scholarly journals Numerical and Experimental Investigation of the Effect of Cavitation on Dual Clearance Squeeze Film Damper

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Zhaojun Feng ◽  
Guihuo Luo ◽  
Hai Yang ◽  
Wangqun Deng ◽  
Wei Chen ◽  
...  
Keyword(s):  
Numerical Model ◽  
Pressure Distribution ◽  
Negative Pressure ◽  
Experimental Results ◽  
Squeeze Film ◽  
Positive Pressure ◽  
Kinetic Properties ◽  
Squeeze Film Damper ◽  
Cavitation Effect ◽  
Pressure Zone

A new dynamic model is developed for the dual clearance squeeze film damper (DCSFD) considering the effect of cavitation in this paper. The relationship between the eccentricities of the inner and outer films is achieved based on the equations of motion. The Reynolds equation and Rayleigh–Plesset equation are employed to describe the kinetic properties of DCSFD and the cavitation effect of film, respectively. Under the assumption of compressible fluid, the pressure distribution of DCSFD is finally obtained by the numerically iterative method. The film pressure distribution in the outer layer (including the positive and negative pressure zones) obtained from the experimental test agrees well with the numerical prediction, which verifies the validity of the proposed numerical model. In Section 5, the effects of oil temperature, inlet pressure, eccentricity, and whirling frequency on the cavitation in the film are investigated systematically and experimentally. The experimental results indicate that cavitation mainly affect the pressure in the negative pressure zone of the inner and outer film of DCSFD, but has little influence on the pressure in the positive pressure zone. The area of cavitation increased with eccentricity; when the inner eccentricity reached 0.1 or above, the area near the injection hole of film also generated a small zone of negative pressure. The numerical model and the experimental results in this paper are valuable for further research and engineering applications of DCSFD.

Airflow-Housing-Induced Resonances of Rotating Optical Disks

2007 ◽  
Vol 74 (6) ◽  
pp. 1252-1263 ◽  
Author(s):  
R. M. C. Mestrom ◽  
R. H. B. Fey ◽  
H. Nijmeijer ◽  
P. M. R. Wortelboer ◽  
W. Aerts
Keyword(s):  
Numerical Model ◽  
Pressure Distribution ◽  
Critical Speed ◽  
Experimental Approach ◽  
Experimental Results ◽  
Lubrication Equation ◽  
Global View ◽  
Optical Disks ◽  
Insight Into ◽  
Finite Difference Techniques

Numerous excitation sources for disk vibrations are present in optical drives. For increasing rotation speeds, airflow-housing-induced vibrations have become more and more important. Currently, drives are designed in which rotation speeds are so high that critical speed resonances may show up. The presence of these resonances depends on the layout of the inner housing geometry of the drive. The influence of the drive inner housing geometry is investigated systematically by means of a numerical-experimental approach. An analytical model is derived, containing disk dynamics and the geometry-induced pressure distribution acting as the excitation mechanism on the disk. The Reynolds’ lubrication equation is used as a first approach for the modeling of the pressure distribution. The model is numerically implemented using an approach based on a combination of finite element and finite difference techniques. An idealized, drive-like environment serves as the experimental setup. This setup resembles the situation in the numerical model, in order to be able to verify the numerical model. Wedge-like airflow disturbances are used in order to obtain insight into the influence of drive inner geometry on the critical speed resonances of optical disks. A disk tilt measurement method is designed that yields a global view of the disk deformation. By means of two newly proposed types of plots, numerical and experimental results can be compared in a straightforward way. A qualitative match between the numerical and experimental results is obtained. The numerical and experimental methods presented provide insight into airflow-housing-induced vibrations in optical drives. Additionally, reduction of some critical speed resonances is found to be possible for certain drive inner geometry configurations.

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.

Dynamic Characterization of a Novel Externally Pressurized Compliantly Damped Gas-Lubricated Bearing With Hermetically Sealed Squeeze Film Damper Modules

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Adolfo Delgado ◽  
Bugra Ertas
Keyword(s):  
Degrees Of Freedom ◽  
Load Capacity ◽  
Operating Conditions ◽  
Experimental Results ◽  
Squeeze Film ◽  
Metal Mesh ◽  
Squeeze Film Damper ◽  
Drive Trains ◽  
Bearing Loads

