scholarly journals Flutter Mechanisms in Low Pressure Turbine Blades

1999 ◽  
Vol 122 (1) ◽  
pp. 82-88 ◽  
Author(s):  
M. Nowinski ◽  
J. Panovsky
Keyword(s):  
Research Effort ◽  
Turbine Blades ◽  
Low Pressure ◽  
Design Parameters ◽  
Computational Techniques ◽  
Influence Coefficient ◽  
Low Pressure Turbine ◽  
Blade Flutter ◽  
Euler Methods ◽  
Annular Cascade

The work described in this paper is part of a comprehensive research effort aimed at eliminating the occurrence of low pressure turbine blade flutter in aircraft engines. The results of fundamental unsteady aerodynamic experiments conducted in an annular cascade are studied in order to improve the overall understanding of the flutter mechanism and to identify the key flutter parameters. In addition to the standard traveling wave tests, several other unique experiments are described. The influence coefficient technique is experimentally verified for this class of blades. The beneficial stabilizing effect of mistuning is also directly demonstrated. Finally, the key design parameters for flutter in low pressure turbine blades are identified. In addition to the experimental effort, correlating analyses utilizing linearized Euler methods demonstrate that these computational techniques are adequate to predict turbine flutter. [S0742-4795(00)01301-6]

scholarly journals Flutter Mechanisms in Low Pressure Turbine Blades

1998 ◽  
Author(s):  
M. Nowinski ◽  
J. Panovsky
Keyword(s):  
Research Effort ◽  
Turbine Blades ◽  
Low Pressure ◽  
Design Parameters ◽  
Computational Techniques ◽  
Influence Coefficient ◽  
Low Pressure Turbine ◽  
Blade Flutter ◽  
Euler Methods ◽  
Annular Cascade

The work described in this paper is part of a comprehensive research effort aimed at eliminating the occurrence of low pressure turbine blade flutter in aircraft engines. The results of fundamental unsteady aerodynamic experiments conducted in an annular cascade are studied in order to improve the overall understanding of the flutter mechanism and to identify the key flutter parameters. In addition to the standard traveling wave tests, several other unique experiments are described. The influence coefficient technique is experimentally verified for this class of blades. The beneficial stabilizing effect of mistuning is also directly demonstrated. Finally, the key design parameters for flutter in low pressure turbine blades are identified. In addition to the experimental effort, correlating analyses utilizing linearized Euler methods demonstrate that these computational techniques are adequate to predict turbine flutter.

scholarly journals A Design Method to Prevent Low Pressure Turbine Blade Flutter

1998 ◽  
Author(s):  
Josef Panovsky ◽  
Robert E. Kielb
Keyword(s):  
Mode Shape ◽  
Design Method ◽  
Turbine Blades ◽  
Low Pressure ◽  
Stability Parameter ◽  
Influence Coefficient ◽  
Low Pressure Turbine ◽  
Reduced Frequency ◽  
Blade Flutter ◽  
The Stability

A design approach to avoid flutter of low pressure turbine blades in aircraft engines is described. A linearized Euler analysis, previously validated using experimental data, is used for a series of parameter studies. The influence of mode shape and reduced frequency are investigated. Mode shape is identified as the most important contributor to determining the stability of a blade design. A new stability parameter is introduced to gain additional insight into the key contributors to flutter. This stability parameter is derived from the influence coefficient representation of the cascade, and includes only contributions from the reference blade and its immediate neighbors. This has the effect of retaining the most important contributions to aerodynamic damping while filtering out terms of less significance. This parameter is utilized to develop a stability map, which provides the critical reduced frequency as a function of torsion axis location. Rules for preliminary design and procedures for detailed design analysis are defined.

