scholarly journals Opportunities and Issues in the Application of Titanium Alloys for Aerospace Components

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 705 ◽  
Author(s):  
James C. Williams ◽  
Rodney R. Boyer
Keyword(s):  
Additive Manufacturing ◽  
Titanium Alloys ◽  
Intermetallic Compounds ◽  
Turbine Blades ◽  
Low Pressure ◽  
Current Status ◽  
Rocket Engines ◽  
Low Pressure Turbine ◽  
Investment Cast ◽  
Ti Alloys

The metal titanium (Ti) and its alloys have many attributes which are attractive as structural materials, but they also have one major disadvantage, high initial cost. Nevertheless, Ti and Ti alloys are used extensively in airframes, gas turbine engines (GTE), and rocket engines (RE). The high cost is a deterrent, particularly in airframe applications, in that the other alloys it competes with are, for the most part, significantly lower cost. This is less of a concern for GTE and RE where the cost of titanium is closer to and sometimes even lower than some of the materials it competes with for these applications. In spacecraft the weight savings are so important that cost is a lesser concern. Ti and its alloys consist of five families of alloys; α-Ti, near α-alloys, α + β alloys, β-alloys, and Ti-based intermetallic compounds. The intermetallic compounds of primary interest today are those based on the compound TiAl which, at this time, are only used for engine applications because of their higher temperature capability. These TiAl-based compounds are used in a relatively low, but growing, amounts. The first production application was for low pressure turbine blades in the GE engine (GEnx) used on the Boeing 787, followed by the GE LEAP engine used on A-320neo and B-737MAX. These air foils are investment cast and machined. The next application is for the GE90X which will power the Boeing B-777X. These air foils will be made by additive manufacturing (AM). Unalloyed titanium and titanium alloys are typically melted by vacuum arc melting and re-melted either once (2X VAR) or twice (3X VAR); however a new and very different melting method (cold hearth melting) has recently become favored, mainly for high performance applications such as rotors in aircraft engines. This process resulted in higher quality ingots with a significant reduction in melt-related defects. Once melted and cast into ingots, the alloys can be processed using all the standard thermomechanical working and casting processes used for making components of other types of structural alloys. Because of their limited ductility, the TiAl-based intermetallic compounds are quite difficult to process using ordinary wrought methods. Consequently, the low-pressure turbine blades currently in service are investment cast and machined to net shape. The AM air foils will require minimal machining, which is an advantage. This paper describes some relatively recent developments as well as some issues and opportunities associated with the production and use of Ti and its alloys in aerospace components. Included are new Ti alloys, new applications of Ti alloys, and the current status of several manufacturing processes including a discussion of the promise and current reality of additive manufacturing as a potentially revolutionary method of producing Ti alloy components.

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.

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.

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.

Novel Designs of Turbine Blades for Additive Manufacturing

2016 ◽  
Author(s):  
Liubov Magerramova ◽  
Boris Vasilyev ◽  
Vladimir Kinzburskiy
Keyword(s):  
Additive Manufacturing ◽  
Complex Geometry ◽  
Turbine Blades ◽  
Engine Performance ◽  
Test Results ◽  
Cooling Systems ◽  
3D Tomography ◽  
Low Pressure Turbine ◽  
Complex Shapes ◽  
Design And Manufacturing

Improving engine performance requires creating new materials and improving design and manufacturing. Additive Manufacturing (AM) is advancing rapidly and allows us to produce details of complex shapes that cannot be produced by traditional methods. The goal of this study was to demonstrate the possibility of using AM for the manufacture of turbine blades with a complex geometry, including those with advanced cooling systems, which cannot be manufactured by conventional methods. This paper presents the results of the design and calculations of high-pressure turbine (HPT) cooled blades, as well as a low-pressure turbine (LPT) uncooled blade that was designed using topology optimization (TO). Several blades were manufactured using AM. 3D tomography test results for those blades confirm the possibility of AM application in production of blades with complex geometry.

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

Effect of Sector Mode Shape Variation on the Aerodynamic Stability of a Low-Pressure Turbine Sectored Vane

2003 ◽  
Author(s):  
Olga V. Chernysheva ◽  
Torsten H. Fransson ◽  
Robert E. Kielb ◽  
John Barter
Keyword(s):  
Turbine Blades ◽  
Low Pressure ◽  
Mode Shapes ◽  
Two Dimensional ◽  
Shape Variation ◽  
Aerodynamic Stability ◽  
Flow Solver ◽  
Low Pressure Turbine ◽  
Influence Coefficients

The paper presents a method to investigate the flutter appearance in a cascade, where blades are connected together in a number of identical sectors. The key parameters of the method are vibration amplitudes and mode shapes of the blades belonging to the same sector. The aerodynamic response from a sectored vane cascade is calculated based on the aerodynamic work influence coefficients of freestanding blades performed with two-dimensional inviscid linearized flow solver. A case study based upon the presented methodology shows that, despite stabilizing effect of tying blades together into sectors, a sectored vane consisting of six low-pressure turbine blades vibrating with real single modes, and identical amplitudes can be unstable at realistic design conditions.

Influence of Tip Shroud Modeling on the Flutter Stability of a Low Pressure Turbine Rotor

2019 ◽  
Author(s):  
Lorenzo Pinelli ◽  
Federico Vanti ◽  
Andrea Arnone ◽  
Benjamin Beßling ◽  
Damian M. Vogt
Keyword(s):  
Modal Analysis ◽  
Open Source ◽  
Linear Method ◽  
Turbine Blades ◽  
Low Pressure ◽  
Turbine Rotor ◽  
Contact Interface ◽  
Aerodynamic Damping ◽  
Low Pressure Turbine ◽  
Tip Shroud

Abstract Since the modern design trend of low pressure turbine blades for aeronautical propulsion leads to lighter and more loaded blades, thus prone to flutter induced vibrations; flutter assessment is now a standard verification within the design loop of these components. Flutter stability assessment requires FEM and CFD tools able to predict the pressure response of fluid flow due to blade oscillation in order to compute the aerodynamic damping. Such tools are mature and validated, yet some geometrical aspects of the blade-row as contact interfaces at the blade tip shroud have to be carefully simulated to obtain accurate flutter results. The aim of this paper is to demonstrate the capability of the Open Source FEM tool (CalculiX) to deal with complex interlocked rotor geometries when performing modal analysis and to show the influence of different contact interface modeling on flutter stability. The solid mesh of a single-pitch row sector has been generated by using the Open Source suite Salome and the modal analysis has been carried out with CalculiX with cyclic symmetry conditions. The following uncoupled flutter simulations have been performed with the CFD TRAF code, an in-house solver developed at the University of Florence, which implements a non-linear method for flutter evaluation. An in-depth comparison among the FEM models with different boundary conditions in terms of mode shape frequency and aerodynamic damping curves are reported. These results show the effect of different contact interface models, especially on the first bending mode family, and confirm the overall row stability detected during a dedicated experimental flutter campaign.

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