Simulations of Multiphase Particle Deposition on a Nonaxisymmetric Contoured Endwall With Film-Cooling

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Seth A. Lawson ◽  
Stephen P. Lynch ◽  
Karen A. Thole
Keyword(s):  
Film Cooling ◽  
Particle Deposition ◽  
Aerodynamic Performance ◽  
Secondary Flows ◽  
Dramatic Reduction ◽  
Turbine Cascade ◽  
Cooling Effectiveness ◽  
Endwall Contouring ◽  
Film Cooling Holes ◽  
Critical Challenge

Designing turbine components for maximum aerodynamic performance with adequate cooling is a critical challenge for gas turbine engineers, particularly at the endwall of a turbine, due to complex secondary flows. To complicate matters, impurities from the fuel and intake air can deposit on film-cooled components downstream of the combustor. Deposition-induced roughness can reduce cooling effectiveness and aerodynamic performance dramatically. One method commonly used for reducing the effects of secondary flows on aerodynamic performance is endwall contouring. The current study evaluates deposition effects on endwall contouring given the change to the secondary flow pattern. For the current study, deposition was dynamically simulated in a turbine cascade to determine its effects on film-cooling with and without endwall contouring. Computationally predicted impactions were in qualitative agreement with experimental deposition simulations, showing that contouring reduced deposition around strategically placed film-cooling holes. Deposition reduced cooling effectiveness by 50% on a flat endwall and 40% on an identically cooled contoured endwall. Although 40% is still a dramatic reduction in effectiveness, the method of using the endwall contouring to alter deposition effects shows promise.

Simulations of Multi-Phase Particle Deposition on a Non-Axisymmetric Contoured Endwall With Film-Cooling

2012 ◽  
Author(s):  
Seth A. Lawson ◽  
Stephen P. Lynch ◽  
Karen A. Thole
Keyword(s):  
Film Cooling ◽  
Particle Deposition ◽  
Phase Particle ◽  
Aerodynamic Performance ◽  
Secondary Flows ◽  
Turbine Cascade ◽  
Cooling Effectiveness ◽  
Endwall Contouring ◽  
Multi Phase ◽  
Film Cooling Holes

Designing turbine components for maximum aerodynamic performance with adequate cooling is a critical challenge for gas turbine engineers, particularly at the endwall of a turbine due to complex secondary flows. To complicate matters, impurities from the fuel and intake air can deposit on film-cooled components downstream of the combustor. Deposition induced roughness can reduce cooling effectiveness and aerodynamic performance dramatically. One method commonly used for reducing the effects of secondary flows on aerodynamic performance is endwall contouring. The current study evaluates deposition effects on endwall contouring given the change to the secondary flow pattern. For the current study, deposition was dynamically simulated in a turbine cascade to determine its effects on film-cooling with and without endwall contouring. Computationally predicted impactions were in qualitative agreement with experimental deposition simulations showing that contouring reduced deposition around strategically placed film-cooling holes. Deposition reduced cooling effectiveness by 50% on a flat endwall and 40% on an identically cooled contoured endwall. Although 40% is still a dramatic reduction in effectiveness, the method of using the endwall contouring to alter deposition effects shows promise.

scholarly journals Experimental Investigation of Disc Cavity Leakage Flow and Hub Endwall Contouring in a Linear Rotor Cascade

2011 ◽  
Author(s):  
Ryan D. Erickson ◽  
Terrence W. Simon ◽  
Luzeng Zhang ◽  
Hee-Koo Moon
Keyword(s):  
Thermal Performance ◽  
Film Cooling ◽  
Leading Edge ◽  
Turbine Rotor ◽  
Secondary Flows ◽  
Temperature Fields ◽  
Leakage Flow ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Endwall Contouring

An experimental study is carried out in a stationary linear cascade which simulates a turbine rotor to compare the thermal performance of two new axisymmetric endwall contour geometries. Measurements of endwall adiabatic film cooling effectiveness and near-endwall passage temperature fields are made for this purpose. In addition to documenting endwall contouring effects, a range of disc cavity leakage flow rates is investigated. This information is meant to quantify, over the range tested, the benefits and penalties of introducing leakage flow into the passage using the designated endwall contouring. Special attention is paid to determine whether the endwall curvature has any effect on the interaction between mainstream and secondary flows within the passage. Results indicate improved thermal performance when strong endwall curvature exists near the blade leading edge. The strong curvature causes cavity leakage flow to remain closer to the endwall, thereby increasing cooling effectiveness.

