Nonlinear Analysis Based on Experiments of the Rotation Shaft System of Mine Drainage Motor and Pump

2011 ◽  
Vol 341-342 ◽  
pp. 271-275
Author(s):  
Wu Zhao ◽  
Gui Yu
Keyword(s):  
Optimization Design ◽  
Critical Speed ◽  
Mine Drainage ◽  
Stable State ◽  
Dynamic Responses ◽  
Mechanical Seal ◽  
Rotating Shaft ◽  
Nonlinear Characteristics ◽  
Study Results ◽  
Multiple Frequencies

The experimental study results show that the system’s nonlinear characteristics, incluing the dynamic responses of the poincare mapping, the bifurcation plots, three-dimensional waterfalls diagrams etc. The effects factors of system experiment are studied and analyzed, including the misalignment and the rub-impact stiffness on system responses. So, the faults characteristics of the misalignment and the rub-impact of the rotation shaft-mechanical seal system on the drainge motor and drainge pump are also gained by the experiment. The dynamic performance of the system show nonlinear characteristics in different working conditions. The rotating shaft-mechanical seal system on the drainge motor and drainge pump can be optimization design and performance prediction based on the studied results of our work. The experiment’s results show that: the multiple frequencies are produced of the rotating shaft-mechanical seal system on drainge motor and drainge pump, and the frequencies of 1-time and 2-time are dominating components under the exciting force effects of misalignment and imbalance. At the fault state of misalignment coupling rub-impact, the multiple frequencies including 2-time, 3-time, 4-time and so on, will be induced under the critical speed. Over the value of the critical speed, will cause the phenomenon of frequency demultiplication and chaos. With rub-impact stiffness value increased, the phenomenon of frequency demultiplication and chaos are induced more frequently; with the degree of misalignment increased, the phenomena of chaos will decrease and the system will tend to be the stable state.

Research on Sealing Performance of Mechanical Seal for Excitation of Rotating Shaft

2012 ◽  
Vol 433-440 ◽  
pp. 544-551
Author(s):  
Wu Zhao ◽  
Gui Yu
Keyword(s):  
Liquid Film ◽  
Optimization Design ◽  
Stable State ◽  
Rectangular Pulse ◽  
Axial Stiffness ◽  
Mechanical Seal ◽  
Rotating Shaft ◽  
Sealing Performance ◽  
Study Results ◽  
Pulse Form

In this study, liquid film perturbed pressure equation is derived firstly using a Taylor Series expanding pressure formula. By linear film assumption, the axial stiffness and damping coefficients of the mechanical seal are derived. Then kinematical equation of the rotating shaft-mechanical seal system is established. The research focus on solving response of the rotating shaft-mechanical seal system and leakage of the mechanical seal when the rotating shaft is under different frequencies excitatied or under frequency disturbed in different form excitatied in this paper. The analytical results show that response of the rotating shaft-mechanical seal system can finally be close to the stable state, when excitatied frequency of the rotating shaft is disturbed in different form. But for amplitude of the displace between the stationary ring, rotating ring and rotating shaft occurs mutation point at the time when the excitatied frequency is disturbed, meanwhile the excitatied frequency of the rotating shaft is disturbed in rectangular pulse form or in instant maximum pulse form. It will cause liquid film thickness to happen mutation until the leakage increases and mechanical seal fails at last. The study results show that the sealing performance of mechanical seal and excitatied frequency of the rotating shaft has closely positive correlation. The rotating shaft-mechanical seal system can be optimization design and performance prediction based on the study of this paper.

