Rotordynamic coefficients of multirecess hybrid journal bearings Part II: Fluid inertia effect

Wear ◽  
1989 ◽  
Vol 129 (2) ◽  
pp. 261-272 ◽  
Author(s):  
S.K. Guha ◽  
M.K. Ghosh ◽  
B.C. Majumdar
Keyword(s):  
Journal Bearings ◽  
Inertia Effect ◽  
Fluid Inertia ◽  
Rotordynamic Coefficients ◽  
Fluid Inertia Effect

Modelling Fluid Inertia Forces of Short Journal Bearings for Rotordynamic Applications

1993 ◽  
Author(s):  
A. El-Shafei
Keyword(s):  
Momentum Equation ◽  
Journal Bearings ◽  
Fluid Inertia ◽  
Radial Acceleration ◽  
Damping Characteristics ◽  
Energy Approximation ◽  
Form Model ◽  
Fluid Inertia Effect ◽  
Stiffness And Damping ◽  
Inertia Forces

Abstract It has been recently suggested that fluid inertia may play an important role in the dynamic behavior of rotors supported on journal bearings. This paper presents a model for fluid inertia forces in short cylindrical journal bearings based on an energy approximation. The inertialess velocity profiles predicted by the solution of Reynolds’ equation are inserted in the axial momentum equation multiplied by the axial velocity profile and integrated across the film thickness, to obtain the pressure in short journal bearings including the fluid inertia effect. The pressure is then integrated to obtain the fluid inertia forces. It is shown that the inertia forces thus obtained are proportional to the usual radial, centripetal, tangential and coriolis accelerations of the journal, in addition to a nonlinear radial acceleration. Moreover, it is shown that the inertia forces contribute to the stiffness and damping characteristics of the journal bearings. The inertia coefficients of the bearings are obtained in cartezian and cylindrical coordinates, for both uncavitated and cavitated bearings, and are plotted versus the eccentricity ratio. The model thus obtained is an analytical closed form model for fluid inertia forces in short journal bearings. Such a model is the most suitable for rotordynamic applications, particularly for time transient rotordynamic simulations.

Fluid inertia effect on the spiral-grooved mechanical face seals considering cavitation effect

2020 ◽  
pp. 1-20
Author(s):  
Xuezhong Ma ◽  
Xiangkai Meng ◽  
Yuming Wang ◽  
Yangyang Liang ◽  
Xudong Peng
Keyword(s):  
Inertia Effect ◽  
Fluid Inertia ◽  
Cavitation Effect ◽  
Face Seals ◽  
Fluid Inertia Effect

758 High Viscosity Fluid Pumping by Micro Fluid Power Source Using Fluid Inertia Effect in Pipe

2006 ◽  
Vol 2006 (0) ◽  
pp. 197-198
Author(s):  
Kazuhiro YOSHIDA ◽  
Takeshi SETO ◽  
Shinichi YOKOTA ◽  
Yohei OSANAI ◽  
Kunihiko TAKAGI
Keyword(s):  
High Viscosity ◽  
Power Source ◽  
Fluid Power ◽  
Inertia Effect ◽  
Fluid Inertia ◽  
Fluid Inertia Effect ◽  
Viscosity Fluid

A Mathematical Analog for Determination of Porous Annular Disk Squeeze Film Behavior Including the Fluid Inertia Effect

1972 ◽  
Vol 94 (2) ◽  
pp. 417-421 ◽  
Author(s):  
L. L. Ting
Keyword(s):  
Squeeze Film ◽  
Inertia Effect ◽  
Fluid Inertia ◽  
Annular Disk ◽  
Inertia Parameter ◽  
Permeability Parameter ◽  
Fluid Inertia Effect ◽  
Annular Disks ◽  
Range Of Values

