Experimental Investigation of the Development of Cavitation in a Squeeze Film Damper

2010 ◽  
Author(s):  
Changhu Xing ◽  
Frank Horvat ◽  
Stefan Moldovan ◽  
Minel J. Braun
Keyword(s):  
High Speed ◽  
Dynamic Properties ◽  
Leaf Shape ◽  
Saturation Pressure ◽  
Angular Speed ◽  
Squeeze Film ◽  
Pressure Curve ◽  
Large Area ◽  
Squeeze Film Damper ◽  
Set Up

When cavitation takes place in the squeeze film damper (SFD), its types and extent affect the performance of the SFD significantly. Thus, a fundamental understanding of the incipience, formation and evolution of this phenomenon becomes important both for predicting the dynamic properties of the damper and for the practitioner designers. A test rig was set up to investigate the formation of the cavitation bubbles during the process of a steady-state operation. By adopting a crankshaft configuration, the SFD journal orbit can be fixed at a specified eccentricity. The journal position and its eccentricity are tracked by means of Bently proximity sensors. When cavitation takes place, its shape and evolution are recorded by a Photron APX-RS high speed camera. With the Dow Corning 200 lubricant, the gaseous bubbles form in a fern-leaf shape even at low whirling speed. The bubbles evolve to a miniature flattened shape and as the angular speed increases, the gaseous cavitation gives way or is joined by vaporous cavitation. With a further increase of whirling speed, the vaporous bubbles can be clearly seen to occupy a large area. The evolution of the cavitation can be explained by the Sommerfeld pressure curve as it relates to the gaseous and vaporous saturation pressure. The experimental results confirm the assumption made by these authors in the previous numerical simulations for the homogeneous cavitation models.

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.

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.

Inertia Effects in Squeeze-Film Damper Bearings Generated by Circumferential Oil Supply Groove

2001 ◽  
Author(s):  
Jørgen W. Lund ◽  
Claus M. Myllerup ◽  
Henning Hartmann
Keyword(s):  
Dynamic Properties ◽  
Bulk Flow ◽  
Squeeze Film ◽  
Perturbation Approach ◽  
Inertia Effects ◽  
Squeeze Film Damper ◽  
Oil Supply ◽  
Reaction Forces ◽  
Flow Approximation ◽  
Acceleration Term

Abstract The dynamic properties of an industrial Squeeze-Film Damper (SFD) bearing design are described using the well-known perturbation approach, where the reaction forces induced by small movements away from the position of equilibrium are expanded into a Taylor series in terms of displacement, velocity, and acceleration. Although generally negligible, the acceleration term can become significant in SFD bearings when inertia effects in the damper lands are enhanced by the flow in a central circumferential oil supply groove. By using a bulk flow approximation in the oil supply groove an explicit expression is derived for the acceleration term. Experimental results confirm the significance of the oil supply groove geometry and appear to validate the bulk flow approximation.

Experimental and Analytical Investigation of Hybrid Squeeze Film Dampers

1993 ◽  
Vol 115 (2) ◽  
pp. 353-359 ◽  
Author(s):  
A. El-Shafei
Keyword(s):  
High Speed ◽  
Extreme Case ◽  
Analytical Investigation ◽  
Rotating Machinery ◽  
Squeeze Film ◽  
Squeeze Film Damper ◽  
Controlling Mechanism ◽  
Squeeze Film Dampers ◽  
Oil Flow ◽  
Hybrid Damper

A new concept for actively controlling high-speed rotating machinery is investigated both analyically and experimentally. The controlling mechanism consists of a hybrid squeeze film damper (patent pending) that can be adaptively controlled to change its characteristics according to the instructions of a controller. In an extreme case the hybrid damper can act as a long damper, which is shown to be effective in reducing the amplitude of vibration of rotating machinery. In the other extreme the hybrid damper acts as a short damper, which is shown to be effective in reducing the force transmitted to the support. In the long damper configuration the oil flow is circumferential, while in the short damper configuration the oil flow is predominantly axial. The hybrid damper is designed to operate in either the short or the long damper configuration by controlling the positions of two movable sealing rings. The hybrid damper was tested on a Bently Nevada Rotor Kit and it is shown experimentally that the long damper configuration is extremely efficient at controlling the amplitude of vibration and the short damper configuration reduces the force transmitted to the support.

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.

Study of the Squeeze Film Damper of Larger Flow Rate High-Speed On/Off Valve

2011 ◽  
Vol 130-134 ◽  
pp. 594-598
Author(s):  
Hai Bing Jiang ◽  
Jian Ruan ◽  
Ming Ming Wu ◽  
Tao Wang
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Response Speed ◽  
Fast Response ◽  
Squeeze Film ◽  
Squeeze Film Damper ◽  
Perfect Performance ◽  
Sealing Performance ◽  
New Type ◽  
Off Time

A new type of squeeze film damper (SFD) is designed to reduce spool’s impact and vibration which happen in the two-stage larger flow rate high-speed on/off valve with the 450 L/min flow rate and 8ms turn-off time, the valve’s sealing performance、reliability and service life improve largely, and the valve’s response speed doesn’t drop. The simulated and experimental results show: The damper has optimum buffering performance when oil film thickness is 0.1mm, and the spool closing process approach ideal state. The valve will has a great potential application in the powerful occasions because of it's perfect performance: larger flow rate、fast response and novel damper.

