Influence of bearing number on high speed air rotor bearing systems

2016 ◽  
Author(s):  
Kuo-Nan Yu ◽  
Chin-Tsung Hsieh ◽  
Cheng-Chi Wang ◽  
Her-Terng Yau ◽  
Ming-Jyi Jang
Keyword(s):  
High Speed ◽  
Rotor Bearing ◽  
Bearing Number

scholarly journals Model Adjustment of Small Rotors for High Speed Gas Turbines

1990 ◽  
Author(s):  
Alain Delbez ◽  
Christian Beth ◽  
Daniel Gay
Keyword(s):  
Gas Turbines ◽  
High Speed ◽  
Dynamic Behaviour ◽  
Design Stage ◽  
Rotor Bearing ◽  
Angular Velocities ◽  
Model Adjustment ◽  
Experimental Approaches

In this paper, we present the studies which are carried out at MICROTURBO relating to rotor-bearing systems mounted in small high speed gas turbines. These studies are based on both theoretical and experimental approaches, and are aimed at providing an improved prediction of the dynamic behaviour of rotors at the design stage, in particular the critical angular velocities and sensitivity to unbalance.

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.

scholarly journals Chaotic Behaviour Investigation of a Front Opposed-Hemispherical Spiral-Grooved Air Bearing System

2017 ◽  
Vol 2017 ◽  
pp. 1-18
Author(s):  
Cheng-Chi Wang
Keyword(s):  
High Speed ◽  
Critical Speed ◽  
Large Scale ◽  
Air Bearing ◽  
Severe Damage ◽  
Design Problems ◽  
Irregular Motion ◽  
Transformation Methods ◽  
Bearing Number ◽  
Bearing System

In recent years, spiral-grooved air bearing systems have attracted much attention and are especially useful in precision instruments and machines with spindles that rotate at high speed. Load support can be multidirectional and this type of bearing can also be very rigid. Studies show that some of the design problems encountered are dynamic and include critical speed, nonlinearity, gas film pressure, unbalanced rotors, and even poor design, all of which can result in the generation of chaotic aperiodic motion and instability under certain conditions. Such irregular motion on a large scale can cause severe damage to a machine or instrument. Therefore, understanding the conditions under which aperiodic behaviour and vibration arise is crucial for prevention. In this study, numerical analysis, including the Finite Difference and Differential Transformation Methods, is used to study these effects in detail in a front opposed-hemispherical spiral-grooved air bearing system. It was found that different rotor masses and bearing number could cause undesirable behaviour including periodic, subperiodic, quasi-periodic, and chaotic motion. The results obtained in this study can be used as a basis for future bearing system design and the prevention of instability.

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

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.

Comparison of Rotordynamic Analysis Predictions With the Test Response of Simple Gas Hybrid Bearings for Oil Free Turbomachinery

2003 ◽  
Author(s):  
Deborah A. Wilde ◽  
Luis San Andre´s
Keyword(s):  
High Speed ◽  
Natural Frequencies ◽  
Damping Ratio ◽  
Rotor Speed ◽  
Gas Bearings ◽  
Model Predictions ◽  
Rotor Bearing ◽  
Frequency Ratios ◽  
Bearing System ◽  
Good Agreement

Current applications of gas film bearings in high-speed oil-free micro-turbomachinery (<0.4 MW) require calibrated predictive tools to successfully deploy their application to mass-produced systems, for example oil-free turbochargers. The present investigation details the linear rotordynamic analysis of a test rotor supported on externally pressurized gas bearings. Model predictions are compared with the test rotordynamic response determined through comprehensive experiments conducted on a small rotor supported on three lobed hybrid (hydrostatic/hydrodynamic) rigid gas bearings. Predictions for the rotor-bearing system synchronous response to imbalance show good agreement with measurements during rotor coast downs, and manifest a decrease in damping ratio as the level of external pressurization increases. The rotor-bearing eigenvalue analysis forwards natural frequencies in accordance with the measurements, and null damping ratios evidence the threshold speeds of rotordynamic instability. Estimated whirl frequency ratios are typically 50% of rotor speed, thus predicting sub synchronous instabilities at lower rotor speeds than found experimentally when increasing the magnitude of feed pressurization. Rationale asserting the nature of the discrepancies calls for further analysis.

