Turbine Nozzle Endwall Film Cooling Study Using Pressure-Sensitive Paint

2001 ◽  
Vol 123 (4) ◽  
pp. 730-738 ◽  
Author(s):  
Luzeng J. Zhang ◽  
Ruchira Sharma Jaiswal
Keyword(s):  
Flow Field ◽  
Mass Flow ◽  
Film Cooling ◽  
Free Stream ◽  
Surface Film ◽  
Secondary Flows ◽  
Pressure Sensitive Paint ◽  
Pressure Sensitive ◽  
Wall Flow ◽  
Near Wall

Endwall surface film cooling effectiveness was measured on a turbine vane endwall surface using the pressure-sensitive paint (PSP) technique. A double staggered row of holes and a single row of discrete slots were used to supply film cooling in front of the nozzle cascade leading edges. Nitrogen gas was used to simulate film cooling flow as well as a tracer gas to indicate oxygen concentration such that film effectiveness by the mass transfer analogy could be obtained. Cooling mass flow was controlled to be 0.5 to 3.0 percent of the mainstream mass flow. The free-stream Reynolds number was about 283,000 and Mach number was about 0.11. The free-stream turbulence intensity was kept at 6.0 percent for all the tests, measured by a thermal anemometer. The PSP was calibrated at various temperatures and pressures to obtain better accuracy before being applied to the endwall surface. Film effectiveness distributions were measured on a flat endwall surface for five different mass flow rates. The film effectiveness increased nonlinearly with mass flow rate, indicating a strong interference between the cooling jets and the endwall secondary flows. At lower mass flow ratios, the secondary flow dominated the near wall flow field, resulting in a low film effectiveness. At higher mass flow ratios, the cooling jet momentum dominated the near wall flow field, resulting in a higher film effectiveness. The comparison between hole injection and slot injection was also made.

Turbine Nozzle Endwall Film Cooling Study Using Pressure Sensitive Paint

2001 ◽  
Author(s):  
Luzeng J. Zhang ◽  
Ruchira Sharma Jaiswal
Keyword(s):  
Flow Field ◽  
Mass Flow ◽  
Film Cooling ◽  
Surface Film ◽  
Secondary Flows ◽  
Hole Injection ◽  
Pressure Sensitive Paint ◽  
Pressure Sensitive ◽  
Wall Flow ◽  
Near Wall

Endwall surface film cooling effectiveness was measured on a turbine vane endwall surface using the pressure sensitive paint (PSP) technique. A double staggered row of holes and a single row of discrete slots were used to supply film cooling in front of the nozzle cascade leading edges. Nitrogen gas was used to simulate film cooling flow as well as a tracer gas to indicate oxygen concentration such that film effectiveness by the mass transfer analogy could be obtained. Cooling mass flow was controlled to be 0.5 to 3.0% of the mainstream mass flow. The freestream Reynolds number was about 283000 and Mach number was about 0.11. The freestream turbulence intensity was kept at 6.0% for all the tests, measured by a thermal anemometer. The PSP was calibrated at various temperatures and pressures to obtain better accuracy before being applied to the endwall surface. Film effectiveness distributions were measured on a flat endwall surface for five different mass flow rates. The film effectiveness increased nonlinearly with mass flow rate, indicating a strong interference between the cooling jets and the endwall secondary flows. At lower mass flow ratios, the secondary flow dominated the near wall flow field, resulting in a low film effectiveness. At higher mass flow ratios, the cooling jet momentum dominated the near wall flow field, resulting in a higher film effectiveness. The comparison between hole injection and slot injection was also made.

