Overview

This course aims at introducing the main concepts related of rotor dynamics and diagnostics.

Rotor dynamics is the key for the design and operation of many machines: turbine of any kind used for power generation, aircraft engines, electrical motors, centrifugal compressors, etc. Thus, the dynamics of the complete machine and of its main components, like shafts, bearings, seals and blades is presented in detail. Several design tools and examples are introduced.

Diagnostics is an emerging requirement in modern mechanical systems in order to shorten out-of-service and reduce operation costs. Very often, the faults are affecting the same components analysed by rotor dynamics and this makes the two parts of the course strictly connected. State-of-the-art techniques, based on both system model and data analysis, are introduced.

All the topics are analysed under practical and theoretical points of view, with several examples of application in real machines, of design cases and of case histories. The seminars, conducted by industry experts, are essential parts of the course.

List of the topics 

Rotor dynamics

• Finite beam models for lateral and torsional vibrations. Supporting structure modelling. Review of design standards (API, ISO). Flexible rotors balancing
• Critical speeds, Campbell diagram, System response to common linear (unbalance, bow, misalignment, cracks) and non linear (rub, magnetic fields) excitations
• Stability (effects of fluid film bearings, of steam flow, of magnetic bearings/fields)

Fluid-film bearings

• Hydrodynamic lubrication, computational hydrodynamics, Geometry of fluid film bearings
• Bearing design (static and dynamic characteristics), Journal bearing testing, Thrust bearing testing, Bearing coating materials, Bearing damages
• Effects of electrical pitting

Seals

• Geometry, modelling (bulk-flow, and CFD), dynamic characteristics calculation

Blade dynamics

• Excitation causes
• Design, HCF, Correction, LCF, Correction
• Damping, snubbing, friction, vibration measurements

Diagnostics

• Maintanance policies, condition monitoring, setting of alarms and trips, review of current standards
• Model based approach (inverse dynamic problem), with case history analysis (steam, gas and hydro turbines)
• Data driven approach (advanced signal analysis: time-frequency transformations, 2nd order cyclostationarity, envelope analysis, spectral kurtosis), with case histories (turbine gearbosx, train traction systems, engine firing)

Special topics

• Wind turbine diagnostics
• Roller element bearings diagnostics
• Gear diagnostics

Seminars (speakers from industry)

1. Industrial steam turbine design and operational requirements
2. Hydro turbine design and operational requirements
3. Industrial gas turbine design and operational requirements
4. ORC (Organic Rankine Cycle) turbine design and operational requirements

The exam is oral.

Slides of the lessons, which include all the topics of the course, are provided via BeeP. The bibliography is suggested and can be fruitful consulted for individual in-depth analysis.

Slides of the lessons

Available on www.biblio.polimi.it - The book is useful for the description of main components of typical rotating machines

Some hardcopies are available in Polimi libraries

Available on www.biblio.polimi.it

Some hardcopies are available in Polimi libraries

Available on www.biblio.polimi.it

Available on www.biblio.polimi.it