Squeeze Film Damper Suppression of Thermal Bow: Morton Effect Instability

2021 ◽  
Author(s):  
Dongil Shin ◽  
Alan Palazzolo ◽  
Xiaomeng Tong
Keyword(s):  
Squeeze Film ◽  
Squeeze Film Damper ◽  
Morton Effect

Squeeze Film Damper Suppression of Thermal Bow: Morton Effect Instability

2020 ◽  
Author(s):  
Dongil Shin ◽  
Alan B. Palazzolo ◽  
Xiaomeng Tong
Keyword(s):  
Squeeze Film ◽  
Viscous Heating ◽  
Fluid Inertia ◽  
Euler Beam ◽  
Nonlinear Simulation ◽  
Squeeze Film Damper ◽  
Morton Effect ◽  
Tilting Pad ◽  
Tilting Pad Journal Bearing ◽  
Rotor Model

Abstract The Morton Effect (ME) is a synchronous vibration problem in turbomachinery caused by the non-uniform viscous heating around the journal circumference, and its resultant thermal bow and ensuing synchronous vibration. This paper treats the unconventional application of the SFD for the mitigation of ME-induced vibration. Installing a properly designed squeeze film damper (SFD) may change the rotor’s critical speed location, damping and deflection shape, and thereby suppress the vibration caused by the ME. The effectiveness of the SFD on suppressing the ME is tested via linear and nonlinear simulation studies employing a 3D thermo-hydrodynamic (THD) tilting pad journal bearing, and a flexible, Euler beam rotor model. The example rotor model is for a compressor that experimentally exhibited an unacceptable vibration level along with significant journal differential heating near 8,000 rpm. The SFD model includes fluid inertia and is installed on the non-drive end bearing location where the asymmetric viscous heating of the journal is highest. The influence of SFD cage stiffness is evaluated.

Squeeze Film Damper Suppression of Thermal Bow-Morton Effect Instability

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Dongil Shin ◽  
Alan B. Palazzolo ◽  
Xiaomeng Tong
Keyword(s):  
Three Dimensional ◽  
Squeeze Film ◽  
Viscous Heating ◽  
Fluid Inertia ◽  
Euler Beam ◽  
Nonlinear Simulation ◽  
Squeeze Film Damper ◽  
Morton Effect ◽  
Tilting Pad Journal Bearing ◽  
Rotor Model

Abstract The Morton effect (ME) is a synchronous vibration problem in turbomachinery caused by the nonuniform viscous heating around the journal circumference, and its resultant thermal bow (TB) and ensuing synchronous vibration. This paper treats the unconventional application of the SFD for the mitigation of ME-induced vibration. Installing a properly designed squeeze film damper (SFD) may change the rotor's critical speed location, damping, and deflection shape, and thereby suppress the vibration caused by the ME. The effectiveness of the SFD on suppressing the ME is tested via linear and nonlinear simulation studies employing a three-dimensional (3D) thermohydrodynamic (THD) tilting pad journal bearing (TJPB), and a flexible, Euler beam rotor model. The example rotor model is for a compressor that experimentally exhibited an unacceptable vibration level along with significant journal differential heating near 8000 rpm. The SFD model includes fluid inertia and is installed on the nondrive end bearing location where the asymmetric viscous heating of the journal is highest. The influence of SFD cage stiffness is evaluated.

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 Influence of Eccentricity and Angular Velocity on Force Effects on Rotor of Magnetorheological Damper

2018 ◽  
Vol 180 ◽  
pp. 02091
Author(s):  
Dominik Šedivý ◽  
Petr Ferfecki ◽  
Simona Fialová
Keyword(s):  
Magnetic Induction ◽  
Magnetorheological Damper ◽  
Squeeze Film ◽  
Fluid Viscosity ◽  
Squeeze Film Damper ◽  
Viscous Forces ◽  
Angular Velocities ◽  
Volume Method ◽  
Gap Width ◽  
Made In

This article presents the evaluation of force effects on squeeze film damper rotor. The rotor is placed eccentrically and its motion is translate-circular. The amplitude of rotor motion is smaller than its initial eccentricity. The force effects are calculated from pressure and viscous forces which were measured by using computational modeling. Damper was filled with magnetorheological fluid. Viscosity of this non-Newtonian fluid is given using Bingham rheology model. Yield stress is not constant and it is a function of magnetic induction which is described by many variables. The most important variables of magnetic induction are electric current and gap width between rotor and stator. The simulations were made in finite volume method based solver. The motion of the inner ring of squeeze film damper was carried out by dynamic mesh. Numerical solution was solved for five different initial eccentricities and angular velocities of rotor motion.