Ever-increasing demand for cleaner energy is driving the need for higher power density turbomachinery while reducing cost and simplifying design. Gas-lubricated bearings are representing one of the enabling technologies that can help maximize these benefits and have been successfully implemented into turbomachinery applications with rotors weights in the order few kg's. However, load capacity and damping limitations of existing gas bearing technologies prevent the development of larger size oil-free drive trains in the MW power output range. Compliantly damped hybrid gas bearings (CHGBs) were introduced as an alternative design to overcome these limitations by providing external pressurization to discrete tilting pads while retaining flexibility in the bearing support to help tolerate misalignment and rotor-pad geometry changes. Additionally, the CHGB concept addresses damping entitlement through the application of bearing support dampers such as metal mesh. An alternative CHGB design, featuring a novel hermetically seal squeeze film damper (HSFD) in the bearing support, was introduced as alternative approach to metal mesh dampers (MMDs) to further improve bearing damping. This paper details the rotordynamic characterization of a CHGB with modular HSFD for various operating conditions. Direct and cross-coupled stiffness and damping coefficients are presented for different rotor speeds up to 12,500 rpm, frequencies of excitation between 20 and 200 Hz, bearing loads between 200 and 400 lbf, and external hydrostatic pressures reaching 180 psi. Direct comparisons to experimental results for a CHGB using MMD show 3× increase in direct damping levels when using HSFD in the compliant bearing support. In addition to the experimental results, an analytical model is presented based on the implementation of the isothermal compressible Reynolds equation coupled to a flexible support possessing a pad with three degrees-of-freedom. The numerical results capture the direct stiffness and frequency dependency but underpredict the absolute values for both cases when compared to experimental data.

scholarly journals Experimental Study on Vibration Reduction Characteristics of Gear Shafts Based on ISFD Installation Position

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Kaihua Lu ◽  
Lidong He ◽  
Yipeng Zhang
Keyword(s):  
Experimental Study ◽  
Vibration Reduction ◽  
First Grade ◽  
Spur Gear ◽  
Gear System ◽  
Experimental Results ◽  
Squeeze Film ◽  
Squeeze Film Damper ◽  
System Vibration ◽  
Reduction Characteristics

A novel type of integral squeeze film damper (ISFD) is proposed to reduce and isolate vibration excitations of the gear system through bearing to the foundation. Four ISFD designs were tested experimentally with an open first-grade spur gear system. Vibration reduction characteristics were experimentally studied at different speeds for cases where ISFD elastic damping supports were simultaneously installed on the driving and driven shafts, installed on the driven shaft, or only installed on the driving shaft. Experimental results show that the ISFD elastic damping support can effectively reduce shock vibration of the gear system. Additionally, resonant modulation in gear shafts caused by meshing impact was significantly reduced. Different vibration amplitudes of gear shafts with ISFD installed only on driven or driving shafts were compared. Results indicated that vibration reduction is better when ISFD is only installed on the driven shaft than on the driving shaft.

Dynamic Characterization of a Novel Externally Pressurized Compliantly Damped Gas-Lubricated Bearing With Hermetically Sealed Squeeze Film Damper Modules

2018 ◽  
Author(s):  
Adolfo Delgado ◽  
Bugra Ertas
Keyword(s):  
Degrees Of Freedom ◽  
Load Capacity ◽  
Operating Conditions ◽  
Experimental Results ◽  
Squeeze Film ◽  
Metal Mesh ◽  
Squeeze Film Damper ◽  
Drive Trains ◽  
Bearing Loads

Ever-increasing demand for cleaner energy is driving the need for higher power density turbomachinery while reducing cost and simplifying design. Gas lubricated bearings, representing one of the enabling technologies that can help maximize these benefits and have been successfully implemented into turbomachinery applications with rotors weights in the order few kg’s. However, load capacity and damping limitations of existing gas bearing technologies prevents the development of larger size oil-free drive trains in the MW power output range. Compliantly damped hybrid gas bearings (CHGB) were introduced as an alternative design to overcome these limitations by providing external pressurization to discrete tilting pads while retaining flexibility in the bearing support to help tolerate misalignment and rotor-pad geometry changes. Additionally, the CHGB concept addresses damping entitlement through the application of bearing support dampers such a metal mesh. An alternative CHGB design, featuring a novel hermetically seal squeeze film damper (HSFD) in the bearing support, was introduced as alternative approach to metal mesh dampers (MMD) to further improve bearing damping. This paper details the rotordynamic characterization of a CHGB with modular HSFD for various operating conditions. Direct and cross-coupled stiffness and damping coefficients are presented for different rotor speeds up to 12,500 rpm, frequencies of excitation between 20–200 Hz, bearing loads between 200–400 1bf, and external hydrostatic pressures reaching 180psi. Direct comparisons to experimental results for a CHGB using (MMD) shows 3X increase in direct damping levels when using HSFD in the compliant bearing support. In addition to the experimental results, an analytical model is presented based on the implementation of the isothermal compressible Reynolds equation coupled to a flexible support possessing a pad with 3 degrees of freedom. The numerical results capture the direct stiffness and frequency dependency but underpredict the absolute values for both case when compared to experimental data.