Turbine Nozzle Endwall Inlet Film Cooling: The Effect of a Back-Facing Step

2003 ◽  
Author(s):  
Luzeng Zhang ◽  
Hee Koo Moon
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Mass Flow ◽  
Film Cooling ◽  
Secondary Flows ◽  
Film Cooling Effectiveness ◽  
Cooling Flow ◽  
Wall Flow ◽  
Cooling Air ◽  
Near Wall

Film cooling effectiveness was measured on a contoured endwall surface using the pressure sensitive paint (PSP) technique. A double staggered row of holes was adopted to supply cooling air in front of the nozzle leading edges. To simulate realistic engine configuration, a back-facing step was built, which was located upstream from the film injection. Nitrogen gas was used to simulate film cooling flow as a tracer gas to indicate oxygen concentration such that film effectiveness by the mass transfer analogy could be obtained. Cooling mass flow was controlled to be from 0.5% to 3.0% of the mainstream mass flow. Film effectiveness distributions were measured on the endwall surface for both smooth (baseline) and back-facing step inlet configurations. For the smooth inlet case, film effectiveness increased nonlinearly with mass flow rate, indicating a strong interference between the cooling jets and the secondary flows. At lower mass flow ratios, the secondary flow dominated the near wall flow field, resulting in a low film effectiveness value. At higher mass flow ratios, the cooling jet momentum dominated the near wall flow field, resulting in a higher film effectiveness. For the back-facing step inlet configuration, the values of film effectiveness were reduced significantly, suggesting a stronger secondary flow interaction. In addition to the comparison between the smooth and back-facing step inlet configurations, comparison to previous data by the authors on a flat endwall was also made.

Single and Multiple Row Endwall Film-Cooling of a Highly Loaded First Turbine Vane With Variation of Loading

2013 ◽  
Vol 136 (6) ◽  
Author(s):  
Martin Kunze ◽  
Konrad Vogeler ◽  
Michael Crawford ◽  
Glenn Brown
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Film Cooling ◽  
Wall Material ◽  
Measured Temperature ◽  
Single Row ◽  
Wall Flow ◽  
Endwall Film Cooling ◽  
Highly Loaded ◽  
Near Wall

This paper reports endwall film-cooling investigations with single and multiple rows of fan-shaped film holes using temperature-sensitive paint (TSP). The experiments are carried out in a six-bladed linear cascade based on the geometry of a highly loaded gas turbine first vane. The film effectiveness performance of the cooling rows is investigated under the influence of enhanced near-wall secondary flow. Tests are conducted at three different loading conditions changing the profile incidence. Film-cooling injection is established at elevated coolant density ratios of 1.4 using heated carbon dioxide. Due to the finite thermal conductivity of the wall material, the heat conduction effects observed in the measured temperature fields are assessed by a newly developed data analysis based on a finite element thermal analysis and tracking algorithms along CFD-computed near-wall surface streamlines. The results showed that the coolant trajectories are visibly influenced revealing the intense interaction between the film jets and the near-wall flow field. These effects are certainly enhanced with higher incidence leading to increased streamwise coolant consumption and reduced wall coverage. At the cascade inlet, the film-cooling injection is significantly affected by the near-wall flow field showing distinct over- and undercooled regions. Due to the enhanced deflection and mixing of the film jets injected from a single row, area-averaged film effectiveness and wall coverage decreases about 9 and 11%, respectively. With adding more cooling holes to this endwall area, the influence of the enhanced secondary flow becomes more pronounced. Hence, larger reduction in film effectiveness of 23% and wall coverage with 28% is observed. For single row injection at the airfoil pressure side, the stronger secondary flow motion with intensified streamwise mixing leads to a visibly decreased endwall coverage ratio of about 38% and maximum flow path reduction of about 41%. In this case, film effectiveness is found to be reduced up to 47% due to the small amount of coolant injected through this row. This effect is significantly smaller when more cooling rows are added showing an almost constant cooling performance for all incidence cases.

