Simulations of Multiphase Particle Deposition on Endwall Film-Cooling

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Seth A. Lawson ◽  
Karen A. Thole
Keyword(s):  
Particulate Matter ◽  
Film Cooling ◽  
Gas Turbines ◽  
Particle Deposition ◽  
Alternative Fuels ◽  
Large Scale ◽  
Clean Energy ◽  
Burning Coal ◽  
Endwall Film Cooling ◽  
Film Cooling Holes

Demand for clean energy has increased motivation to design gas turbines capable of burning alternative fuels such as coal derived synthesis gas (syngas). One challenge associated with burning coal derived syngas is that trace amounts of particulate matter in the fuel and air can deposit on turbine hardware reducing the effectiveness of film-cooling. For the current study, a method was developed to dynamically simulate multiphase particle deposition through injection of a low melting temperature wax. The method was developed so the effects of deposition on endwall film-cooling could be quantified using a large scale vane cascade in a low speed wind tunnel. A microcrystalline wax was injected into the mainstream flow using atomizing spray nozzles to simulate both solid and molten particulate matter in a turbine gas path. Infrared thermography was used to quantify cooling effectiveness with and without deposition at various locations on a film-cooled endwall. Measured results indicated reductions in adiabatic effectiveness by as much as 30% whereby the reduction was highly dependent on the location of the film-cooling holes relative to the vane.

Simulations of Multi-Phase Particle Deposition on Endwall Film-Cooling

2010 ◽  
Author(s):  
Seth A. Lawson ◽  
Karen A. Thole
Keyword(s):  
Particulate Matter ◽  
Film Cooling ◽  
Gas Turbines ◽  
Particle Deposition ◽  
Alternative Fuels ◽  
Large Scale ◽  
Phase Particle ◽  
Clean Energy ◽  
Multi Phase ◽  
Endwall Film Cooling

Demand for clean energy has increased motivation to design gas turbines capable of burning alternative fuels such as coal derived synthesis gas (syngas). One challenge associated with burning coal derived syngas is that trace amounts of particulate matter in the fuel and air can deposit on turbine hardware reducing the effectiveness of film cooling. For the current study, a method was developed to dynamically simulate multi-phase particle deposition through injection of a low melting temperature wax. The method was developed so the effects of deposition on endwall film cooling could be quantified using a large scale vane cascade in a low speed wind tunnel. A microcrystalline wax was injected into the mainstream flow using atomizing spray nozzles to simulate both solid and molten particulate matter in a turbine gas path. Infrared thermography was used to quantify cooling effectiveness with and without deposition at various locations on a film cooled endwall. Measured results indicated reductions in adiabatic effectiveness by as much as 30% whereby the reduction was highly dependent upon the location of the film-cooling holes relative to the vane.

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.

The Effects of Simulated Particle Deposition on Film Cooling

2009 ◽  
Author(s):  
S. A. Lawson ◽  
K. A. Thole
Keyword(s):  
Film Cooling ◽  
Momentum Flux ◽  
Particle Deposition ◽  
Power Plants ◽  
Alternative Fuels ◽  
Flux Ratio ◽  
Combined Cycle ◽  
Spatially Resolved ◽  
Film Cooling Holes ◽  
Low Speed Wind Tunnel

Diminishing natural gas resources has increased incentive to develop cleaner, more efficient combined cycle power plants capable of burning alternative fuels such as coal-derived synthesis gas (syngas). Although syngas is typically filtered, particulate matter still exists in the hot gas path that has proven to be detrimental to the life of turbine components. Solid and molten particles deposit on film cooled surfaces that can alter cooling dynamics and block cooling holes. To gain an understanding of the effects that particle deposits have on film cooling, a methodology was developed to simulate deposition in a low speed wind tunnel using a low melt wax, which can simulate solid and molten phases. A facility was constructed to simulate particle deposition on a flat plate with a row of film cooling holes. Infrared thermography was used to measure wall temperatures for quantifying spatially resolved adiabatic effectiveness values in the vicinity of the film cooling holes as deposition occurred. Results showed that deposition reduced cooling effectiveness by approximately 20% at momentum flux ratios of 0.23 and 0.5 and only 6% at a momentum flux ratio of 0.95.

