USE OF OIL FILM PROPERTIES AT DEVELOPMENT AND IMPROVEMENT OF COMPAX® SYSTEMS FOR MONITORING AND TECHNICAL DIAGNOSTICS
Abstract and keywords
Abstract (English):
One of key factors at the vibration reliability support of turbo-sets in operation – a correct design of journal bearings, and also the assurance of supporting system normal operation during a life cycle of a unit with possibility to control basic technical parameters characterizing a technical state. To solve this problem first of all a method for the permanent control of gaps in bearings and also static and dynamic forces affecting every bearing is required. In accordance with new RSS 55263-2012 gaps and shaft misalignments are to be controlled with the aid of two couples of shaft sensors for every supporting bearing. For the evolvement of forces affecting bearings it is necessary to solve the equations of lubrication in supporting bearings. In this work there is offered a method which allows carrying out all hydro-dynamic computations in advance. In the mode of real-time for the forces definition it is offered to use the interpolation on ready computation results. To realize this task there are formed fields of possible movements (FPM) of shaft journals in each bearing taking into account single geometrical peculiarities and actual gaps. In the FPM there is formed a grid and for every grid node a computation of essential static and dynamic characteristics is carried out, and the results are saved in a database. In a real-time mode according to the known position of a journal in a gap one defines a point in the FPM and essential characteristics are interpolated. In such a way are calculated all necessary characteristics of a bearing: vertical and horizontal loads, loss power for friction, mean temperature of lubrication in a lubricating oil wedge, a minimum gap, stiffness and damping coefficients. This information of a bearing state is necessary for the diagnostics of a technical state of a turbo-set, and it is impossible to obtain with the aid of common means of control existing at an electric power station. In the paper there is shown an example of FPM formation and a computation of basic static characteristics for an elliptical bearing throughout the entire field of possible movements. The analysis of the influence of gaps deviations from nominal values defined by repair lists is presented. The notion of the field of possible movements is introduced beyond which one diagnoses an abnormal mode of a turbo-set operation characterized by increased temperatures of lubricant or babbit and/or grazes. The methods for the computation of slider bearing characteristics throughout the whole of the field of possible movements with the possibility of smooth interpolation are developed for the application in the real-time diagnostic system of COMPAX

Keywords:
slider bearing, hydro-dynamic theory of lubrication, turbo-set, triangulation, interpolation, technical diagnostics, technological dispersion, oil film
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References

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