A Design Method to Prevent Low Pressure Turbine Blade Flutter

1999 ◽  
Vol 122 (1) ◽  
pp. 89-98 ◽  
Author(s):  
J. Panovsky ◽  
R. E. Kielb
Keyword(s):  
Mode Shape ◽  
Design Method ◽  
Turbine Blades ◽  
Low Pressure ◽  
Stability Parameter ◽  
Influence Coefficient ◽  
Low Pressure Turbine ◽  
Reduced Frequency ◽  
Blade Flutter ◽  
The Stability

A design approach to avoid flutter of low pressure turbine blades in aircraft engines is described. A linearized Euler analysis, previously validated using experimental data, is used for a series of parameter studies. The influence of mode shape and reduced frequency are investigated. Mode shape is identified as the most important contributor to determining the stability of a blade design. A new stability parameter is introduced to gain additional insight into the key contributors to flutter. This stability parameter is derived from the influence coefficient representation of the cascade, and includes only contributions from the reference blade and its immediate neighbors. This has the effect of retaining the most important contributions to aerodynamic damping while filtering out terms of less significance. This parameter is utilized to develop a stability map, which provides the critical reduced frequency as a function of torsion axis location. Rules for preliminary design and procedures for detailed design analysis are defined. [S0742-4795(00)01401-0]

Cracks on the Roots of Turbine Blades of the Low-Pressure Turbine in a Steam Power Plant

2015 ◽  
Vol 52 (4) ◽  
pp. 214-225 ◽  
Author(s):  
E. Plesiutschnig ◽  
R. Vallant ◽  
G. Stöfan ◽  
C. Sommitsch ◽  
M. Mayr ◽  
...  
Keyword(s):  
Power Plant ◽  
Turbine Blades ◽  
Low Pressure ◽  
Steam Power ◽  
Steam Power Plant ◽  
Low Pressure Turbine

Analysis on High Rates of Scaling and Salt Accumulation of 600MW Supercritical once-through Boiler

2012 ◽  
Vol 166-169 ◽  
pp. 620-626
Author(s):  
Xiao Ni Zhang ◽  
Xian Min Li ◽  
Chang Ming Li
Keyword(s):  
Turbine Blades ◽  
Low Pressure ◽  
Fossil Plants ◽  
Salt Accumulation ◽  
Accelerated Corrosion ◽  
Low Pressure Turbine ◽  
Salt Deposition ◽  
Boiler Units ◽  
Salt Deposits ◽  
Flow Accelerated Corrosion

The chemistry check-ups were reviewed in the first maintenance of 600 MW supercritical once-through boiler units in Henan. Several problems were found: (1) high rates of scaling on the waterwall and economizer; (2) high rates of salt deposition on the turbine blades; (3) the formation of salt deposits on blades were complicated; (4) corrosion of low pressure turbine blades in period of maintenance was a universal phenomenon; (5) FAC (flow-accelerated corrosion) were most frequent in HP heaters and HP drain lines in most fossil plants. The reasons have been analyzed and the suggestions have been provided.

The Science, Technology, and Implementation of TiAl Alloys in Commercial Aircraft Engines

2013 ◽  
Vol 1516 ◽  
pp. 49-58 ◽  
Author(s):  
B. P. Bewlay ◽  
M. Weimer ◽  
T. Kelly ◽  
A. Suzuki ◽  
P.R. Subramanian
Keyword(s):  
Titanium Aluminide ◽  
Turbine Blades ◽  
Aircraft Engine ◽  
Low Pressure ◽  
Major Advance ◽  
Commercial Aircraft ◽  
Tial Alloys ◽  
Low Pressure Turbine ◽  
Titanium Aluminide Alloy ◽  
History Of

ABSTRACTThe present article will describe the science and technology of titanium aluminide (TiAl) alloys and the engineering development of TiAl for commercial aircraft engine applications. The GEnxTM engine is the first commercial aircraft engine that is flying titanium aluminide (alloy 4822) blades and it represents a major advance in propulsion efficiency, realizing a 20% reduction in fuel consumption, a 50% reduction in noise, and an 80% reduction in NOx emissions compared with prior engines in its class. The GEnxTM uses the latest materials and design processes to reduce weight, improve performance, and reduce maintenance costs.GE’s TiAl low-pressure turbine blade production status will be discussed along with the history of implementation. In 2006, GE began to explore near net shape casting as an alternative to the initial overstock conventional gravity casting plus machining approach. To date, more than 40,000 TiAl low-pressure turbine blades have been manufactured for the GEnxTM 1B (Boeing 787) and the GEnxTM 2B (Boeing 747-8) applications. The implementation of TiAl in other GE and non-GE engines will also be discussed.

