scholarly journals Gas-Dynamic Foil Bearings Application in High-Speed Turbines

2015 ◽  
Vol 27 (1) ◽  
pp. 99-108 ◽  
Author(s):  
Bolesław Giemza ◽  
Emil Nowiński ◽  
Marek Domański
Keyword(s):  
High Temperature ◽  
High Speed ◽  
Foil Bearings ◽  
Gas Dynamic ◽  
Aviation Technology ◽  
Turbo Machinery

Abstract Authors present the general characteristics of the gas-dynamic foil bearings in the paper. The short analysis of the application and possibilities of using gas-dynamic bearings in turbo machinery, especially in the aspect of aviation technology were described. Authors also pointed out possible directions of development and gas-dynamic foil bearings application in high-speed turbines, especially working in high temperature.

Comparative Assessment of Thermal Protective Characteristics of Metal and Ceramic Shields of Flow Paths of High-Temperature Gas Dynamic Facilities

2020 ◽  
pp. 52-75
Author(s):  
V.A. Tovstonog
Keyword(s):  
High Temperature ◽  
High Speed ◽  
Thermal Protection ◽  
Modern Technology ◽  
Flow Path ◽  
Comparative Assessment ◽  
Working Fluid ◽  
Gas Dynamic ◽  
Heat Shields ◽  
Ramjet Engines

In modern technology, gas dynamic facilities with a flow path of a high-temperature working fluid are widely used. Their effectiveness largely depends on the maximum achievable temperature, which is to a great extent determined by the heat resistance of structural materials and thermal protection systems of the most heat-stressed structural units. Most often, mass transfer thermal protection methods using the coolant of fuel components are used in such plants. However, in some gas dynamic facilities, such as high-speed ramjet engines, the use of such methods is only sufficient to maintain an acceptable temperature level for the elements of the flow path itself. As for the thermal protection of the enclosing structural elements which are adjacent to the path, it can be provided with either uncooled screens or heat-insulating linings. The study gives a comparative assessment of the temperature regime and characteristics of alternative types of heat shields

Experimental Studies on Air Foil Thrust Bearing Load Capabilities Considering the Effect of Foil Configuration

2015 ◽  
Vol 813-814 ◽  
pp. 1007-1011
Author(s):  
R.N. Ravikumar ◽  
K.J. Rathanraj ◽  
V. Arun Kumar
Keyword(s):  
High Speed ◽  
Thrust Bearing ◽  
Experimental Studies ◽  
Ambient Air ◽  
Outer Edge ◽  
Foil Thickness ◽  
Foil Bearings ◽  
Load Carrying ◽  
Turbo Machinery ◽  
Foil Thrust Bearing

Abstract. Foil bearings are self-acting hydrodynamics bearings used to support lightly loaded high speed rotating machinery. The advantages that they offer to process fluid lubricated machines usingworking fluid as a lubricant (ambient air) physically non-contacting high speed operation. Foil bearings have been considered as an alternative to conventional bearings with the capacity to cater for high-speeds and hostile environment (high temperature). However, the lack of load carrying capacity at relatively lower speeds limits their applications in heavy turbo machinery and as such are highly suitable in lightly loaded, high speed turbo machinery like small gas turbines.This paper discusses the design and assessment of dynamic characteristics in terms of load carrying capabilities as a function of speed, gap between the bearing and the runner as well as shape of foils for an air foil thrust bearing. The effects of various bearing parameters like foil thickness, number of foils fixed circumferentially and along the axis of rotation and with foil geometry configuration. Characteristics of performance defined essentially in terms of load carrying capabilities and static stiffness have been used for evaluation. Experiments were conducted both for angular foils (with inner edge height less than outer edge height) and square foils by varying number of foils. The experimental results shows that the effect of foil configuration enhances the load carrying capabilities of air foil thrust bearing.

Low-Friction Wear Resistant Coatings for High-Temperature Foil Bearings

2005 ◽  
Author(s):  
Hooshang Heshmat ◽  
Piotr Hryniewicz ◽  
James F. Walton ◽  
John P. Willis ◽  
Said Jahanmir
Keyword(s):  
High Temperature ◽  
High Speed ◽  
Tribological Behavior ◽  
Operating Conditions ◽  
Hard Coatings ◽  
Wear Resistant Coatings ◽  
Foil Bearings ◽  
Foil Bearing ◽  
Chrome Coating ◽  
Maximum Coefficient