Development of an Efficient Oil Film Damper for Improving the Control of Rotor Vibration

1991 ◽  
Vol 113 (4) ◽  
pp. 557-562 ◽  
Author(s):  
Shiping Zhang ◽  
Litang Yan
Keyword(s):  
High Speed ◽  
Porous Metal ◽  
Porous Matrix ◽  
Squeeze Film ◽  
Oil Film ◽  
Squeeze Film Damper ◽  
Outer Race ◽  
Typical Experiment ◽  
Stiffness And Damping ◽  
Film Stiffness

An efficient oil film damper known as a porous squeeze film damper (PSFD) was developed for more effective and reliable vibration control of high-speed rotors based on the conventional squeeze film damper (SFD). The outer race of the PSFD is made of permeable sintered porous metal materials. The permeability allows some of the oil to permeate into and seep out of the porous matrix, with remarkable improvement of the squeeze film damping properties. The characteristics of PSFD oil film stiffness and damping coefficients and permeability, and also, the steady-state unbalance response of a simple rigid rotor and flexible Jeffcott’s rotor supported on PSFD and SFD are investigated. A typical experiment is presented. Investigations show that the nonlinear vibration characteristics of the unpressurized SFD system such as bistable jump phenomena and “lockup” at rotor pin-pin critical speeds could be avoided and virtually disappear under much greater unbalance levels with properly designed PSFD system. PSFD has the potential advantage of operating effectively under relatively large unbalance conditions.

scholarly journals Analysis on Influences of Squeeze Film Damper on Vibrations of Rotor System in Aeroengine

2022 ◽  
Vol 12 (2) ◽  
pp. 615
Author(s):  
Haobo Wang ◽  
Yulai Zhao ◽  
Zhong Luo ◽  
Qingkai Han
Keyword(s):  
High Speed ◽  
Vibration Suppression ◽  
Rotor System ◽  
Operating Conditions ◽  
Squeeze Film ◽  
Lumped Mass ◽  
Squeeze Film Damper ◽  
Rotor Systems ◽  
Vibration Responses ◽  
Stiffness And Damping

Squeeze film damper (SFD) is widely used in the vibration suppression of aeroengine rotor systems, but will cause complex motions of the rotor system under specific operating conditions. In this paper, a lumped-mass dynamic model of the high-pressure rotor system in an aeroengine is established, and the nonlinear stiffness and damping formula of SFD are introduced into the above model. The vibration responses of the rotor system under different rotating speeds and with different unbalances are investigated numerically, and the influence of SFD on the rotor system vibration and the change of suppression ability are compared and analyzed. The results show that in the case of high speed, together with a small unbalance, the rotor system will perform a complex vibration or a bistable vibration due to SFD. If the unbalance is properly increased under the same case of high speed, the vibration of the rotor becomes single-harmonic and the bistable vibration disappears. The research results can provide a helpful reference for analyzing complex vibration mechanisms of the rotor system with SFD and achieving an effective vibration suppression through unbalance regulation.

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.

Squeeze film dampers supporting high-speed rotors: Rotordynamics

2020 ◽  
pp. 135065012092208
Author(s):  
Sina Hamzehlouia ◽  
Kamran Behdinan
Keyword(s):  
Finite Element ◽  
Steady State ◽  
Gas Turbines ◽  
High Speed ◽  
Squeeze Film ◽  
Jet Engines ◽  
Transient Vibration ◽  
Element Analysis ◽  
Squeeze Film Damper ◽  
The Time Domain

This work develops a finite element based multi-mass flexible rotor model for theoretical investigation of the influence of the squeeze film damper lubricant inertia on the unbalance-induced steady-state and transient vibration amplitudes of high speed turbomachinery. The rotordynamic model is developed by applying the principles of finite element analysis to discretize the rotor components, including the rotor shaft and disk, into local elements with mass, stiffness, and gyroscopic matrices. Subsequently, the local matrices are assembled together to develop the global model of the rotordynamic system. The influence of squeeze film damper lubricant inertia is incorporated into the model by using short-length cavitated damper models with retaining springs executing circular-centered orbits. Additionally, the rotordynamic model incorporating the nonlinear squeeze film damper models is iteratively solved in the time domain by applying a predictor-corrector transient modal integration numerical method and the steady-state and transient motions of the rotor system are investigated under different rotor and squeeze film damper parameters. The results of the study verify the substantial influence of squeeze film damper lubricant inertia on attenuating the vibrations of high-speed turbomachinery. Furthermore, the developed rotordynamic model delivers an efficient and powerful platform for the analysis of high-speed turbomachinery, including jet engines and gas turbines.

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