Effectiveness Measurements of Additively Manufactured Film Cooling Holes

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Curtis K. Stimpson ◽  
Jacob C. Snyder ◽  
Karen A. Thole ◽  
Dominic Mongillo
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Relative Size ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Metal Powders ◽  
Cooling Effectiveness ◽  
Internal Surfaces ◽  
Film Cooling Holes ◽  
Am Processes

As additive manufacturing (AM) technologies utilizing metal powders continue to mature, the usage of AM parts in gas turbine engines will increase. Current metal AM technologies produce parts with substantial surface roughness that can only be removed from external surfaces and internal surfaces that are accessible for smoothing. Difficulties arise in making smooth the surfaces of small internal channels, which means the augmentation of pressure loss and heat transfer due to roughness must be accounted for in the design. As gas turbine manufacturers have only recently adopted metal AM technologies, much remains to be examined before the full impacts of applying AM to turbine parts are understood. Although discrete film cooling holes have been extensively studied for decades, this objective of this study was to understand how the roughness of film cooling holes made using AM can affect the overall cooling effectiveness. Coupons made from a high temperature nickel alloy with engine-scale film holes were tested in a rig designed to simulate engine relevant conditions. Two different hole sizes and two different build directions were examined at various blowing ratios. Results showed that the effectiveness is dependent on the build direction and the relative size of the hole. It was also discovered that commercially available AM processes could not reliably produce small holes with predictable behavior.

Effectiveness Measurements of Additively Manufactured Film Cooling Holes

2017 ◽  
Author(s):  
Curtis K. Stimpson ◽  
Jacob C. Snyder ◽  
Karen A. Thole ◽  
Dominic Mongillo
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Relative Size ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Metal Powders ◽  
Cooling Effectiveness ◽  
Internal Surfaces ◽  
Film Cooling Holes ◽  
Am Processes

As additive manufacturing (AM) technologies utilizing metal powders continue to mature, the usage of AM parts in gas turbine engines will increase. Current metal AM technologies produce parts with substantial surface roughness that can only be removed from external surfaces and internal surfaces that are accessible for smoothing. Difficulties arise in making smooth the surfaces of small internal channels, which means the augmentation of pressure loss and heat transfer due to roughness must be accounted for in the design. As gas turbine manufacturers have only recently adopted metal AM technologies, much remains to be examined before the full impacts of applying AM to turbine parts are understood. Although discrete film cooling holes have been extensively studied for decades, this objective of this study was to understand how the roughness of film cooling holes made using AM can affect the overall cooling effectiveness. Coupons made from a high temperature nickel alloy with engine-scale film holes were tested in a rig designed to simulate engine relevant conditions. Two different hole sizes and two different build directions were examined at various blowing ratios. Results showed that the effectiveness is dependent on the build direction and the relative size of the hole. It was also discovered that commercially available AM processes could not reliably produce small holes with predictable behavior.

Simulation of a Multi-Stage Cooling Scheme for Gas Turbine Engines: Part I

2007 ◽  
Author(s):  
M. Ghorab ◽  
I. Hassan ◽  
M. Beauchamp
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Lateral Spreading ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Multi Stage ◽  
Gap Height ◽  
Internal Gap

This paper presents heat transfer characteristics for a Multi-Stage Cooling Scheme (MSCS) design applicable to high temperature gas turbine engines in aerospace and electric power generation. The film cooling and impingement techniques are considered concurrently throughout this study. The proposed design involves passing cooling air from the inside of the turbine blade to the outside through three designed stages. The coolant air is passed through a circular hole into an internal gap creating an impingement of air inside the blade. It then exits through a sequence of two differently shaped holes onto the blade’s external surface. The film cooling effectiveness is enhanced by increasing the internal gap height and offset distance. This effect is significantly diminished however by changing the inclination angle from 90° to 30° at large gap height. The coolant momentum became more uniform by creating the internal gap consequently the coolant air is spread closer to the external blade surface. This reduces jet liftoff as the air exits its hole and also provides internal cooling for the blade. The hole exit positioned on the outer surface of the blade is designed to give a positive and a wide downstream lateral spreading. The MSCS demonstrates greater film cooling effectiveness performance than traditional schemes.

NETL Research Efforts on Development and Integration of Advanced Material Systems and Airfoil Cooling Configurations for Future Land-Based Gas Turbine Engines

2014 ◽  
Author(s):  
M. A. Alvin ◽  
J. Klinger ◽  
B. McMordie ◽  
M. Chyu ◽  
S. Siw ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Low Cost ◽  
Oxide Dispersion Strengthened ◽  
Advanced Materials ◽  
Turbine Engines ◽  
Internal Cooling ◽  
Gas Turbine Engines ◽  
Near Surface ◽  
Material Systems

As future land-based gas turbine engines are being designed to operate with inlet temperatures exceeding 1300°C (2370°F), efforts at NETL have been focused on developing advanced materials systems that are integrated with novel airfoil cooling architectures. Recent achievements in the areas of low cost diffusion bond coat systems applied to single- and poly-crystalline nickel-based superalloys, as well as development of thin nickel-based oxide dispersion strengthened layers are presented in this paper. Integration of these material systems with commercially cast, novel, pin-fin internal cooling airfoil arrays, tripod film cooling hole architectures, trailing edge cooling geometries, and near surface micro-channel concepts is also presented.

