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LATERAL CRITICAL SPEED ANALYSIS OF MULTISTAGE CENTRIFUGAL PUMP ROTOR USING FEA

Naveena M, Dr. Suresh P M

Modal analysis is the study of the dynamic properties of structures under vibrational excitation. Modal analysis is the field of measuring and analysing the dynamic response of structures, when excited by an input. The modal analysis of the centrifugal pump is performed using FEM technology to find the centrifugal rotor natural frequencies. To meet the higher target of power, machines have to run at higher speeds. The pump shaft will be subjected to higher lateral and torsional vibrations because of gyroscopic effect and centrifugal force of the rotating elements mounted on the shaft. The resonance is produced when the rotor natural frequency coincides with operating frequency, the deflection of the rotor will be maximum. To avoid resonance condition, it is necessary to evaluate all stiffness and damping coefficients of wear rings, mechanical seals, throttle seals and bearings. In this work an attempt is made to evaluate the Lateral critical speeds using ANSYS® software by plotting Campbell diagrams and is compared with theoretical calculations and RBTS (Rotor Bearing Testing Software). It is very difficult to eliminate all interference points in the system since there are so many external excitations. Forced response analysis was conducted to know the peak amplitudes at the resonance points. The rotor has been designed and analyzed by using the guidelines as per API 610 standards.