Iranian Journal of Chemical Engineering (IJChE)

Abstract The purpose of this research is CFD modeling of the fluid flow inside an industrial valve in order to discover the areas with high shear stress and to determine the effect of hydrodynamic on the erosion rate. CFD results are compared with the existing experimental data in a valid reference and the model is verified with high accuracy. The impact of the pressure at inlet and the disc angle on the erosion is investigated. By increasing inlet pressure, maximum velocity, turbulence intensity, wall shear stress and particle erosion increased. However, the wall shear stress, turbulence intensity, and particle erosion are clearly reduced as the disc angle decreases. When the disc angle is less than 50o, the range of dependent parameters changes has a small value. Reducing the disc angle or increasing the inlet pressure led to an increase in cavitation. Therefore, to prevent the erosion of the butterfly valve, it is necessary to increase the disc angle or reduce the pressure at inlet. Erosion of the butterfly valve significantly occurred at the front and rear of the disc. Depending on the disc angle, the shear stress of wall for the modified configuration is 10 to 80 times lower than the original butterfly valve. Therefore, it can be stated that the modified geometry can reduce the wall shear stress and consequently the erosive for all the disc angles of the studied butterfly valve.

Abstract "> In this research an extensive literature search into the mechanism of cavitation dynamics and its consequences was conducted. A cavitation venturie rig was designed and constructed, and the cavitation number was checked mathematically. A new camera technique was developed to capture the cavitation cloud. Carbon steel (AISI 1020), stainless steel (AISI 304 and 316), ferritic alloy steel (B1274), brass (C27000), phosphor bronze (C51000) and aluminum bronze (C60800) test pieces were prepared and tested in the venturie tube. Aluminum bronze was the most and carbon steel the least resistant of these alloys, the measured mechanical properties could not systematically be correlated with cavitation resistance. The microscopic examinations showed that cavitation induced plastic deformation had caused the misalignment of polishing lines. A field study into the susceptibility of an Iranian sugar cane company’s centrifugal pumps showed that deviation from the manuals hydraulic settings caused cavitation and that the gray cast iron had a poor resistance. Besides the venturie tube, other configurations were considered, of which an oil industry choke valve was constructed and examined for cavitation.