| Dynamic analysis of the rotor system should be fully taken into account the role of gear meshing when the rotor system containing gears. Radial and tangential force between the gears will cause bending vibration and torsional vibration. In addition, rotor system may contain multiple gear units and each gear unit has different form. Because the transmission shafts have different speeds and directions, makes the coupled vibration problem of rotor system with gears become more complex.The main purpose of this paper is researching the vibration characteristic problems of the gear compressor rotor system, by using the rotor dynamic and finite element theories. Vibration characteristics of the parts of the compressor rotor system and the whole rotor system under different conditions were studied. This work includes the following aspects:(1) Introduced the basic theory of the rotor system dynamics, through the collation of existing literatures, summed up the several expression forms of gear mesh stiffness matrix.(2) Established the dynamic analysis model of H518gear transmission. Considered the inherent characteristics of system with different mesh stiffness matrix, and analyzed the inherent characteristics with different helix angle.(3) By simplifying the technical drawings, established a compressor rotor system dynamic model, and analyzed the influence of gear coupling to the inherent characteristics of the system.(4) Analyzed the stability of the system, loaded through API standards, and analyzed the unbalance response under different loading conditions.(5) The dynamic model of coupling angle misalignment fault and parallel misalignment fault were derived, described the calculation method of force in these two faults. Vibration responses when rotor system has varying degrees of fault were simulated.Came to the conclusion, because of the gear coupling, the rotor system with gear meshing compared with the rotor system without gear meshing, will generate new frequency components and the vibration modes will change too. For the presence of gear, new frequency components will produce also after the couple of bending and torsional vibration. Through the analysis of resonance region, stability and vibration response, the H518compressor works safely. The vibration characteristics of the rotor system with misalignment faults are obtained as following:there is not only rotating frequency but also multiple frequencies appearing in the spectrum, and the ratio of the multiple frequencies increase with the rise of the degrees of misalignment. Under the condition of misalignment, the shaft center orbit presents a "banana" shape or "8" shape. |
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