The Effect of Internal Crossflow on the Adiabatic Effectiveness of Compound Angle Film Cooling Holes

2015 ◽  
Vol 137 (7) ◽  
Author(s):  
John W. McClintic ◽  
Sean R. Klavetter ◽  
James R. Winka ◽  
Joshua B. Anderson ◽  
David G. Bogard ◽  
...  
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Experimental Studies ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Experimental Conditions ◽  
Turbine Engine ◽  
Adiabatic Effectiveness ◽  
Film Cooling Holes ◽  
Compound Angle

In gas turbine engines, film cooling holes are often fed by an internal crossflow, with flow normal to the direction of the external flow around the airfoil. Many experimental studies have used a quiescent plenum to feed model film cooling holes and thus do not account for the effects of internal crossflow. In this study, an experimental flat plate facility was constructed to study the effects of internal crossflow on a row of cylindrical compound angle film cooling holes. There are relatively few studies available in literature that focus on the effects of crossflow on film cooling performance, with no studies examining the effects of internal crossflow on film cooling with round, compound angled holes. A crossflow channel allowed for coolant to flow alternately in either direction perpendicular to the mainstream flow. Experimental conditions were scaled to match realistic turbine engine conditions at low speeds. Cylindrical compound angle film cooling holes were operated at blowing ratios ranging from 0.5 to 2.0 and at a density ratio (DR) of 1.5. The results from the crossflow experiments were compared to a baseline plenum-fed configuration. This study showed that significantly greater adiabatic effectiveness was achieved for crossflow counter to the direction of coolant injection.

scholarly journals Numerical Analysis of Film Cooling from Micro-Hole

2021 ◽  
Author(s):  
Silambarasan Balasubrammaniyan
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Lateral Direction ◽  
Cooling Performance ◽  
Turbine Engine ◽  
Hot Gas ◽  
Micro Hole ◽  
Micro Flow

The performance of aircraft gas turbine engines mainly depends on performance of the turbine which expands the combusted air into the atmosphere. The turbine is a critical part which gets affected by the hot gas from combustor exhaust. So in order to enhance the performance of gas turbine engines, a proposed cooling type called film cooling is used for more than six decades. The current work is also an attempt to enhance the performance of the gas turbine engine by enhancing the film cooling performance. The film cooling performance was numerically calculated on a flat plate with micro-hole and compared the cooling performance from the macro-hole. The analysis was carried out for different blowing ratios and found that the coolant from micro-hole performs better in the vicinity region and also spreads well in the lateral direction. The vortex structure is also captured from the proposed turbulence model and discussed. The behaviour of micro flow inside the coolant pipe was also analyzed. The comparison between multiple micro-hole jets and discrete jets was also made and discussed.

scholarly journals The Combustion of a Range of Distillate Fuels in Small Gas Turbine Engines

1979 ◽  
Author(s):  
E. Carr
Keyword(s):  
Gas Turbine ◽  
Reverse Flow ◽  
Volume Ratio ◽  
High Standard ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Combustion System ◽  
Flame Tube ◽  
Internal Surfaces ◽  
Marine Diesel

A compact engine configuration is obtained on small gas turbine engines by the use of a reverse flow annular combustion system. Such combustion systems are usually of narrow width and of relatively large flame tube surface area/volume ratio. In consequence, there is a tendency for excessive concentrations of fuel near to the flame tube internal surfaces and fuel impingement on the flame tube which can give rise to performance deficiencies, such as carbon build, loss of efficiency at low load conditions, smoke, and metal overheating particularly with fuels similar to ASTM D 975 Type 2-D diesel. Since there is an increasing requirement for engines to operate with such heavier fuels, research and development programs were initiated to evolve an improved combustion system. The paper briefly describes the main features of these work programs and outlines the configuration evolved and the performance achieved. An arrangement has been obtained which gives a high standard of performance with fuels ranging from aviation kerosene fuel to gas oil and marine diesel.