Optimum Design of Journal Bearings Dimensions for Rotating Machines

2020 ◽  
Vol 38 (10A) ◽  
pp. 1481-1488
Author(s):  
Tariq M. Hammza ◽  
Ehab N. Abas ◽  
Nassear R. Hmoad
Keyword(s):  
Aspect Ratio ◽  
Dynamic Response ◽  
Numerical Solution ◽  
Critical Speed ◽  
Design Method ◽  
Considerable Effect ◽  
Journal Bearings ◽  
Rotating Machines ◽  
Bearing Clearance ◽  
Study Results

The values of Many parameters which involve in the design of fluid film journal bearings mainly depend on the bearing applied load when using the conventional design method to design the journal bearings, in this study, as well as applied bearing load, the dynamic response and critical speed have been used to calculate the dimensions of journal bearings. In the field of rotating machine, especially a heavy-duty rotating machines, the critical speed and response are the main parameters that specify bearing dimensions. The bearing aspect ratio (bearing length to bore diameter) and bearing clearance have been determined based on rotor maximum critical speed and minimum response displacement. The analytical solution of rotor Eq. of motion was verified by numerical solution via using ANSYS Mechanical APDL 18.0 and by comparing the numerical solution with the preceding study. The final study results clearly showed that the bearing aspect ratio has little effect on the critical speed, but it has a high effect on the dynamic response also the bearing clearance has little effect on the critical speed and considerable effect on the dynamic response. The study showed that the more accurate values of bearing aspect ratio to make the response of rotor as low as possible are about 0.65 - 1 and bearing percent clearance is about 0.15 - 0.2 for different rotor dimensions.

Experimental Investigation on the Dynamic Response of a Three Legged Articulated Type Offshore Wind Tower

2016 ◽  
Author(s):  
Chinsu Mereena Joy ◽  
Anitha Joseph ◽  
Lalu Mangal
Keyword(s):  
Dynamic Response ◽  
Wind Turbine ◽  
Renewable Energy Sources ◽  
Offshore Structures ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Experimental Investigations ◽  
Offshore Wind Turbine ◽  
Ocean Engineering ◽  
Study Results

Demand for renewable energy sources is rapidly increasing since they are able to replace depleting fossil fuels and their capacity to act as a carbon neutral energy source. A substantial amount of such clean, renewable and reliable energy potential exists in offshore winds. The major engineering challenge in establishing an offshore wind energy facility is the design of a reliable and financially viable offshore support for the wind turbine tower. An economically feasible support for an offshore wind turbine is a compliant platform since it moves with wave forces and offer less resistance to them. Amongst the several compliant type offshore structures, articulated type is an innovative one. It is flexibly linked to the seafloor and can move along with the waves and restoring is achieved by large buoyancy force. This study focuses on the experimental investigations on the dynamic response of a three-legged articulated structure supporting a 5MW wind turbine. The experimental investigations are done on a 1: 60 scaled model in a 4m wide wave flume at the Department of Ocean Engineering, Indian Institute of Technology, Madras. The tests were conducted for regular waves of various wave periods and wave heights and for various orientations of the platform. The dynamic responses are presented in the form of Response Amplitude Operators (RAO). The study results revealed that the proposed articulated structure is technically feasible in supporting an offshore wind turbine because the natural frequencies are away from ocean wave frequencies and the RAOs obtained are relatively small.

scholarly journals Dynamic Response Analysis of Planar Multilink Mechanism considering Wear in Clearances

2019 ◽  
Vol 2019 ◽  
pp. 1-18 ◽  
Author(s):  
Shuai Jiang ◽  
Xiulong Chen ◽  
Yu Deng
Keyword(s):  
Theoretical Basis ◽  
Dynamic Responses ◽  
Response Analysis ◽  
Nonlinear Characteristics ◽  
Wear Prediction ◽  
Normal Contact ◽  
Normal Contact Force ◽  
Clearance Joints ◽  
Revolute Joints ◽  
Analysis Of Dynamics

