An Adaptive Squeeze-Film Bearing

1984 ◽  
Vol 106 (1) ◽  
pp. 145-151 ◽  
Author(s):  
C. R. Burrows ◽  
M. N. Sahinkaya ◽  
O. S. Turkay
Keyword(s):  
Computer Simulation ◽  
Vibration Control ◽  
Mass Distribution ◽  
Squeeze Film ◽  
Shaft Length ◽  
Squeeze Film Damper ◽  
Oil Supply ◽  
Supply Pressure ◽  
Transmission Shaft

This paper examines the effect of controlling the oil supply pressure to squeeze-film bearings in applications where these elements are used to provide damping for a light flexible transmission shaft having an arbitrary unbalance mass distribution. The shaft length and diameter selected for the study are typical of those used for helicopter tail rotor transmissions. A computer simulation is undertaken to study the effect of a squeeze-film damper located at: 1) The end supports. 2) Mid-span with undamped end supports. 3) Mid-span with damped end supports. The simulation shows that in this type of application, good vibration control can be achieved by using a squeeze-film damper which is capable of switching between two levels of damping. The feasibility of attaining such a characteristic is examined experimentally.

Study of Static Fluid Forces in a Squeeze Film Damper with a Circumferential Groove

1995 ◽  
Vol 209 (4) ◽  
pp. 263-274
Author(s):  
J X Zhang
Keyword(s):  
Fluid Pressure ◽  
Squeeze Film ◽  
Fluid Inertia ◽  
Traditional Use ◽  
Fluid Force ◽  
Squeeze Film Damper ◽  
Fluid Forces ◽  
Supply Pressure ◽  
Static Fluid ◽  
Approximate Expressions

Approximate expressions are obtained for static fluid pressure and force for a centrally grooved squeeze film damper (SFD) resting at an equilibrium position without vibration. The analysis shows that, to some extent, grooved SFDs may share some characteristics with hydrostatic bearings, due to the existence of the lubricant supply pressure. Thus static fluid force and hence oil stiffness may exist in SFDs, in addition to the conventional inertial and damping coefficients for SFDs. This paper is solely focused on the static fluid forces and oil stiffness generated in an SFD with a finite length groove. Flow continuity is used at the centre of the groove, which takes into account the effects of the inlet oil flowrate and oil supply pressure. This use of flow continuity differs substantially from the traditional use of constant pressure in the central groove, and it provides better results. At the interface between the groove and the thin film land, a step bearing model with ignored fluid inertia is employed. It is verified by both the theory and previous experiments that the static fluid force and stiffness are linearly proportional to both the lubricant supply pressure and the eccentricity ratio of the SFD journal.

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.

Identification of Non-Linear Force Coefficients for the Radial Motion of a Squeeze Film Damper

1994 ◽  
Vol 208 (4) ◽  
pp. 235-245 ◽  
Author(s):  
J X Zhang ◽  
J B Roberts
Keyword(s):  
Experimental Data ◽  
Linear Model ◽  
Radial Motion ◽  
Squeeze Film ◽  
Static Force ◽  
Fluid Force ◽  
Squeeze Film Damper ◽  
Force Coefficients ◽  
Supply Pressure ◽  
Non Linear

The fluid force generated in a squeeze film damper undergoing large amplitude radial motion is described in terms of non-linear hydrodynamic inertial and damping coefficients, together with afluid static force. Linear-in-the-parameter polynomial forms are introduced to represent the variation of these contributions with radial position. A generalized state variable filter identification method is developed which enables all the parameters in the non-linear model to be estimated from experimental data. The method is validated by processing simulated data and then applied to some new experimental data. Experimental results, relating to the influence of the supply pressure and the operating frequency on the coefficients, are presented and discussed. Comparisons are made with corresponding predictions derived from existing lubrication theory. The parametric non-linear model is found to give a good fit to experimental data over a significant region within the vicinity of the initial static equilibrium position. Through a combination of results, the variation of the fluid force coefficients and the fluid static force with eccentricity, over nearly the whole range of the radial clearance, is obtained. Temporal inertia is found to be more important than convective inertia for motion near the centre of the clearance circle. The existence of a fluid static force, suggested by previous work is confirmed. It is found that this force is linearly proportional to the oil supply pressure.

scholarly journals Elastomer Damper Performance: A Comparison With a Squeeze Film for a Supercritical Power Transmission Shaft

1980 ◽  
Author(s):  
E. S. Zorzi ◽  
G. Burgess ◽  
R. Cunningham
Keyword(s):  
Critical Power ◽  
Power Transmission ◽  
Squeeze Film ◽  
Squeeze Film Damper ◽  
Operating Range ◽  
Transmission Shaft ◽  
Bending Mode ◽  
Squeeze Film Dampers ◽  
Design And Testing

This paper describes the design and testing of an elastomer damper on a super-critical power transmission shaft. The elastomers were designed to provide acceptable operation through the fourth bending mode and to control synchronous as well as nonsynchronous vibration throughout the operating range. The design of the elastomer was such that it could be incorporated into the system as a replacement for a squeeze-film damper without a reassembly, which could have altered the imbalance of the shaft. This provided a direct comparison of the elastomer and squeeze-film dampers without having to assess the effect of shaft imbalance changes.

