Influence of Damping on the Calculation Results of the Vibration Parameters of the Support of a Turbine-Generator Set wi
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Vol. 54, No. 3, September, 2020
INFLUENCE OF DAMPING ON THE CALCULATION RESULTS OF THE VIBRATION PARAMETERS OF THE SUPPORT OF A TURBINE-GENERATOR SET WITH AN ATTACHED DYNAMIC VIBRATION DAMPER V. M. Pan’kin1 Translated from Élektricheskie Stantsii, No. 3, March 2020, pp. 39 – 42.
Formulas for calculating the change of vibration of the support of a turbine-generator set with an attached dynamic vibration damper are given in the frequency band of its efficient operation. In calculation with the relative damping ratio of the dynamic vibration damper, the value of which is determined by the proposed method, taking account of the changes of the dynamic properties of a mechanical system, the best approximation to the measured values was obtained in conducting bench trials. Keywords: calculation; vibration; damping ratio; dynamic vibration damper; support; turbine-generator set.
nation of the parameters of vibration of the designed mechanical system, taking into account the damping ratio at the resonant frequency (ùnom) [3 – 5]. In accordance with [3], the amplitude of residual vibration of the support of a turbine-generator set (AS) relative to the parameter X, for a linear model of a two-mass mechanical system, at the central operating frequency of the DVD (ùcof) when fulfilling the conditions of its optimal tuning ùcof = = ùnom can be determined from the following formula:
Accounting for the value of the damping ratio is necessary in solving the problems of decreasing the resonant vibration of the supports at the nominal frequency of rotation (ùnom) of a turbine generator shaft train by connecting an inertial dynamic vibration damper (DVD). Here the damping ratio in links of the support of a turbine-generator set with the base and in connecting DVD on the support of a turbinegenerator set [1 – 6] is taken into account. However, the initial calculated mechanical properties of a system with an increased term of operation are lost, due to the natural processes of aging, wear on the built devices, and development of any type of defects that result in the loss of the integrity of construction that cannot be fully accounted for in conducting theoretical calculations of the scattering of mechanical energy. Hence, reliable estimates of the total damping ratio can be obtained only from experimental data [2]. In connection with the features of installation and operating conditions of even single-type turbine-generator sets, the value of the damping ratio of the supports can differ significantly. Therefore, in performing calculations of the DVD for a specific support, it is necessary to use the amplitude-frequency characteristics (AFC) of vibration, measured before connecting the DVD. This makes it possible to take into account the change of response characteristics of the studied support of a turbine-generator set under conditions of perturbing forces actually acting on it and to calculate the static deflection of the support (X), which is necessary for determi1
As X
=2
b cof m
,
(1)
where âcof is the relative coefficie
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