الفهرس 
Introduction and BackgroundOnly 14 pages are availabe for public view
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Abstract
Using an orifice plate for pressure reduction is common in industrial application as it has many advantages; some of them are low initial cost, low maintenance cost and simplicity. One of the most important disadvantages is the turbulence downstream which could generate fluid induced noise, strong enough to cause failure in piping connections. Using multi-stage orifices and multi-hole orifices are two solutions for such a problem. This thesis investigates the effectiveness of using multi-hole orifices and comparing this alternative solution with single-hole orifices. For all orifice designs the pressure upstream, pressure downstream, mass flow rate, pipe size and orifice thickness are constant.
Three types of multi-hole orifices with different numbers of holes were studied to investigate the effect of number of holes on the fluid domain downstream the orifice. The effect of varying the distance between holes was also studied. ANSYS CFX is the CFD tool used in this study using ANSYS 14.5 workbench.
The present work shows that, the multi-hole orifice has better performance in reducing the turbulence kinetic energy, which would reduce the fluid induced noise generated in pressure reducing orifices. Furthermore, the effect of this alternative solution of multi-hole orifices on the orifice plate structure was studied. This study is made by importing the fluid loads to ANSYS structure and studying the fluid structure interaction (FSI) through one-way FSI. Multi-hole orifices showed that increasing the number of holes would affect the orifice plate overall safety factor. The safety factor for the orifice plates are reduced significantly and in some cases showed that the orifice plate would fail when increasing the number of holes and reducing the distance between them.