This research investigation aims to characterize the aerodynamic and structural performance of a micro scale axial turbine operated with the Brayton cycle, at various boundary conditions, by using the numerical integration finite element method and 3D computational fluid dynamics; the stresses on the rotor blade, in particular, were investigated. Firstly, the turbine was designed with a power output of 0.5–1 kW and efficiency of 81.3%. Then, together the turbine's shaft and its blades were structurally investigated under a variety of loading conditions, with the purpose of visualising the effect of different geometrical and operational factors on the stress values, distributions and displacements over the rotor's blades. After evaluating the structural stresses, rotor blade design changes to decrease these stresses will be proposed, to attain the best turbine performance, using multidisciplinary optimization; these will be reported in the next research publication from this study. The results showed that the maximum Von Mises and maximum principle stresses are highly influenced by the rotor stagger and trailing edge wedge angles, the turbine's rotational speed, the inlet pressure and the working fluid inlet temperature. Additionally, the maximum allowable deformation was highly influenced by the rotational speed, around 16.5%. Moreover, the fatigue life was also determined and both the rotor stagger and trailing edge wedge angles significantly affected its value. The simulated increases in fluid temperature lead to a decrease in the rotor fatigue life of 38%, at an inlet pressure of 5 bar. Such a result can open the door for more research studies and investigations to develop this (domestic) system for ground based (i.e. sea level) uses.
Bibliographical noteFunding Information:
The authors would like to the University of Birmingham and the University of Mosul for the facilities provided for the present research study.
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