In this work, a compressible Reynolds-averaged Navier-Stokes code is used to investigate low Reynolds number and low Mach flows, which are typical of micro air vehicles (MAVs). The current work serves as a step toward developing a computational methodology that can serve as a predictive tool for a variety of conventional and unconventional rotary wing MAVs. The performance of unsteady low Mach preconditioning is demonstrated using two-dimensional inviscid isentropic vortex propagation in low Mach number flow. This is followed by extensive validation studies on a micro hovering rotor. The effect of leading and trailing edge geometries is investigated by looking at blunt and sharp profiles and comparing with the experimental data. The thrust and power are reasonably well predicted for all the geometries. Blunt leading edge geometries show poorer performance compared to the corresponding sharp leading edge geometries mainly because of large pressure drag acting at the blunt front. Blunt leading edge geometry also shows a significant leading edge laminar separation bubble, which results in complete separation near the tip. Sharpening the trailing edge shows performance improvement for the blunt leading edge geometry, but not for the sharp leading edge geometry. Flow visualization shows that the tip vortex flow field is very complicated with the presence of secondary vortices and additional vortices formed due to separation near the trailing edge. The tip vortex profiles are reasonably well predicted, but the inadequacy of the turbulence model leads to some discrepancies during tip vortex formation. The swirl velocities for the micro-rotor is found to be significantly larger compared to full-scale rotor, which could be one of the reasons for additional power loss in the smaller scale rotors.
Computational investigation of micro hovering rotor aerodynamics
Numerische Untersuchung der Aerodynamik eines Mikro-Schweberotors
Journal of the American Helicopter Society ; 55 , 2 ; 022001/1-022001/25
2010
25 Seiten, 31 Bilder, 24 Quellen
Aufsatz (Zeitschrift)
Englisch
Aerodynamik , Mikrosystemtechnik , CFD-Simulation , Reynolds-Zahl , Mach-Zahl , Navier-Stokes-Gleichung , Schallgeschwindigkeit , Rotor (Drehflügel) , Koordinatensystem , Koordinatentransformation , Profilumströmung , kompressible Strömung , 3D-Strömung , Anstellwinkel (Tragflügel) , Turbulenzmodell , reibungsbehaftete Strömung , Drehbewegung
Computational Investigation of Micro Hovering Rotor Aerodynamics
British Library Conference Proceedings | 2006
|Computational Investigation of Micro Hovering Rotor Aerodynamics 022001
Online Contents | 2010
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