Numerical investigation of dynamic and hydrodynamic characteristics of the pad in the fluid pivot journal bearing

2021 ◽  
pp. 135065012110330
Author(s):  
Tuyen Vu Nguyen ◽  
Weiguang Li
Keyword(s):  
Computational Models ◽  
Journal Bearing ◽  
Squeeze Film ◽  
Hydrodynamic Characteristics ◽  
Hydrodynamic Properties ◽  
Squeeze Film Damper ◽  
Lubricant Oil ◽  
Oil Flow ◽  
Flow Through ◽  
Bearing System

The dynamic and hydrodynamic properties of the pad in the fluid pivot journal bearing are investigated in this paper. Preload coefficients, recess area, and size gap, which were selected as input parameters to investigate, are important parameters of fluid pivot journal bearing. The pad’s pendulum angle, lubricant oil flow through the gap, and recess pressure which characterizes the squeeze film damper were investigated with different preload coefficients, recess area, and gap sizes. The computational models were established and numerical methods were used to determine the equilibrium position of the shaft-bearing system. Since then, the pendulum angle of the pad, liquid flow, and recess pressure were determined by different eccentricities.

scholarly journals Dynamic Performance of a Squeeze Film Damper with a Cylindrical Roller Bearing under a Large Static Radial Loading Range

Machines ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 14 ◽  
Author(s):  
Hans Meeus ◽  
Jakob Fiszer ◽  
Gabriël Van De Velde ◽  
Björn Verrelst ◽  
Wim Desmet ◽  
...  
Keyword(s):  
Roller Bearing ◽  
Squeeze Film ◽  
Stable Operation ◽  
Large Power ◽  
Squeeze Film Damper ◽  
Depth Analysis ◽  
Rotor Support ◽  
Cylindrical Roller Bearing ◽  
Radial Loading ◽  
Cylindrical Roller

Turbomachine rotors, supported by little damped rolling element bearings, are generally sensitive to unbalance excitation. Accordingly, most machines incorporate squeeze film damper technology to dissipate mechanical energy caused by rotor vibrations and to ensure stable operation. When developing a novel geared turbomachine able to cover a large power range, a uniform mechanical drivetrain needs to perform well over the large operational loading range. Especially, the rotor support, containing a squeeze film damper and cylindrical roller bearing in series, is of vital importance in this respect. Thus, the direct objective of this research project was to map the performance of the envisioned rotor support by estimating the damping ratio based on the simulated and measured vibration response during run-up. An academic test rig was developed to provide an in-depth analysis on the key components in a more controlled setting. Both the numerical simulation and measurement results exposed severe vibration problems for an insufficiently radial loaded bearing due to a pronounced anisotropic bearing stiffness. As a result, a split first whirl mode arose with its backward component heavily triggered by the synchronous unbalance excitation. Hence, the proposed SFD does not function properly in the lower radial loading range. Increasing the static load on the bearing or providing a modified rotor support for the lower power variants will help mitigating the vibration issues.

scholarly journals Effectiveness Testing of an Inverse Method for Balancing Nonlinear Rotordynamic Systems

2018 ◽  
Author(s):  
Sergio G. Torres Cedillo ◽  
Philip Bonello ◽  
Ghaith Ghanim Al-Ghazal ◽  
Jacinto Cortés Pérez ◽  
Alberto Reyes Solis
Keyword(s):  
Inverse Problem ◽  
Inverse Method ◽  
Linear Connection ◽  
The Other ◽  
Squeeze Film ◽  
Squeeze Film Damper ◽  
Operational Conditions ◽  
Non Invasive ◽  
Highly Nonlinear ◽  
Aero Engine

Modern aero-engine structures typically have at least two nested rotors mounted within a flexible casing via squeeze-film damper (SFD) bearings. The inaccessibility of the HP rotor under operational conditions motivates the use of a non-invasive inverse problem procedure for identifying the unbalance. Such an inverse problem requires prior knowledge of the structure and measurements of the vibrations at the casing. Recent work by the authors reported a non-invasive inverse method for the balancing of rotordynamic systems with nonlinear squeeze-film damper (SFD) bearings, which overcomes several limitations of earlier works. However, it was not applied to a common practical configuration wherein the HP rotor is mounted on the casing via just one weak linear connection (retainer spring), with the other connections being highly nonlinear SFDs. The analysis of the present paper considers such a system. It explores the influence of the condition number and how it is affected as the number of sensors and/or measurement speeds is increased. The results show that increasing the number of measurement speeds has a far more significant impact on the conditioning of the problem than increasing the number of sensors. The balancing effectiveness is reasonably good under practical noise level conditions, but significantly lower than obtained for the previously considered simpler configurations.

scholarly journals A computational fluid dynamics investigation of the segmented integral squeeze film damper

2019 ◽  
Vol 254 ◽  
pp. 08005 ◽  
Author(s):  
Petr Ferfecki ◽  
Jaroslav Zapoměl ◽  
Marek Gebauer ◽  
Václav Polreich ◽  
Jiří Křenek
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Squeeze Film ◽  
Squeeze Film Damper ◽  
Ansys Cfx ◽  
Squeeze Film Dampers ◽  
Tilting Pad ◽  
Vibration Attenuation ◽  
Tilting Pad Journal Bearing

Rotor vibration attenuation is achieved with damping devices which work on different, often mutually coupled, physical principles. Squeeze film dampers are damping devices that have been widely used in rotordynamic applications. A new concept of a 5-segmented integral squeeze film damper, in which a flexure pivot tilting pad journal bearing is integrated, was investigated. The damper is studied for the eccentric position between the outer and inner ring of the squeeze film land. The ANSYS CFX software was used for solving the pressure and velocity distribution. The development of the complex three-dimensional computational fluid dynamics model of the squeeze film damper, learning more about the effect of the forces in the damper, and the knowledge about the behaviour of the flow are the principal contributions of this article.

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