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The necessity to change systems generating electrical energy is evident. The best solution would be to use installations utilizing renewable energy sources, complemented by efficient electric energy storage. This process requires time and further development, as well as new achievements in this area. Improving the situation can also result from enhancing the efficiency of devices already in operation. For a coal-fired power block, an important aspect is the variability of loads and ensuring the highest efficiency of all devices that make up the technological chain of such a unit, especially in variable working conditions. The article presents a new solution for regulating the working parameters of a radial fan for use in power engineering, which has high efficiency over a wide range of loads. The proposed six-blade solution allows one to obtain 115 Pa higher total pressure compared to four-blade systems, and efficiencies higher by 4.6 percentage points. The process of selecting elements and design parameters of the fan and its control system is discussed. The performance characteristics of the device with the new control system are presented. [ABSTRACT FROM AUTHOR]

Results obtained with computational fluid dynamics (CFD) rely on assumptions made during a pre-processing stage, including a mathematical description of a fluid rheology. Up to this date there is no clear answer to several aspects, mainly related to the question of whether and under what conditions blood can be simplified to a Newtonian fluid during CFD analyses. Different research groups present contradictory results, leaving the question unanswered. Therefore, the objective of this research was to perform steady-state and pulsatile blood flow simulations using eight different rheological models in geometries of varying complexity. A qualitative comparison of shear- and viscosity-related parameters showed no meaningful discrepancies, but a quantitative analysis revealed significant differences, especially in the magnitudes of wall shear stress (WSS) and its gradient (WSSG). We suggest that for the large arteries blood should be modelled as a non-Newtonian fluid, whereas for the cerebral vasculature the assumption of blood as a simple Newtonian fluid can be treated as a valid simplification. [ABSTRACT FROM AUTHOR]