Analysis of the error obtaining while determining characteristics of rotor system within the run-down
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- Category: Geotechnical and mining mechanical engineering, machine building
- Last Updated on 06 September 2017
- Published on 06 September 2017
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Authors:
I.O.Taran, Dr. Sc. (Tech.), Prof., State Higher Educational Institution “National Mining University”, Dnipro, Ukrainе, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
M.M.Trubitsyn, Cand. Sc. (Tech.), Assoc. Prof., State Higher Educational Institution “National Mining University”, Dnipro, Ukrainе, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
Abstract:
Purpose. The objective of the paper is to determine reasons of origin and conditions of reducing errors while obtaining combined geometrical (axial moment of inertia, mass centre location), mass (rotor weight), frictional (relative radii of bearings) characteristics of rotor system within the run-down. This is required to determine constant (gravitational moment), linear (being proportional to rotational velocity), and quadratic (ventilator moment) components of complete moment of rotor rotation resistance with the following balance problem solving with the help of peak method.
Methodology. Theoretical research of rotating rotors relies upon basic theoretical provisions (dynamics) of machines and mechanisms, pre-developed algorithm of 1.2… of N-planar balancing of rigid rotors using peak method as well as analysis of calculation error obtaining.
Findings. A statement concerning the necessity of equality of initial errors while measuring experimental values (i.e. time, turning angle, rotational velocity) of run-down has been developed. The statement results in minimization of an error while determining required characteristics of a rotor. The developed algorithm of serial computations identifies definitely geometrical, mass, and frictional characteristics of balanced rotor system in the case of negative discriminant of total moment of rotational resistance. In the context of another, arbitrary relation of rotor system parameters (not negative discriminant), both methodology and order of rotor characteristics determination remain similar. It is planned to use the algorithm as one of the potential alternatives to obtain values of the rotor characteristics with the following substantiated selection of sets of characteristics using the least square method and to come to the balancing problem.
Originality. The basic reason or a source to form the error while determining geometrical, mass, and frictional characteristics of rotor systems within the run-down has been identified – difference in measuring errors of certain run-down parameters: time and rotational velocity of rotor turning angle. Theoretically, in terms of any measuring errors being similar in value within the run-down (for example, its time) we obtain true value of target characteristics in the process of each experiment.
Practical value is in potential use of permanent stoppages of rotor systems to monitor basic total rotor characteristics – wear and tear of operating devices, block bearings, changes in a value of a process moment, redistribution of bulk weight of a rotor, and the following moment balancing problem solving with the help of a peak method. The proposed solution technique involving the least square method will make it possible to select reasonably the most adequate set of characteristics from the solution set for zero (two possible solutions), non-zero (generalized case), and positive discriminant of a rotor rotational resistance moment.
References
1. Barkova, N.А. and Borisov, А.A., 2009. Vibration diagnosis of machinery and equipment. Calculation of the main vibration frequencies of machine components, measuring instrument parameters and practical examination. SPb.: Publishing center SPbMTU.
2. Taran, I.А. and Trubitsyn, М.N., 2013. Generalized formula of one-plane balancing. Messenger of NTU “KhPI”, 8(1051), pp.114‒119.
3. Goldin, А.S., 2009. Vibrations of rotor machines. Мoscow: Mashinostroeniie.
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