Experimental Investigation of Squeeze Film Damper Characteristics at High Speed Rotor Configurations

2014 ◽  
Author(s):  
Jayaraman Kandasamy ◽  
B. L. Jaiswal ◽  
P. Sarasu ◽  
S. Sivaperumal ◽  
Dilli Babu ◽  
...  
Keyword(s):  
High Speed ◽  
High Performance ◽  
Critical Speed ◽  
Advanced Materials ◽  
Squeeze Film ◽  
Test Rig ◽  
Variable Frequency Drive ◽  
Squeeze Film Damper ◽  
Essential Components ◽  
Turbo Machinery

High performance turbo machinery demands high shaft speeds, increased rotor flexibility, tighter clearances in flow passages, advanced materials, and increased tolerance to imbalances. Operation at high speeds induces severe dynamic loading with large amplitude journal motions at the bearing supports. Squeeze film dampers are essential components of high-speed turbo machinery since they offer the unique advantages of dissipation of vibration energy and isolation of structural components, as well as the capability to improve the dynamic stability characteristics of inherently unstable rotor-bearing systems. A bearing test rig is developed using 350 KW motor with variable frequency drive and has the potential of maximum operating speed up to 20,000 rpm. A squeeze film damper is used between the bearings and housing to reduce the unbalance forces transmitted to the pedestal by introducing an additional damping and thereby reduces the amplitude of vibration to acceptable level. The test rig instrumentation is capable of detecting bearing critical speed of the test rotor, and has been used for parametric studies and to monitor the temperature profile, vibration levels and pressure distribution of SFD oil film. The first critical speed of the test rotor is measured. The vibration level of the rotor system is increased with the rise of axial load together with speed. It is estimated that under all the conditions presence of oil in SFD zone reduces the vibration levels.

A System to Measure the Response of a High-Speed Rotor to a Sudden Imbalance

1981 ◽  
Author(s):  
R. J. Trippett
Keyword(s):  
High Speed ◽  
Dynamic Test ◽  
Data Acquisition System ◽  
Squeeze Film ◽  
Sudden Increase ◽  
Test Rig ◽  
Dynamic Data ◽  
Squeeze Film Damper ◽  
Rotor Dynamic ◽  
Dynamic Data Acquisition

A unique rotor dynamic data acquisition system is described to control the gathering and display of rotor displacement data measured at rotor speeds up to 70 000 r/min. The first published results measured with this system are demonstrated with plots of measured transient shaft motion after a sudden increase in shaft imbalance at speeds up to 44 500 r/min. The displacements of the rotor in the forms of Lissajous plots with and without a squeeze film damper are presented at four axial shaft locations below and above the shafts critical speeds. The blade-loss, dynamic test rig is also described.

Experimental research on suppressing unbalanced vibration of rotor by integral squeeze film damper

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Wei Yan ◽  
Lidong He ◽  
Zhe Deng ◽  
Xingyun Jia
Keyword(s):  
Rotational Speed ◽  
Critical Speed ◽  
Structural Characteristics ◽  
Experimental Studies ◽  
Rotor System ◽  
Squeeze Film ◽  
Rigid Rotor ◽  
Flexible Rotor ◽  
Test Rig ◽  
Squeeze Film Damper

Abstract As a novel structural damper, the unique structural characteristics of the integral squeeze film damper (ISFD) solve the nonlinear problem of the traditional squeeze film damper (SFD), and it has good linear damping characteristics. In this research, the experimental studies of ISFD vibration reduction performance are carried out for various working conditions of unbalanced rotors. Two ball bearing-rotor system test rigs are built based on ISFD: a rigid rotor test rig and a flexible rotor test rig. When the rotational speed of rigid rotor is 1500 rpm, ISFD can reduce the amplitude of the rotor by 41.79%. Under different unbalance conditions, ISFD can effectively improve the different degrees of unbalanced faults in the rotor system, reduce the amplitude by 43.21%, and reduce the sensitivity of the rotor to unbalance. Under different rotational speed conditions, ISFD can effectively suppress the unbalanced vibration of rigid rotor, and the amplitude can be reduced by 53.51%. In the experiment of the unbalanced response of the flexible rotor, it is found that ISFD can improve the damping of the rotor system, effectively suppress the resonance of the rotor at the critical speed, and the amplitude at the first-order critical speed can be reduced by 31.72%.

