Experimental studies of orifice-induced wall pressure fluctuations and pipe vibration

A hydraulic test for studying orifice-induced random wall pressure fluctuations and vibration in a pipeline is presented. Natural frequencies of the structure, statistical characteristics of the fluctuating pressure and structure acceleration response have been studied. The orifice significantly disturbed the pipe flow and greatly increased the fluctuating pressure level and the dominating energy is concentrated at the lower frequency range. The highest fluctuating pressure level appears at 1.7 diameters downstream of the orifice in the axial direction, while the Power Spectral Density and the root mean square of the pressure fluctuations do not show significant difference in the radial direction. The test results also confirm the weakly coupled fluid-structure system assumption for the test pipe system.