Effects of Surface Deposition, Hole Blockage, and TBC Spallation on Vane Endwall Film-Cooling

2006 ◽  
Author(s):  
N. Sundaram ◽  
K. A. Thole
Keyword(s):  
Film Cooling ◽  
Gas Turbines ◽  
Large Scale ◽  
Leading Edge ◽  
Cooling Effectiveness ◽  
Blowing Ratio ◽  
Barrier Coating ◽  
Cooling Hole ◽  
Endwall Film Cooling ◽  
Alternate Fuels

With the increase in usage of gas turbines for power generation and given that natural gas resources continue to be depleted, it has become increasingly important to search for alternate fuels. One source of alternate fuels is coal derived synthetic fuels. Coal derived fuels, however, contain traces of ash and other contaminants that can deposit on vane and turbine surfaces affecting their heat transfer through reduced film-cooling. The endwall of a first stage vane is one such region that can be susceptible to depositions from these contaminants. This study uses a large-scale turbine vane cascade in which the following effects on film-cooling adiabatic effectiveness were investigated in the endwall region: the effect of near-hole deposition, the effect of partial film-cooling hole blockage, and the effect of spallation of a thermal barrier coating. The results indicated that deposits near the hole exit can sometimes improve the cooling effectiveness at the leading edge, but with increased deposition heights the cooling deteriorates. Partial hole blockage studies revealed that the cooling effectiveness deteriorates with increases in the number of blocked holes. Spallation studies showed that for a spalled endwall surface downstream of the leading edge cooling row, cooling effectiveness worsened with an increase in blowing ratio.

Effects of Simulated Particle Deposition on Film Cooling

2010 ◽  
Vol 133 (2) ◽  
Author(s):  
S. A. Lawson ◽  
K. A. Thole
Keyword(s):  
Film Cooling ◽  
Momentum Flux ◽  
Particle Deposition ◽  
Power Plants ◽  
Alternative Fuels ◽  
Flux Ratio ◽  
Combined Cycle ◽  
Spatially Resolved ◽  
Film Cooling Holes ◽  
Low Speed Wind Tunnel

Diminishing natural gas resources has increased incentive to develop cleaner, more efficient combined-cycle power plants capable of burning alternative fuels such as coal-derived synthesis gas (syngas). Although syngas is typically filtered, particulate matter still exists in the hot gas path that has proven to be detrimental to the life of turbine components. Solid and molten particles deposit on film-cooled surfaces that can alter cooling dynamics and block cooling holes. To gain an understanding of the effects that particle deposits have on film cooling, a methodology was developed to simulate deposition in a low speed wind tunnel using a low melt wax, which can simulate solid and molten phases. A facility was constructed to simulate particle deposition on a flat plate with a row of film cooling holes. Infrared thermography was used to measure wall temperatures for quantifying spatially resolved adiabatic effectiveness values in the vicinity of the film cooling holes as deposition occurred. Results showed that deposition reduced cooling effectiveness by approximately 20% at momentum flux ratios of 0.23 and 0.5 and only 6% at a momentum flux ratio of 0.95.

scholarly journals The Design of an Improved Endwall Film-Cooling Configuration

1998 ◽  
Author(s):  
S. Friedrichs ◽  
H. P. Hodson ◽  
W. N. Dawes
Keyword(s):  
Secondary Flow ◽  
Film Cooling ◽  
Large Scale ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Aerodynamic Loss ◽  
Cooling Flow ◽  
High Static Pressure ◽  
Endwall Film Cooling ◽  
Aerodynamic Losses

The endwall film-cooling cooling configuration investigated by Friedrichs et al. (1996, 1997) had in principle sufficient cooling flow for the endwall, but in practice, the redistribution of this coolant by secondary flows left large endwall areas uncooled. This paper describes the attempt to improve upon this datum cooling configuration by redistributing the available coolant to provide a better coolant coverage on the endwall surface, whilst keeping the associated aerodynamic losses small. The design of the new, improved cooling configuration was based on the understanding of endwall film-cooling described by Friedrichs et al. (1996, 1997). Computational fluid dynamics were used to predict the basic flow and pressure field without coolant ejection. Using this as a basis, the above described understanding was used to place cooling holes so that they would provide the necessary cooling coverage at minimal aerodynamic penalty. The simple analytical modelling developed in Friedrichs et al. (1997) was then used to check that the coolant consumption and the increase in aerodynamic loss lay within the limits of the design goal. The improved cooling configuration was tested experimentally in a large scale, low speed linear cascade. An analysis of the results shows that the redesign of the cooling configuration has been successful in achieving an improved coolant coverage with lower aerodynamic losses, whilst using the same amount of coolant as in the datum cooling configuration. The improved cooling configuration has reconfirmed conclusions from Friedrichs et al. (1996, 1997); firstly, coolant ejection downstream of the three-dimensional separation lines on the endwall does not change the secondary flow structures; secondly, placement of holes in regions of high static pressure helps reduce the aerodynamic penalties of platform coolant ejection; finally, taking account of secondary flow can improve the design of endwall film-cooling configurations.