scholarly journals Nonlinear Response and Stability of an Experimental Overhung Compressor Mounted With a Squeeze Film Damper

2020 ◽  
Author(s):  
William J. Gooding ◽  
Matthew A. Meier ◽  
Edgar J. Gunter ◽  
Nicole L. Key
Keyword(s):  
High Speed ◽  
Critical Speed ◽  
Test Facility ◽  
Squeeze Film ◽  
Stable Operation ◽  
Static Structure ◽  
Squeeze Film Damper ◽  
Inertial Interaction ◽  
Rolling Element ◽  
Shaft Deflection

Abstract This paper presents rotordynamic data obtained within a test facility studying the aerodynamics of a high-speed centrifugal compressor for aero-engine applications. The experimental overhung compressor is supported by two rolling element bearings. The compressor-end ball bearing is supported by an oil-fed squeeze film damper. After some period of operation, the compressor began to exhibit a unique nonlinear increase in the rotordynamic response followed by an unexpected subsynchronous whirl instability as the speed continued to increase. Finally, as the rotor speed was increased further, the rotor re-stabilized. A numerical model of the compressor system was created using a commercially available software suite. This model indicates the effective weight of the damper support has a significant effect on the frequency of the second critical speed. Increasing this weight causes the second critical speed, originally predicted at 35,200 RPM, to shift down to 15,650 RPM. This increase in the support weight is due to inertial interaction between the damper support and the surrounding static structure. The increased shaft deflection that occurs as the rotor passes through this shifted critical speed causes the damper to lockup, resulting in the increased response observed experimentally. At a slightly higher speed, Alford-type aerodynamic cross-coupling forces excite the two subsynchronous critical speeds. Finally, as the rotor departs from the second critical speed, the damper unlocks and is able to effectively suppress the Alford-type instabilities, allowing the rotor to return to stable operation.

Failure of a Test Rig Operating With Pressurized Gas Bearings: A Lesson on Humility

2015 ◽  
Author(s):  
Luis San Andrés ◽  
Michael Rohmer ◽  
Sangshin Park
Keyword(s):  
High Speed ◽  
High Performance ◽  
Critical Speed ◽  
Rocket Engine ◽  
Test Rig ◽  
Data Set ◽  
Gas Bearings ◽  
Thrust Bearings ◽  
Damped System ◽  
Rotor Bearing

Process fluid lubrication of rotating machinery offers advantage of compactness and efficiency while dispensing with complicated oil lubricant supply systems. Prior work in a dedicated test rig demonstrated the performance of water lubricated radial and thrust bearings into high speed and high load conditions. The application related to a high performance rocket engine turbo pump. The test rig was revamped to operate with gas bearings in a program aiming to measure the performance of gas thrust bearings. The gas bearings for lateral support of the rotor are of hybrid type (hydrostatic/hydrodynamic) with flexure pivots and multiple ports for inlet gas pressurization. The paper details the design of the flexure pivot bearings and predictions of the lateral rotordynamics of the rotor supported on the hybrid gas bearings. Troubleshooting operation of the test rotor supported on the novel gas bearings followed with preliminary runs with the bearings supplied with air at 7.9 bar, then 6.5 bar and at 5.1 bar, and shaft speeds to 25 krpm (surface speed=50 m/s). The data recorded showed a very lightly damped system with a critical speed at ∼6 krpm, and susceptible to excite sub synchronous whirl motions when operating above the first critical speed. Ignoring the initial warnings, the operator persisted in operating the rotor to a high speed of 28 krpm while lowering the air supply pressure to 5.1 bar into the bearings. Suddenly, the shaft experienced large amplitude sub synchronous whirl motions, contacted the bearings, and produced a catastrophic failure. The incident produced much damage including a broken coupling, a twisted rotor, sheared covers, and welded pads into the bearing casing. Post-mortem analysis shows the failure is due to a sub synchronous whirl instability of the first rigid body rotor-bearing mode also exacerbated by the rotor approaching second natural frequency of the rotor-bearing system. The rotordynamics model includes the rotor rigidly connected to a long quill shaft and coupling produces results in agreement with the last vibration data set acquired prior to the incident. The experience demonstrates the need for following proper operating procedures while also paying attention to early evidence that could have prevented the mishap.

