scholarly journals Theoretical Modeling of the Vapor Cavitation in Dynamically Loaded Journal Bearings

1986 ◽  
Vol 108 (4) ◽  
pp. 628-637 ◽  
Author(s):  
D. E. Brewe
Keyword(s):  
High Speed ◽  
Reynolds Equation ◽  
Control Volume ◽  
Circular Path ◽  
High Speed Photography ◽  
Computational Domain ◽  
Alternating Direction Implicit ◽  
Alternating Direction ◽  
Dynamically Loaded ◽  
Volume Method

A theoretical investigation is made of the evolution of a vapor bubble for a submerged journal bearing under dynamically loaded conditions. The solution to the Reynolds equation is determined numerically using a control volume method (Elrod algorithm). This method conserves mass throughout the computational domain including the liquid-vapor interface which may or may not be in motion relative to the minimum film line. An ADI (Alternating Direction Implicit) method is used to effect the time march. Excellent agreement was found with the experimental work of Jakobsson and Floberg for stationary cavitation. Predictions of bubble life for nonstationary cavitation compare reasonably well with that measured by Jacobson and Hamrock using high-speed photography. A comparison study was performed to determine some of the consequences of applying a nonconservative theory to a dynamic problem. A complete dynamic cycle of a journal whirling in a circular path was chosen for the basis of comparison. Significant differences were observed in the load components near the end of the cycle. In each case, onset of cavitation was observed followed by bubble growth and subsequent collapse. More complete details of this phenomena are illustrated with the use of perspective graphic plots depicting the associated pressure distribution and region of cavitation with position and motion of the journal within the housing.

scholarly journals A High Speed Photography Study of Cavitation in a Dynamically Loaded Journal Bearing

1991 ◽  
Vol 113 (2) ◽  
pp. 287-292 ◽  
Author(s):  
D. C. Sun ◽  
D. E. Brewe
Keyword(s):  
High Speed ◽  
Journal Bearing ◽  
High Speed Photography ◽  
Test Rig ◽  
Liquid Lubricant ◽  
Lubricant Films ◽  
Dynamically Loaded ◽  
Experimental Errors

The earlier study made by Jacobson and Hamrock on the cavitation of liquid lubricant films in a dynamically loaded journal bearing was repeated with a quartz sleeve, which was more rigid than the Polymethylmethacrylate (PMMA) sleeve used previously. Various improvements of the test rig were made concomitantly so that the experimental errors could be better controlled and assessed. This paper describes the updated high-speed photography experiment and its results.

Pressure Drop Characteristics of Parallel-Plate Channel Flow With Porous Obstructions at Both Walls

2003 ◽  
Author(s):  
Marcelo J. S. de Lemos ◽  
Luzia A. Tofaneli
Keyword(s):  
Numerical Solutions ◽  
Control Volume ◽  
Computational Domain ◽  
Algebraic Equations ◽  
Clear Fluid ◽  
Simple Method ◽  
Periodic Cell ◽  
Porosity And Permeability ◽  
Volume Method ◽  
Turbulence Transport

In this work, numerical solutions are presented for turbulent flow in a channel containing fins made with porous material. The condition of spatially periodic cell is applied longitudinally along the channel. A macroscopic tow-equation turbulence model is employed in both the porous region and the clear fluid. The equations of momentum, mass continuity and turbulence transport equations are written for an elementary representative volume yielding a set of equations valid for the entire computational domain. These equations are discretized using the control volume method and the resulting systems of algebraic equations is relaxed with the SIMPLE method. Results are presented for the velocity field as a function of Reynolds number, porosity and permeability of the fins.

scholarly journals Simultaneous Pressure Measurement and High-Speed Photography Study of Cavitation in a Dynamically Loaded Journal Bearing

1993 ◽  
Vol 115 (1) ◽  
pp. 88-95 ◽  
Author(s):  
D. C. Sun ◽  
D. E. Brewe ◽  
P. B. Abel
Keyword(s):  
Pressure Measurement ◽  
Cavitation Bubble ◽  
High Speed ◽  
Journal Bearing ◽  
Operating Conditions ◽  
High Speed Photography ◽  
Pressure Data ◽  
Oil Film ◽  
Dynamically Loaded ◽  
Insight Into

Cavitation of the oil film in a dynamically loaded journal bearing was studied using high-speed photography and pressure measurement simultaneously. Comparison of the visual and pressure data provided considerable insight into the occurrence and non-occurrence of cavitation. It was found that (1), cavitation typically occurred in the form of one bubble with the pressure in the cavitation bubble close to the absolute zero; and (2), for cavitation-producing operating conditions, cavitation did not always occur; with the oil film then supporting a tensile stress.

scholarly journals The Solution of the Elrod Algorithm for a Dynamically Loaded Journal Bearing Using Multigrid Techniques

1989 ◽  
Vol 111 (2) ◽  
pp. 302-308 ◽  
Author(s):  
C. M. Woods ◽  
D. E. Brewe
Keyword(s):  
Reynolds Equation ◽  
Journal Bearing ◽  
Control Volume ◽  
Computational Time ◽  
Iterative Technique ◽  
Solution Approach ◽  
Present Solution ◽  
Dynamically Loaded ◽  
Control Volume Approach ◽  
Mixed Nature

Numerical solution to a theoretical model of vapor cavitation in a dynamically loaded journal bearing is developed, utilizing a multigrid iterative technique. The method is compared with a noniterative approach in terms of computational time and accuracy. The computational model is based on the Elrod algorithm, a control volume approach to the Reynolds equation which mimics the Jakobsson-Floberg and Olsson cavitation theory. Besides accounting for a moving cavitation boundary and conservation of mass at the boundary, it also conserves mass within the cavitated region via a smeared mass or striated flow extending to both surfaces in the film gap. The mixed nature of the equations (parabolic in the full film zone and hyperbolic in the cavitated zone) coupled with the dynamic aspects of the problem create interesting difficulties for the present solution approach. Emphasis is placed on the methods found to eliminate solution instabilities. Excellent results are obtained for both accuracy and reduction of computational time.

A Theoretical Model for Squeeze Film Dampers Operating with Air Entrainment

2007 ◽  
Vol 353-358 ◽  
pp. 1683-1687
Author(s):  
Chun Yu Zhao ◽  
Hong Liang Yao ◽  
Feng Lin ◽  
Bang Chun Wen
Keyword(s):  
Hydrodynamic Lubrication ◽  
Control Volume ◽  
Air Entrainment ◽  
Ideal Gas ◽  
Squeeze Film ◽  
Computational Domain ◽  
Squeeze Film Dampers ◽  
Hydrodynamic Lubrication Theory ◽  
Volume Method ◽  
San Andres

A continuum model of the evolution of air ingestion and entrainment for open-ended squeeze film dampers is proposed in this paper. Hydrodynamic lubrication theory is extended to lubrication with mixture of a Newtonian liquid and an ideal gas. The solution to the universal Reynolds equation is determined numerically using a control volume method (Elrod algorithm) and the forth-order Range-Kutta method. This method conserves mass throughout the computational domain including air ingestion and entrainment. Excellent agreement is found with the experimental works of Diaz and San Andrès for the squeeze film damper [1, 2].

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