Experimental Optimization of MAV-Scale Cycloidal Rotor Performance

Benedict, Moble; Jarugumilli, Tejaswi; Chopra, Inderjit

doi:10.4050/jahs.56.022005

Cited by 30 publications

(20 citation statements)

References 19 publications

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“…[15]. Previous studies performed at the University of Maryland [10,[15][16][17][18][19][20] included systematic experimental studies on a micro-scale cycloidal rotor with rotor dimensions of approximately 6 inches (0.152 meters) in diameter and span. A wide range of kinematic and geometric parameters were systematically varied to study their impact on rotor performance in hover.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Computational Studies to Understand the Role of Flow Curvature Effects on the Aerodynamic Performance of a MAV-Scale Cycloidal Rotor in Forward Flight

Benedict¹,

Jarugumilli²,

Lakshminarayan³

et al. 2012

53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials ConferenceSelf Cite

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This paper describes the systematic experimental and computational (2-D CFD) studies performed to obtain a fundamental understanding of the physics behind the lift and thrust production of a cycloidal rotor (cyclorotor) in forward flight for a unique blade pitching kinematics. The flow curvature effect (virtual camber and incidence due to the curvilinear flow) was identified to be the key factor affecting the lift, thrust and power of the cyclorotor in forward flight. The experimental study involved systematic testing of an MAV-scale cyclorotor in an open-jet wind tunnel using a custom built three-component balance by varying rotor chord/radius ratio and blade pitching axis location, since these two parameters have a strong impact on flow curvature effects. Because of the virtual camber/incidence effects and the differences in the aerodynamic velocities around the azimuth, the blades produce a small downward lift when they operate in the upper half of circular trajectory and a large upward lift in the lower half producing a net lift in the upward direction. The magnitude of this lift depends on the chord/radius ratio and the blade pitching axis location and the direction of lift depends on the sense of rotation. The positive thrust on the cyclorotor is produced when the blades operate in the rear half of the rotor, while they produce a small negative thrust as they operate in the frontal half. The lift per unit power of the rotor is increased with chord/radius ratio until a c/R of 0.67. Moving the pitching axis location closer to the leading edge also increased the lift producing efficiency of the cyclorotor. It was observed that the optimum chord/radius ratio for maximum thrust per unit power decreased with forward speed. A key conclusion was that the lift producing efficiency (lift per unit power) of the rotor (for a constant thrust) increased with forward speed while the thrust producing efficiency (for a constant lift) decreased with forward speed. This study also disproves the conventional argument that a cyclorotor needs two completely different pitching schedules for efficient hover and forward flight because it is clearly shown that a simple phase shifting of the hover kinematics could result in an efficient forward flight kinematics provided the cyclorotor has a high chord/radius ratio. Nomenclature bBlade span c Blade chord C P Coefficient of pressure C L

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Section: Introductionmentioning
confidence: 99%

Experimental and Computational Studies to Understand the Role of Flow Curvature Effects on the Aerodynamic Performance of a MAV-Scale Cycloidal Rotor in Forward Flight
Benedict¹,
Jarugumilli²,
Lakshminarayan³
et al. 2012
53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials ConferenceSelf Cite
9
0
7
1
View full text Add to dashboard Cite

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“…[10][11][12][13]. The understanding gained from these studies was used to design the cyclorotor used on the Twincyclo.…”

Section: Rotor Performancementioning
confidence: 99%

“…Previous studies at the University of Maryland have shown that the cyclorotors, if systematically optimized, can reach aerodynamic efficiencies higher than conventional rotor systems (Refs. [10][11][12][13][14]. Figure 3 shows that the power loading (thrust/power) of an optimized cyclorotor is higher than that of a conventional microrotor of similar actuator area (diameter = 9 inches, solidity = 0.137) at the same disk loading (Ref.…”

Section: Introductionmentioning
confidence: 99%

Design, Development, and Open-Loop Flight-Testing of a Twin-Rotor Cyclocopter Micro Air Vehicle
2013
J Am Helicopter Soc
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This paper describes the systematic design and development of a hover-capable cyclocopter/cyclogyro, which is a 100-yearold vertical takeoff and landing (VTOL) concept that was invented during the early 20th century. The cyclocopter is an aircraft that utilizes cycloidal rotors (cyclorotors), a revolutionary horizontal axis propulsion concept that appears to be aerodynamically more efficient than a conventional rotor. Another key advantage of the cyclorotor is its thrust vectoring capability, which is utilized in the present study for attitude control. The present vehicle has a twin-cyclorotor and a horizontal tail rotor configuration where each of the rotors is powered using independent motors. A novel attitude control technique is developed using differential rotational speed control and thrust vectoring of the cyclorotors for rolling and yawing and horizontal tail rotor for pitch control. Using this control strategy, for the first time in the history, the stable flight of a cyclocopter was demonstrated.

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“…5,(12)(13)(14). The rotor consisted of a span and diameter of approximately 15 cm, and the effects of blade kinematics and rotor geometry on hover performance were examined through a wide range of parameters.…”

Section: Introductionmentioning
confidence: 99%

Wind Tunnel Studies on a Micro Air Vehicle–Scale Cycloidal Rotor
Jarugumilli¹,
Benedict²,
Chopra³
2014
J Am Helicopter Soc
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Systematic wind tunnel measurements were conducted on a small-scale cycloidal rotor (cyclorotor) with a span and diameter of approximately 15 cm. The three parameters varied in the studies were the blade pitch amplitude, phasing of blade pitch with respect to the freestream direction, and advance ratio. The measured quantities included the rotor lift, propulsive force, and power. At low advance ratios, both pitch amplitude and phase angle were effective in varying the rotor lift and propulsive force. At high advance ratios, the propulsive force was a stronger function of pitch amplitude than phase angle. At all advance ratios tested, power was a stronger function of pitch amplitude than phase angle. The parametric study results were interpolated to determine the power consumption, lift-to-drag ratio, and control input requirements of the cyclorotor in straight and level flight conditions. In the interpolation process, the blade pitch amplitude and pitch phase angle were assumed as the two primary control variables (rotational speed was held constant) and a 500-g twin-cyclorotor MAV was used as a reference for the baseline lift values. The effects of varying lift, propulsive force, and rotational speed on rotor power and control input requirements were examined at various forward speeds. The maximum forward speed tested for the cyclorotor in straight and level flight was 13 m/s (advance ratio = 0.94); at this speed, the power was 36% lower than in hover and the rotor operated at 1740 rpm with a lift of 2.82 N.

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Experimental Optimization of MAV-Scale Cycloidal Rotor Performance

Cited by 30 publications

References 19 publications

Experimental and Computational Studies to Understand the Role of Flow Curvature Effects on the Aerodynamic Performance of a MAV-Scale Cycloidal Rotor in Forward Flight

Experimental and Computational Studies to Understand the Role of Flow Curvature Effects on the Aerodynamic Performance of a MAV-Scale Cycloidal Rotor in Forward Flight

Design, Development, and Open-Loop Flight-Testing of a Twin-Rotor Cyclocopter Micro Air Vehicle

Wind Tunnel Studies on a Micro Air Vehicle–Scale Cycloidal Rotor

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