Film-Cooling Effectiveness on a Rotating Blade Platform

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
A. Suryanarayanan ◽  
S. P. Mhetras ◽  
M. T. Schobeiri ◽  
J. C. Han
Keyword(s):  
Mass Flow ◽  
Film Cooling ◽  
Rotor Blade ◽  
Turbine Rotor ◽  
Pressure Sensitive Paint ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Pressure Sensitive ◽  
Rotating Blade ◽  
Mainstream Flow

Film cooling effectiveness measurements under rotation were performed on the rotor blade platform using a pressure sensitive paint (PSP) technique. The present study examines, in particular, the film cooling effectiveness due to purging of coolant from the wheel-space cavity through the circumferential clearance gap provided between the stationary and rotating components of the turbine. The experimental investigation is carried out in a new three-stage turbine facility, recently designed and taken into operation at the Turbomachinery Performance and Flow Research Laboratory (TPFL) of Texas A&M University. This new turbine rotor has been used to facilitate coolant injection through this stator-rotor gap upstream of the first stage rotor blade. The gap was inclined at 25deg to mainstream flow to allow the injected coolant to form a film along the passage platform. The effects of turbine rotating conditions on the blade platform film cooling effectiveness were investigated at three speeds of 2550rpm, 2000rpm, and 1500rpm with corresponding incidence angles of 23.2deg, 43.4deg, and 54.8deg, respectively. Four different coolant-to-mainstream mass flow ratios varying from 0.5% to 2.0% were tested at each rotational speed. Aerodynamic measurements were performed at the first stage stator exit using a radially traversed five-hole probe to quantify the mainstream flow at this station. Results indicate that film cooling effectiveness increases with an increase in the coolant-to-mainstream mass flow ratios for all turbine speeds. Higher turbine rotation speeds show more local film cooling effectiveness spread on the platform with increasing magnitudes.

Film-Cooling Effectiveness on a Rotating Blade Platform

2006 ◽  
Author(s):  
A. Suryanarayanan ◽  
S. P. Mhetras ◽  
M. T. Schobeiri ◽  
J. C. Han
Keyword(s):  
Mass Flow ◽  
Film Cooling ◽  
Rotor Blade ◽  
Turbine Rotor ◽  
Pressure Sensitive Paint ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Pressure Sensitive ◽  
Rotating Blade ◽  
Mainstream Flow

Film cooling effectiveness measurements under rotation were performed on the rotor blade platform using a pressure sensitive paint (PSP) technique. The present study examines, in particular, the film cooling effectiveness due to purging of coolant from the wheel-space cavity through the circumferential clearance gap provided between the stationary and rotating components of the turbine. The experimental investigation is carried out in a new three-stage turbine facility, recently designed and taken into operation at the Turbomachinery Performance and Flow Research Laboratory (TPFL) of Texas A&M University. This new turbine rotor has been used to facilitate coolant injection through this stator-rotor gap upstream of the 1st stage rotor blade. The gap was inclined at 25° to mainstream flow to allow the injected coolant to form a film along the passage platform. The effects of turbine rotating conditions on the blade platform film cooling effectiveness were investigated at three speeds of 2550 rpm, 2000 rpm and 1500 rpm with corresponding incidence angles of 23.2°, 43.4° and 54.8° respectively. Four different coolant-to-mainstream mass flow ratios varying from 0.5% to 2.0% were tested at each rotational speed. Aerodynamic measurements were performed at the 1st stage stator exit using a radially traversed five-hole probe to quantify the mainstream flow at this station. Results indicate that film cooling effectiveness increases with an increase in the coolant-to-mainstream mass flow ratios for all turbine speeds. Higher turbine rotation speeds show more local film cooling effectiveness spread on the platform with increasing magnitudes.

Turbine Nozzle Endwall Inlet Film Cooling: The Effect of a Back-Facing Step and Velocity Ratio

2004 ◽  
Author(s):  
Luzeng Zhang ◽  
Hee Koo Moon
Keyword(s):  
Mass Flow ◽  
Film Cooling ◽  
Velocity Ratio ◽  
Secondary Flows ◽  
Tracer Gas ◽  
Nitrogen Gas ◽  
Cooling Flow ◽  
Pressure Sensitive ◽  
Jet Velocity ◽  
Cooling Air

