Analytical Study of Piping Flow-Induced Vibration. Example of Implementation
SMIRT 17,Prague, Czech Republic, August 17-22, 2003, Paper N J280
The paper presents methodology for analysis of piping vibration state. The acoustic resonance of medium (steam or water) is considered as most probable source of flow-induced vibration.
For analysis of piping vibration induced by steady-state processes in a transmitted medium the mathematical model and corresponding computer code NETPULS are developed for evaluation of an acoustic oscillation in a liquid or gaseous medium. Acoustic excitation can arise in the pipeline discontinuities such as tees, branches etc. and also can be caused by external sources connected to the pipeline. NETPULS is based on linearized mathematical model of quasistationary acoustic oscillation in the compressed medium. Mathematical model of this process takes into account influence of non-linear damping due to hydraulic friction and local hydraulic losses.
The amplitude-frequency and phase-frequency characteristics of the gas-dynamic forces acting upon the piping discontinuities (bends, tees, branches etc.) are defined. The output obtained by NETPULS can be used as input data for consequent calculation of mechanical vibrations of pipelines and evaluation of effectiveness of damping devices.
Implementation of the described approach is illustrated on a basis of practical measurements and numerical analysis of typical NPP steam line.