Magnetorheological (MR) dampers have attracted the interest of suspension designers and researchers because of their variable damping feature, mechanical simplicity, robustness, low power consumption and fast response. This study deals with the optimal configuration of an MR damper using the Taguchi experimental design approach. The optimal solutions of the MR damper are evaluated for the maximum dynamic range and the maximum damper force separately. The MR dampers are constrained in a cylindrical container defined by radius and height. The optimal damper configurations obtained from this study are fabricated and tested for verification. The verification tests show that the dampers provide the specified damper force and dynamic range.

Performance of centrifugal fans with unshrouded impellers strongly depends upon complex configuration of the asymmetrical flowfield in the axial direction, which is highly unsteady. The flowfield, in turn, is considerably affected by the design parameters of both scroll and impeller geometry, for which tip clearance is of particular interest. This article presents a three-dimensional computational fluid dynamics (CFD) simulation of the flowfield in three different unshrouded centrifugal fan impellers with varying tip clearances. A commercial CFD code, namely, Fluent V6.2.16 with a k-ɛ two-equation turbulence model was utilized in order to study the effects of tip clearance on the overall performance of each fan with the tip clearances ranging from 5 to 30 mm. The numerical results were compared with the experimental data reported previously in the literature by the present author and his colleagues, and excellent agreements were observed for each fan.

In this study, a cooling radiator developed specifically for unmanned aerial vehicles was analyzed using computational fluid dynamics (CFD). The radiator consisted of turbulator pins (core side) placed between two vertical columns (column side). While the air passes from the core side, the cooling fluid takes place between two streams on the column side. CFD modeling of the radiator, which was developed, prototyped, and tested by Kale Oto Radyatör Co. was performed. Modeling of the turbulators and the fins outside the radiator channels is almost impossible due to the tremendous number of required cells. Therefore, the porous media approach was adopted for the core side. Although there are some studies in the article that used porous medium approach in CFD analyses of vehicle radiators, they are generally restricted to CFD modeling of conceptual designs with no experimental validation, making their results questionable. Radiator tests and CFD results showed very good agreement. The maximum differences between experimental and CFD analyses results were 5.6% for pressure drop, 3.1% for radiator outlet temperature, and 2.9% for heat capacity. Therefore, it was concluded that a proper porous media model can be effectively used for both design and optimization considerations.

The shell-and-tube type heat exchangers have long been widely used in many fields of industry. These types of heat exchangers are generally easy to design, manufacturing, and maintenance, but require relatively large spaces to install. Therefore, the optimization of such heat exchangers from thermal and economical points of view is of particular interest. In this article, an optimization procedure based on the minimum total cost (initial investment plus operational costs) has been applied. Then the flow analysis of the optimized heat exchanger has been carried out to reveal possible flow field and temperature distribution inside the equipment using CFD. The experimental results were compared with CFD analyses results. It has been concluded that the baffles play an important role in the development of the shell side flow field. This prompted us to investigate new baffle geometries without compromising from the overall thermal performance. It has been found that the heat exchanger with the new baffle design gives rise to considerably lower pressure drops in the shell side, which in turn reducing operating cost. The new baffle design is particularly well suited for shell-and-tube heat exchangers, where a viscous fluid-flows through shell side with/out phase change.

This paper has focused on the predictive methods for relative efficiency reduction of centrifugal pumps handling slurries based on empirical- and artificial-neural network (ANN) approaches. A new correlation has been developed to predict the relative efficiency reduction of the centrifugal slurry pumps, and the range of validity of the present correlation has been verified using the data available in the literature. Then, the applicability of ANNs for the same purpose has been investigated using a total of 315 data. The comparisons of both methods showed that the present correlation produced the lowest deviation among some recent correlations in the literature, and, if properly constructed, ANNs could be used as a predictive tool with higher accuracy than the conventional empirical methods.