Improved Understanding of Negative Stiffness in Filament Seals

2012 ◽  
Author(s):  
Gervas Franceschini ◽  
Ingo H. J. Jahn ◽  
Andrew K. Owen ◽  
Terry V. Jones ◽  
David R. H. Gillespie
Keyword(s):  
Experimental Testing ◽  
Negative Stiffness ◽  
Turbine Engines ◽  
Inertia Force ◽  
Central Position ◽  
Gas Turbine Engines ◽  
Leaf Pack ◽  
Seal Design ◽  
Geometric Configurations ◽  
D Model

Leaf seals have previously been proposed as an improved filament seal for gas turbine engines. Recently, a phenomenon known as negative stiffness has been reported from experimental testing. Good understanding of this phenomenon is required to ensure stable interaction between the seal and the rotor. In negative stiffness the displacement of the seal or rotor into an eccentric position causes a resultant force, which, rather than restoring the rotor to a central position, acts to amplify its displacement. The seal consists of a pack of thin planar leaves arranged around the rotor, with coverplates on either side of the leaf pack, offset from its surface. It is notable that negative stiffness only occurs when certain geometric configurations of the coverplates are employed. This paper gives insight into the fluid phenomena that contribute to the negative stiffness effect through the creation of a general 2-D model of the flow upstream of the leaf pack and between the leaves. These show that there is the capacity for the inertia force to be a significant contributor to the overall force acting on individual leaves depending on the coverplate configuration surrounding the leaf pack. The influence of a key parameter, coverplate height, is explored. Results from a test campaign with varying seal geometry are compared to the forces predicted by modeling to justify the proposed mechanisms for negative stiffness. The close agreement between the experimental and predicted data extends the previously published insight on negative stiffness to allow more general considerations for leaf seal design to be inferred.

High Power Density Silicon Combustion Systems for Micro Gas Turbine Engines

2003 ◽  
Vol 125 (3) ◽  
pp. 709-719 ◽  
Author(s):  
C. M. Spadaccini ◽  
A. Mehra ◽  
J. Lee ◽  
X. Zhang ◽  
S. Lukachko ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Large Scale ◽  
Experimental Testing ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Deep Reactive Ion Etching ◽  
Turbine Engine ◽  
Micro Gas Turbine ◽  
Power Densities ◽  
Important Design

As part of an effort to develop a microscale gas turbine engine for power generation and micropropulsion applications, this paper presents the design, fabrication, experimental testing, and modeling of the combustion system. Two radial inflow combustor designs were examined; a single-zone arrangement and a primary and dilution-zone configuration. Both combustors were micromachined from silicon using deep reactive ion etching (DRIE) and aligned fusion wafer bonding. Hydrogen-air and hydrocarbon-air combustion were stabilized in both devices, each with chamber volumes of 191mm3. Exit gas temperatures as high as 1800 K and power densities in excess of 1100MW/m3 were achieved. For the same equivalence ratio and overall efficiency, the dual-zone combustor reached power densities nearly double that of the single-zone design. Because diagnostics in microscale devices are often highly intrusive, numerical simulations were used to gain insight into the fluid and combustion physics. Unlike large-scale combustors, the performance of the microcombustors was found to be more severely limited by heat transfer and chemical kinetics constraints. Important design trades are identified and recommendations for microcombustor design are presented.

Negative Stiffness in Gas Turbine Leaf Seals

2011 ◽  
Author(s):  
Ingo H. J. Jahn ◽  
Andrew K. Owen ◽  
Gervas Franceschini ◽  
David R. H. Gillespie
Keyword(s):  
Flow Field ◽  
Gas Turbine ◽  
Empirical Model ◽  
Negative Stiffness ◽  
Central Position ◽  
Mechanical Stiffness ◽  
Turbine Engine ◽  
Leaf Pack ◽  
Eccentric Rotor ◽  
Shaft Seals

The stiffness of contacting shaft seals such as brush seals and leaf seals is a required characteristic to accurately predict their performance and life in the gas turbine engine. This paper describes the results of a test campaign in which a series of eccentric rotor excursions are applied at low rotational speed and engine representative pressure differences to characterise the behaviour of a prototype leaf seal. A phenomenon that may best be described as negative seal stiffness is reported. Here, the displacement of the seal rotor to an eccentric position causes a resultant force, which, rather than trying to return the rotor to a central position, acts to amplify its displacement. These data were used to develop an empirical model of the seal behaviour. It was possible to model the negative stiffness phenomenon and show that it is caused by a combination of two effects: the inherent mechanical stiffness of the leaf pack, and the aerodynamic stiffness of the seal. The latter is caused by the pressure distribution and changes in the flow field through the leaf pack as a result of the displacement of the rotor.

