Rotor/Seal Experimental and Analytical Study on Full Annular Rub

2000 ◽  
Author(s):  
John J. Yu ◽  
Paul Goldman ◽  
Donald E. Bently
Keyword(s):  
Mathematical Model ◽  
Dry Friction ◽  
Analytical Study ◽  
Experimental Results ◽  
Triggering Mechanism ◽  
Mass Unbalance ◽  
Destabilizing Factors ◽  
Small Clearance ◽  
Nonlinear Solutions ◽  
Simplified Mathematical Model

Rotor/seal full annular rub, including synchronous (forward) and reverse (backward) precessions, has been investigated both experimentally and analytically. Of particular interest is the finding of reverse precessional full annular rub (dry whip) that occurs repeatedly in small clearance cases without any outside disturbance. The experimental results include rub triggering mechanism, mass unbalance, and rotative speed effects. A simplified mathematical model is used to interpret experimental results. Nonlinear solutions for both synchronous and reverse precessions are obtained along with instability zones. Mass unbalance effect on shifting from synchronous response to reverse rub and destabilizing factors such as dry friction, rotor damping, and seal stiffness, are discussed.

Rotor/Seal Experimental and Analytical Study on Full Annular Rub

2002 ◽  
Vol 124 (2) ◽  
pp. 340-350 ◽  
Author(s):  
J. J. Yu ◽  
P. Goldman ◽  
D. E. Bently ◽  
A. Muzynska
Keyword(s):  
Mathematical Model ◽  
Dry Friction ◽  
Analytical Study ◽  
Experimental Results ◽  
Triggering Mechanism ◽  
Mass Unbalance ◽  
Destabilizing Factors ◽  
Small Clearance ◽  
Nonlinear Solutions ◽  
Simplified Mathematical Model

Rotor/seal full annular rub, including synchronous (forward) and reverse (backward) precessions, has been investigated both experimentally and analytically. Of particular interest is the finding of reverse precessional full annular rub (dry whip) that occurs repeatedly in small clearance cases without any outside disturbance. The experimental results include rub triggering mechanism, mass unbalance, and rotative speed effects. A simplified mathematical model is used to interpret experimental results. Nonlinear solutions for both synchronous and reverse precessions are obtained along with instability zones. Mass unbalance effect on shifting from synchronous response to reverse rub and destabilizing factors such as dry friction, rotor damping, and seal stiffness, are discussed.

Interaction of a Whirling Rotor with a Vibrating Stator across a Clearance Annulus

1968 ◽  
Vol 10 (1) ◽  
pp. 1-12 ◽  
Author(s):  
H. F. Black
Keyword(s):  
Dry Friction ◽  
Ball Bearing ◽  
Radial Symmetry ◽  
Experimental Results ◽  
Equilibrium Conditions ◽  
General Behaviour ◽  
Mass Unbalance ◽  
Jump Phenomena ◽  
Rotor Stator Interaction ◽  
Rotor Mass

Where a rotor runs within a clearance space, the clearance being comparable with rotor mass unbalance, the synchronous whirling behaviour of the rotor may be considerably affected by intermittent interaction with the stator at the clearance position. Discontinuity and jump phenomena may occur: in general, behaviour will be different with increasing speed from that with decreasing speed, and in either case zones may exist in which rotor-stator interaction is possible but not certain. In the analysis here presented, rotor and stator are regarded as linear multi-degree-of-freedom systems including damping; dry friction at the clearance space is taken into account. Discussion is limited to cases with radial symmetry, and interaction is assumed limited to the position of the clearance space. Polar receptances are used to establish equilibrium conditions with interaction, and speed zones are defined within which interaction may occur. Some hypothetical cases are fully explored, demonstrating that rotor-stator interactions may occur in a variety of forms and circumstances. Interactions with dry friction counterwhirling are also considered. Some experimental results on counterwhirl within a ball bearing are given and qualitatively compared with theory.