Theoretical and Experimental Studies on Squeeze Film Stabilizers for Flexible Rotor-Bearing Systems Using Newtonian and Viscoelastic Lubricants

1990 ◽  
Vol 112 (4) ◽  
pp. 473-482 ◽  
Author(s):  
B. Halder ◽  
A. Mukherjee ◽  
R. Karmakar
Keyword(s):  
High Speed ◽  
Experimental Studies ◽  
Squeeze Film ◽  
Experimental Investigations ◽  
Flexible Rotor ◽  
Stability Range ◽  
High Speeds ◽  
Flexible Rotors ◽  
Rotor Bearing

A combination of a squeeze film damper and a plane journal bearing is studied as a stabilizing scheme. The damper is made to play the role of a stabilizer to postpone the instability threshold speeds of flexible rotors. Both Newtonian and viscoelastic fluids are used in the rotor-bearing system. Dynamics of the system is theoretically analyzed using bond graphs. Analysis reveals that the use of a Newtonian fluid in the stabilizer largely improves the high speed stability range. However, viscoelastic stabilizing fluid has a detrimental effect on highly flexible rotors. Experimental investigations, conducted on a flexible rotor (natural frequency, 30 Hz), confirm the theoretical findings. In addition, experiments indicate that though the use of viscoelastic stabilizing fluids leads to instability in flexible rotors, the growth of large amplitude whirl is postponed to very high speeds.

Experimental and Numerical Studies on Spherical Roller Bearings Using Multivariable Regression Analysis

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
R. G. Desavale ◽  
R. Venkatachalam ◽  
S. P. Chavan
Keyword(s):  
Regression Analysis ◽  
Sugar Cane ◽  
High Speed ◽  
Roller Bearing ◽  
Vibration Characteristics ◽  
Multivariable Regression Analysis ◽  
Rotor Bearing ◽  
Multivariable Regression ◽  
Bearing Structure ◽  
Bearing System

Many industries make wide use of rotor bearing systems such as high speed turbines and generators. However, the vibration of antifriction rotor–bearings is a key factor in reducing the life of the bearings; thus significantly influencing the performance and working life of the whole power plant. In earlier research on the vibration characteristics of high speed rotor–bearing systems, such as in induced draft (ID) fans, an application used in sugar cane factories, the supporting antifriction bearings were simplified as a particle on a shaft with radial stiffness and damping coefficient. However, such simplification neglects the effects of the bearing structure on the vibration performance of the rotor–bearing system. This paper demonstrates the benefits of a more holistic approach and establishes a numerical model of the stiffness of the spherical roller bearing through Buckingham's π theorem (BPT). On the basis of this model, we argue for the benefits of a new dimensional analysis (DA) technique for rotor–bearing systems. Our new DA also considers the influences of the bearing structure parameters on the vibration of rotor–bearing systems. We demonstrate the effectiveness of our approach by conducting a comparative BPT study using an ID fan, a rotor–bearing system in use in sugar cane factories. We first analyzed an ID fan using the simplified model to obtain the defect frequencies and vibration amplitude responses of the ID fan system. Subsequently the same ID fan rotor was also analyzed using our new multivariable regression analysis (MVRA) approach to verify the validity of our new and holistic BPT. The results indicate that the new method we propose in this paper for the calculation of vibration characteristics of a high speed rotor–bearing (ID fan) is credible and will save time and costs by the accurate detection of imminent bearing failure.

Reliability Sensitivity Analyses for Oil Whip in Rotor-Bearing System

2012 ◽  
Vol 538-541 ◽  
pp. 1967-1970
Author(s):  
Chang Qing Su ◽  
Yi Yu Sun ◽  
Le Xin Li
Keyword(s):  
High Speed ◽  
Sensitivity Analyses ◽  
Analysis Method ◽  
Random Parameters ◽  
Work Condition ◽  
Oil Whip ◽  
Reliability Sensitivity ◽  
Rotor Bearing ◽  
The Common ◽  
Bearing System

Oil whip phenomenon is the common fault in rotor-bearing system. The reason why oil whip happens often has been researched in high-speed rotor-bearing system. But in practice engineering, due to the requirement of work condition, oil whip cannot be avoided all the time in rotor-bearing system. The paper is based on the relation criterion of oil whip happens in rotor-bearing system, the reliability mode and system reliability of oil whip are defined, and the reliability analysis method for avoiding oil whip in rotor-bearing system is carried out. The effect on reliability sensitivity of random parameters is studied. Numerical results are also presented and discussed.

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