Dynamics Characteristics and Diagnosis of a Rotor-Bearing's System Through a Dimensional Analysis Approach: An Experimental Study

2018 ◽  
Vol 14 (1) ◽  
Author(s):  
R. G. Desavale
Keyword(s):  
Experimental Study ◽  
Real Time ◽  
Dimensional Analysis ◽  
Empirical Model ◽  
Vibration Amplitude ◽  
Experimental Setup ◽  
Vibration Characteristic ◽  
Model Predictions ◽  
Rotor Bearing ◽  
Bearing System

In this work, vibration characteristic diagnosis of misalignment rotor in loosely fitted bearing is investigated using dimensional analysis (DA) approach. A comprehensive empirical model (EM) using nondimensional parameters is developed to diagnose the rotor-bearing system, and EM model has been validated through an experimental setup developed in-house. Experiments are performed for various defects such as misalignment and bearing looseness. The EM results can be used to monitor the real-time conditions of the rotor-bearing system. This work also presents the effect of misalignment and bearing looseness under various load and speed conditions. Further, work has been extended to predict the combined effect of bearing looseness and misalignment. It has been found that EM model predictions of the vibration amplitude are better when compared to experimental results.

Comparison of Rotordynamic Analysis Predictions With the Test Response of Simple Gas Hybrid Bearings for Oil Free Turbomachinery

2003 ◽  
Author(s):  
Deborah A. Wilde ◽  
Luis San Andre´s
Keyword(s):  
High Speed ◽  
Natural Frequencies ◽  
Damping Ratio ◽  
Rotor Speed ◽  
Gas Bearings ◽  
Model Predictions ◽  
Rotor Bearing ◽  
Frequency Ratios ◽  
Bearing System ◽  
Good Agreement

Current applications of gas film bearings in high-speed oil-free micro-turbomachinery (<0.4 MW) require calibrated predictive tools to successfully deploy their application to mass-produced systems, for example oil-free turbochargers. The present investigation details the linear rotordynamic analysis of a test rotor supported on externally pressurized gas bearings. Model predictions are compared with the test rotordynamic response determined through comprehensive experiments conducted on a small rotor supported on three lobed hybrid (hydrostatic/hydrodynamic) rigid gas bearings. Predictions for the rotor-bearing system synchronous response to imbalance show good agreement with measurements during rotor coast downs, and manifest a decrease in damping ratio as the level of external pressurization increases. The rotor-bearing eigenvalue analysis forwards natural frequencies in accordance with the measurements, and null damping ratios evidence the threshold speeds of rotordynamic instability. Estimated whirl frequency ratios are typically 50% of rotor speed, thus predicting sub synchronous instabilities at lower rotor speeds than found experimentally when increasing the magnitude of feed pressurization. Rationale asserting the nature of the discrepancies calls for further analysis.

Experimental dynamic analysis of rod-fastening rotor bearing system with a transverse crack

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Nanshan Wang ◽  
Heng Liu ◽  
Qidan Wang ◽  
Shemiao Qi ◽  
Yi Liu
Keyword(s):  
Peer Review ◽  
Dynamic Characteristics ◽  
Vibration Amplitude ◽  
Critical Speed ◽  
Transverse Crack ◽  
Content Type ◽  
Rotor Bearing ◽  
Speed Up ◽  
Rod Fastening Rotor ◽  
Bearing System

Purpose This study aims to obtain the dynamic behaviours of cracked rod-fastening rotor bearing system (RFBS), and experimental investigation was carried out to examine the dynamic characteristics of this kind of assembled rotor bearing system with a transverse crack passing through the critical speed. Design/methodology/approach An experimental test rig of cracked RFBS was established for examining the vibration behaviours between intact and cracked system. The crack on the surface of a fastening rod was simulated by wire-electrode cutting processing method. The comprehensive analysis method of vibration was used to obtain the dynamic characteristics such as vibration amplitude, acceleration and whirling orbits before and after the critical speed as well as the instantaneous response in the process of speed up. Findings Some experimental vibration datum is obtained for cracked RFBS. The appearance of a crack will introduce the initial bending and make the vibration amplitude, acceleration and instant response in the process of speed up increase greatly as well as the change of whirling orbits. Originality/value The actual vibration characteristics for this complex assembled rotor system with a transverse crack are given passing through the critical speed. It can provide some useful help for monitoring the vibration behaviours of this kind of assembled rotor system as well as the detection of the crack fault. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0260/

Analysis and Experimental Study on Stability of Nonlinear Rotor-Bearing System

2011 ◽  
Vol 236-238 ◽  
pp. 2626-2629
Author(s):  
Wei Dong Gu ◽  
Yong Liang Wang ◽  
Bo Fang ◽  
Zhan Sheng Liu ◽  
Wen Hu Huang
Keyword(s):  
Finite Element Method ◽  
Experimental Study ◽  
Test Rig ◽  
Model Simulations ◽  
Oil Whip ◽  
Film Instability ◽  
Oil Whirl ◽  
Rotor Bearing ◽  
Practical Model ◽  
Bearing System

The paper established the model of the practical Model test rig rotor-bearing system using finite element method, and discusses the phenomena of oil whirl and oil whip occurred in fluid lubricated bearing. The characteristics of stability of the nonlinear rotor-bearing system were numerically studied under different unbalance and different parameter of bearings, the model simulations are compared with measurements at the test rig, which can provide the theoretical reference for forecasting malfunction of oil film instability.