Effect of Increasing Pitch-to-Diameter Ratio on the Film Cooling Effectiveness of Shaped and Cylindrical Holes Embedded in Trenches

2009 ◽  
Author(s):  
Humberto A. Zuniga ◽  
Jayanta S. Kapat
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Recent Literature ◽  
Narrow Range ◽  
Diameter Ratio ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Current Trends ◽  
Cylindrical Holes ◽  
Film Cooling Holes

The continuous push for higher gas turbine inlet temperatures and operating efficiencies has led to increasingly sophisticated film cooling schemes. One such setup—trench cooling—consists of having film cooling holes embedded inside a gap, commonly called a trench. The coolant hits the downstream trench wall which forces it to spread laterally, resulting in more even film coverage downstream. Recent literature has focused on the effect that trenching has on cylindrical cooling holes only. In addition, researchers have limited their findings to a narrow range of pitch-to-diameter ratios (P/D). The current trends in the turbine industry of increasing or maintaining film cooling effectiveness while reducing the amount of coolant used dictate that P/D be increased, meaning less holes per row. In this study, we address both cylindrical and fan-shaped holes embedded in trenches. Tests have been conducted on 8 test plates with one row of cooling holes each varying the pitch-to-diameter ratio from 4 to 12 (12 configurations in total), and the blowing ratios from 0.5 to 2.0. We investigate the effect that P/D has on film cooling effectiveness for both hole geometries and compare them to similarly pitched baseline plates—fan and cylindrical—not in trenches. It is a known fact that increasing the pitch between holes, while maintaining all other conditions constant, decreases the average film effectiveness, however trenching has been shown to significantly increase film coverage. In this study, it has been shown that film cooling effectiveness of a cylindrical configuration can be maintained by the addition of a trench while cutting the number of holes in half. We also explore the behavior of shaped trenched holes, of which little has been said and find that their performance is actually hurt by trenching.

Film Cooling Performance of Tripod Holes on the Endwall Upstream of a First Stage Nozzle Guide Vane

2015 ◽  
Author(s):  
Bharath Viswanath Ravi ◽  
Samruddhi Deshpande ◽  
Sridharan Ramesh ◽  
Prethive Dhilip Dhilipkumar ◽  
Srinath Ekkad
Keyword(s):  
Gas Turbine ◽  
Mass Flow ◽  
Film Cooling ◽  
Guide Vane ◽  
Turbine Engines ◽  
Inlet Temperature ◽  
Gas Turbine Engines ◽  
Film Cooling Effectiveness ◽  
The Difference ◽  
Nozzle Guide

In view of the growing energy demand, there is an increasing need to augment the thermal efficiency of gas turbine engines. The thermal efficiency and power output of gas turbine engines increase with increasing overall pressure ratio which in turn leads to an increase in turbine inlet temperature. The maximum permissible turbine inlet temperature is limited by the material strength of the components of the gas turbine engines. In this regard, it is important to ensure that the endwalls of the first stage nozzle guide vane, which is one of the critical regions, are adequately cooled. The cooling of the endwall is of particular interest because the leading edge region along the endwall of the stator vane experiences high heat transfer rates resulting from formation of horseshoe vortices. In this paper, the performance of upstream purge slot has been compared against discrete film cooling holes. Three different cooling configurations — slot, cylindrical holes and tripod holes have been investigated by comparing the adiabatic film cooling effectiveness. Furthermore, the effect of coolant to mainstream mass flow ratio on the effectiveness of the different cooling schemes has also been studied. The steady-state experiments were conducted in a low speed, linear cascade wind tunnel. Spatially resolved temperature data was captured using infrared thermography technique to compute adiabatic film cooling effectiveness. Amongst the configurations studied, slot ejection offered the best cooling performance at all mass flow ratios. The performance of tripod ejection was comparable to slot ejection at mass flow ratios between 0.5 and 1.5, with the difference in laterally averaged effectiveness being ∼5%. However, at the highest mass flow ratio (MFR=2.5), the difference increased to ∼20%. Low effectiveness values were observed downstream of cylindrical ejection which could be attributed to jet lift-off.

scholarly journals Numerical Analysis of Film Cooling from Micro-Hole

2021 ◽  
Author(s):  
Silambarasan Balasubrammaniyan
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Lateral Direction ◽  
Cooling Performance ◽  
Turbine Engine ◽  
Hot Gas ◽  
Micro Hole ◽  
Micro Flow

The performance of aircraft gas turbine engines mainly depends on performance of the turbine which expands the combusted air into the atmosphere. The turbine is a critical part which gets affected by the hot gas from combustor exhaust. So in order to enhance the performance of gas turbine engines, a proposed cooling type called film cooling is used for more than six decades. The current work is also an attempt to enhance the performance of the gas turbine engine by enhancing the film cooling performance. The film cooling performance was numerically calculated on a flat plate with micro-hole and compared the cooling performance from the macro-hole. The analysis was carried out for different blowing ratios and found that the coolant from micro-hole performs better in the vicinity region and also spreads well in the lateral direction. The vortex structure is also captured from the proposed turbulence model and discussed. The behaviour of micro flow inside the coolant pipe was also analyzed. The comparison between multiple micro-hole jets and discrete jets was also made and discussed.

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