Search results for: Cezmi Nursen

Authors: Fevzi Çakmak Bolat, Cezmi Nursen, Neven Alujevic

Abstract:

In this study, numerical modeling and analysis of the rotor of a high-pressure multistage centrifugal pump were performed. The pump rotor used in the study consists of four impellers, a shaft element, a balance drum, and bearings. First, free vibration analyses of the rotor impellers and shaft were performed separately. Then, the impellers and shaft were assembled, and damped and undamped vibration analyses were performed under different boundary conditions. Static analyses were performed for the rotor system as a whole under appropriate boundary conditions by including the pressure values on the impellers obtained as a result of experimental measurements and the gravity acceleration. By applying variable torque values to the rotor system, the deformation and stress calculations that may occur during sudden stops and starts were made transiently. Again, random vibration analysis was performed by entering different PSD acceleration data into the rotor system, and the changes in the rotor dynamics were analyzed. Within the scope of the study, critical speed analysis was performed by checking whether there was a conflict between the pump operating frequencies and the frequencies of the rotor system and using Campbell diagrams.

Keywords: vibration of high-pressure pump rotor, dynamic analysis, numeric analysis, rotor dynamics

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Authors: Nursen Saklakoglu, Adnan Turker

Abstract:

The main objective of this study is to reveal the effect of the Thixoforming process on the microstructure and mechanical properties of the AlSi12 alloy with trace amounts of silver. It is concluded that Thixoforming has an important effect on the morphology of intermetallics and Si formation, as well as globular α-Al morphology. The intermetallics have been fractured during thixoforming. It is believed that the fine distribution of the intermetallics is one mechanism for the improved mechanical properties of Thixoformed alloys. The discrete Si particles have been observed during both isothermal heating to the semi-solid range and Thixoforming, also have an important effect on mechanical properties. The Thixoforming process has a greater effect on hardness than the addition of Ag does.

Keywords: AlSi alloys, intermetallic phases, mechanical properties trace element, silver, thixoforming

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