Torsional vibration analysis of rotating machinery is very important in defining the operational reliability of rotary equipment trains. Severe torsional vibrations often occur in rotating types of equipment with only an indication of the problem being gear noise or coupling wear. This makes it very critical to analyze systems’ torsional response accurately during the design stage itself.

A Torsional Vibration project carried out by Analyser Team

Torsional analysis of a turbine-driven pump was carried out for our client to predict the torsional response of the entire powertrain system. A Mass elastic data model was created capturing all major Inertias and stiffness of complete power train representing components like the turbine, couplings, gearboxes and the pump using ANSYS CLASSIC software and dynamic analysis was carried out on same

Results of Analysis (Identification of a concern at the design phase by analysis)

A torsional natural frequency analysis (modal analysis) revealed that the first natural frequency of the rotary power train was within the 10% range of operating frequency of the pump. As per API, this design is not acceptable as it can cause resonance and involves a high risk of failure.

Solution provided by Analyzer Team

Our team at Analyzer carried out a sensitivity analysis of all the feasible design changes that could change the torsional natural frequency of the rotating system. The first natural frequency was most sensitive to Low-speed coupling torsional stiffness. Hence It was suggested to change the stiffness of the low-speed coupling. The client worked out with a coupling vendor for a different coupling with torsional stiffness value as suggested by our team based on torsional vibration Analysis.

The Analysis helped our client to choose appropriate coupling based on Torsional Analysis. Timely mitigation of risk by analysis saved time and cost.