Electro-Rheological Multi-layer Squeeze Film Damper and Its Application to Vibration Control of Rotor System

1999 ◽  
Vol 122 (1) ◽  
pp. 7-11 ◽  
Author(s):  
Yao Guozhi ◽  
Yap Fook Fah ◽  
Chen Guang ◽  
Meng Guang ◽  
Fang Tong ◽  
...  
Keyword(s):  
Vibration Control ◽  
Large Amplitude ◽  
Critical Speed ◽  
Reynolds Equation ◽  
Control Method ◽  
Rotor System ◽  
Squeeze Film ◽  
Squeeze Film Damper ◽  
Unbalance Response ◽  
Er Damper

In this paper, a new electro-rheological multi-layer squeeze film damper (ERMSFD in short) is designed first and the constitutional Reynolds equation is established. Then the behavior of the rotor system is analyzed, the vibration around the first critical speed is suppressed and an on/off control is proposed to control the large amplitude around the first critical speed. A control method is used to suppress the sudden unbalance response. Finally, experiments are carried out to investigate the behavior of the rotor system to prove the effectiveness of the ER damper to suppress the vibration around the critical speed and the sudden unbalance response. [S0739-3717(00)00301-9]

Experimental Investigation on the Dynamic Pressure and Force Response of a Partially Sealed Squeeze Film Damper

1991 ◽  
Author(s):  
G. Meng ◽  
L. A. San Andres ◽  
J. M. Vance
Keyword(s):  
Rotational Speed ◽  
Dynamic Pressure ◽  
Tangential Force ◽  
Radial Force ◽  
Squeeze Film ◽  
Damping Force ◽  
Film Pressure ◽  
Squeeze Film Damper ◽  
Fluid Forces ◽  
Supply Pressure

Abstract The influence of rotational speed, oil temperature and supply pressure on the squeeze film pressure and fluid forces is investigated experimentally for a partially sealed squeeze film damper (SFD) test rig executing circular centered orbits. Experimental Tesults show that the sealed damper produces higher damping forces than an open end SFD, though it is more prone to produce oil cavitation. As a result, the peak-to-peak pressures and the tangential force (damping force) decrease with increasing rotational speed; while, the radial force (stiffhening force) becomes negative due to the large extent of the cavitation zone. The tangential force decreases and the radial force increases with increasing lubricant temperature. The squeeze film pressure and film force increase as the supply pressure rises. The film cavitation onset is determined by the level of supply pressure and rotational speed.

An Appraisal of a Proposed Active Squeeze Film Damper

1991 ◽  
Vol 113 (4) ◽  
pp. 750-754 ◽  
Author(s):  
C. Mu ◽  
J. Darling ◽  
C. R. Burrows
Keyword(s):  
Theoretical Model ◽  
Vibration Control ◽  
Numerical Experiments ◽  
Squeeze Film ◽  
Radial Clearance ◽  
Flexible Rotor ◽  
Oil Film ◽  
Squeeze Film Damper

A theoretical model for an active squeeze film damper (SFD) is introduced. The design makes it possible to change the radial clearance and land length of the SFD by adjusting the position of the damper ring. Expressions for the oil film forces are obtained. The vibration control of a flexible rotor is taken as an example of the application of the new design. The possibility of controlling rotor vibrations is demonstrated by means of numerical experiments.

Experimental Behavior of a Short Cylindrical Squeeze Film Damper Executing Circular Centered Orbits

1994 ◽  
Vol 116 (3) ◽  
pp. 528-534 ◽  
Author(s):  
J. Zhang ◽  
J. B. Roberts ◽  
J. Ellis
Keyword(s):  
Algebraic Method ◽  
Squeeze Film ◽  
Fluid Inertia ◽  
Circular Orbits ◽  
Fluid Force ◽  
Squeeze Film Damper ◽  
Supply Pressure ◽  
Experimental Behavior ◽  
Applied Forces ◽  
Total Fluid

The experimentally determined behavior of a short radial squeeze-film damper with no end seals, executing circular centered orbits, is discussed. Accurate circular orbits were achieved, for ε values in the range 0.1 and 0.8, by using digitally generated signals to drive two electromagnetic shakers. Radial and tangential dynamic fluid force coefficients were estimated from measurements of the applied forces and the orbit radii, using a simple algebraic method. Cavitation was found to occur when ε exceeded 0.5, at large orbit frequencies, and was the cause of an observed jump-up phenomenon. The magnitude of an oil stiffness effect, previously reported by the authors and confirmed by the present results, was found to depend significantly on the oil supply pressure. Its contribution to the total fluid force was of the same order as that from fluid inertia, in the case of small orbits (ε ≪ 1).

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