Using Operating Deflection Shape (ODS) and Experimental Modal Analysis (EMA) Modeling and Simulation Techniques to Predict the Effects of Pumping System Upgrades

An ODS model is a method to animate the reaction of a machine and structure to the forces generated during operation. EMA identifies the natural frequencies within a specified bandwidth that, if excited, can resonate the structure. A pumping system is to be modified to accommodate higher production rates. The pump is a vertical design. To accommodate the increased capacity, a larger drive motor and more robust discharge/motor support head is required. The effects of the higher flow rates on the piping systems are not known. ODS and EMA studies were commissioned. Frequency response functions (FRF) were acquired for the operating ODS, and for the EMA with the system at rest. The ODS revealed the response modes of the pump and piping system. The EMA FRF’s were entered into the model with the upgrade system specification. The modified model indicated the excitation forces generated during operation would result in unacceptable resonance responses of several structural components. Virtual system modifications were made and new resonance response functions were generated. The model’s modified responses revealed the results of the excitation forces were mitigated when the recommended structural modifications are incorporated into the upgrade design specifications; therefore, preventing costly post-upgrade modifications.

References
1. Barry PE, James E. Applied Modal and Operating Deflection Shape Analysis, second edition, Chapter 6, “Operating Deflection Shape Analysis (ODS),” Section 6.03, pp. 17-18. August 11, 2005. 2. Barry PE, James E. Applied Modal and Operating Deflection Shape Analysis, second edition, Chapter 9, “Experimental Modal Analysis,” Section 9, pp. 1-44. August 11, 2005. 3. Mohitpour, M., J. Szabo and T. Van Hardeveld. Pipeline Operation and Maintenance – A Practical Approach, pp 82, ISBN 0-7918-0232-9, Chapter 3, section 3.1 “Liquid Transportation.” 4. Mohitpour, M., J. Szabo and T. Van Hardeveld. Pipeline Operation and Maintenance – A Practical Approach, Chapter 8, section 8.11 “Troubleshooting and Failure Investigation” pp 514.
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