On the Design of a Multi-Megawatt Oil-Free Centrifugal Compressor for Hydrogen Gas Transportation and Delivery: Operation Beyond Supercritical Speeds

2010 ◽  
Author(s):  
Hooshang Heshmat ◽  
Andrew Hunsberger ◽  
Zhaohui Ren ◽  
Said Jahanmir ◽  
James Walton
Keyword(s):  
Centrifugal Compressor ◽  
High Speed ◽  
System Analysis ◽  
Structural Integrity ◽  
Fluid Dynamic ◽  
Hydrogen Gas ◽  
Foil Bearings ◽  
Rotor Bearing ◽  
Cfd Analyses ◽  
Bearing System

Deployment of a safe, efficient hydrogen production and delivery infrastructure on a scale that can compete economically with current fuels is needed in order to realize the hydrogen economy. While hydrogen compression technology is crucial to pipeline delivery, positive displacement (PD) compressors are costly, have poor reliability and use oil, which contaminates the hydrogen. To overcome poor reliability of the PD compressor, duplicate units are installed but at substantial costs. A totally oil-free, high-speed, efficient centrifugal compressor using 4th generation compliant foil bearings and seals has been designed for hydrogen pipeline delivery. Using 6-12 megawatt drives operating at speeds to 56,000 rpm, a modular, double entry compressor was configured to deliver 500,000 kg/day at pressures greater than 8 MPa. Each of the two or three multi-stage compressor frames operate above its bending critical speed since speeds are 5 to 7 times faster than conventional compressors. To assure a structurally and economically feasible design, the rotor of each compressor spins at the same speed with blade tip velocities below 600 m/s. An iterative aerodynamic/structural/rotordynamic design process was used, including both quasi-three dimensional inviscid internal flow and Computational Fluid Dynamic (CFD) analyses. The flow field was carefully analyzed for areas of excessive diffusion, sudden velocity gradients and flow separation. Excellent correlation between the preliminary design and CFD analyses was obtained. Structural and rotor-bearing system dynamic analyses were also completed to finalize the compressor system configuration. Finite element analysis of the compressor impeller was used to verify structural integrity and fatigue limits for selected materials. Rotor-bearing system analysis was used to define acceptable bearing locations and dynamic coefficients, system critical speeds and dynamic stability. Given the high speeds, supercritical operation, and required reliability, efficiency and freedom from contaminants, compliant foil gas bearings were selected and designed. Since hydrogen will be used as the bearing lubricant for the foil bearings, substantially lower power loss than oil lubricated bearings will be experienced and the auxiliary supply or scavenge system is eliminated.

Foil Bearings Makes Oil-Free Turbocharger Possible

2005 ◽  
Author(s):  
Crystal A. Heshmat ◽  
Hooshang Heshmat ◽  
Mark J. Valco ◽  
Kevin C. Radil ◽  
Christopher Della Corte
Keyword(s):  
High Speed ◽  
Solid Lubricant ◽  
Load Capacity ◽  
Maximum Load ◽  
Solid Lubricant Coating ◽  
Foil Bearings ◽  
Wide Range ◽  
Rotor Bearing ◽  
Component Development ◽  
Bearing System

