| A new class of Hex-rotor SUAV (Small Unmanned Air Vehicle) with non-planarmulti-rotor rotary vehicle is introduced that has the capability of independent controlof both thrust and torque vectors in three dimensions. The vehicle configuration isbased around the use of six thrust-producing rotors arranged in pairs on three separatereference planes which we named as FF (Face to face rotor pair) and BB (Back toback rotor pair). Variable thrust can be provided via fxed-pitch/variable-speed rotors.Size restrictions force SUAVs to operate in a low Reynolds number (Re) aerodynamicregime where viscous effects are dominant. This dissertation explores the designissues that affect the hover performance of rotor pairs and the implementation of aworking Hex-rotor SUAV prototype. Also it is shown how the rotor arrangement canbe traded with propulsive efficiency, which was examined through both experimentsand numerical analysis. The main content is followed below:(1) The involved air viscosity in low Re and the induced interference between thetwo adjacent rotors are usually ignored in the traditional model and it will lead to alower accuracy of force and torque control in the rotor aerodynamic model. To avoidany instance like this, more aerodynamic effects caused by different rotor spacing anddisk plane angle are introduced in this dissertation. Combined with the coaxial rotorpair and two non-planar rotor pairs mentioned above, more experimental and numerical studies are conducted in this paper.(2) The corrected aerodynamic methodology is combined with the simplemomentum theory and the blade element momentum theory to help analyses theaerodynamic complexities involved in the arrangement optimization of the multi-rotorsystem. Furthermore, the theory about the numerical method is investigated withNavier Stokes (N-S) solver and extended to investigate the aerodynamics and thesignificant streamline in the flow-field are observed for these three rotor pairconfiguration in hover flight. Finally, the experimental study of the single rotor isproceeded to validate the efficiency of this numerical method.(3) A hover test stand is settled for the systematic testing of rotor pairs, andsystematic performance measurements have been conducted to understand the effectof the rotational speed, rotor spacing, disk plane angle and the rotor pair status on theaerodynamic performance of the rotor pairs, where the measurement is focused on thethrust force and the power consumption. Experimental results show that theperformance of the rotor pair can be improved significantly by having an optimalcombination with a higher degree and a moderate spacing. Additionally, the numericalresults are also introduced to compare the experimental results and confirm the bestarrangement of the rotor pairs.(4) Flow measurements with averaged thrust and power consumption are alsoperformed in a wind-tunnel with a fluctuating wind speed, which permit tocharacterize the aerodynamic performance as a function of wind turbulence with afrequency that is roughly ranging from0to4m/s. Measurements results are finallyconfirmed the rotor pair configuration for the non-planar rotor system both with goodaerodynamic performance and wind resistance.Considering the complex relationship between the aerodynamic configuration ofthe non-planar rotor system and the aerodynamic performance of the Hex-rotor SUAV,the current work only seeks to provide unprecedented insight into the rotorinterference in the low Re envrionment with the goal of developing theoretical andexperimental methods to refine the design of future prototype configurations. Overall,useful conclusions are provided for the further aerodynamic analysis and controlstrategy to meet design requirements. |
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