Study on the Ultrahigh Speed Grinding of Superhard Materials with Squeeze Film Damping Technology

2010 ◽  
Vol 638-642 ◽  
pp. 2369-2374
Author(s):  
Tian Biao Yu ◽  
Hu Li ◽  
Jian Yu Yang ◽  
Wan Shan Wang
Keyword(s):  
Pressure Distribution ◽  
Experimental Result ◽  
Squeeze Film ◽  
Grinding Wheel ◽  
Superhard Materials ◽  
Squeeze Film Damper ◽  
Machining Quality ◽  
Squeeze Film Damping ◽  
Theory Research

In order to further improve machining quality of superhard materials, it was presented that adds a squeeze film damper on the wheel spindle of ultrahigh speed grinder as a assistant elastic sustain to attenuate the vibration of the wheel spindle. Work principle of squeeze film damper was analyzed; the squeeze film pressure distribution was researched through simulation and damper parameters effect on damping coefficient was studied. Base on the theory research the damper was designed and experiments was done. Experimental result shows the amplitude of the grinding wheel spindle can be reduced 20% and machining quality of superhard materials can be improved 10%～20%. Research works provides a new method for superhard materials machining.

Perturbation Solutions for Eccentric Operation of Squeeze Film Damper Systems

1986 ◽  
Vol 108 (4) ◽  
pp. 619-623 ◽  
Author(s):  
Xuehai Li ◽  
D. L. Taylor
Keyword(s):  
Numerical Simulation ◽  
Experimental Results ◽  
Squeeze Film ◽  
Rigid Rotor ◽  
Squeeze Film Damper ◽  
Synchronous Motion ◽  
Squeeze Film Dampers ◽  
Large Speed ◽  
Good Agreement ◽  
Perturbation Solutions

The study focuses on the effect of a small unidirectional load such as comes from imperfect balance between preloading on centering springs and gravitational load on squeeze film dampers. A rigid rotor-squeeze film damper system is considered, and a thorough study of the synchronous motion of the system is performed. Two perturbation solutions are developed: one for large speed and one for small speed. The perturbation solutions are shown to be in good agreement with numerical simulation and published experimental results.

Squeeze film dampers supporting high-speed rotors: Fluid inertia effects

2019 ◽  
Vol 234 (1) ◽  
pp. 18-32 ◽  
Author(s):  
Sina Hamzehlouia ◽  
Kamran Behdinan
Keyword(s):  
Thin Film ◽  
Pressure Distribution ◽  
Closed Form ◽  
Hydrodynamic Pressure ◽  
Fluid Film ◽  
Squeeze Film ◽  
Squeeze Film Damper ◽  
Thin Film Equations ◽  
Squeeze Film Dampers ◽  
Reaction Forces

This work represents closed-form analytical expressions for the operating parameters for short-length open-ended squeeze film dampers, including the lubricant velocity profiles, hydrodynamic pressure distribution, and lubricant reaction forces. The proposed closed-form expressions provide an accelerated calculation of the squeeze film damper parameters, specifically for rotordynamics applications. In order to determine the analytical solutions for the squeeze film damper parameters, the thin film equations for lubricant are introduced in the presence of the influence of lubricant inertia. Subsequently, two different analytical techniques, namely the momentum approximation method, and the perturbation method are applied to the thin film equations. Moreover, the solution for the lubricant flow equations are analytically determined to represent closed-form expressions for the hydrodynamic pressure distribution and the velocity component profiles in squeeze film dampers. Additionally, the expressions for the hydrodynamic pressure distribution are integrated over the journal surface, either numerically or analytically by using Booker’s integrals, to develop expressions for the fluid film reaction forces. Lastly, the developed squeeze film damper models are incorporated into simulation models in Matlab and Simulink®, and the results are compared against a well-established force coefficient model to verify the accuracy of the calculations. The results of the simulations verify the effect of the lubricant inertia components, namely the convective and temporal (i.e., unsteady) inertia components on the squeeze film damper dynamics, including hydrodynamic pressure distribution and fluid film reaction forces. Additionally, the simulation results suggest a close agreement between the proposed models and the results in the literature.

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