Performance Improvement Program for Kawasaki Gas Turbine

2017 ◽  
Author(s):  
Tomoki Taniguchi ◽  
Ryoji Tamai ◽  
Yoshihiko Muto ◽  
Satoshi Takami ◽  
Ryozo Tanaka ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Thermal Performance ◽  
Film Cooling ◽  
Gas Turbines ◽  
Large Scale ◽  
New Technologies ◽  
Design Procedure ◽  
Product Line ◽  
Combined Cycle ◽  
Improvement Program

Kawasaki Heavy Industries, Ltd (KHI) has started a comprehensive program to further improve performance and availability of existing Kawasaki gas turbines. In the program, one of the Kawasaki’s existing gas turbine was selected from the broad product line and various kinds of technology were investigated and adopted to further improve its thermal performance and availability. The new technologies involve novel film cooling of turbine nozzles, advanced and large-scale numerical simulations, new thermal barrier coating. The thermal performance target is combined cycle efficiency of 51.6% and the target ramp rate is 20% load per minute. The program started in 2015 and engine testing has just started. In this paper, details of the program are described, focusing on design procedure.

Computational Predictions of Endwall Film Cooling for a Turbine Nozzle Vane With an Asymmetric Contoured Passage

2008 ◽  
Author(s):  
Yoji Okita ◽  
Chiyuki Nakamata
Keyword(s):  
Film Cooling ◽  
Computational Study ◽  
Suction Side ◽  
Geometrical Parameters ◽  
Passage Vortex ◽  
Rear Part ◽  
Cooling Hole ◽  
Secondary Vortices ◽  
Endwall Film Cooling ◽  
Film Cooling Holes

This paper presents results of a computational study for the endwall film cooling of an annular nozzle cascade employing a circumferentially asymmetric contoured passage. The investigated geometrical parameters and the flow conditions are set consistent with a generic modern HP-turbine nozzle. Rows of cylindrical film cooling holes on the contoured endwall are arranged with a design practice for the ordinary axisymmetric endwall. The solution domain, which includes the mainflow, cooling hole paths, and the coolant plenum, is discretized in the RANS equations with the realizable k-epsilon model. The calculated flow field shows that the pressure gradients across the passage between the pressure and the suction side are reduced with the asymmetric endwall, and consequently, the rolling up of the inlet boundary layer into the passage vortex is delayed and the separation line has moved further downstream. With the asymmetric endwall, because of the effective suppression of the secondary flow, more uniform film coverage is achieved especially in the rear part of the passage and the laterally averaged effectiveness is also significantly improved in this region. The closer inspection of the calculated thermal field reveals that, with the asymmetric passage, the coolant ejected from the holes are less deflected by the secondary vortices, and it attaches better to the endwall in this rear part.

The Effect of Area Ratio Change via Increased Hole Length for Shaped Film Cooling Holes With Constant Expansion Angles

2017 ◽  
Author(s):  
Shane Haydt ◽  
Stephen Lynch ◽  
Scott Lewis
Keyword(s):  
Film Cooling ◽  
Gas Turbines ◽  
Area Ratio ◽  
Lateral Expansion ◽  
Blowing Ratio ◽  
High Area ◽  
Expansion Angle ◽  
Ratio Change ◽  
Adiabatic Effectiveness ◽  
Film Cooling Holes

Shaped film cooling holes are used as a cooling technology in gas turbines to reduce metal temperatures and improve durability, and they generally consist of a small metering section connected to a diffuser that expands in one or more directions. The area ratio of these holes is defined as the area at the exit of the diffuser, divided by the area at the metering section. A larger area ratio increases the diffusion of the coolant momentum, leading to lower average momentum of the coolant jet at the exit of the hole and generally better cooling performance. Cooling holes with larger area ratios are also more tolerant of high blowing ratio conditions, and the increased coolant diffusion typically better prevents jet liftoff from occurring. Higher area ratios have traditionally been accomplished by increasing the expansion angle of the diffuser while keeping the overall length of the hole constant. The present study maintains the diffuser expansion angles and instead increases the length of the diffuser, which results in longer holes. Various area ratios have been examined for two shaped holes: one with forward and lateral expansion angles of 7° (7-7-7 hole) and one with forward and lateral expansion angles of 12° (12-12-12 hole). Each hole shape was tested at numerous blowing ratios to capture trends across various flow rates. Adiabatic effectiveness measurements indicate that for the baseline 7-7-7 hole, a larger area ratio provides higher effectiveness, especially at higher blowing ratios. Measurements also indicate that for the 12-12-12 hole, a larger area ratio performs better at high blowing ratios but the hole experiences ingestion at low blowing ratios. Steady RANS simulations did not accurately predict the levels of adiabatic effectiveness, but did predict the trend of improving effectiveness with increasing area ratio for both hole shapes. Flowfield measurements with PIV were also performed at one downstream plane for a low and high area ratio case, and the results indicate an expected decrease in jet velocity due to a larger diffuser.

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