M.Ing. / It is well known that all flow meters in common use are sensitive to the structure of the flow as it approaches the meter. A flow conditioner is a device installed upstream of for instance a flow meter to remove swirl and correct a distorted flow profile. Many flow conditioners are used in aviation, and in the mining and chemical industry and in the environment every year all over the world. Considerable research has been done on different flow conditioners. In the design and analysis of a flow conditioner, it is vital to have a proper understanding of its fluid mechanical properties. Recent work with computational fluid dynamics (CFD) method has shown that this technique can help to improve flow conditioner technology. The aim of this dissertation is to determine how the different parameters effect the flow performance of the perforated plate and attempt to modify the design. Nine different designs have been simulated by the CFD methodology and have been studied experimentally as well at a specific Reynolds number of 16000. The results obtained show that a different overall porosity can effect the performance of the plate when the other factors are kept constant; the thickness of plate is also a considerable factor for a perforated plate; and the difference in geometry is an important factor for the perforated plate conditioner.