Exact Two-Dimensional Analysis of Circular Disk Spiral Groove Bearing (Part II)

1979 ◽  
Vol 101 (4) ◽  
pp. 431-436
Author(s):  
S. Murata ◽  
Y. Miyake ◽  
N. Kawabata
Keyword(s):  
Velocity Field ◽  
Infinite Number ◽  
Thrust Bearing ◽  
Pressure Field ◽  
Circular Disk ◽  
Pressure Jump ◽  
Two Dimensional ◽  
Spiral Groove ◽  
Bearing Part ◽  
Spiral Groove Bearing

Two-dimensional pressure field of circular disk grooved thrust bearing when it does three kinds of elementary unsteady motions has been successfully analyzed using potential flow theory. The cancellation of the pressure jump by putting line vortices on the groove-land boundaries is demonstrated to be useful. The analysis of the velocity field can be carried out only in one basic domain, while the pressure field must be calculated in every domain by doing rather complicated selection among infinite number of values of inverse tangent.

Influence of Groove Molded Lines on the Lubrication Performance of Water-Lubricated Spiral Groove Thrust Bearings

2013 ◽  
Vol 694-697 ◽  
pp. 538-542 ◽  
Author(s):  
Xiao Yan Liu ◽  
Jia Sheng Wang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Thrust Bearing ◽  
Pressure Field ◽  
Load Capacity ◽  
Loading Capacity ◽  
Spiral Groove ◽  
Thrust Bearings ◽  
Pressure Fields ◽  
Lubrication Performance

The water lubrication performance of spiral groove thrust bearings was affected by different groove molded lines. The pressure fields and the load capacity of water-lubricated spiral groove thrust bearings with different groove molded lines were simulated by computational fluid dynamics. The results show that the spiral groove which can produce the best loading capacity and steadier pressure field is appropriate to water-lubricated spiral groove thrust bearing. The line spiral groove can be used for decrease the process difficult when the loading capacity require is low.

Exact Two-Dimensional Theory of Spherical Spiral Groove Bearings

1980 ◽  
Vol 102 (4) ◽  
pp. 430-438 ◽  
Author(s):  
Susumu Murata ◽  
Yutaka Miyake ◽  
Nobuyoshi Kawabata
Keyword(s):  
Exact Solution ◽  
Iterative Method ◽  
Load Capacity ◽  
Perturbation Technique ◽  
Fluid Film ◽  
Two Dimensional ◽  
Spiral Groove ◽  
Dimensional Theory ◽  
New Iterative Method ◽  
Spiral Groove Bearing

This paper is concerned with a method of obtaining exact solution for the flow of fluid film of spherical spiral groove bearing. The problem is analyzed for three cases where the centers of two elements of a bearing coincide, slightly offset vertically and arbitrarily offset vertically. Effects of bearing parameters on the load capacity are examined. A perturbation technique is applied for the case of slight offset of centers of two spheres, and the stiffness is calculated. For the case of large offset, a new iterative method is developed in this paper.

Exact Two-Dimensional Analysis of Circular Disk Spiral Groove Bearing (Part I)

1979 ◽  
Vol 101 (4) ◽  
pp. 424-430 ◽  
Author(s):  
S. Murata ◽  
Y. Miyake ◽  
N. Kawabata
Keyword(s):  
Circular Disk ◽  
Inviscid Flow ◽  
Fluid Film ◽  
Two Dimensional ◽  
Spiral Groove ◽  
Singularity Method ◽  
Load Carrying ◽  
Circular Wing ◽  
Basic Equations ◽  
Detailed Technique

Basic equations and idea of the method are described concerning the new two-dimensional theory of thin fluid film of spiral groove bearings. Two-dimensional inviscid flow theory of circular wing lattice is the basis of the proposed method. Detailed technique to perform numerical calculation has been established utilizing singularity method. Two-dimensional pressure formation of the fluid film is calculated together with load carrying capacity.

scholarly journals Blur-readable two-dimensional barcode based on blur-invariant shape and geometric features

2021 ◽  
Vol 18 (2) ◽  
pp. 172988142199958
Author(s):  
Shundao Xie ◽  
Hong-Zhou Tan
Keyword(s):  
Circular Disk ◽  
Geometric Features ◽  
Two Dimensional ◽  
Common Solution ◽  
Ringing Artifacts ◽  
2D Barcode ◽  
Defocus Blur ◽  
Blurred Image ◽  
Decoding Accuracy ◽  
Invariant Shape

