Coast Down Time Analysis to Analyze the Effect of Misalignment in Rotating Machinery
G. R. Rameshkumar1, B. V. A. Rao2, K. P. Ramachandran3
1Dr. G.R. Rameshkumar, Department of Mechanical & Industrial Engineering, Caledonian College of Engineering, Muscat, Sultanate of Oman, India.
2Prof. B.V.A. Rao, Advisor, Human Resources and International Relations, KL University, Vijayawada, India.
3Prof. K.P. Ramachandran, Associate Dean (PG&R), Caledonian College of Engineering, Muscat, Sultanate of Oman, India.
Manuscript received on March 01, 2012. | Revised Manuscript received on March 15, 2012. | Manuscript published on April 30, 2012. | PP: 149-156 | Volume-1 Issue-4, April 2012 | Retrieval Number: D0316041412/2012©BEIESP

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Abstract: Shaft misalignment in rotating machinery is one of the major industrial concerns. When the power supply to any rotating system is cut-off, the system begins to lose the momentum gained during sustained operation and finally comes to rest. The exact time period between the power cut-off time and the time at which the rotor stops is called Coast Down Time. In this paper an experimental study was conducted to investigate the effect of angular misalignment in forward curved centrifugal blower test setup. Tests were conducted for various level of angular misalignment at different shaft cut-off speeds. The results show that the coast down time decreases with increase in level of angular misalignment. At higher speed and at higher level of angular misalignment, the impact on percentage reduction in CDT is very high and there is a specific correlation between the percentage reduction, cut-off speeds and the level of introduced angular misalignment. The vibration signatures acquired at different cut-off speeds and at the various level of angular misalignment conditions. The 2X and 3X vibration amplitude components are predominant frequencies and increase as the angular misalignment and shaft rotational speed increases, thereby establishing the fact that the CDT analysis can be used as one of the diagnostic condition monitoring parameter for rotating machinery.
Keywords: Angular Misalignment, Coast Down Time, Condition Monitoring, Forward Curved Centrifugal Blower.