In this work, a compressible Reynolds Averaged Navier Stokes (RANS) solver is used to investigate the aerodynamics of a micro-scale shrouded rotor configuration in hover; in order to evaluate the predictive capability of the computational approach and to understand the flow physics of the micro-scale shrouded systems. The overall performance is well predicted for a range of RPMs. The shrouded configuration shows improved performance over the free rotor, mainly seen as an increase in thrust. The thrust produced by the rotor in the shrouded configuration is lower than that of the free rotor, but the thrust generated by the shroud more than compensates for the deficit. The thrust produced from the shroud is identified to come from two main sources. First, the low pressure created primarily by the blades and partly by the tip vortex around the shroud inlet generates large shroud thrust at sections near the blade location. Second, the suction created due to the flow accelerating around the shroud inlet generates additional thrust, and becomes the primary source of thrust production at shroud sections away from the blades. The low pressure due to the tip vortex can help in enhancing the flow acceleration. A study of the effect of various shroud parameters show that diffuser angle and diffuser length did not have much influence on the performance of the system, while smaller tip clearance and use of elliptic shroud inlet significantly improve the overall performance. Finally, an improved shroud design is proposed that might be better suited for non-hovering flight conditions.
Computational investigation of micro-scale shrouded rotor aerodynamics in hover
Rechnerische Untersuchung der Aerodynamik eines ummantelten Mikrorotors im Schwebezustand
2010
23 Seiten, 31 Bilder, 4 Tabellen, 24 Quellen
Conference paper
English
Computational Investigation of Micro-Scale Shrouded Rotor Aerodynamics in Hover
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