In recent years, the application of two-dimensional (2D) barcode is more and more extensive and has been used as landmarks for robots to detect and peruse the information. However, it is hard to obtain a sharp 2D barcode image because of the moving robot, and the common solution is to deblur the blurry image before decoding the barcode. Image deblurring is an ill-posed problem, where ringing artifacts are commonly presented in the deblurred image, which causes the increase of decoding time and the limited improvement of decoding accuracy. In this article, a novel approach is proposed using blur-invariant shape and geometric features to make a blur-readable (BR) 2D barcode, which can be directly decoded even when seriously blurred. The finder patterns of BR code consist of two concentric rings and five disjoint disks, whose centroids form two triangles. The outer edges of the concentric rings can be regarded as blur-invariant shapes, which enable BR code to be quickly located even in a blurred image. The inner angles of the triangle are of blur-invariant geometric features, which can be used to store the format information of BR code. When suffering from severe defocus blur, the BR code can not only reduce the decoding time by skipping the deblurring process but also improve the decoding accuracy. With the defocus blur described by circular disk point-spread function, simulation results verify the performance of blur-invariant shape and the performance of BR code under blurred image situation.

scholarly journals Energy budget in internal wave attractor experiments

2019 ◽  
Vol 880 ◽  
pp. 743-763 ◽  
Author(s):  
Géraldine Davis ◽  
Thierry Dauxois ◽  
Timothée Jamin ◽  
Sylvain Joubaud
Keyword(s):  
Velocity Field ◽  
Internal Wave ◽  
Boundary Layers ◽  
Energy Budget ◽  
Dissipation Rate ◽  
Theoretical Expression ◽  
Two Dimensional ◽  
Energy Sink ◽  
Set Up ◽  
Different Sources

The current paper presents an experimental study of the energy budget of a two-dimensional internal wave attractor in a trapezoidal domain filled with uniformly stratified fluid. The injected energy flux and the dissipation rate are simultaneously measured from a two-dimensional, two-component, experimental velocity field. The pressure perturbation field needed to quantify the injected energy is determined from the linear inviscid theory. The dissipation rate in the bulk of the domain is directly computed from the measurements, while the energy sink occurring in the boundary layers is estimated using the theoretical expression for the velocity field in the boundary layers, derived recently by Beckebanze et al. (J. Fluid Mech., vol. 841, 2018, pp. 614–635). In the linear regime, we show that the energy budget is closed, in the steady state and also in the transient regime, by taking into account the bulk dissipation and, more importantly, the dissipation in the boundary layers, without any adjustable parameters. The dependence of the different sources on the thickness of the experimental set-up is also discussed. In the nonlinear regime, the analysis is extended by estimating the dissipation due to the secondary waves generated by triadic resonant instabilities, showing the importance of the energy transfer from large scales to small scales. The method tested here on internal wave attractors can be generalized straightforwardly to any quasi-two-dimensional stratified flow.

Restoration of the velocity field of the heart from two-dimensional echocardiograms

1989 ◽  
Vol 8 (2) ◽  
pp. 143-153 ◽  
Author(s):  
G.E. Mailloux ◽  
F. Langlois ◽  
P.Y. Simard ◽  
M. Bertrand
Keyword(s):  
Velocity Field ◽  
Two Dimensional

Internal waves in a viscous atmosphere

1975 ◽  
Vol 72 (4) ◽  
pp. 773-786 ◽  
Author(s):  
W. L. Chang ◽  
T. N. Stevenson
Keyword(s):  
Energy Source ◽  
Incompressible Fluid ◽  
Internal Waves ◽  
Infinite Number ◽  
Similarity Solution ◽  
Small Amplitude ◽  
Horizontal Plane ◽  
Two Dimensional ◽  
The Waves ◽  
Isothermal Atmosphere

The way in which internal waves change in amplitude as they propagate through an incompressible fluid or an isothermal atmosphere is considered. A similarity solution for the small amplitude isolated viscous internal wave which is generated by a localized two-dimensional disturbance or energy source was given by Thomas & Stevenson (1972). It will be shown how summations or superpositions of this solution may be used to examine the behaviour of groups of internal waves. In particular the paper considers the waves produced by an infinite number of sources distributed in a horizontal plane such that they produce a sinusoidal velocity distribution. The results of this analysis lead to a new small perturbation solution of the linearized equations.

Dynamics of Flywheel Energy Storage System With Permanent Magnetic Bearing and Spiral Groove Bearing

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Yujiang Qiu ◽  
Shuyun Jiang
Keyword(s):  
Energy Storage ◽  
Dynamic Model ◽  
Storage System ◽  
Energy Storage System ◽  
Tuned Mass Damper ◽  
Magnetic Bearing ◽  
Spiral Groove ◽  
Flywheel Energy Storage System ◽  
Mass Damper ◽  
Spiral Groove Bearing

Developing a flywheel energy storage system (FESS) with permanent magnetic bearing (PMB) and spiral groove bearing (SGB) brings a great challenge to dynamic control for the rotor system. In this paper, a pendulum-tuned mass damper is developed for 100 kg-class FESS to suppress low-frequency vibration of the system; the dynamic model with four degrees-of-freedom is built for the FESS using Lagrange's theorem; mode characteristics, critical speeds, and unbalance responses of the system are analyzed via theory and experiment. A comparison between the theoretical results and the experiment ones shows that the pendulum-tuned mass damper is effective, the dynamic model is appropriate, and the FESS can run smoothly within the working speed range.

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