A simple mathematical analog for determination of the squeeze film behavior between two parallel annular disks, one having a porous facing, from the already available solutions of comparable nonporous disks is presented. A comparison of the analog solution with a Fourier-Bessel solution has been made and the agreement is found to be good for a range of values of the permeability parameter and the porous facing thickness. The results also have been extended to include the rotating inertia effect of the film fluid. The resulting dimensionless pressure distribution and the dimensionless squeeze film load are expressed in terms of a permeability parameter, inertia parameter, squeeze film number, and the disk dimensions. For constant squeeze film load, a relationship between squeeze time and film thickness also has been obtained. Generally, the presence of the porous facing will decrease the squeeze film load and will reduce the total squeeze time to some finite value. The inertia effect will further decrease the squeeze film load and the squeeze time, however, the squeeze time reduction due to the inertia effect will become small if the porous facing has high permeability and is thick.

scholarly journals An ER Microactuator with Built-in Pump and Valve

2012 ◽  
Vol 6 (4) ◽  
pp. 468-475 ◽  
Author(s):  
Kazuhiro Yoshida ◽  
◽  
Tomohisa Muto ◽  
Joon-Wan Kim ◽  
Shinichi Yokota
Keyword(s):  
Electric Field ◽  
Apparent Viscosity ◽  
Check Valve ◽  
High Viscosity ◽  
Inertia Effect ◽  
Fluid Inertia ◽  
Viscosity Increase ◽  
Reed Valve ◽  
Fluid Inertia Effect ◽  
High Output

The paper presents a 3-DOF microactuator having a Fluid Inertia (FI) micropump and ER microvalves for in-pipe working micromachines of about 10 mm in diameter, and so on. The ER microvalve controls an Electro-Rheological Fluid (ERF) flow due to the apparent viscosity increase in the electric field. The FI micropump generates high-output-fluid power using the fluid inertia effect in an outlet pipe. First, the 3-DOF ER microactuator with built-in pump and valves was proposed, and its construction was clarified. Second, in order to pump high viscosity fluids such as ERFs, a multi-reed valve was proposed for the inlet check valve of the FI micropump. The characteristics of the newly-devised pump were clarified through simulation and experiments. Then, based on the results, a 10 mm-diameter FI micropump was successfully developed. Finally, in the first stage of this study, a 1-DOF valve-integrated ER microactuator was designed and fabricated. The validity of the actuator with the fabricated 10 mm-diameter FI micropump was experimentally confirmed.

Modeling Fluid Inertia Forces of Short Journal Bearings for Rotordynamic Applications

1995 ◽  
Vol 117 (4) ◽  
pp. 462-469 ◽  
Author(s):  
A. El-Shafei
Keyword(s):  
Momentum Equation ◽  
Journal Bearings ◽  
Fluid Inertia ◽  
Radial Acceleration ◽  
Damping Characteristics ◽  
Energy Approximation ◽  
Form Model ◽  
Fluid Inertia Effect ◽  
Stiffness And Damping ◽  
Inertia Forces

It has been recently suggested that fluid inertia may play an important role in the dynamic behavior of rotors supported on journal bearings. This paper presents a model for fluid inertia forces in short cylindrical journal bearings based on an energy approximation. The inertialess velocity profiles predicted by the solution of Reynolds’ equation are inserted in the axial momentum equation multiplied by the axial velocity profile and integrated across the film thickness, to obtain the pressure in short journal bearings including the fluid inertia effect. The pressure is then integrated to obtain the fluid inertia forces. It is shown that the inertia forces thus obtained are proportional to the usual radial, centripetal, tangential and coriolis accelerations of the journal, in addition to a nonlinear radial acceleration. Moreover, it is shown that the inertia forces contribute to the stiffness and damping characteristics of the journal bearings. The inertia coefficients of the bearings are obtained in cartesian and cylindrical coordinates, for both uncavitated and cavitated bearings, and are plotted versus the eccentricity ratio. The model thus obtained is an approximate analytical closed form model for fluid inertia forces in short journal bearings. Such a model is the most suitable for rotordynamic applications, particularly for time transient rotordynamic simulations.

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