Effects of Endwall 3D Contouring on Film Cooling Effectiveness of Cylindrical Hole Injections at Different Locations on Vane Endwall

2018 ◽  
Author(s):  
Pingting Chen ◽  
Hongyu Gao ◽  
Xueying Li ◽  
Jing Ren ◽  
Hongde Jiang
Keyword(s):  
Secondary Flow ◽  
Film Cooling ◽  
Guide Vane ◽  
Density Ratio ◽  
Secondary Flows ◽  
Cylindrical Hole ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Endwall Contouring

With the development of gas turbine, the secondary flow loss in vane passage is getting higher. To reduce the strength of secondary flows within vane passage, endwall 3D contouring is an effective design. Endwall 3D contouring can lead to significant changes in the secondary flow vortices, which lead to changes on jet-to-secondary flow interaction and then changes on the film cooling effectiveness. Meanwhile, the geometry configuration of the contoured endwall, such as the rising and falling on the endwall, can also have an impact on film cooling performance. As a result, the film cooling performance on contoured endwall differs from that on flat endwall. Understanding the difference in film cooling characteristics on the contoured endwall and flat endwall may help to make better endwall contouring design and better endwall film cooling arrangement. The present experiment compares the film cooling effectiveness of cylindrical hole injections at different locations on 3D contoured endwall versus flat endwall in an NGV (nozzle guide vane) passage. The measurement is performed in a low speed wind tunnel with a F-class annular sector NGV cascade. The cylindrical hole injections are located as 4 different rows at −30% axial chord, 30% axial chord, 50% axial chord and 70% axial chord. Endwall pressure distribution is measured with pressure taps by pressure sensor while film cooling effectiveness is measured using PSP (Pressure Sensitive Paint). Two density ratios with 1.0 and 1.5 and several average blowing ratios are investigated. Effects of endwall contouring, density ratio and blowing ratio on film cooling effectiveness are obtained and the results are presented and explained in this investigation.

Simulations of Multi-Phase Particle Deposition on Endwall Film-Cooling Holes in Transverse Trenches

2011 ◽  
Author(s):  
Seth A. Lawson ◽  
Karen A. Thole
Keyword(s):  
Film Cooling ◽  
Particle Deposition ◽  
Power Plants ◽  
Large Scale ◽  
Phase Particle ◽  
Flux Ratio ◽  
Combined Cycle ◽  
Cooling Effectiveness ◽  
Endwall Film Cooling ◽  
Film Cooling Holes

Integrated gasification combined cycle (IGCC) power plants allow for increased efficiency and reduced emissions as compared to pulverized coal plants. A concern with IGCCs is that impurities in the fuel from the gasification of coal can deposit on turbine components reducing the performance of sophisticated film-cooling geometries. Studies have shown that recessing a row of film-cooling holes in a transverse trench can improve cooling performance; however, the question remains as to whether or not these improvements exist in severe environments such as when particle deposition occurs. Dynamic simulations of deposition were completed using wax injection in a large-scale vane cascade with endwall film-cooling. Endwall cooling effectiveness was quantified in two specific endwall locations using trenches with depths of 0.4D, 0.8D, and 1.2D, where D is the diameter of a film-cooling hole. The effects of trench depth, momentum flux ratio, and particle phase on adiabatic effectiveness were quantified using infrared thermography. Results showed that the 0.8D trench outperformed other geometries with and without deposition on the surface. Deposition of particles reduced the cooling effectiveness by as much as 15% at I = 0.23 with the trenched holes as compared to 30% for holes that were not placed in a transverse trench.

