Modeling of the Turbine Rotor Journal Restoration on Horizontal Balancing Machines

AbstractDuring the normal operational life of a turbine, its rotor journal seating surfaces are wearing and therefore, repair operations, including turning and grinding of such surfaces and next rotor balancing on the balancing machines, are carried out. Traditional turbine rotors machining is provided by fixing them through the centers and demands the corresponding large size machine tools and the strategy «machine tool to rotor» is often used. To minimize mobilization and transportation cost, the problem of the turbine rotor restoration by using centerless grinding technique on the lightweight horizontal balancing machines is resolved. A computer simulation model of such grinding with workpieces located on their machining surfaces is presented. To validate the approaches, a proposed computer simulation was carried out. Theoretical and computational investigations demonstrate that the deviation from the roundness of a workpiece may be reduced from the initial value of half a millimeter to a final value of 10 micrometers by using a special location of cutting tools

The two accretion states of the polar 1RXS J184542 in 2012

We present the photometric investigation of the newly discovered magnetic cataclysmic variable (polar) 1RXS J184542 during four months in 2012. We used the CCD observations in R-band obtained with the 0.5-m ARCSAT telescope at the Apache Point Observatory. It was found that during this time the object changed its relatively high accretion state to the low one. There was a two-pole accretion at the high state and one-pole accretion at the low state

Variations in the Period of Negative Superhumps in SU UMa-Type Dwarf Novae. I. Mn Dra (2012-2017)

© 2020, Springer Science+Business Media, LLC, part of Springer Nature. This is a photometric study of the dwarf nova MN Dra made during 2012-2017 on nine telescopes over 152 nights. Overall, the observations covered 4 superoutbursts, 7 normal outbursts and the quiescent state. The interval between neighboring superoutbursts in 2017 was 65 days, and between neighboring normal bursts, 15 days. During the superoutbursts of 2012 and 2017, positive superhumps with a period of 0.10558(6) and 0.10500(2) days, respectively, were observed and in the quiescent state, negative superhumps with an average period of 0.095921(3) days, It is shown that the period of the negative superhumps varied cyclically between normal outbursts: sharply decreasing during an outburst and gradually increasing toward the onset of the next outburst. This feature of the variation in the period of the negative superhumps may correspond to a rapid increase in the radius of the accretion disk during the time of an outburst followed by a slow decrease, in agreement with the theory of thermal-tidal instability