The Impact of Blade-to-Blade Flow Variability on Turbine Blade Cooling Performance

2005 ◽  
Vol 127 (4) ◽  
pp. 763-770 ◽  
Author(s):  
Vince Sidwell ◽  
David Darmofal
Keyword(s):  
Turbine Blade ◽  
High Flow ◽  
Low Flow ◽  
Simplified Model ◽  
Selective Assembly ◽  
Turbine Blade Cooling ◽  
Cooling Flow ◽  
Blade Cooling ◽  
Blade Row ◽  
The Impact

The focus of this paper is the impact of manufacturing variability on turbine blade cooling flow and, subsequently, its impact on oxidation life. A simplified flow network model of the cooling air supply system and a row of blades is proposed. Using this simplified model, the controlling parameters which affect the distribution of cooling flow in a blade row are identified. Small changes in the blade flow tolerances (prior to assembly of the blades into a row) are shown to have a significant impact on the minimum flow observed in a row of blades resulting in substantial increases in the life of a blade row. A selective assembly method is described in which blades are classified into a low-flow and a high-flow group based on passage flow capability (effective areas) in life-limiting regions and assembled into rows from within the groups. Since assembling rows from only high-flow blades is equivalent to raising the low-flow tolerance limit, high-flow blade rows will have the same improvements in minimum flow and life that would result from more stringent tolerances. Furthermore, low-flow blade rows are shown to have minimum blade flows which are the same or somewhat better than a low-flow blade that is isolated in a row of otherwise higher-flowing blades. As a result, low-flow blade rows are shown to have lives that are no worse than random assembly from the full population. Using a higher fidelity model for the auxiliary air system of an existing jet engine, the impact of selective assembly on minimum blade flow and life of a row is estimated and shown to be in qualitative and quantitative agreement with the simplified model analysis.

A Selective Assembly Method to Reduce the Impact of Blade Flow Variability on Turbine Life

2004 ◽  
Author(s):  
Vince Sidwell ◽  
David Darmofal
Keyword(s):  
Turbine Blades ◽  
High Flow ◽  
Metal Temperature ◽  
Low Flow ◽  
Inlet Temperature ◽  
Selective Assembly ◽  
Turbine Inlet Temperature ◽  
Assembly Method ◽  
Turbine Inlet ◽  
The Impact

A selective assembly method is proposed that decreases the impact of blade passage manufacturing variability on the life of a row of cooled turbine blades. The method classifies turbine blades into groups based on the effective flow areas of the blade passages, then a row of blades is assembled exclusively from blades of a single group. A simplified classification is considered in which blades are divided into low-flow, nominal-flow, and high-flow groups. For rows assembled from the low-flow class, the blade plenum pressure will tend to rise and the individual blade flows will be closer to the design intent than for a single low-flow blade in a randomly-assembled row. Since the blade metal temperature is strongly dependent on the blade flow, selective assembly can lower the metal temperature of the lowest-flowing blades and increase the life of a turbine row beyond what is possible from a randomly-assembled row. Furthermore, the life of a nominal-flow or high-flow row will be significantly increased (relative to a randomly-assembled row) since the life-limiting low-flow blades would not be included in these higher-flowing rows. The impact of selective assembly is estimated using a model of the first turbine rotor of an existing high-bypass turbofan. The oxidation lives of the nominal-flow and high-flow blade rows are estimated to increase approximately 50% and 100% compared to randomly-assembled rows, while the life of the low-flow rows are the same as the randomly-assembled rows. Alternatively, selective assembly can be used to increase turbine inlet temperature while maintaining the maximum blade metal temperatures at random-assembly levels. For the nominal-flow and high-flow classes, turbine inlet temperature increases are estimated to be equivalent to the turbine inlet temperature increases observed over several years of gas turbine technology development.

A Computer Model for Gas Turbine Blade Cooling Analysis

1982 ◽  
Author(s):  
J. C. Han ◽  
D. W. Ortman ◽  
C. P. Lee
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Computer Model ◽  
Film Cooling ◽  
Flow Characteristics ◽  
Gas Turbine Blade ◽  
Turbine Blade Cooling ◽  
Cooling Flow ◽  
Blade Cooling ◽  
Flow Balance

A computer model for gas turbine blade cooling analysis has been developed. The finite difference technique over the chord and span of the blade is employed. A flow balance and an energy balance program are included in the model. The model is capable of predicting cooling flow characteristics (mass flow rate and internal pressure distribution) and metal temperature profiles of multipass coolant passages in rotating blades with local film cooling. The paper first presents the analytical model of coolant flow and heat transfer, then the computer program is discussed. Finally, the computed results of a sample blade at engine conditions is presented and discussed.