Simulations of Multiphase Particle Deposition on Endwall Film-Cooling Holes in Transverse Trenches

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Seth A. Lawson ◽  
Karen A. Thole
Keyword(s):  
Film Cooling ◽  
Particle Deposition ◽  
Power Plants ◽  
Large Scale ◽  
Flux Ratio ◽  
Combined Cycle ◽  
Dynamic Simulations ◽  
Cooling Effectiveness ◽  
Endwall Film Cooling ◽  
Film Cooling Holes

Integrated gasification combined cycle (IGCC) power plants allow for increased efficiency and reduced emissions as compared to pulverized coal plants. A concern with IGCCs is that impurities in the fuel from the gasification of coal can deposit on turbine components reducing the performance of sophisticated film-cooling geometries. Studies have shown that recessing a row of film-cooling holes in a transverse trench can improve cooling performance; however, the question remains as to whether or not these improvements exist in severe environments such as when particle deposition occurs. Dynamic simulations of deposition were completed using wax injection in a large-scale vane cascade with endwall film cooling. Endwall cooling effectiveness was quantified in two specific endwall locations using trenches with depths of 0.4D, 0.8D, and 1.2D, where D is the diameter of a film-cooling hole. The effects of trench depth, momentum flux ratio, and particle phase on adiabatic effectiveness were quantified using infrared thermography. Results showed that the 0.8D trench outperformed other geometries with and without deposition on the surface. Deposition of particles reduced the cooling effectiveness by as much as 15% at I = 0.23 with the trenched holes as compared to 30% for holes that were not placed in a transverse trench.

Assessment of a Double Hole Film Cooling Geometry Using S-PIV and PSP

2013 ◽  
Author(s):  
Lesley M. Wright ◽  
Stephen T. McClain ◽  
Charles P. Brown ◽  
Weston V. Harmon
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Three Dimensional ◽  
Field Measurements ◽  
Secondary Flows ◽  
Cylindrical Hole ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Hole Geometry ◽  
Compound Angle

A novel, double hole film cooling configuration is investigated as an alternative to traditional cylindrical and fanshaped, laidback holes. This experimental investigation utilizes a Stereo-Particle Image Velocimetry (S-PIV) to quantitatively assess the ability of the proposed, double hole geometry to weaken or mitigate the counter-rotating vortices formed within the jet structure. The three-dimensional flow field measurements are combined with surface film cooling effectiveness measurements obtained using Pressure Sensitive Paint (PSP). The double hole geometry consists of two compound angle holes. The inclination of each hole is θ = 35°, and the compound angle of the holes is β = ± 45° (with the holes angled toward one another). The simple angle cylindrical and shaped holes both have an inclination angle of θ = 35°. The blowing ratio is varied from M = 0.5 to 1.5 for all three film cooling geometries while the density ratio is maintained at DR = 1.0. Time averaged velocity distributions are obtained for both the mainstream and coolant flows at five streamwise planes across the fluid domain (x/d = −4, 0, 1, 5, and 10). These transverse velocity distributions are combined with the detailed film cooling effectiveness distributions on the surface to evaluate the proposed double hole configuration (compared to the traditional hole designs). The fanshaped, laidback geometry effectively reduces the strength of the kidney-shaped vortices within the structure of the jet (over the entire range of blowing ratios considered). The three-dimensional velocity field measurements indicate the secondary flows formed from the double hole geometry strengthen in the plane perpendicular to the mainstream flow. At the exit of the double hole geometry, the streamwise momentum of the jets is reduced (compared to the single, cylindrical hole), and the geometry offers improved film cooling coverage. However, moving downstream in the steamwise direction, the two jets form a single jet, and the counter-rotating vortices are comparable to those formed within the jet from a single, cylindrical hole. These strong secondary flows lift the coolant off the surface, and the film cooling coverage offered by the double hole geometry is reduced.

Turbine Nozzle Endwall Phantom Cooling With Compound Angled Pressure Side Injection

2018 ◽  
Author(s):  
Kevin Liu ◽  
Hongzhou Xu ◽  
Michael Fox
Keyword(s):  
Film Cooling ◽  
High Speed ◽  
Axial Direction ◽  
Secondary Flows ◽  
Test Case ◽  
Pressure Side ◽  
Complex Flow ◽  
Trailing Edge ◽  
Cooling Effectiveness ◽  
Extended Area