This paper describes an oil-free, 150 Hp turbocharger that was successfully operated with compliant foil bearings in a range of pitch and roll angles, including vertical operation, thereby demonstrating its viability for aircraft applications. On a gas test stand the turbocharger was operated to 120,000 rpm, under extreme conditions. In addition, the compliant foil bearing-supported turbocharger successfully tolerated shock and vibration of 40 g. Advanced technologies have been applied to the second generation of this turbocharger, shown in Figure 1, including self acting, compliant foil hydrodynamic air bearings with advanced coatings capable, of operation above 815 °C (1500°F). Journal foil bearings with maximum load capacity up to 670 kPa (97 psi) were used in conjunction with thrust foil bearings capable of maximum loads to 570 kPa (83 psi). Bearing component development tests demonstrated 30,000 start stop cycles at 815 °C (1500°F) with a newly developed, solid lubricant coating, KOROLON™. KOROLON™ exhibits a coefficient of friction of less than 0.1 at a wide range of temperatures. Current-designed foil bearings with KOROLON™ have immensely decreased turbolag, allowing acceleration from rest to over 100,000 rpm in less than 2 seconds. Advanced bearing stiffness maintained rotor total axial end-to-end motion within 100 microns (0.004 inch). Total radial static and dynamic motion was controlled within 25 microns (0.001 inch). Development of this high speed turbomachine included bearing and solid lubricant component development tests, rotor-bearing dynamic simulator qualification and gas stand tests of the assembled turbocharger. Gas stand and simulator test results revealed stable bearing temperatures, low rotor vibrations, good shock tolerance and the ability of the rotor bearing system to sustain overspeed conditions beyond 120,000 rpm. This combination of component and integrated rotor-bearing system technology addresses many of the issues associated with application of compliant foil bearings to industrial compressors, blowers, and gas turbine engines, overcoming many of the inherently show-stopping and debilitating features of rolling element bearings, i.e., speed and temperature limitations.

Subsynchronous Vibrations in Rotating Machinery: Methodologies to Identify Potential Instability

2007 ◽  
Author(s):  
Rahul Kar ◽  
John Vance
Keyword(s):  
Phase Angle ◽  
High Speed ◽  
Fluid Dynamic ◽  
Dynamic Pressure ◽  
Rotating Machinery ◽  
Diagnostic Tools ◽  
Study Methods ◽  
Frequency Tracking ◽  
Rotor Bearing ◽  
Bearing System

Rotordynamic instability can be disastrous for the operation of high speed turbomachines in the industry. Most ‘instabilities’ are due to de-stabilizing cross coupled forces from variable fluid dynamic pressure around a rotor component, acting in the direction of forward whirl and causing subsynchronous orbiting of the rotor. However, all subsynchronous whirling are not unstable and methods to diagnose the potentially unstable kind from the benign are critical to the health of the rotor-bearing system. In this study, methods to demarcate between the two are detailed. Orbit shape, “frequency tracking” and agreement of subsynchronous frequencies with known eigenvalues are used as diagnostic tools. It is shown that a change in synchronous phase angle produced by de-stabilizing cross coupled forces can be used as a definitive indicator of incipient instability. Typical signatures of subharmonic vibrations induced from non-linear stiffness of the rotor- bearing system are examined analytically and through experiments.

scholarly journals Development and Application of Integrated Aerodynamic Protuberant Foil Journal and Thrust Bearing in Turboexpander

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Tianwei Lai ◽  
Yu Guo ◽  
Wei Wang ◽  
Yu Wang ◽  
Yu Hou
Keyword(s):  
High Speed ◽  
Least Square Method ◽  
Air Separation ◽  
Least Square ◽  
Thrust Bearings ◽  
Foil Bearings ◽  
Foil Bearing ◽  
Rotor Bearing ◽  
Speed Up ◽  
Bearing System

Foil bearing provides compliant support and moderate Coulomb friction for rotor-bearing system, which is conducive to stability and reliability of high speed rotating machinery. In this paper, both hydrodynamic lubricated foil journal and foil thrust bearings are applied in a 150 m3·h−1 turboexpander for air separation. In the bearings, protuberant foil is chosen as the supporting subfoil due to its merits of easy fabrication and assembly. Static loading and deflection of the bearings are tested, respectively, before integration into the turboexpander. Afterwards, the loading and deflection curves of the journal and thrust bearings are polynomial fitted using least-square method. Then, performance tests are carried out on the rotor-bearing system, including transient speed-up, high speed, and speed-down processes. In the tests, the turboexpander supported by the hydrodynamic foil bearings operates smoothly with repeatability. Maximal rotor speed of the turboexpander reaches 52000 rpm with hydrodynamic lubricated protuberant foil bearings.

