Piping system dynamic characteristics are determined utilizing the classical Eigen-Value problem solution. Systems with integrated inline rotating components would experience some changes in these characteristics. The intensity of these changes depends on the relative magnitudes of their rotational momentums. Pseudo single degree of freedom ‘SDOF’, systems that include gyroscopic momentum of a rotating shaft are formulated and are subjected to seismic base excitations. The comparative responses of these SDOF are investigated. The gyroscopic inertia significantly alters their predicted seismic responses. For multi-degree of freedom system, simplified methodology is formulated to provide quick assessment of including the gyroscopic effects of the rotating components. The lumped parameters of the inline-rotating component within the piping system require the velocity degrees of freedom to be included in the analysis. This results in the non-classical Eigen-Value problem type of formulation. The latter is simplified utilizing the classical Eigen-Value solution conventionally termed as normal modes extraction. The normal modes synthesis reduces the number of degrees of freedom for the non-classical Eigen-Value problem to a manageable level. The concept of mode shape utilization coefficient ‘MSUC’, is introduced to provide quick assessment of the system. The gyroscopic inertia does not dominate the system dynamic characteristics. Low to moderate rotational momentums, typically installed by the industry, slightly affect the piping system dynamic characteristics. This justifies the industry practice of ignoring the rotational momentums within the piping systems routine analysis. It is also found that very high rotational momentums are artificially required to dramatically change the system dynamic characteristics.
- Pressure Vessels and Piping Division
Effects of Inline Rotating Component on Piping System Dynamic Characteristics
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Ibrahim, ZN. "Effects of Inline Rotating Component on Piping System Dynamic Characteristics." Proceedings of the ASME 2003 Pressure Vessels and Piping Conference. Design and Analysis of Pressure Vessels and Piping: Implementation of ASME B31, Fatigue, ASME Section VIII, and Buckling Analyses. Cleveland, Ohio, USA. July 20–24, 2003. pp. 53-61. ASME. https://doi.org/10.1115/PVP2003-2184
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