Frequency domain modelling of pipe transient flow with the virtual valves method to reduce linearization errors

Autor: Mohammad Hadi Ranginkaman, Pedro J. Lee, Ali Haghighi
Rok vydání: 2019
Předmět:
Zdroj: Mechanical Systems and Signal Processing. 131:486-504
ISSN: 0888-3270
DOI: 10.1016/j.ymssp.2019.05.065
Popis: For Modeling the transient flow in a pipeline by Frequency Response Method (FRM), the nonlinear terms of the governing equations and boundary conditions should be linearized. Significant nonlinearities are associated with the steady friction and valve equations. This study reviews the FRM and its range of validity in accordance with the linearization errors and, proposes some remedies to reduce the errors. To improve the FRM accuracy, the linearization of valve equation is modified and a new frequency-dependent correction factor is introduced. Also, to capture the system responses at the higher-order frequencies due to the nonlinear terms, the method of virtual valves is introduced. Through this method, the system’s real nonlinear valve oscillating at a main frequency ω is represented by a number of linear virtual valves oscillating at the main and some higher-order frequencies 2 ω , 3 ω , ⋯ that may appear in the system’s response spectra due to the nonlinearity of valve equation. The modified FRM (M-FRM) is compared with the standard FRM (S-FRM) as well as the Method of Characteristics (MOC) on the energy phase diagram. The results demonstrate that the modifications dramatically improve the validity of the FRM even for large sizes of valve perturbation. The generality of the method is also validated by solving several pipe-reservoir-valve systems with different specifications.
Databáze: OpenAIRE
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