Internal Turbulent Flow Induced Pipe Vibrations with and without Baffle Plates

摘要

The induced vibration in pipes due to turbulent flow through them is important in many industries and applications. This paper presents the results of an experimental investigation that characterizes pipe wall vibration caused by turbulent internal flow. Experiments were conducted using a water flow loop to characterize how the pipe wall vibration depends on the average flow speed, the pipe diameter, and the pipe thickness for fully-developed turbulent pipe flow. Experiments were also conducted to characterize the influence on the pipe response of turbulence generation due to the flow passing through baffle plates with various hole sizes and constant through area. All experiments were conducted using PVC pipe with diameters ranging from 51 mm to 102 mm and diameter to thickness ratios ranging from 8.9 to 16.9. Average flow speeds for the experiments ranged from 3 to 11.5 m/s and the baffle plates employed exhibited hole sizes ranging from 1.6 to 25 mm. Accelerometers mounted on the pipe walls were used to characterize the pipe vibrations. The results show that for fully developed turbulent flow the rms of the pipe wall acceleration scales nominally as the square of the average fluid speed and increases with decreasing pipe wall thickness. Based on the data, a non-dimensional parameter describing the pipe wall acceleration for the fully-developed turbulent flow scenario is proposed and its dependence on relevant independent nondimensional parameters is presented. Lastly, when turbulence was induced using baffle plates the localized turbulence intensity was greatly increased. For the largest holed baffle plates, cavitation was observed to occur, significantly increasing the rms pipe wall acceleration. As baffle plate hole size decreased, vibration levels were observed to approach levels that were measured when no baffle plate was employed. For all baffle plate experiments the magnitude of the vibration was observed to decrease with increasing downstream distance from the turbulence source, approaching the baseline no baffle plate case.