Abstract
It’s difficult to test repeatedly for large heavy-load bearings (LHLBs) with full-scale and real load due to complexity and costliness, so simulated identification on dynamic characteristics of 1750 MW nuclear generator bearing with diameter 800 mm and specific pressure 3.3 MPa is provided in this paper. The identification model of bearing dynamic characteristic is established, the calculating method of positive and negative dynamic problems is provided, and effects of signal disturbances on identification precision are analyzed. The results show that the LHLBs’ permitted displacement disturbance should not be over 5 μm and the permitted ratio of dynamic load and static load is about 1 %-2 %, which is different from common knowledge of 15 %-20 % for small light-load bearings. If identification error of the main stiffness and main damping coefficients is less than 5 %, the amplitude of periodical disturbance of the dynamic load and displacement signals should be less than 5 %. If identification error of the main damping coefficients is less than 10 %, the phase of these two signals should be less than 1°. The roundness error and rotation error of the large shaft should be eliminated.
Highlights
Nuclear energy is becoming one of the main new energies explored by countries in the world due to its economy and cleanness
If identification error of the main stiffness and main damping coefficients is less than 5 %, the amplitude disturbance of dynamic load should be less than 5 %
Simulated test on dynamic characteristics of the large heavy-load bearings (LHLBs) is investigated in this work
Summary
Nuclear energy is becoming one of the main new energies explored by countries in the world due to its economy and cleanness. China has been in the stage of fully developing nuclear power technology of kMW unit capacity, such as 1000 MW [1], 1550 MW [2] and 1750 MW [3]. As the promotion of unit capacity of nuclear generators, their bearings must be larger (diameter, over 800 mm) and heavier (specific pressure, , over 3.3 MPa) [4, 5]. The dynamic characteristics of large heavy-load bearings (LHLBs) directly determine equipment’s operation quality. Obtaining the LHLBs’ dynamic characteristic coefficients is meaningful to assess stability and fault diagnosis of rotor-bearing system. The high identification precision on bearing dynamic characteristic is difficult in the dynamics field for a long period. The sine excitation is the most frequent stable excitation [6]. Single-frequency twice excitation method [7], time domain least mean method [8], pulse excitation method [9, 10], unbalanced quality method [11, 12] and impulse response method [13] are available
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