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- Type of Document: M.Sc. Thesis
- Language: Farsi
- Document No: 41032 (08)
- University: Sharif University of Technology
- Department: Mechanical Engineering
- Advisor(s): Zohoor, Hassan
- Abstract:
- Vibrational modeling of a gas turbine considering simultaneous faults is considered. Faults including: unbalance, misalignment, and rotor crack are selected to be modeled. Oil film forces of hydrodynamic bearings are chosen as the supports of the rotor. Modeling starts with choosing an appropriate finite element model for the rotor which includes the effects of shear deflection, rotary inertia, gyroscopic moment, and rotor cross section variation. Modeling of unbalance is in fact a part of rotor finite element modeling. The forces that origniate form misalignment are computed using the static relations of a rigid coupling. Modeling of bearing faults along with bearing forces is performed via solving the Reynolds equation for a plain journal bearing. Finally, the assembeled model is solved numerically to obtain the vibration signatures of the resulting signal. In the end, a system for vibrational simulation of a gas turbine is presented which yields the vibrational behavior of the rotor in case of coexistance of the considered faults. This system is suitable for examining new designs as well as serving as a crusial step towards building a vibrational fault diagnosis scheme. The validation of the obtained model is conducted through camparison with simpler cases which have well-known models and also using general characteristics of individual faults. As is shown, good agreement is observed
- Keywords:
- Gas Turbines ; Crack ; Misalignment ; Vibration Modeling ; Unbalance
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