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Stability Analysis

The rotor stability analysis is used to estimate the high amplification factor of first critical speed for sensitive machine, and it is composed with simplified Level I and detailed Level II analysis. Stability study has two (2) purposes: first, it provides an initial screening to identify rotors that do not required a more detailed study. Second, this stability study specifies a standardized procedure applied to equipment manufacturers. This analysis is one of procedure of lateral study (rotordynamics), and damping and instability factor is calculated.

Stability-analysis
Stability-analysis

Stability Study

Stability analysis includes below kinds of procedure;

  • Estimate the anticipated cross coupling coefficients
  • For centrifugal and axial compressors
  • Damping and log decrement
  • Stability experience plot
  • Gas density and critical speed ratio
  • Level 1 analysis (Level I)
  • Level 2 analysis (Level II)
  • For labyrinth seals, damper seals, impeller/blade flow aerodynamic effects
  • Acceptance criteria for stability study
  • Assessment of instability factor
Stability-Study-Density-Map
Stability-Study-Density-Map

Lateral Study

After lateral study completed, Level 1 analysis shall be performed the rotating equpment that meet the following;

  • Rotors whose maximum continuous speed is greater than the first undamped critical speed on rigid support condition.
  • Rotor with fixed gometry bearings
Lateral-study (Mode-shape)
Lateral-study (Mode-shape)

Damping & Instability

As results of Level 1 analysis, the damping and instability factor is lower than 0.1, Level 2 stability analysis shall be performed. Final log decrement shall be greater than 0.1.

Level II-Stability-for-Damping-and-Instability
Level II-Stability-for-Damping-and-Instability

These analysis shall be calculated at the defined maximum continuous speed of rotating equipment.

INERTANCE has a capability regarding sound and vibration engineering, and our experts are familiar with assessment of Stability analysis as rotordynamics analysis. For further information, contact us at (admin@inertance.com).

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