Analysis and Experiments on Pulse Vibrating Suction Method for Wall Climbing Robot

2011 ◽  
Vol 201-203 ◽  
pp. 1837-1844
Author(s):  
Xiao Yang Zhao ◽  
Rong Liu ◽  
Ke Wang ◽  
Jun Hu He
Keyword(s):  
Mathematical Model ◽  
Small Deviation ◽  
Experimental Results ◽  
Control Parameters ◽  
Climbing Robot ◽  
Experimental Platform ◽  
Suction Cup ◽  
Suction Cups ◽  
The Mathematical Model ◽  
Simplified Mathematical Model

This template explains and demonstrates how to prepare your camera-ready paper for In this paper, the pulse vibrating suction method (PVSM) for wall climbing robot is presented, which is based on the principle of vibrating suction method. To analyze this method in depth and evaluate its performance, a simplified mathematical model based on some assumptions is built, and a new experimental platform for single suction cup is developed as well. Experiments on single suction cups indicate that the experimental results match the mathematical model well with only small deviation, which is caused by some unknown factors. Then experiments are carried out on a vibrating suction module which was developed previously. With the PVSM, the suction module can stay on the wall stabely, which verifies the vadality of this vibrating method. Suction failures for the module are also analyzed with different control parameters.

Research on Flux Damping Control Strategy of DFIG during Grid Voltage Dips

2015 ◽  
Vol 713-715 ◽  
pp. 756-759
Author(s):  
Xu Guang Zhang ◽  
Zhen Xie
Keyword(s):  
Mathematical Model ◽  
Control Strategy ◽  
Grid Voltage ◽  
Damping Control ◽  
Simulink Simulation ◽  
Voltage Dips ◽  
Simulation Results ◽  
Stator Flux ◽  
Natural Component ◽  
Simplified Mathematical Model

A flux damping control strategy was proposed to accelerate the decay of stator flux and restrain stator, rotor current and torque oscillation caused by grid voltage dips. Firstly, this paper analyzes the simplified mathematical model of DFIG during symmetrical voltage dips. Then, the mechanism of flux damping control strategy to restrain stator, rotor current oscillation and increase flux damping was analyzed. The flux damping control strategy can increase the damping of stator side, which accelerates the decay of the stator flux natural component and improve the dynamic LVRT performance of DFIG. The correctness and effectiveness of this method is verified by MATLAB/Simulink simulation results.

Friction and Tribological Considerations for Nanometer Range Machining

2001 ◽  
Author(s):  
Som Chattopadhyay
Keyword(s):  
Mathematical Model ◽  
High Precision ◽  
Local Deformation ◽  
Experimental Results ◽  
Precision Machining ◽  
Complex Motion ◽  
Positioning Accuracy ◽  
Nanometer Range ◽  
Motion Characteristic ◽  
Low Speeds

Abstract Positioning accuracy within the range of nanometers is required for high precision machining applications. The implementation of such a range is difficult through the slides because of (a) irregular nature of friction at the slider-guideway interface, and (b) complex motion characteristic at very low speeds. The complexity arises due to the local deformation at the interface prior to breakaway, which is known as microdynamics. In this work prior experimental results exhibiting microdynamics have been appraised, and mathematical model developed to understand this behavior.

scholarly journals Mathematical model to estimate of the deterioration of wooden poles in contact with soil used in rural areas

2011 ◽  
Vol 31 (5) ◽  
pp. 1015-1026
Author(s):  
Julio C. Molina ◽  
Carlito Calil Júnior ◽  
Roberto R. de Freitas
Keyword(s):  
Mathematical Model ◽  
Rural Areas ◽  
Sao Paulo ◽  
São Paulo ◽  
Climatological Data ◽  
Paulo State ◽  
São Paulo State ◽  
Useful Life ◽  
Wooden Structures ◽  
Simplified Mathematical Model

In São Paulo State, mainly in rural areas, the utilization of wooden poles is observed for different purposes. In this context, wood in contact with the ground presents faster deterioration, which is generally associated to environmental factors and, especially to the presence of fungi and insects. With the use of mathematical models, the useful life of wooden structures can be predicted by obtaining "climatic indexes" to indicate, comparatively among the areas studied, which have more or less tendency to fungi and insects attacks. In this work, by using climatological data of several cities at São Paulo State, a simplified mathematical model was obtained to measure the aggressiveness of the wood in contact with the soil.

Analytical Study of Hydro-Pneumatic Processes for Gorlov's Power System

1994 ◽  
Vol 208 (1) ◽  
pp. 67-70
Author(s):  
A I Ryazanov
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Power System ◽  
Analytical Study ◽  
Model Tests ◽  
Air Pressure ◽  
Pneumatic Power ◽  
Time Required ◽  
The Mathematical Model

This paper describes the aerohydrodvnamics of processes in chambers of Gorlov's hydro-pneumatic power system. The mathematical model is developed to determine the main parameters of the processes: water and air velocities, air pressure in the chamber, the periods of time required to fill and empty the chambers and the output of energy during the cycle. The results obtained are in agreement with experimental data and model tests.

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