Experimental Study on Rubbing Acoustic Emission for Rotor-Bearing System Based on Parameter Analysis

2009 ◽  
Vol 413-414 ◽  
pp. 513-519
Author(s):  
Yong Yong He ◽  
Xin Yun Yin
Keyword(s):  
Experimental Study ◽  
Acoustic Emission ◽  
Elastic Strain ◽  
Rotating Machinery ◽  
Parameter Analysis ◽  
Analysis Method ◽  
Traditional Methods ◽  
Rotor Bearing ◽  
Bearing System

Rubbing between the rotor and the stator is the frequent fault and will cause very serious accident, even catastrophe, to rotating machinery. Therefore, timely detection of such rubbing is very important avoid severe consequences. Vibration based methods are very mature and traditional methods but not effective to detect incipient rubbing in rotating machinery. Rubbing between the rotor and the stator will cause elastic strain in the rubbing location and thus can produce acoustic emission (AE). Apparently, such AE contains direct and abundant information about the rubbing and can be used to detect and diagnose such fault effectively. In this paper, the AE based method is proposed for detecting and identifying the rubbing of the rotor-bearing system. An experimental study is presented to investigate the characteristics and features of rubbing AE using parameter analysis method. The results show that AE is very sensitive to the rubbing and AE parameters can reveal the characteristics and features of rubbing AE. Parameter analysis demonstrates that rubbing AE contains multiple modals, which will attenuate with propagation by negative exponent manner.

Fractional Dynamics in Mechanical Manipulation

2007 ◽  
Author(s):  
Miguel F. M. Lima ◽  
J. A. Tenreiro Machado ◽  
Manuel Criso´stomo
Keyword(s):  
Experimental Study ◽  
Control System ◽  
Real Time ◽  
Fourier Spectrum ◽  
Fractional Dynamics ◽  
Second Phase ◽  
Experimental Setup ◽  
Recorded Data ◽  
Analysis Package ◽  
Mechanical Manipulation

This paper analyzes the signals captured during the movement of a mechanical manipulator carrying a liquid container. In order to study the signals an experimental setup is implemented. The system acquires data from the sensors, in real time, and, in a second phase, processes them through an analysis package. The analysis package runs off-line and handles the recorded data. The results show that the Fourier spectrum of several signals presents a fractional behavior. The experimental study provides useful information that can assist in the design of a control system to be used in reducing or eliminating the effect of vibrations.

Comparison of Rotordynamic Analysis Predictions With the Test Response of Simple Gas Hybrid Bearings for Oil Free Turbomachinery

2006 ◽  
Vol 128 (3) ◽  
pp. 634-643 ◽  
Author(s):  
Deborah A. Osborne ◽  
Luis San Andre´s
Keyword(s):  
High Speed ◽  
Natural Frequencies ◽  
Damping Ratio ◽  
Rotor Speed ◽  
Gas Bearings ◽  
Model Predictions ◽  
Rotor Bearing ◽  
Frequency Ratios ◽  
Bearing System ◽  
Good Agreement

Current applications of gas film bearings in high-speed oil-free microturbomachinery (<0.4 MW) require calibrated predictive tools to successfully deploy their application to mass-produced systems, for example, oil-free turbochargers. The present investigation details the linear rotordynamic analysis of a test rotor supported on externally pressurized gas bearings. Model predictions are compared with the test rotordynamic response determined through comprehensive experiments conducted on a small rotor supported on three lobed hybrid (hydrostatic/hydrodynamic) rigid gas bearings. Predictions for the rotor-bearing system synchronous response to imbalance show good agreement with measurements during rotor coastdowns, and manifest a decrease in damping ratio as the level of external pressurization increases. The rotor-bearing eigenvalue analysis forwards natural frequencies in accordance with the measurements, and null damping ratios evidence the threshold speeds of rotordynamic instability. Estimated whirl frequency ratios are typically 50% of rotor speed, thus predicting subsynchronous instabilities at lower rotor speeds than found experimentally when increasing the magnitude of feed pressurization. Rationale asserting the nature of the discrepancies calls for further analysis.

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