Exploring the Impact of Elevated Turbine Blade Cooling Effectiveness and Turbine Material Temperatures on Gas Turbine Engine Performance and Cost

2015 ◽  
Author(s):  
Aaron R. Byerley ◽  
August J. Rolling
Keyword(s):  
Gas Turbine ◽  
Fuel Consumption ◽  
Turbine Blade ◽  
Inlet Temperature ◽  
Turbine Inlet Temperature ◽  
Cooling Effectiveness ◽  
Turbine Blade Cooling ◽  
Blade Cooling ◽  
Turbine Inlet ◽  
The Impact

Since the 1950’s, the turbine inlet temperatures of gas turbine engines have been steadily increasing as engine designers have sought to increase engine thrust-to-weight and reduce fuel consumption. In turbojets and low-bypass turbofan engines, increasing the turbine inlet temperature boosts specific thrust, which in some cases can support supersonic flight without the use of an afterburner. In high-bypass gas turbine engines, increasing the turbine inlet temperature makes possible higher bypass ratios and overall pressure ratios, both of which reduce specific fuel consumption. Increased turbine inlet temperatures, without sacrificing blade life, have been made possible through advances in blade cooling effectiveness and high-temperature turbine blade materials. Investigating the impact of higher turbine inlet temperatures and the corresponding cooling air flow rates on specific thrust, specific fuel consumption, and engine development cost is the subject of this paper. A physics-based cooling effectiveness correlation is presented for linking turbine inlet temperature to cooling flow fraction. Two cases are considered: 1) a low-bypass, mixed-exhaust, non-afterburning turbofan engine intended to support supercruising at Mach 1.5 and 2) a high-bypass, unmixed-exhaust turbofan engine intended to support highly efficient, long range flight at Mach 0.8. For each of these two cases, both baseline and enhanced cooling effectiveness values as well as both baseline and elevated turbine blade material temperatures are considered. Comparing these cases will ensure that students taking courses in preliminary engine design understand why huge research investments continue to be made in turbine blade cooling and advanced, high-temperature turbine blade material development.

TURBINE BLADE COOLING AT BUAA

2018 ◽  
Author(s):  
Zhi Tao ◽  
Haiwang Li ◽  
Ruquan You
Keyword(s):  
Turbine Blade ◽  
Turbine Blade Cooling ◽  
Blade Cooling

Flow in a Simulated Turbine Blade Cooling Channel With Spatially Varying Roughness Caused by Additive Manufacturing Orientation

2020 ◽  
Author(s):  
Stephen T. McClain ◽  
David R. Hanson ◽  
Emily Cinnamon ◽  
Jacob C. Snyder ◽  
Robert F. Kunz ◽  
...  
Keyword(s):  
Turbine Blade ◽  
Inconel 718 ◽  
Rough Surfaces ◽  
Structured Light ◽  
Internal Flow ◽  
Smooth Wall ◽  
Number Range ◽  
Turbine Blade Cooling ◽  
Blade Cooling ◽  
Hot Film

Abstract Because of the effects of gravity acting on the melt region created during the laser sintering process, additively manufactured surfaces that are pointed upward have been shown to exhibit roughness characteristics different from those seen on surfaces that point downward. For this investigation, the Roughness Internal Flow Tunnel (RIFT) and computational fluid dynamics models were used to investigate flow in channels with different roughness on opposing walls of the channel. Three rough surfaces were employed for the investigation. Two of the surfaces were created using scaled, structured-light scans of the upskin and downskin surfaces of an Inconel 718 component which was created at a 45° angle to the printing surface and documented by Snyder et al. [1]. A third rough surface was created for the RIFT investigation using a structured-light scan of a surface similar to the Inconel 718 downskin surface, but a different scaling was used to provide larger roughness elements in the RIFT. The resulting roughness dimensions (Rq/Dh) of the three surfaces used were 0.0064, 0.0156, and 0.0405. The friction coefficients were measured over the range of 10,000 < ReDh < 70,000 for each surface opposed by a smooth wall and opposed by each of the other rough walls. At multiple ReDh values, x-array hot film anemometry was used to characterize the velocity and turbulence profiles for each roughness combination. The friction factor variations for each rough wall opposed by a smooth wall approached complete turbulence. However, when rough surfaces were opposed, the surfaces did not reach complete turbulence over the Reynolds number range investigated. The results of inner variable analysis demonstrate that the roughness function (ΔU+) becomes independent of the roughness condition of the opposing wall providing evidence that Townsend’s Hypothesis holds for the relative roughness values expected for additively manufactured turbine-blade cooling passages.

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