Oil-Free Turbocharger Demonstration Paves Way to Gas Turbine Engine Applications

2000 ◽  
Author(s):  
Hooshang Heshmat ◽  
James F. Walton ◽  
Christopher Della Corte ◽  
Mark Valco
Keyword(s):  
Gas Turbine ◽  
High Speed ◽  
Foil Bearings ◽  
Foil Bearing ◽  
Rotor Bearing ◽  
Component Development ◽  
Solid Film ◽  
Dynamic Simulator ◽  
Bearing Loads ◽  
Bearing System

An oil-free, 150 Hp turbocharger was successfully operated to 100% speed (95,000 rpm), with turbine inlet temperatures to 650°C on a turbocharger gas test stand. Development of this high speed turbomachine included bearing and lubricant component development tests, rotor-bearing dynamic simulator qualification and gas stand tests of the assembled turbocharger. Self acting, compliant foil hydrodynamic air bearings capable of sustained operation at 650°C and maximum loads to 750 N were used in conjunction with a newly designed shaft and system center housing. Gas stand and simulator test results revealed stable bearing temperatures, low rotor vibrations, good shock tolerance and the ability of the rotor bearing system to sustain overspeed conditions to 121,500 rpm. Bearing component development tests demonstrated 100,000 start stop cycles at 650°C with a newly developed solid film lubricant coating. In a separate demonstration of a 100 mm compliant foil bearing, loads approaching 4,500 N were supported by a compliant foil bearing. This combination of component and integrated rotor-bearing system technology demonstrations addresses many of the issues associated with application of compliant foil bearings to gas turbine engines.

Improving a one-dimensional centrifugal compressor performance prediction method

2005 ◽  
Vol 219 (8) ◽  
pp. 653-659 ◽  
Author(s):  
E Swain
Keyword(s):  
Centrifugal Compressor ◽  
Performance Prediction ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Prediction Method ◽  
Compressor Cascade ◽  
One Dimensional ◽  
Compressor Performance ◽  
Cfd Analyses

A one-dimensional centrifugal compressor performance prediction technique that has been available for some time is updated as a result of extracting the component performance from three-dimensional computational fluid dynamic (CFD) analyses. Confidence in the CFD results is provided by comparison of overall performance for one of the compressor examples. The extracted impeller characteristic is compared with the original impeller loss model, and this indicated that some improvement was desirable. The position of least impeller loss was determined using a traditional axial compressor cascade method, and suitable algebraic expressions were derived to match the CFD data. The merit of the approach lies with the relative ease that CFD component performance currently can be achieved and adjusting one-dimensional methods to agree with the CFD-derived models.

Rotordynamic Performance of a Shaft With Large Overhung Mass Supported by Foil Bearings

2016 ◽  
Vol 139 (4) ◽  
Author(s):  
Nguyen LaTray ◽  
Daejong Kim
Keyword(s):  
High Speed ◽  
Foil Bearings ◽  
Speed Test ◽  
Foil Bearing ◽  
Stable Conditions ◽  
Bending Mode ◽  
Mode Vibration ◽  
Lift Off ◽  
Compact Design ◽  
Bearing System

This work presents the theoretical and experimental rotordynamic evaluations of a rotor–air foil bearing (AFB) system supporting a large overhung mass for high-speed application. The proposed system highlights the compact design of a single shaft rotor configuration with turbomachine components arranged on one side of the bearing span. In this work, low-speed tests up to 45 krpm are performed to measure lift-off speed and to check bearing manufacturing quality. Rotordynamic performance at high speeds is evaluated both analytically and experimentally. In the analytical approach, simulated imbalance responses are studied using both rigid and flexible shaft models with bearing forces calculated from the transient Reynolds equation along with the rotor motion. The simulation predicts that the system experiences small synchronous rigid mode vibration at 20 krpm and bending mode at 200 krpm. A high-speed test rig is designed to experimentally evaluate the rotor–air foil bearing system. The high-speed tests are operated up to 160 krpm. The vibration spectrum indicates that the rotor–air foil bearing system operates under stable conditions. The experimental waterfall plots also show very small subsynchronous vibrations with frequency locked to the system natural frequency. Overall, this work demonstrates potential capability of the air foil bearings in supporting a shaft with a large overhung mass at high speed.