Clearance wear is one of the factors that affects dynamics for mechanical systems. A numerical methodology suitable for modeling and calculation of wear at multiple revolute clearance pairs in the field of the planar multilink mechanism is proposed. In this paper, the 2-DOF nine-bar mechanism considering two revolute clearance joints is regarded as the study object. Normal contact force and friction force models of revolute clearance joints used Lankarani–Nikravesh (L-N) and LuGre models, respectively. The iterative wear prediction process based upon Archard’s model has been applied to calculate wear characteristics. The wear prediction procedure is integrated with multibody dynamics, wear depths at revolute clearance joints are calculated, and the surface of shaft and bearing is reconstructed twice. The dynamic responses of mechanism considering two nonregular revolute clearances caused by wear are studied in depth. The nonlinear characteristics of the mechanism after wear are studied by the phase diagram and Poincaré map. Influences of different initial constant clearance values and different driving speeds on wear of two revolute joints are also researched. The results show that it is necessary to consider the factor of irregular clearances caused by wear in analysis of dynamics of precision mechanisms. Initial constant clearance values and driving speeds have some influence on wear phenomenon. This research provides a theoretical basis for studying dynamics of the planar multilink mechanism considering wear in multiple clearances.

scholarly journals A Review of the Flow-Induced Noise Study for Centrifugal Pumps

2020 ◽  
Vol 10 (3) ◽  
pp. 1022 ◽  
Author(s):  
Chang Guo ◽  
Ming Gao ◽  
Suoying He
Keyword(s):  
Optimization Design ◽  
Sound Field ◽  
Operating Conditions ◽  
Response Analysis ◽  
Centrifugal Pumps ◽  
Noise Optimization ◽  
Operating Stability ◽  
Study Results ◽  
Flow Induced Noise ◽  
Negative Impacts

Flow-induced noise is a significant concern for the design and operation of centrifugal pumps. The negative impacts of flow-induced noise on operating stability, human health and the environment have been shown in many cases. This paper presents a comprehensive review of the flow-induced noise study for centrifugal pumps to synthesize the current study status. First, the generation mechanism and propagation route of flow-induced noise are discussed. Then, three kinds of study methodologies, including the theoretical study of hydrodynamic noise, numerical simulation and experimental measurement study, are summarized. Subsequently, the application of the three study methodologies to the analysis of the distribution characteristics of flow-induced noise is analyzed from aspects of the noise source identification and comparison, the frequency response analysis, the directivity characteristics of sound field and the noise changing characteristics under various operating conditions. After that, the analysis of the noise optimization design of centrifugal pumps is summarized. Finally, based on previous study results, this paper puts forward the unsolved problems and implications for future study. In conclusion, the information collected in this review paper could guide further study of the flow-induced noise of centrifugal pumps.

scholarly journals A Dynamic Analysis of the Rotary Cutting System of King Grass Shredder

2020 ◽  
Vol 145 ◽  
pp. 02080
Author(s):  
Zunxiang Li ◽  
Ou Zhongqing ◽  
Jiao jing ◽  
Huang xiaohong ◽  
Du jihua
Keyword(s):  
Finite Element ◽  
Critical Speed ◽  
Great Influence ◽  
Second Order ◽  
Belt Drive ◽  
Finite Element Models ◽  
Rotating Shaft ◽  
First Order ◽  
Rotary Cutting ◽  
Cutting System

With the rotary cutting system of king grass shredder as the research object, this paper established finite element models for rotating shaft, rotating shaft-belt pulley, rotating shaft-rotary cutting part and rotary cutting system and analyzed the influences of belt pulley and rotary cutting part on the dynamic characteristics of rotary cutting system. The results showed that the belt pulley and rotary cutting part had a great influence on the second order critical speed of rotary cutting system, and the rotary cutting part had a greater influence on the critical speed of first order forward precession than the belt pulley. Meanwhile, the critical speed of rotary cutting system that conformed to facts was calculated. There was a big difference between its first order and second order critical speeds, but the critical speed of first order backward precession was lower. Finally, it was found after analysis that the natural frequency of rotary cutting system was lower than the vibration frequency induced by belt drive, so the shredder can run safely.

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