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Prediction of the transient force subsequent to a liquid mass impact on an elbow of an initially voided line

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2009
Kayhan, Bülent Abbas
The aim of the thesis, is to find the transient force applied by an individual transient liquid slug on an elbow at the end of a horizontal line due to an impact. The liquid slug is driven by pressurized air in a tank located upstream of the pipeline. The time dependent pressure distribution along the elbow and a vertical extension segment after the elbow was solved, with a 1-D numerical approach along a curved line mesh. For this purpose; firstly, a 3-D axial turbulent velocity profile function was assumed for the slug, with its shape allowed to sway towards the convex side of the elbow along the curved mesh with the aid of a calibration tool. Then, the pressure values were calculated by using 1-D application of Reynolds Equations in cylindrical polar and cartesian coordinates for the elbow and the vertical extension segment, respectively. The transient force acting on the elbow and the following vertical extension segment was found by using these calculated pressure values and applying conservation of momentum principle over the volume elements selected along the elbow and the vertical extension segment. For the analysis of the slug motion from the pressurizer tank to the elbow, a previously written computer code BOZKUŞ-2 was utilized. Then, the elbow and the vertical extension segment calculations in this study were made with a new code KAYHAN, which is an improved version of BOZKUŞ-2. The calculated transient force and impact pressures at the elbow were also compared with those from previous studies.