Endwall inlet film cooling serves two purposes: to suppress the secondary flows and to provide effective cooling. To optimize endwall inlet film cooling, the combined effects of a back facing step and jet velocity ratio were studied in a warm cascade simulating realistic engine conditions. Film effectiveness distribution was measured on a nozzle endwall surface using the pressure sensitive paint (PSP) technique. A double staggered row of holes was used to supply cooling air in front of the nozzle leading edges. Changing the diameter of the film injection hole varied the velocity ratio and the back-facing step was designed to simulate the discontinuity of the nozzle inlet to the combustor exit cone. Nitrogen gas was used to simulate cooling flow as well as a tracer gas to indicate oxygen concentration such that film effectiveness by the mass transfer analogy could be obtained. Cooling mass flow was controlled to be from 0.5% to 3.0% of the mainstream mass flow. The film effectiveness distribution was locally measured for each of the cooling mass flows. It was demonstrated that by optimizing the jet velocity ratio the adverse effect of the back-facing step could be reduced, particularly for the range of mass flow practical in design. The pattern of the film effectiveness distribution suggested the opposite effect of the film injection and the back-facing step on the secondary flows, while one suppresses and the other enhances it.

scholarly journals Turbine Nozzle Film Cooling Study Using the Pressure Sensitive Paint (PSP) Technique

1999 ◽  
Author(s):  
Luzeng Zhang ◽  
Michael Baltz ◽  
Ram Pudupatty ◽  
Michael Fox
Keyword(s):  
Reynolds Number ◽  
Mach Number ◽  
Film Cooling ◽  
High Speed ◽  
Surface Film ◽  
Pressure Sensitive Paint ◽  
Suction Surface ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Pressure Sensitive

The use of pressure sensitive paint (PSP) to measure film cooling effectiveness on a turbine nozzle surface was demonstrated in a high speed wind tunnel. Film cooling effectiveness was measured from a single row of holes located on a turbine vane suction surface with a shaped exit. Nitrogen gas was used to simulate film cooling flow as well as a tracer gas to indicate oxygen concentration such that film effectiveness by the mass transfer analogy could be obtained. Three blowing ratios were studied for each of the five freestream conditions: a reference condition, a reduced and an increased Reynolds number condition, and a reduced and an increased Mach number condition. The freestream turbulence intensity was kept at 12.0% for all the tests. The PSP was calibrated at various temperatures and pressures to obtain better accuracy before being applied to the airfoil surface. The film effectiveness increased with blowing ratio for all the freestream conditions. The effects of secondary flow and freestream Mach number and Reynolds number on turbine nozzle suction surface film cooling are also discussed.

Algebraic Anisotropic Turbulence Modeling of Compound Angled Film Cooling Validated by Particle Image Velocimetry and Pressure Sensitive Paint Measurements

2013 ◽  
Vol 136 (3) ◽  
Author(s):  
Xueying Li ◽  
Yanmin Qin ◽  
Jing Ren ◽  
Hongde Jiang
Keyword(s):  
Particle Image Velocimetry ◽  
Flow Field ◽  
Film Cooling ◽  
Eddy Viscosity ◽  
Particle Image ◽  
Pressure Sensitive Paint ◽  
Anisotropic Model ◽  
Scalar Flux ◽  
Pressure Sensitive ◽  
Image Velocimetry

The complex structures in the film cooling flow field of gas turbines lead to the anisotropic property of the turbulent eddy viscosity and scalar diffusivity. An algebraic anisotropic turbulence model is developed aiming at a more accurate modeling of the Reynolds stress and turbulent scalar flux. In this study, the algebraic anisotropic model is validated by a series of in-house experiments for cylindrical film cooling with compound angle injection of 0, 45, and 90 deg. Adiabatic film cooling effectiveness and flow field are measured using pressure sensitive paint and particle image velocimetry techniques on film cooling test rig in Tsinghua University. Detailed analyses of computational simulations are performed. The algebraic anisotropic model gives a good prediction of the secondary vortices associated with the jet and the trajectory of the jet, therefore improves the prediction of the scalar field. On one hand, the anisotropic eddy viscosity improves the modeling of Reynolds stress and the predictive flow field. On the other hand, the anisotropic turbulent scalar-flux model includes the role of anisotropic eddy viscosity in modeling of scalar flux and directly improves the turbulent scalar flux prediction.

