Optimization of vacuum cleaner fan components is a low-cost and time-saving solution to satisfy the increasing requirement for compact energy-efficient cleaners. In this study, surrogate-based optimization technique is used and for the first time it is focused on maximization of Airwatt parameter, which describes the fan suction power, as an objective function (Case II). Besides, the shaft power is minimized (Case I) as another optimization target in order to reduce the power consumption of the vacuum cleaner. 11 geometrical variables of 3 fan components including impeller, diffuser and return channel are selected as the optimization design variables. 80 training points are distributed in the sample space using Advanced Latin Hypercube Sampling (ALHS) technique and the outputs of sample points are calculated by means of CFD simulations. Kriging and RSA surrogate models have been fitted to the outputs of the sample space. Through coupling of constructed Kriging models and Multi-Island Genetic Algorithm (MIGA), the optimal design for each of the optimization cases is presented and evaluated using numerical simulations. A 20.22% reduction in shaft power in Case I and an improvement of 27.73% in Airwatt in Case II have been achieved as the overall results of this study. Despite achieving goals in both optimization cases, a slight decrease in Airwatt in Case I (−6.20%) and a slight increase in shaft power in Case II (+4.82%) are observed relative to primary fan. Furthermore, the Analysis of Variance (ANOVA) determines the importance level of design variables and their 2-way interactions on the objective functions. It was concluded that geometrical parameters related to all of the fan components must be considered simultaneously to conduct a comprehensive optimization. The reasons of enhancement in optimal cases compared with the reference design have been further investigated by analysis of the fan internal flow field. Post-processing of the CFD results demonstrates that the applied geometrical modifications cause a more uniform flow through the flow passages of the optimal fan components.

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In some plasma applications, such as confinement and pinches, an ultrahigh magnetic field (several teslas) is required. Such magnetic flux densities can be produced by using flux compression generators (FCGs). This paper has proposed a joint thermodynamic and electromagnetic simulation method for a common type of FCGs (i.e., helical type) with respect to the magnetic coupled plasma studies. The images of displacements, pressure, and magnetic flux density distribution in generator and plasma chamber are presented as simulation results. Index Terms-Explosions, flux compression generators (FCGs), magnetic coupled plasmas, thermodynamic and electromagnetic simulation.S TUDYING plasma-flow behaviors under ultrahigh magnetic field is attractive [1] in many applications such as confinement and pinches. Ultrahigh magnetic fields can be produced by using capacitor-inductor sets or flux compression generators (FCGs) with lower weight and volume [2]. There are many analytical studies over the past 60 years; however, these analyses are mostly based on experimental results. In addition, only one of two dominant facets of explosively driven FCGs, i.e., thermodynamic aspects [3] or electromagnetic issues [4], has been taken into account in each study, and the other aspect is referred to the set of data which is elicited from experiments. This method is not applicable for some cases, particularly novel structures, because of constructional and/or diagnostic difficulties. In this paper, one of the most common types of FCGs, i.e., Helical type [2], has been chosen to simulate by using combined simulation tool in which thermodynamic and electromagnetic equations are joined together, since much more accurate records are available for HFCGs. For this purpose, two sets of equations, i.e., Maxwell equations and Jones-Wilkens-Lee equation of state [3], have been modeled and solved in a 3-D finite element method. In these simulations, the space between armature and stator has been considered to be filled with sulfur hexafluoride initially at one atmosphere. In addition, substance of helix wires has been considered as Manuscript