Gas Screen in Components of Gas Turbine Engines

1997 ◽  
Vol 28 (7-8) ◽  
pp. 536-542
Author(s):  
A. A. Khalatov ◽  
I. S. Varganov
Keyword(s):  
Gas Turbine ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Gas Screen

Potential Application of Composite Materials to Future Gas Turbine Engines

1988 ◽  
Author(s):  
James C. Birdsall ◽  
William J. Davies ◽  
Richard Dixon ◽  
Matthew J. Ivary ◽  
Gary A. Wigell
Keyword(s):  
Composite Materials ◽  
Gas Turbine ◽  
Potential Application ◽  
Turbine Engines ◽  
Gas Turbine Engines

PYROMET ALLOY CTX-1

Alloy Digest ◽  
1997 ◽  
Vol 46 (5) ◽  
Keyword(s):  
Coefficient Of Thermal Expansion ◽  
High Strength ◽  
Heat Treating ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Thermal Fatigue Resistance ◽  
Temperature Performance ◽  
Hot Work Die ◽  
Pressure Hydrogen ◽  
Hot Hardness

Abstract Pyromet CTX-1 is a high-strength, precipitation-hardenable superalloy exhibiting a low coefficient of thermal expansion and high strength up to about 1200 deg F. The alloy possesses high hot hardness and good thermal fatigue resistance. Its applications include components for gas turbine engines, hot-work die applications and high-pressure hydrogen environments. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: FE-56. Producer or source: Carpenter. Originally published February 1976, revised May 1997.

HAYNES ALLOY 75

Alloy Digest ◽  
1999 ◽  
Vol 48 (7) ◽  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Heat Treating ◽  
Turbine Engines ◽  
Chromium Alloy ◽  
Gas Turbine Engines ◽  
Typical Application ◽  
Good Oxidation Resistance ◽  
Temperature Performance ◽  
Haynes Alloy

Abstract Haynes alloy 75 is an 80 nickel-20 chromium alloy with both good oxidation resistance and good mechanical properties at high temperatures. It is amenable to all forms of fabrication and welding. A typical application for sheet metal is fabrications in gas turbine engines. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance as well as forming and heat treating. Filing Code: Ni-557. Producer or source: Haynes International Inc.

Method of tribodiagnostics of d-30KU engines/KP with the use of a microwave plasma complex: results of metrological examination and analysis of the accuracy

2020 ◽  
pp. 22-29
Author(s):  
A. Bogoyavlenskiy ◽  
A. Bokov
Keyword(s):  
Gas Turbine ◽  
Microwave Plasma ◽  
Technical Condition ◽  
The State ◽  
Turbine Engines ◽  
Metrological Examination ◽  
Gas Turbine Engines ◽  
High Frequency Plasma ◽  
Frequency Plasma ◽  
Primary Standards

The article contains the results of the metrological examination and research of the accuracy indicators of a method for diagnosing aircraft gas turbine engines of the D30KU/KP family using an ultra-high-frequency plasma complex. The results of metrological examination of a complete set of regulatory documents related to the diagnostic methodology, and an analysis of the state of metrological support are provided as well. During the metrological examination, the traceability of a measuring instrument (diagnostics) – an ultrahigh-frequency plasma complex – is evaluated based on the scintillation analyzer SAM-DT-01–2. To achieve that, local verification schemes from the state primary standards of the corresponding types of measurements were built. The implementation of measures to eliminate inconsistencies identified during metrological examination allows to reduce to an acceptable level the metrological risks of adverse situations when carrying out aviation activities in industry and air transportation. In addition, the probability of occurrence of errors of the first and second kind in the technological processes of tribodiagnostics of aviation gas turbine engines is reduced when implementing a method that has passed metrological examination in real practice. At the same time, the error in determining ratings and wear indicators provides acceptable accuracy indicators and sufficient reliability in assessing the technical condition of friction units of the D-30KP/KP2/KU/KU-154 aircraft engines.

On the prospects of application of nanostructured heterophase polyfunctional composite materials inengine building industry

2019 ◽  
pp. 50-57
Author(s):  
O. B. Silchenko ◽  
M. V. Siluyanova ◽  
V. Е. Nizovtsev ◽  
D. A. Klimov ◽  
A. A. Kornilov
Keyword(s):  
Composite Materials ◽  
Gas Turbine ◽  
Developed Countries ◽  
The United States ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Nanostructured Composite ◽  
Polymer Metal ◽  
Long Operation ◽  
Prospects Of Application

The paper gives a brief review of properties and applications of developed extra-hard nanostructured composite materials and coatings based on them. The presentresearch suggestsaerospace applications of nanostructured composite materials based on carbides, carbonitrides and diboridesof transition and refractory metals. To improve the technical and economic performance of gas turbine engines, it is advisable to use new composite structural materials whose basic physicomechanical properties are several times superior to traditional ones. The greatest progress in developing new composites should be expected in the area of materials created on the basis of polymer, metal, intermetallic and ceramic matrices. Currently components and assemblies of gas turbine engines and multiple lighting power units with long operation life and durability will vigorously develop. Next-generation composites are studied in all developed countries, primarily in the United States and Japan.

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