratio, and coolant-to-mainstream density ratio. The measurement technique adopted was temperature sensitive paint (TSP) technique. Two turbulence intensities of 4.2% and 10.5%; three purge flows between the range of 0.25% and 0.75% of mainstream flow rate; three blowing ratios between 1.0 and 2.0; and three density ratios between 1.1 and 2.1 were investigated. Purge flow was supplied via a typical double-toothed stator-rotor seal, whereas the discrete-hole film cooling was accomplished via two rows of cylindrical holes arranged along the length of the platform. The inlet and the exit Mach numbers were 0.27 and 0.44, respectively. Reynolds number of the mainstream flow was 7.5*105 based on the exit velocity and chord length of the blade. Results indicated that platform film-cooling effectiveness decreased with turbulence intensity, increased with purge flow rate and density ratio, and possessed an optimum blowing ratio value. The improved effectiveness with density ratio was further validated by the pressure sensitive paint (PSP) technique.

Film Cooling Effectiveness Distributions on a Turbine Blade Cascade Platform With Stator-Rotor Purge and Discrete Film Hole Flows

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Lesley M. Wright ◽  
Sarah A. Blake ◽  
Je-Chin Han
Keyword(s):  
Turbine Blade ◽  
Flow Rate ◽  
Film Cooling ◽  
Coolant Flow ◽  
Coolant Flow Rate ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Wide Range ◽  
Mainstream Flow ◽  
Purge Flow

An experimental investigation to obtain detailed film cooling effectiveness distributions on a cooled turbine blade platform within a linear cascade has been completed. The Reynolds number of the freestream flow is 3.1×105, and the platform has a labyrinthlike seal upstream of the blades to model a realistic stator-rotor seal configuration. An additional coolant is supplied to the downstream half of the platform via discrete film cooling holes. The coolant flow rate through the upstream seal varies from 0.5% to 2.0% of the mainstream flow, while the blowing ratio of the coolant through the discrete holes varies from 0.5 to 2.0 (based on the mainstream velocity at the exit of the cascade). Detailed film cooling effectiveness distributions are obtained using the pressure sensitive paint (PSP) technique under a wide range of coolant flow conditions and various freestream turbulence levels (0.75% or 13.4%). The PSP technique clearly shows how adversely the coolant is affected by the passage induced flow. With only purge flow from the upstream seal, the coolant flow rate must exceed 1.5% of the mainstream flow in order to adequately cover the entire passage. However, if discrete film holes are used on the downstream half of the passage, the platform can be protected while using less coolant (i.e., the seal flow rate can be reduced).

Turbine Blade Platform Film Cooling With Simulated Swirl Purge Flow and Slashface Leakage Conditions

2016 ◽  
Author(s):  
Andrew F. Chen ◽  
Chao-Cheng Shiau ◽  
Je-Chin Han
Keyword(s):  
Turbine Blade ◽  
Film Cooling ◽  
Leading Edge ◽  
Suction Side ◽  
Leakage Flow ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Purge Flow ◽  
Endwall Film Cooling ◽  
Film Cooling Holes

The combined effects of inlet purge flow and the slashface leakage flow on the film cooling effectiveness of a turbine blade platform were studied using the pressure sensitive paint (PSP) technique. Detailed film cooling effectiveness distributions on the endwall were obtained and analyzed. The inlet purge flow was generated by a row of equally-spaced cylindrical injection holes inside a single-tooth generic stator-rotor seal. In addition to the traditional 90 degree (radial outward) injection for the inlet purge flow, injection at a 45 degree angle was adopted to create a circumferential/azimuthal velocity component toward the suction side of the blades, which created a swirl ratio (SR) of 0.6. Discrete cylindrical film cooling holes were arranged to achieve an improved coverage on the endwall. Backward injection was attempted by placing backward injection holes near the pressure side leading edge portion. Slashface leakage flow was simulated by equally-spaced cylindrical injection holes inside a slot. Experiments were done in a five-blade linear cascade with an average turbulence intensity of 10.5%. The inlet and exit Mach numbers were 0.26 and 0.43, respectively. The inlet and exit mainstream Reynolds numbers based on the axial chord length of the blade were 475,000 and 720,000, respectively. The coolant-to-mainstream mass flow ratios (MFR) were varied from 0.5%, 0.75%, to 1% for the inlet purge flow. For the endwall film cooling holes and slashface leakage flow, blowing ratios (M) of 0.5, 1.0, and 1.5 were examined. Coolant-to-mainstream density ratios (DR) that range from 1.0 (close to low temperature experiments) to 1.5 (intermediate DR) and 2.0 (close to engine conditions) were also examined. The results provide the gas turbine engine designers a better insight into improved film cooling hole configurations as well as various parametric effects on endwall film cooling when the inlet (swirl) purge flow and slashface leakage flow were incorporated.

