Vibration and power flow analysis for 3-D piping systems by wave approach

Abstract

The main objectives of this study are to propose 1) the vibration analysis method of 3-dimensional piping systems conveying fluid by wave approach, 2) vibration reduction method by the design of periodic pipe supports, and 3) power flow analysis and measurement method. The proposed wave approach can be a powerful tool to analyze the 3- dimensional piping systems conveying fluid with straight pipe sections, curved pipe sections and branched pipe sections. In this study the pipe internal flow is assumed as plug flow model and slender body theory is adopted to formulate the pipe element. And the curved pipe section is formulated by the mixed methodology using the dynamic stiffness matrix and transfer matrix obtained by wave approach. Therefore, the proposed method can treat the straight or curved pipe section with only a single pipe element. The periodic system has a free wave propagation characteristics such as wave stop frequency bands and wave propagation frequency bands. In this study the applications of periodic characteristics to the pipe support design are presented to reduce the vibration level. From this study if the dominant excitation frequency bands are known, the periodic support systems can be applied to reject these frequency bands. The vibration energy flow in piping system conveying flow is investigated by power flow analysis by wave approach. The power flow can be a very good tool to identify the dominant vibration energy flow paths. In this study the effects of the measurement methods, internal loss factor, and sensor array distance in power flow measurements are investigated. These effects give a severe measurement errors, therefore care should be given in power flow measurements.