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- MakaleYalnız künye2022Effect of Working Conditions on the Lubricated Wear Behavior of Zn-40Al-2Cu-2Si Alloy in the As- Cast and T6 Heat-Treated States
Savaskan, Temel; Hekimoglu, Ali Pasa; Azakli, Zeki; Calis, Merve
In order to determine the effect of working conditions on the lubricated wear behavior of Zn-40Al-2Cu-2Si alloy in the as-cast and T6 heat-treated states, its tribological properties were studied at different oil flowrates, contact pressures, and sliding speeds in comparison with SAE 660 bronze. It was observed that the friction coefficient, temperature, and wear volume of both materials decrease, but their average surface roughness increase with increasing oil flowrate. As the pressure increased, the friction coefficient and average surface roughness of the experimental materials decreased, but their temperature and wear volume increased. It was also found that the working temperature of these materials increased, but their wear volume showed a decrement and a subsequent increment with increasing sliding speed. In addition, their wear volume and average surface roughness showed opposite changes with the sliding speed. Zn-40Al-2Cu-2Si alloy in both as-cast and heat-treated conditions showed lower wear volume and friction coefficient than SAE 660 bronze. This indicates that Zn-40Al-2Cu-2Si alloy can be used to manufacture diesel engine crankshaft journal bearings.
- MakaleYalnız künye2018Constructal Placement of Discrete Heat Sources with Different Lengths in Vertical Ducts under Natural and Mixed Convection
Sarper, Bugra; Saglam, Mehmet; Aydin, Orhan
In this study, convective heat transfer in a discretely heated parallel-plate vertical channel which simulates an IC package is investigated experimentally and numerically. Both natural and mixed convection cases are considered. The primary focus of the study is on determining optimum relative lengths of the heat sources in order to reduce the hot spot temperature and to maximize heat transfer from the sources to air. Various values of the length ratio and the modified Grashof number (for the natural convection case)/the Richardson number (for the mixed convection case) are examined. Conductive and radiative heat transfer is included in the analysis while air is used as the working fluid. Surface temperatures of the heat sources and the channel walls are measured in the experimental study. The numerical studies are performed using a commercial CFD code, ANSYS FLUENT. The variations of surface temperature, hot spot temperature, Nusselt number, and global conductance of the system are obtained for varying values of the working parameters. From the experimental studies, it is showed that the use of identical heat sources reduces the overall cooling performance both in natural and mixed convection. However, relatively decreasing heat sources lengths provides better cooling performance.
- DergiJournal of Heat Transfer
- DergiJournal of Tribology