Ball bearing turbocharger vibration management: application on high speed balancer

2020 ◽  
Vol 21 (6) ◽  
pp. 619
Author(s):  
Kostandin Gjika ◽  
Antoine Costeux ◽  
Gerry LaRue ◽  
John Wilson
Keyword(s):  
Dynamic Behavior ◽  
High Speed ◽  
Internal Combustion Engines ◽  
Ball Bearing ◽  
Squeeze Film ◽  
Design And Technology ◽  
Squeeze Film Damper ◽  
Damping Coefficients ◽  
Bearing Loads ◽  
Stiffness And Damping

Today's modern internal combustion engines are increasingly focused on downsizing, high fuel efficiency and low emissions, which requires appropriate design and technology of turbocharger bearing systems. Automotive turbochargers operate faster and with strong engine excitation; vibration management is becoming a challenge and manufacturers are increasingly focusing on the design of low vibration and high-performance balancing technology. This paper discusses the synchronous vibration management of the ball bearing cartridge turbocharger on high-speed balancer and it is a continuation of papers [1–3]. In a first step, the synchronous rotordynamics behavior is identified. A prediction code is developed to calculate the static and dynamic performance of “ball bearing cartridge-squeeze film damper”. The dynamic behavior of balls is modeled by a spring with stiffness calculated from Tedric Harris formulas and the damping is considered null. The squeeze film damper model is derived from the Osborne Reynolds equation for incompressible and synchronous fluid loading; the stiffness and damping coefficients are calculated assuming that the bearing is infinitely short, and the oil film pressure is modeled as a cavitated π film model. The stiffness and damping coefficients are integrated on a rotordynamics code and the bearing loads are calculated by converging with the bearing eccentricity ratio. In a second step, a finite element structural dynamics model is built for the system “turbocharger housing-high speed balancer fixture” and validated by experimental frequency response functions. In the last step, the rotating dynamic bearing loads on the squeeze film damper are coupled with transfer functions and the vibration on the housings is predicted. The vibration response under single and multi-plane unbalances correlates very well with test data from turbocharger unbalance masters. The prediction model allows a thorough understanding of ball bearing turbocharger vibration on a high speed balancer, thus optimizing the dynamic behavior of the “turbocharger-high speed balancer” structural system for better rotordynamics performance identification and selection of the appropriate balancing process at the development stage of the turbocharger.

scholarly journals The Damping Capacity of a Sealed Squeeze Film Bearing

1985 ◽  
Vol 107 (3) ◽  
pp. 411-418 ◽  
Author(s):  
M. M. Dede ◽  
M. Dogan ◽  
R. Holmes
Keyword(s):  
Theoretical Model ◽  
Gas Turbine ◽  
Squeeze Film ◽  
Damping Capacity ◽  
Test Rig ◽  
Squeeze Film Damper ◽  
Aero Engine

The purpose of this paper is to establish a theoretical model to represent a sealed squeeze-film damper bearing and to assess it against results from a test rig, simulating the essential features of a medium-sized gas turbine aero engine.