Numerical modeling of innovative film cooling hole schemes

2021 ◽  
Author(s):  
Siavash Khajehhasani
Keyword(s):  
Flat Plate ◽  
Turbine Blade ◽  
Film Cooling ◽  
Leading Edge ◽  
Lateral Spread ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Mainstream Flow ◽  
Hole Geometry

A numerical investigation of the film cooling performance on novel film hole schemes is presented using Reynolds-Averaged Navier-Stokes analysis. The investigation considers low and high blowing ratios for both flat plate film cooling and the leading edge of a turbine blade. A novel film hole geometry using a circular exit shaped hole is proposed, and the influence of an existing sister holes’ technique is investigated. The results indicate that high film cooling effectiveness is achieved at higher blowing ratios, results of which are even greater when in the presence of discrete sister holes where film cooling effectiveness results reach a plateau. Furthermore, a decrease in the strength of the counter-rotating vortex pairs is evident, which results in more attached coolant to the plate’s surface and a reduction in aerodynamic losses. Modifications are made to the spanwise and streamwise locations of the sister holes around the conventional cylindrical hole geometry. It is found that the spanwise variations have a significant influence on the film cooling effectiveness results, while only minor effects are observed for the streamwise variations. Positioning the sister holes in locations farther from the centerline increases the lateral spreading of the coolant air over the plate’s surface. This result is further verified through the flow structure analysis. Combinations of sister holes are joined with the primary injection hole to produce innovative variant sister shaped single-holes. The jet lift-off is significantly decreased for the downstream and up/downstream configurations of the proposed scheme for the flat plate film cooling. These schemes have shown notable film cooling improvements whereby more lateral distribution of coolant is obtained and less penetration of coolant into the mainstream flow is observed. The performance of the sister shaped single-holes are evaluated at the leading edge of a turbine blade. At the higher blowing ratios, a noticeable improvement in film cooling performance including the effectiveness and the lateral spread of the cooling air jet has been observed for the upstream and up/downstream schemes, in particular on the suction side. It is determined that the mixing of the coolant with the high mainstream flow at the leading edge of the blade is considerably decreased for the upstream and up/downstream configurations and more adhered coolant to the blade’s surface is achieved.

Effect of Upstream Wake on Passage Flow and Tip Film Cooling Characteristics

2012 ◽  
Author(s):  
Jin Wang ◽  
Bengt Sundén ◽  
Min Zeng ◽  
Qiu-Wang Wang
Keyword(s):  
Film Cooling ◽  
Three Dimensional ◽  
Flow Distribution ◽  
Tip Leakage Flow ◽  
Delta Wings ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Passage Vortex ◽  
Film Cooling Holes

Three-dimensional simulations of the squealer tip on the GE-E3 blade with eight film cooling holes were carried out. To form the wake by the trailing edges of the stator vanes, cylindrical rods and delta wings were placed upstream of the blades. The rods were placed according to three positions, and the influence on the film cooling effectiveness was calculated. Because delta wings were placed upstream of the blades to generate in the vane passage, the passage flow also was investigated. However, the passage vortex generated by the delta wings had a profound effect on the passage flow distribution. For the squealer tip, the cavity contributes to the improvement of the cooling effect in the tip zone. The passage flow and the tip leakage flow influenced by cylindrical rods and delta wings were analyzed using numerical simulations with the blowing ratio of M = 0.5. In addition, calculations with and without cylindrical rods and delta wings were performed and then comparisons were enabled. It was found that the vortex created by delta wings made the passage flow more turbulent and the result indicates a slight effect on the film cooling effectiveness in the tip gap.

Turbine Blade Platform Film Cooling With Fan-Shaped Holes Under Simulated Swirl Purge Flow and Slashface Leakage Conditions

2017 ◽  
Author(s):  
Andrew F. Chen ◽  
Chao-Cheng Shiau ◽  
Je-Chin Han
Keyword(s):  
Turbine Blade ◽  
Film Cooling ◽  
Leakage Flow ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Flow Swirl ◽  
Wide Range ◽  
Parametric Effects ◽  
Purge Flow ◽  
Cylindrical Holes

The combined effects of upstream purge flow, slashface leakage flow, and discrete hole film cooling on turbine blade platform film cooling effectiveness were studied using the pressure sensitive paint (PSP) technique. Detailed adiabatic film cooling effectiveness distributions on the platform were obtained and analyzed. As a continued study, discrete cylindrical holes [1] were replaced by laidback fan-shaped (10-10-5) holes which generally provide better film coverages on the endwall. Experiments were done in a five-blade linear cascade with an average turbulence intensity of 10.5%. The inlet and exit Mach numbers were 0.26 and 0.43, respectively. The inlet and exit mainstream Reynolds numbers based on the axial chord length of the blade were 475,000 and 720,000, respectively. A wide range of parameters were evaluated in this study. The coolant-to-mainstream mass flow ratio (MFR) was varied from 0.5%, 0.75%, to 1% for the upstream purge flow. For the platform film cooling holes and slashface gap, average blowing ratios (M) of 0.5, 1.0, and 1.5 were examined. Coolant-to-mainstream density ratios (DR) that range from 1 (close to low-temperature experiments) to 1.5 (intermediate DR) and 2 (close to engine conditions) were also examined. Purge flow swirl effect was studied particularly at a typical swirl ratio of 0.6. The results provide the gas turbine engine community a better insight into various parametric effects on turbine blade platform film cooling with fan-shaped holes when the upstream swirl purge flow and slashface leakage flow were presented. Area-averaged film cooling effectiveness results were compared between cylindrical and fan-shaped holes under various parametric conditions. The results indicate that the fan-shaped holes provide superior film coverage than cylindrical holes for platform film cooling especially at higher blowing ratios and momentum flux ratios.

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