Upstream Film Cooling on the Contoured Endwall of a Transonic Turbine Vane in an Annular Cascade

2020 ◽  
Author(s):  
Daniel A. Salinas ◽  
Izhar Ullah ◽  
Lesley M. Wright ◽  
Je-Chin Han ◽  
John W. McClintic ◽  
...  
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Lateral Spread ◽  
Pressure Sensitive Paint ◽  
Blow Down ◽  
Film Cooling Effectiveness ◽  
Pressure Sensitive ◽  
Mainstream Flow ◽  
Additional Protection ◽  
Annular Cascade

Abstract The effects of mainstream flow velocity, density ratio (DR), and coolant-to-mainstream mass flow ratio (MFR) were investigated on a vane endwall in a transonic, annular cascade. A blow down facility consisting of five vanes was used. The film cooling effectiveness was measured using binary pressure sensitive paint (BPSP). The mainstream flow was set using isentropic exit Mach numbers of 0.7 and 0.9. The coolant-to-mainstream density ratio varied from 1.0 to 2.0. The coolant to mainstream MFR varied from 0.75% to 1.25%. The endwall was cooled by eighteen discrete holes located upstream of the vane passage to provide cooling to the upstream half of the endwall. Due to the curvature of the vane endwall, the upstream holes provided uniform coverage entering the endwall passage. The coverage was effective leading to the throat of the passage, where the downstream holes could provide additional protection. Increasing the coolant flowrate increased the effectiveness provided by the film cooling holes. Increasing the density of the coolant increases the effectiveness on the endwall while enhancing the lateral spread of the coolant. Finally, increasing the velocity of the mainstream while holding the MFR constant also yields increased protection on the endwall. Over the range of flow conditions considered in this study, the binary pressure sensitive paint proved to be a valuable tool for obtaining detailed pressure and film effectiveness distributions.

Film Cooling Effectiveness on a Rotating Turbine Platform Using Pressure Sensitive Paint Technique

2007 ◽  
Author(s):  
A. Suryanarayanan ◽  
B. Ozturk ◽  
M. T. Schobeiri ◽  
J. C. Han
Keyword(s):  
Film Cooling ◽  
Gas Injection ◽  
Turbine Rotor ◽  
Pressure Sensitive Paint ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Pressure Sensitive ◽  
Coolant Injection ◽  
Purge Flow ◽  
Effects Of Rotation

Film cooling effectiveness is measured on a rotating turbine blade platform for coolant injection through discrete holes using pressure sensitive paint technique (PSP). Most of the existing literatures provide information only for stationary end-walls. The effects of rotation on the platform film cooling effectiveness are not well documented. Hence, the existing 3-stage turbine research facility at TPFL, Texas A&M University was re-designed and installed to enable coolant gas injection on the 1st stage rotor platform. Two distinct coolant supply loops were incorporated into the rotor to facilitate separate feeds for upstream cooling using stator-rotor gap purge flow and downstream discrete-hole film cooling. As a continuation of the previously published work involving stator-rotor gap purge cooling, this study investigates film cooling effectiveness on the 1st stage rotor platform due to coolant gas injection through nine discrete holes located downstream within the passage region. Film cooling effectiveness is measured for turbine rotor frequencies of 2400rpm, 2550rpm and 3000rpm corresponding to rotation numbers of Ro = 0.18, 0.19 and 0.23 respectively. For each of the turbine rotational frequencies, film cooling effectiveness is determined for average film-hole blowing ratios of Mholes = 0.5, 0.75, 1.0, 1.25, 1.5 and 2.0. To provide a complete picture of hub cooling under rotating conditions, simultaneous injection of coolant gas through upstream stator-rotor purge gap and downstream discrete film-hole is also studied. The combined tests are conducted for gap purge flow corresponding to coolant to mainstream mass flow ratio of MFR = 1% with three downstream film-hole blowing ratios of Mholes = 0.75, 1.0 and 1.25 for each of the three turbine speeds. The results for combined upstream stator-rotor gap purge flow and downstream discrete holes provide information about the optimum purge flow coolant mass, average coolant hole blowing ratios for each rotational speed and coolant injection location along the passage to obtain efficient platform film cooling.

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