Validation of a squeeze-film-damper test rig by using multibody cosimulation

2014 ◽  
Vol 34 (3) ◽  
pp. 243-257 ◽  
Author(s):  
Steffen Jäger ◽  
Sabrina Vogel
Keyword(s):  
Squeeze Film ◽  
Test Rig ◽  
Squeeze Film Damper

Flow Visualization and Forces From a Squeeze Film Damper Operating With Natural Air Entrainment

2003 ◽  
Vol 125 (2) ◽  
pp. 325-333 ◽  
Author(s):  
Luis San Andre´s ◽  
Sergio E. Diaz
Keyword(s):  
High Speed ◽  
Air Entrainment ◽  
Squeeze Film ◽  
Natural Phenomenon ◽  
Squeeze Film Damper ◽  
Feed Pressure ◽  
Video Recordings ◽  
Free Air ◽  
Through Flow ◽  
Discharge Operation

Measurements of dynamic film pressures and high-speed photographs of the flow field in an open-ended Squeeze Film Damper (SFD) operating with natural free air entrainment are presented for increasing whirl frequencies (8.33–50 Hz), and a range of feed pressures to 250 kPa (37 psig). The flow conditions range from lubricant starvation (air ingestion) to a fully flooded discharge operation. The test dynamic pressures and video recordings show that air entrainment leads to large and irregular gas fingering and striation patterns. This is a natural phenomenon in SFDs operating with low levels of external pressurization (reduced lubricant through flow rates). Air ingestion and entrapment becomes more prevalent as the whirl frequency raises, and increasing the feed pressure aids little to ameliorate the loss in dynamic forced performance. As a result of the severity of air entrainment, experimentally estimated damping forces decrease steadily as the whirl frequency (operating speed) increases.

CFD Simulation of Air Ingestion in a Squeeze Film Damper

2019 ◽  
Author(s):  
Wang Yan ◽  
Li Xuesong ◽  
Li Yuhong
Keyword(s):  
High Performance ◽  
Cfd Simulation ◽  
Pressure Effect ◽  
Hydrodynamic Pressure ◽  
Squeeze Film ◽  
Rotor Vibration ◽  
Squeeze Film Damper ◽  
Bearing Clearance ◽  
Oil Flow ◽  
Computational Fluid Dynamics Cfd

Abstract Squeeze film damper (SFD) is widely adopted in the high performance rotor-bearing systems to eliminate rotor vibration and improve stability. Experiments show that the air ingestion from the open end would have notable impact on the SFD performance. Multiphase Computational Fluid Dynamics (CFD) calculation on the air ingestion in the SFD is conducted in this work. Results are validated with the experimental data to prove the capability of the multiphase CFD on predicting the air ingestion. Air and oil flow in the SFD are analyzed in details. By comparing the CFD results with and without air ingestion, the effect of air ingestion is revealed. Results show that CFD is capable of predicting the air-oil flow in the SFD. The maximum air region is located in the vicinity of the largest bearing clearance region rather than the low pressure zone. And air ingestion in the largest bearing clearance region counteracts the hydrodynamic pressure effect in the vicinity.

scholarly journals Research on Blade-Casing Rub-Impact Mechanism by Experiment and Simulation in Aeroengines

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Jie Hong ◽  
Tianrang Li ◽  
Zhichao Liang ◽  
Dayi Zhang ◽  
Yanhong Ma
Keyword(s):  
High Speed ◽  
High Performance ◽  
Element Model ◽  
Physical Parameters ◽  
Test Rig ◽  
Calculation Results ◽  
Rotor Support ◽  
Blade Tip ◽  
Set Up ◽  
The Impact

Aeroengines pursue high performance, and compressing blade-casing clearance has become one of the main ways to improve turbomachinery efficiency. Rub-impact faults occur frequently with clearance decreasing. A high-speed rotor-support-casing test rig was set up, and the mechanism tests of light and heavy rub-impact were carried out. A finite element model of the test rig was established, and the calculation results were in good agreement with the experimental results under both kinds of rub-impact conditions. Based on the actual blade-casing structure model, the effects of the major physical parameters including imbalance and material characteristics were investigated. During the rub-impact, the highest stress occurs at the blade tip first and then it is transmitted to the blade root. Deformation on the impact blade tip generates easily with decreased yield strength, and stress concentration at the blade tip occurs obviously with weaker stiffness. The agreement of the computation results with the experimental data indicates the method could be used to estimate rub-impact characteristics and is effective in design and analyses process.

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