Vibration Signature Analysis of a Rotor Bearing System Using Response Surface Method

2009 ◽  
Author(s):  
P. K. Kankar ◽  
Satish C. Sharma ◽  
S. P. Harsha
Keyword(s):  
Response Surface ◽  
Response Surface Method ◽  
High Speed ◽  
Vibration Response ◽  
Radial Clearance ◽  
System Response ◽  
Surface Waviness ◽  
Surface Method ◽  
Rotor Bearing ◽  
Bearing System

The vibration response of a rotor bearing system is extremely important in industries and is challenged by their highly non-linear and complex properties. This paper focuses on performance prediction using response surface method (RSM), which is essential to the design of high performance rotor bearing system. Response surface method is utilized to analysis the effects of design and operating parameters on the vibration response of a rotor-bearing system. A test rig of high speed rotor supported on rolling bearings is used. Vibration response of the healthy ball bearing and ball bearings with various faults are obtained and analyzed. Distributed defects are considered as surface waviness of the bearing components. Effects of internal radial clearance and surface waviness of the bearing components and their interaction are analyzed using design of experiment (DOE) and RSM.

Hybrid composite shaft of High-Speed Rotor-Bearing System - A rotor dynamics preview

2020 ◽  
pp. 1-23
Author(s):  
Thimothy Harold Gonsalves ◽  
Mohan Kumar Garje Channabasappa ◽  
Ramesh Motagondanahalli Rangarasaiah
Keyword(s):  
Hybrid Composite ◽  
High Speed ◽  
Rotor Dynamics ◽  
System A ◽  
Composite Shaft ◽  
Rotor Bearing ◽  
Bearing System

The Role of High Performance Foil Bearings in an Advanced, Oil-Free, Integral Permanent Magnet Motor Driven, High-Speed Turbo-Compressor Operating Above the First Bending Critical Speed

2002 ◽  
Author(s):  
E. E. Swanson ◽  
H. Heshmat ◽  
J. S. Shin
Keyword(s):  
Permanent Magnet ◽  
High Speed ◽  
High Performance ◽  
Critical Speed ◽  
Elevated Temperatures ◽  
Development Program ◽  
Permanent Magnet Motor ◽  
Foil Bearings ◽  
Turbo Compressor ◽  
Bearing System

The demand for high power density, reliable, low maintenance, oil-free turbomachinery imposes significant demands on the bearing system. The full benefits of high speed, permanent magnet driven machines, for example are realized at speeds exceeding the capabilities of rolling element bearings. The high speeds, and a desire for oil-free operation also make conventional liquid lubricated bearings an undesirable alternative. The modern, oil-free foil bearing provides an excellent alternative, providing low power loss, adequate damping for supercritical operation, tolerance of elevated temperatures and long life. In this paper, the application of modern foil bearings to a high speed, oil-free turbo-compressor is discussed. In this demanding application, foil bearings support a 24 pound, multi-component rotor operating at 70,000 RPM with a bending critical speed of approximately 43,000 RPM. Stable and reliable operation over the full speed range has been demonstrated. This application also required low bearing start-up torque for compatibility with the constant torque characteristic of the integral permanent magnet motor. This work discusses the rotor bearing system design, the development program approach, and the results of testing to date. Data for both a turbine driven configuration, as well as a high speed integral motor driven configuration are presented.

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