Rotor dynamics and machinery vibrations

Integrally geared compressor rotor dynamics RotMach

We perform lateral and torsional dynamics analysis of isolated rotors and complete drivetrains including bearing support structures, housings and frames. Undamped, damped analysis, damped unbalanced response, stability. We follow standards API 612/613/617/684 or according to customer standards. We asses machinery vibrations. Our analysis and calculations are based on many years of practical experience and experimental research activities in field of rotor dynamics and rotating machinery.

Rotor dynamics and machinery vibrations services

Lateral rotor dynamics

  • According to API612/613/617/684 or to customer standard
  • Isolated rotor or complete drivetrain analysis
  • Eigen mode shapes and frequencies
  • Damped unbalanced response analysis
  • Stability analysis
  • Gas flow effect on stability (Alfords)
  • Campbell diagram
  • Logarithmic decrement diagram (stability)
  • Undamped critical speed map
  • Bode diagrams
Dynamika rotorů a vibrace strojů, Mapa netlumených kmitů, RotMach
Rotor dynamics and machinery vibrations, Campbell diagram, RotMach
FEM Harmonická analýza, Rotmach

Modal analysis

Modal analysis is an effective tool in solving machinery problems associated with vibration. Modal analysis makes it possible to find eigenmodes and “problematic” resonant frequencies of systems without the need for knowledge of damping or excitation effects.

The modal analysis includes in particular:

  • determination of frequencies of natural frequencies (Campbell diagram) and shapes of oscillations
  • evaluation of the relative damping of individual eigenmodes

Harmonic analysis

Harmonic analysis provides a more comprehensive insight into vibration calculations. The result of the harmonic analysis is the knowledge of the magnitude of vibrations in the dimensional quantity (mm/s, mm/s2 or the magnitude of the Pk-Pk oscillation). The values ​​calculated in this way can be directly compared with the vibration values ​​measured on the actual equipment in operation or on the test bench.

  • Based on information from the customer about the excitation, or our knowledge of effects such as component residual imbalance etc., we introduce into the mathematical model one or a combination of several excitations sources (represented by amplitude & frequency).
  • The amount of damping introduced into the calculation is also based on our experience or consultation with the customer based on his requirements and available input data.
  • The output of the harmonic analysis is, in addition to the identification of problematic resonances, also frequency-amplitude characteristics (Bode diagram) across the operating spectrum of the device.

Torsional rotor dynamics

  • According to API612/613/617/684 or to customer standard
  • Isolated rotor or complete drivetrain analysis
  • Campbell diagram, mode shapes
Dynamika rotorů a vibrace strojů, Torzní model turbosoustroji, RotMach
Dynamika rotorů a vibrace strojů, Rotorová dynamika RotMach

Vibrodiagnostic measurement evaluation

  • Machinery vibrations measurement evaluation and assessment, we specialize in relative rotor vibrations
  • Rotor dynamics measurement and simulation identification
  • Analysis of Bode diagram, orbit, frequency spectrum etc.
  • Recommendations, methodology and best-practice limits for low and high-speed rotor balancing
  • Proposals and corrective actions to suppress vibration levels of existing rotating machinery
  • optimization of hydrodynamic bearing geometry
  • suppressing rotor instabilities (damper seals   applications, etc.)

Rotor-bearing systems

  • Bearing type selection, review and optimization of bearing supports (supporting structures)
  • Resonance and instability suppressions
  • Hydrodynamic and roller bearing dynamic properties approximation
Radiální segmentové ložisko, Rotmach
Dynamika rotorů a vibrace strojů, Zkušební stand kluzných ložisek, RotMach

Experimental and R&D activities

  • Concept and detailed design of test beds and experimental stands for validation of rotor dynamics and bearing properties
  • Development and implementation of new analysis methods and procedures
  • High speed motor – blower (18000rpm, 100kW) with aero bearings available for testing, research and development activities
  • Cooperation on R&D and grant projects

Vibration problem?