Cooling of the turbine nozzle endwall is challenging due to its complex flow field involving strong secondary flows. Increasingly-effective cooling schemes are required to meet the higher turbine inlet temperatures required by today’s gas turbine applications. Therefore, in order to cool the endwall surface near the pressure side of the airfoil and the trailing edge extended area, the spent cooling air from the airfoil film cooling and pressure side discharge slots, referred to as “phantom cooling” is utilized. This paper studies the effect of compound angled pressure side injection on nozzle endwall surface. The measurements were conducted in a high speed linear cascade, which consists of three nozzle vanes and four flow passages. Two nozzle test models with a similar film cooling design were investigated, one with an axial pressure side film cooling row and trailing edge slots; the other with the same cooling features but with compound angled injection, aiming at the test endwall. Phantom cooling effectiveness on the endwall was measured using a Pressure Sensitive Paint (PSP) technique through the mass transfer analogy. Two-dimensional phantom cooling effectiveness distributions on the endwall surface are presented for four MFR (Mass Flow Ratio) values in each test case. Then the phantom cooling effectiveness distributions are pitchwise-averaged along the axial direction and comparisons were made to show the effect of the compound angled injection. The results indicated that the endwall phantom cooling effectiveness increases with the MFR significantly. A compound angle of the pressure side slots also enhanced the endwall phantom cooling significantly. For combined injections, the phantom cooling effectiveness is much higher than the pressure side slots injection only in the endwall downstream extended area.

Rib Turbulator Effects on Crossflow-Fed Shaped Film Cooling Holes

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Dale W. Fox ◽  
Fraser B. Jones ◽  
John W. McClintic ◽  
David G. Bogard ◽  
Thomas E. Dyson ◽  
...  
Keyword(s):  
Film Cooling ◽  
Velocity Ratio ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Smooth Channel ◽  
Cooling Hole ◽  
Film Cooling Holes ◽  
Inlet Position ◽  
The Impact

Most studies of turbine airfoil film cooling in laboratory test facilities have used relatively large plenums to feed flow into the coolant holes. However, a more realistic inlet condition for the film cooling holes is a relatively small channel. Previous studies have shown that the film cooling performance is significantly degraded when fed by perpendicular internal crossflow in a smooth channel. In this study, angled rib turbulators were installed in two geometric configurations inside the internal crossflow channel, at 45 deg and 135 deg, to assess the impact on film cooling effectiveness. Film cooling hole inlets were positioned in both prerib and postrib locations to test the effect of hole inlet position on film cooling performance. A test was performed independently varying channel velocity ratio and jet to mainstream velocity ratio. These results were compared to the film cooling performance of previously measured shaped holes fed by a smooth internal channel. The film cooling hole discharge coefficients and channel friction factors were also measured for both rib configurations with varying channel and inlet velocity ratios. Spatially averaged film cooling effectiveness is largely similar to the holes fed by the smooth internal crossflow channel, but hole-to-hole variation due to inlet position was observed.

Effect of Internal Crossflow Velocity on Film Cooling Effectiveness: Part II — Compound Angle Shaped Holes

2017 ◽  
Author(s):  
John W. McClintic ◽  
Joshua B. Anderson ◽  
David G. Bogard ◽  
Thomas E. Dyson ◽  
Zachary D. Webster
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Film Cooling ◽  
Velocity Ratio ◽  
Injection Rate ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Crossflow Velocity ◽  
Film Cooling Holes ◽  
Compound Angle

In gas turbine engines, film cooling holes are commonly fed with an internal crossflow, the magnitude of which has been shown to have a notable effect on film cooling effectiveness. In Part I of this study, as well as in a few previous studies, the magnitude of internal crossflow velocity was shown to have a substantial effect on film cooling effectiveness of axial shaped holes. There is, however, almost no data available in the literature that shows how internal crossflow affects compound angle shaped film cooling holes. In Part II, film cooling effectiveness, heat transfer coefficient augmentation, and discharge coefficients were measured for a single row of compound angle shaped film cooling holes fed by internal crossflow flowing both in-line and counter to the span-wise direction of coolant injection. The crossflow-to-mainstream velocity ratio was varied from 0.2–0.6 and the injection velocity ratio was varied from 0.2–1.7. It was found that increasing the magnitude of the crossflow velocity generally caused degradation of the film cooling effectiveness, especially for in-line crossflow. An analysis of jet characteristic parameters demonstrated the importance of crossflow effects relative to the effect of varying the film cooling injection rate. Heat transfer coefficient augmentation was found to be primarily dependent on injection rate, although for in-line crossflow, increasing crossflow velocity significantly increased augmentation for certain conditions.

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.

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