Compliant foil bearings offer many advantages over rolling element bearings in high-speed and high-temperature applications. However, implementation of foil bearings in these applications requires development of solid lubricant coatings that can survive the severe operating conditions encountered at high speeds and high temperatures. The objective of this paper is to present results on development of an advanced coating system for use with compliant foil bearings that permits higher operating speeds and temperatures. In order to evaluate the coating performance and to select the best coating combination for implementation, a number tests were conducted using a high-temperature, high-speed tribometer up to 810 °C. Inconel test substrates, representative of a portion of a foil bearing, were coated with several different Korolon™ coatings. The counterface disks were coated with four different hard coatings. The test results confirmed the excellent tribological behavior of Korolon™ coatings for high-speed high-temperature foil bearing applications. While the tribological behavior of Korolon™ coatings were determined to be a function of temperature, in most cases a maximum coefficient of friction less than 0.1 was observed during startup/shutdown periods. Subsequently, a foil journal bearing was designed and a composite Korolon™ coating was applied to the bearing top foil; and a dense chrome coating was applied to the journal surface. The foil bearing was installed in a turbojet engine and operated successfully to 54,000 rpm for over 70 start-stop cycles.

Experimental and Numerical Investigation of the High-Speed Instability of Aerodynamic Foil Journal Bearings for Micro Turbomachinery

2012 ◽  
Author(s):  
Kei Somaya ◽  
Toru Yamashita ◽  
Shigeka Yoshimoto
Keyword(s):  
High Temperature ◽  
High Speed ◽  
First Generation ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Orbit Method ◽  
Foil Bearings ◽  
High Speeds ◽  
Foil Bearing ◽  
Excellent Stability

Foil bearings have been attracting considerable attention for their applications to micro turbomachinery, such as blowers and compressors, because of their excellent stability at high speeds and durability in high-temperature environments. This paper investigates experimentally and numerically the high-speed instability of a rotor supported by small aerodynamic foil journal bearings. Two types of foil journal bearings were prepared: a first-generation bump-type foil bearing and a dimple-type foil bearing; these consist of a top foil and a support foil with bumps or dimples, respectively. The dynamic characteristics of a support foil using the frequency response and the threshold speed of instability at high speeds were measured experimentally. Furthermore, the numerical threshold speed of instability was obtained using the nonlinear orbit method. It was confirmed experimentally and numerically that a 6 mm diameter rotor with a mass of 4.7 g supported by either of the two types of foil journal bearing treated in this paper could rotate stably at speeds of more than 760,000 rpm.

scholarly journals Application of Gas Foil Bearings in China

2021 ◽  
Vol 11 (13) ◽  
pp. 6210
Author(s):  
Yu Hou ◽  
Qi Zhao ◽  
Yu Guo ◽  
Xionghao Ren ◽  
Tianwei Lai ◽  
...  
Keyword(s):  
High Speed ◽  
Low Cost ◽  
Small Scale ◽  
Environmental Friendliness ◽  
Wear Resistant Coatings ◽  
Foil Bearings ◽  
Foil Bearing ◽  
Turbo Machinery ◽  
Principle Theory ◽  
Rotor Dynamic

Gas foil bearing has been widely used in high-speed turbo machinery due to its oil-free, wide temperature range, low cost, high adaptability, high stability and environmental friendliness. In this paper, state-of-the-art investigations of gas foil bearings are reviewed, mainly on the development of the high-speed turbo machinery in China. After decades of development, progress has been achieved in the field of gas foil bearing in China. Small-scale applications of gas foil bearing have been realized in a variety of high-speed turbo machinery. The prospects and markets of high-speed turbo machinery are very broad. Various high-speed turbomachines with gas foil bearings have been developed. Due to the different application occasions, higher reliability requirements are imposed on the foil bearing technology. Therefore, its design principle, theory, and manufacturing technology should be adaptive to new application occasions before mass production. Thus, there are still a number of inherent challenges that must be addressed, for example, thermal management, rotor-dynamic stability and wear-resistant coatings.

scholarly journals Application of multi-leaf foil bearings in high-speed turbo-machinery

2020 ◽  
Vol 14 (6) ◽  
pp. JAMDSM0085-JAMDSM0085
Author(s):  
Yu GUO ◽  
Yu HOU ◽  
Qi ZHAO ◽  
Xionghao REN ◽  
Tianwei LAI
Keyword(s):  
High Speed ◽  
Foil Bearings ◽  
Turbo Machinery

A Study on Low Velocity Impact Behaviour of Functionally Graded Sandwich Conical Shell Under Thermal Environment