Flutter of Low Pressure Turbine Blades With Cyclic Symmetric Modes: A Preliminary Design Method

2004 ◽  
Vol 126 (2) ◽  
pp. 306-309 ◽  
Author(s):  
Robert Kielb ◽  
Jack Barter ◽  
Olga Chernycheva ◽  
Torsten Fransson
Keyword(s):  
Mode Shape ◽  
Design Method ◽  
Turbine Blades ◽  
Current Method ◽  
Low Pressure ◽  
Mode Shapes ◽  
Preliminary Design ◽  
Complex Mode ◽  
Low Pressure Turbine ◽  
Reduced Frequency

A current preliminary design method for flutter of low pressure turbine blades and vanes only requires knowledge of the reduced frequency and mode shape (real). However, many low pressure turbine (LPT) blade designs include a tip shroud that mechanically connects the blades together in a structure exhibiting cyclic symmetry. A proper vibration analysis produces a frequency and complex mode shape that represents two real modes phase shifted by 90 deg. This paper describes an extension to the current design method to consider these complex mode shapes. As in the current method, baseline unsteady aerodynamic analyses must be performed for the three fundamental motions, two translations and a rotation. Unlike the current method work matrices must be saved for a range of reduced frequencies and interblade phase angles. These work matrices are used to generate the total work for the complex mode shape. Since it still only requires knowledge of the reduced frequency and mode shape (complex), this new method is still very quick and easy to use. Theory and an example application are presented.

The Influence of Reynolds Number, Mach Number and Incidence Effects on Loss Production in Low Pressure Turbine Airfoils

2006 ◽  
Author(s):  
Rau´l Va´zquez ◽  
Antonio Antoranz ◽  
David Cadrecha ◽  
Leyre Arman˜anzas
Keyword(s):  
Reynolds Number ◽  
Mach Number ◽  
Low Pressure ◽  
Low Pressure Turbine ◽  
Wide Range ◽  
Flow Features ◽  
Mach Numbers ◽  
Turbine Airfoils ◽  
Annular Cascade ◽  
The Impact

This paper presents an experimental study of the flow field in an annular cascade of Low Pressure Turbine airfoils. The influence of Reynolds number, Mach number and incidence on profile and end wall losses have been investigated. The annular cascade consisted of 100 high lift, high aspect ratio, high turning blades that are characteristic of modern LP Turbines. The investigation was carried out for a wide range of Reynolds numbers, extending from 120k to 315k, exit Mach numbers, from 0.5 to 0.9, and incidences from −20 to +14 degrees. Results clearly indicate a significant effect of incidence and Mach number in secondary loss production; however, the Reynolds number shows it much weaker impact. It has also been found that the profile loss production is strongly influenced by both Reynolds and Mach numbers, being the impact of the incidence weaker. Finally, measured data suggest that, in order to properly reproduce the performance of these types of airfoils, annular cascades can be required as far as linear cascades may miss some essential flow features.

scholarly journals Application of Laser Peening Technology for Low-Pressure Turbine Blades

2020 ◽  
Vol 42 (6) ◽  
pp. 467
Author(s):  
Itaru CHIDA ◽  
Yuji SANO ◽  
Keiichi HIROTA ◽  
Takao INUKAI ◽  
Rie SUMIYA ◽  
...  
Keyword(s):  
Turbine Blades ◽  
Low Pressure ◽  
Laser Peening ◽  
Low Pressure Turbine
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