scholarly journals Small plane oscillations of satellite in an weakly elliptical orbit

2013 ◽  
pp. 671-696 ◽  
Author(s):  
P. S. Krasilnikov ◽  
Keyword(s):  
Elliptical Orbit ◽  
Plane Oscillations ◽  
Weakly Elliptical Orbit

scholarly journals Orbit Decomposition Method for Rotordynamic Coefficients Identification of Annular Seals

2021 ◽  
Vol 11 (9) ◽  
pp. 4237
Author(s):  
Mingjie Zhang ◽  
Jiangang Yang ◽  
Wanfu Zhang ◽  
Qianlei Gu
Keyword(s):  
Circular Orbit ◽  
Present Method ◽  
Decomposition Method ◽  
Parameter Analysis ◽  
Elliptical Orbit ◽  
Computational Time ◽  
Solution Technique ◽  
Rotordynamic Coefficients ◽  
Cfd Method ◽  
Annular Seals

The elliptical orbit whirl model is widely used to identify the frequency-dependent rotordynamic coefficients of annular seals. The existing solution technique of an elliptical orbit whirl model is the transient computational fluid dynamics (CFD) method. Its computational time is very long. For rapid computation, this paper proposes the orbit decomposition method. The elliptical whirl orbit is decomposed into the forward and backward circular whirl orbits. Under small perturbation circumstances, the fluid-induced forces of the elliptical orbit model can be obtained by the linear superposition of the fluid-induced forces arising from the two decomposed circular orbit models. Due to that the fluid-induced forces of circular orbit, the model can be calculated with the steady CFD method, and the transient computations can be replaced with steady ones when calculating the elliptical orbit whirl model. The computational time is significantly reduced. To validate the present method, its rotordynamic results are compared with those of the transient CFD method and experimental data. Comparisons show that the present method can accurately calculate the rotordynamic coefficients. Elliptical orbit parameter analysis reveals that the present method is valid when the whirl amplitude is less than 20% of seal clearance. The effect of ellipticity on rotordynamic coefficients can be ignored.

On the Deployment of a Tether from an Elliptical Orbit

1998 ◽  
Vol 46 (2) ◽  
pp. 119-133 ◽  
Author(s):  
M. Ruiz ◽  
J. Peláez
Keyword(s):  
Elliptical Orbit

Growth Induced Grain Boundary Plane Oscillations in YBa2Cu3O7

1998 ◽  
Vol 294-296 ◽  
pp. 119-122
Author(s):  
J. Ayache ◽  
A. Thorel ◽  
S. Jong Kim ◽  
J. Lesueur ◽  
K.H. Westmacott ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Boundary Plane ◽  
Grain Boundary Plane ◽  
Plane Oscillations

Elliptical Orbit of Asteroid 1986 QE1

1989 ◽  
Vol 12 ◽  
pp. 21-24
Author(s):  
H. Debehogne ◽  
L.E. Machado ◽  
S. Vaz ◽  
E.R. Netto
Keyword(s):  
Photographic Plate ◽  
Elliptical Orbit ◽  
Orbital Elements ◽  
European Southern Observatory ◽  
Geocentric Distance ◽  
Before And After

We present the orbital elements of asteroid QE1 (pro visional designation) identified in august 26, 1986, on a photographic plate obtained at the GPO telescope of the European Southern Observatory (ESO), La Silla, Chile, as well as the positions (AR and Dec) referred to 1950.0. Residues (0 - C) of the position in AR and Dec of the asteroid are given, both before and after applying variation in the geocentric distance.

Study of In-Plane Motions in a Thin Rotating Disk

2000 ◽  
Author(s):  
Moreshwar Deshpande ◽  
C. D. Mote
Keyword(s):  
Critical Speed ◽  
Natural Frequencies ◽  
Rotation Speed ◽  
Rotating Disk ◽  
Travelling Wave ◽  
Linear Strain ◽  
Strain Measure ◽  
Nodal Diameter ◽  
Plane Oscillations ◽  
Disk Energy

Abstract A model for the in-plane oscillations of a thin rotating disk has been derived using a nonlinear strain measure to calculate the disk energy. This accounts for the stiffening of the disk due the radial expansion resulting from its rotation. The corresponding non-dimensionalized natural frequencies are seen to depend only on rotation speed and have been calculated. The radially expanded disk configuration is linearly stable over the range of rotation speeds studied here. The sine and cosine modes for all nodal diameters couple to each other at all nonzero rotation speeds and the strength of this coupling increases with rotation speed. This coupling causes the reported frequencies of the stationary disk to split. The zero, one and two nodal diameter in-plane modes do not have a critical speed corresponding to the vanishing of the backward travelling wave frequency. The use of a linear strain measure in earlier work incorrectly predicts instability of the rotating equilibrium and the existence of critical speeds in these modes.

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