2021 ◽  
Author(s):  
Apurba Das ◽  
Subhendu Pal ◽  
Gopal Agarwal ◽  
Kazuaki Inaba ◽  
Tripuresh Deb Singha ◽  
...  
Keyword(s):  
High Temperature ◽  
Outer Surface ◽  
High Speed ◽  
Operating Temperature ◽  
Functionally Graded ◽  
Low Velocity Impact ◽  
Potential Hazard ◽  
Low Velocity ◽  
Velocity Impact ◽  
Turbo Machinery

Abstract Turbo machinery rotating blades are a vital component of aero-engines for transferring the energy of gas flow to kinetic energy. Rotating turbo-machinery blades are prone to fail under working field with high temperature, high speed, high pressure and impact of blades. Recently Functionally graded materials (FGMs) are used in turbo-machinery blades due to its advantage of delamination and debonding free structure and ability to withstand high temperature during operation. As these aero-engine blade works in high temperature condition therefore use of ceramic FGM in the outer surface of the blades gives potential advantage. However, low velocity impact is a potential hazard of the blade due to rigid structure of the blade while considerable thickness of ceramic present in the outer surface of the blade. The chances of impact failure of the blade also increase in that case. Hence, low velocity impact of the turbo-machinery blades need to study carefully for safe and reliable operation of the engine. In this present work the low velocity impact characteristics of the FGM sandwich turbine blade under various operating temperature are determined using finite element technique. The low velocity impact performances are evaluated in terms of time histories of the contact force, velocity of the projectile, shell deflection and indentation considering various impactor initial velocities, core to FGM thickness ratio (hcore/hfgm) and blade operating temperature. The upper and lower surfaces of the functionally graded structure reinforced by ductile pure metal layers appear to play a significant role in protecting the structure’s functional integrity from damage.

Coatings for High Temperature Foil Bearings

2007 ◽  
Author(s):  
Hooshang Heshmat ◽  
Said Jahanmir ◽  
James F. Walton
Keyword(s):  
High Temperature ◽  
High Speed ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Turbine Engine ◽  
Foil Bearings ◽  
Limited Life ◽  
Wear Life ◽  
Tribological Coatings ◽  
Rolling Element

High operating speeds and temperatures required for advanced turbomachinery necessitate the development of bearings capable of continuous operation between 3 to 4 million DN at temperatures up to 820°C. Non-contact oil-free bearings such as compliant foil bearings, active magnetic bearings and hybrid foil and magnetic bearings are alternate solutions to the current liquid-lubricated hydrodynamic and rolling element bearings, which have limited life under these extreme conditions. A critical component in these oil-free bearings is the tribological coating system that must be used on the journal and the foil pads to ensure reliable operation during transient periods and start-stop cycles. The purpose of the present investigation was to assess the reliability of tribological coatings being implemented for a large (150 mm diameter) hybrid foil/magnetic bearing. In order to be suitable for use in large turbine engine type applications, the journal coating must accommodate the thermal and centrifugal growth experienced as well as providing the wear life and friction coefficient. Based upon the limitations identified in PS304, this coating is not yet suitable for demanding high temperature and high-speed applications. On the other hand an alternative nickel-chrome based coating applied to the foils versus a shaft with thin dense chrome or a nickel-chrome based coating a has shown excellent characteristics under conditions up to 820°C.

ALX ALLOY

Alloy Digest ◽  
1963 ◽  
Vol 12 (1) ◽  
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
High Speed ◽  
Heat Treating ◽  
Temperature Performance ◽  
Cobalt Base

Abstract ALX is a composition of nonferrous materials with a cobalt base containing chromium, tungsten and carbon. This alloy is commonly supplied in the cast-to-shape form, having an as-cast hardness of Rockwell C60-62 and requiring no further heat treatment. ALX is also supplied as cast tool bit material and is useful where conventional high-speed steels or carbides do not function effectively. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as casting, forming, heat treating, and machining. Filing Code: Co-35. Producer or source: Allegheny Ludlum Corporation.

CYCLOPS M4

Alloy Digest ◽  
1978 ◽  
Vol 27 (7) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Abrasion Resistance ◽  
High Speed ◽  
Heat Treating ◽  
Heavy Duty ◽  
Maximum Hardness ◽  
Temperature Performance ◽  
Sharp Edges ◽  
Normal Carbon

Abstract CYCLOPS M4 is a deep-hardening steel that was developed to utilize the excellent abrasion resistance that results from higher-than-normal carbon and vanadium contents in the molybdenum-tungsten family of high-speed steels. It is recommended for heavy-duty cutting operations and for sharp edges for fine cuts. Cyclops M4 should always be used at or near maximum hardness. This datasheet provides information on composition, physical properties, hardness, and elasticity. It also includes information on high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: TS-335. Producer or source: Cyclops Corporation.

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