The Oscillating Fluid Mechanics Method (OFMM) for Studying Oil Film Oscillation and Dynamic Characteristics of Journal Bearings

1996 ◽  
Vol 118 (1) ◽  
pp. 239-245 ◽  
Author(s):  
Chen Zuoyi ◽  
Sun Yongzhong
Keyword(s):  
Fluid Mechanics ◽  
Journal Bearings ◽  
Previous Method ◽  
New Method ◽  
Oil Film ◽  
Rotordynamic Coefficients ◽  
Steady State Method ◽  
Calculational Procedure ◽  
State Method ◽  
Oscillating Fluid Mechanics

A new method to study oil film oscillation and to determine the unstable rotational speed and rotordynamic coefficients of bearings is presented. Differences between the new method called the Oscillating Fluid Mechanics Method (OFMM) and the previous method (quasi-steady state method) are discussed. Insufficiencies of the previous method are analyzed. The theory and calculational procedure of OFMM are given. Calculated results show that this new method provides significantly improved predictions.

scholarly journals The 15O Steady-State Method: Correction for Variation in Arterial Concentration

1988 ◽  
Vol 8 (5) ◽  
pp. 681-690 ◽  
Author(s):  
Michio Senda ◽  
Richard B. Buxton ◽  
Nathaniel M. Alpert ◽  
John A. Correia ◽  
Bruce C. Mackay ◽  
...  
Keyword(s):  
Steady State ◽  
Statistical Error ◽  
Repeated Measurements ◽  
New Method ◽  
Oxygen Extraction Fraction ◽  
Inhalation Technique ◽  
Arterial Blood ◽  
Steady State Method ◽  
Arterial Concentration ◽  
State Method

One of the factors limiting the accuracy of the 15O steady-state method for the measurement of regional cerebral blood flow and oxygen metabolism is the requirement that a constant arterial blood concentration be maintained over long periods. A new method has been developed to correct for the variation of the arterial concentration in the C15O2 and 15O2 steady-state inhalation technique. The time course of the arterial activity is obtained by multiple sampling over the study period. The same 15O model as is used in the steady-state method is employed but is solved without assuming equilibrium. Look-up tables are generated to relate flow and oxygen extraction fraction to tissue activity, and from them the regional parameters are estimated. Theory and simulation studies suggest that substantial improvement in accuracy can be obtained with no increase in statistical error. The validity of the method was checked experimentally by making repeated measurements in the same subject after perturbing the gas delivery. The conventional steady-state method showed significantly larger deviations in repeat measurement than did the new method. Thus, it is concluded that the proposed method is superior.

Steady State Measurement of Oxygenation Capacity

1985 ◽  
Vol 17 (2-3) ◽  
pp. 303-311
Author(s):  
Kees de Korte ◽  
Peter Smits
Keyword(s):  
Steady State ◽  
Activated Sludge ◽  
Plug Flow ◽  
Usual Method ◽  
Steady State Method ◽  
State Measurement ◽  
Flow Systems ◽  
Air System ◽  
State Method ◽  
Steady State Measurement

The usual method for OC measurement is the non-steady state method (reaeration) in tapwater or, sometimes, in activated sludge. Both methods are more or less difficult and expensive. The steady state method with activated sludge is presented. Fundamentals are discussed. For complete mixed aeration tanks, plug flow systems with diffused air aeration and carousels the method is described more in detail and the results of measurements are presented. The results of the steady state measurements of the diffused air system are compared with those of the reaeration method in tapwater. The accuracy of the measurements in the 3 systems is discussed. Measurements in other aeration systems are described briefly. It is concluded that the steady state OC measurement offers advantages in comparison with the non-steady state method and is useful for most purposes.

Improved Method Based on Fluid Mechanics Analysis for Buoy Gauge Design and Experimental Research

2012 ◽  
Vol 163 ◽  
pp. 133-137
Author(s):  
Ao Yu Chen ◽  
Xu Dong Pan ◽  
Guang Lin Wang
Keyword(s):  
Fluid Mechanics ◽  
Experimental Research ◽  
Traditional Method ◽  
New Method ◽  
Improved Method ◽  
Advanced Method ◽  
Inner Surface ◽  
Mechanics Analysis ◽  
Linear Property

Traditional method of buoy gauge design is rather complicated, so an advanced method by building and solving fluid mechanics equations is proposed in this paper. The curve of the taper pipe inner surface is calculated, according to different buoy gravity and diameter. In order to examine the effect of this improved method, an experiment is carried out. Results show that linear property of the buoy gauge improved by new method is excellent.

A Theoretical Analysis of Floating Bush Journal Bearing With Axial Oil Film Rupture Being Considered

2002 ◽  
Vol 124 (3) ◽  
pp. 494-505 ◽  
Author(s):  
Kiyoshi Hatakenaka ◽  
Masato Tanaka ◽  
Kenji Suzuki
Keyword(s):  
Steady State ◽  
Reynolds Equation ◽  
Speed Ratio ◽  
Shaft Speed ◽  
Film Rupture ◽  
State Behavior ◽  
Oil Film ◽  
Rotordynamic Coefficients ◽  
The Stability ◽  
Very High

A new modified Reynolds equation is derived with centrifugal force acting on the hydrodynamic oil film being considered. This equation, together with a cavitation model, is used to obtain the steady-state equilibrium and calculate the rotordynamic coefficients of lightly loaded floating bush journal bearings operating at very high shaft speeds. The bush-to-shaft speed ratio and the linear cross-coupling spring coefficients of the inner oil film is found to decrease with the increase in shaft speed as the axial oil film rupture develops in the inner oil film. The present model can give reasonable explanation to the steady-state behavior and the stability behavior of the bearing observed in actual machines.

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