In Situ Estimation of the Dynamic Characteristics of an Uncavitated Squeeze-Film Damper

1988 ◽  
Vol 110 (1) ◽  
pp. 162-166
Author(s):  
C. R. Burrows ◽  
M. N. Sahinkaya ◽  
N. C. Kucuk ◽  
M. L. Tong
Keyword(s):  
Frequency Domain ◽  
Dynamic Characteristics ◽  
Estimation Algorithm ◽  
Squeeze Film ◽  
Oil Film ◽  
Squeeze Film Damper ◽  
Damping Coefficients ◽  
Theoretical Predictions

A modified form of the author’s frequency-domain estimation algorithm has been applied to estimate the inertia and damping coefficients of an uncavitated squeeze-film bearing. These estimates are obtained in situ from measurements on a specially designed rig. The experiments provided further evidence that oil-film inertia coefficients may be significant and showed that theoretical predictions are inadequate.

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.

Effect of flight/structural parameters and operating conditions on dynamic behavior of a squeeze-film damped rotor system during diving–climbing maneuver

2020 ◽  
pp. 095441002094261
Author(s):  
Xi Chen ◽  
Xiaohua Gan ◽  
Guangming Ren
Keyword(s):  
Dynamic Characteristics ◽  
Rotor System ◽  
Elastic Support ◽  
Outer Ring ◽  
Squeeze Film ◽  
Inertial Forces ◽  
Oil Film ◽  
Maneuvering Flight ◽  
Mass Unbalance ◽  
Static Eccentricity

During aircraft maneuvering flights, engine's rotor-bearing systems are subjected to parametric excitations and additional inertial forces, which may cause severe vibration and abnormal operation. Based on Lagrange's principle combined with finite element modeling, the differential equations of motion for a squeeze film damped rotor-bearing system mounted on an aircraft in maneuvering flight are derived. Using Newmark–Hilber–Hughes–Taylor integration method, dynamic characteristics of the nonlinear rotor system under maneuvering flight are investigated. The factors are considered, involving mass unbalance, oil–film force, gravity, parametric excitations and additional inertial forces, and instantaneous static eccentricity of journal induced by maneuvering loads. The effects of forward velocity, radius of curvature, rotating speed, mass unbalance, oil–film clearance, and elastic support stiffness on transient responses of rotor system are discussed during diving–climbing maneuver. The results indicate that when the aircraft performs a diving–climbing maneuver in the vertical plane, the journal deviates from the center of oil–film outer ring, and the excursion direction of whirl orbit is determined by centrifugal acceleration and additional gyroscopic moment. The journal whirls asynchronously around the instantaneous static eccentricity and its magnitude is related to the maneuvering loads and the supporting stiffness. Increasing forward velocity or decreasing pitching radius, the rotor vibration will enter earlier into or withdraw later from the relatively large eccentricity. Rotating near critical speeds or excessive mass unbalances should be prevented during maneuvering flights. For large maneuver, the oil–film radial clearance needs to be enlarged properly to avoid hard contact between journal and outer ring. In addition, the stiffness of elastic support needs to be appropriately determined for damping performance. Overall, it provides a flexible approach with good expandability to predict dynamic characteristics of on-board squeeze-film damped rotor system during maneuvering flights in the design process.

The Control of Engine Vibration Using Squeeze Film Dampers

1983 ◽  
Vol 105 (3) ◽  
pp. 525-529 ◽  
Author(s):  
R. Holmes
Keyword(s):  
Experimental Work ◽  
Squeeze Film ◽  
Vibration Isolator ◽  
Squeeze Film Damper ◽  
Engine Vibration ◽  
Transmitted Force ◽  
Squeeze Film Dampers ◽  
Jump Phenomena ◽  
Theoretical Predictions ◽  
In Series

This paper describes the following roles of a squeeze-film damper when used in gas turbine applications as a means of reducing vibration and transmitted force due to unbalance: (a) as an element in parallel with a soft spring in a vibration isolator; and (b) as an element in series with the stiffness of the engine pedestal. The effects of cavitation on performance are elucidated, and the dangers of jump phenomena and subsynchronous response are discussed. Experimental work is described in which both roles of the squeeze-film damper are investigated and the results are compared with theoretical predictions.

Identification of the Dynamic Characteristics of Long Annular Seals Using a Time Domain Technique

1998 ◽  
Vol 120 (3) ◽  
pp. 705-712 ◽  
Author(s):  
M. Ismail ◽  
R. D. Brown
Keyword(s):  
Dynamic Characteristics ◽  
Time Domain ◽  
Theoretical Models ◽  
Rotational Frequency ◽  
Singular Value Decomposition Method ◽  
Damping Coefficients ◽  
Theoretical Predictions ◽  
The Time Domain ◽  
Value Decomposition ◽  
Annular Seals

This paper describes experimental results from a research program aimed at a study of the static and dynamic characteristics of liquid long annular seals. A seal test rig permits the identification in the time domain of mass, stiffness, and damping coefficients using a least-squares technique based on the singular value decomposition method. The experimental method relies on the forced excitation of a flexibly supported stator by two hydraulic shakers. The forcing signal is composed from a small number of frequencies which are not related to the rotational frequency of the rigid shaft rotating inside the stator. The test data consisting of two inertia, four stiffness, and four damping coefficients is compared with theoretical predictions based on two theoretical models: (i) the model of Black et al. (1971 and 1981) and (ii) the model of Childs and Kim (1985).

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.

Sealing Effect on the Performance of Squeeze Film Damper

2009 ◽  
Author(s):  
Changhu Xing ◽  
Minel J. Braun ◽  
Hongmin Li
Keyword(s):  
Pressure Distribution ◽  
Finite Volume ◽  
Piston Ring ◽  
Hydrodynamic Forces ◽  
Squeeze Film ◽  
Squeeze Film Damper ◽  
Damping Coefficients ◽  
End Plate ◽  
Inertia Coefficient ◽  
Ring Seal

Seals used in the squeeze film damper restrict the side leakage of the lubricant, thus providing a measure of additional damping. In this paper, the serrated piston ring and end-plate seals are studied numerically using CFD-ACE+, a commercially available finite volume based algorithm. Research shows that the damping coefficients for the piston ring seal decrease in magnitude with the increase in the number of axial grooves in the circumferential direction until they reach a fairly constant value. However, the pressure distribution and hence the hydrodynamic forces are strongly affected by the number and geometry of the axial grooves. The damping coefficients for the end plate seal increase in magnitude rapidly with the decrease of the seal clearance below the clearance of the damper, but increase slowly when the seal clearance is larger than that of the damper. The direct inertia coefficient increases with the decrease in the seal clearance but the magnitude of cross-coupled inertia coefficients increases with the decrease in the seal clearance, and then falls down towards the values for the infinitely long bearing assumption. Both the damping and inertia coefficients increase with the increase in seal length.

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