Novel Cyclorotor Pitching Mechanism for Operation at Curtate and Prolate Advance Ratios

Adams, Zachary; Fagley, Casey

doi:10.2514/6.2013-501

Cited by 4 publications

(5 citation statements)

References 4 publications

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“…2-a. More complex mechanisms, like the three-dimensional cam proposed by Adams et al Adams and Fagley 2013) can also be envisaged, whose analysis is however beyond the scope of the present study. Focusing on the four-bar linkage, by looking at Fig.…”

Section: Kinematic Representationmentioning

confidence: 89%

Parametric Analysis of a Large-Scale Cycloidal Rotor in Hovering Conditions

et al. 2017

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In this work, four key design parameters of cycloidal rotors, namely the airfoil section, number of blades, chord-to-radius ratio, and pitching axis location, are addressed. The four parameters, which have a strong effect on rotor aerodynamic efficiency, are analyzed with an analytical model and a numerical approach. The numerical method, which is based on a finite-volume discretization of two-dimensional unsteady Reynolds averaged Navier-Stokes equations on a multiple sliding mesh, is proposed and validated against experimental data. A parametric analysis is then carried out considering a large-scale cyclogyro, suitable for payloads above 100 kg, in hovering conditions. Results demonstrate that the airfoil thickness significantly affects the rotor performance; such a result is partly in contrast with previous findings for small-scale and microscale configurations. Moreover, it will be shown that increasing the number of blades could result in a decrease of the rotor efficiency. The effect of chord-to-radius will demonstrate that values of around 0.5 result in higher efficiency. Finally it is found out that for these large systems, in contrast with microscale cyclogyros, the generated thrust increases as the pitching axis is located away from the leading edge, up to 35% of chord length. Furthermore, the shortcomings of using simplified analytical tools in the prediction of thrust and power in nonideal flow conditions are discussed

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Section: Kinematic Representationmentioning

confidence: 89%

Parametric Analysis of a Large-Scale Cycloidal Rotor in Hovering Conditions

et al. 2017

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“…Finally, another pitching profile was considered in some studies (Adams and Fagley, 2013; Adams et al , 2013): …”

Section: Mathematical Formulation Of the Problemmentioning

confidence: 99%

“…The first term on the right hand side of equation (6) is often called zero-angle of attack profile . This type of pattern, for example, can be approximately achieved by a 3D-cam cyclorotor (3D: three-dimensional) (Adams and Fagley, 2013; Adams et al , 2013).…”

Section: Mathematical Formulation Of the Problemmentioning

confidence: 99%

“…Cycloidal rotors for aeronautical propulsion were first introduced in the 1930s, starting with the pioneering work of Wheatley (1933; Wheatley and Windler, 1935) and later of Eastman et al (1943; Eastman, 1951). Recent years saw a rediscovery of this rather unexploited concept, documented in a diversity of experimental and theoretical works, including that of Gibbens and Boschma (1999; Boschma, 2001; Hwang (2005, 2007; Higashi, 2006; Hu et al , 2006; Iosilevski, 2003; Kim et al , 2003; Lee et al , 2014) and the thorough investigations of Benedict and co-workers (Benedict et al , 2008, 2010a, 2010b, 2011; Adams and Fagley, 2013; Adams et al , 2013). In the frame of the CROP project, a further analysis of the potentialities of the cyclogyro concept for the propulsion of manned and unmanned lightweight aircraft was undertaken, leading to the development of prototypes (Wills and Schwaiger, 2012) and numerical and analytical models (Páscoa et al , 2013; Xisto et al , 2014).…”

Section: Introductionmentioning

confidence: 99%

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Optimal pitching schedules for a cycloidal rotor in hovering

Andrisani

Angeli

Dumas

2016

AEAT

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Purpose: The purpose of this paper is to define an optimal pitching profile for the blades of a cycloidal rotor which minimizes the mean power consumption for a given mean thrust of the rotor. Design/methodology/approach: A simple analytical model of the kinematics and aerodynamics of a cycloidal rotor is defined first to obtain expressions for thrust and power depending on the pitching profile and geometrical parameters of the rotor. Then, Lagrange optimization is applied to obtain the optimal pitching schedule under hovering conditions. Finally, results of the theoretical analysis are compared with those of a two-dimensional computational fluid dynamics (CFD) model. Findings: Results of the optimization suggest that the optimal profile is a combination of sinusoidal functions. It is shown that the adoption of the optimal pitching schedule could improve the power efficiency of the rotor by approximately 25 per cent. Practical implications: The possibility to increase the efficiency of a cycloidal rotor by acting on its pitching schedule could be a significant factor of success for this alternative propulsion concept. Originality/value: The present work represents the first attempt at a definition of an optimal pitching profile for a cycloidal rotor. Moreover, although being carried out on the basis of simplified analytical considerations, the present investigation sets a methodological framework which could be successfully applied to the design of similar kinds of systems

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“…This mechanism could generate the nonsinusoidal pitch kinematics required for both curtate and prolate advance ratios (This range of pitching kinematics is shown in Fig. 4) [1]. The mechanism optimizes blade pitch motions for each operating advance ratio and enables control over both blade pitch amplitude and phasing.…”

Section: Introductionmentioning

confidence: 99%

Design, Development, and Flight Test of a Small-Scale Cyclogyro UAV Utilizing a Novel Cam-Based Passive Blade Pitching Mechanism

Adams

Benedict

Hrishikeshavan

et al. 2013

International Journal of Micro Air Vehicles

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A cycloidal rotor is an innovative horizontal axis propulsion system, which is utilized in the present study to develop a fully-controllable flying aircraft (known as "Cyclogyro"). The present 535 gram cyclogyro uses a hybrid configuration with two cyclorotors and a horizontal tail rotor. Since a cycloidal rotor relies on cyclic blade pitching for producing thrust and also for control, designing a reliable pitch mechanism that can provide the required blade pitching kinematics (depending on the advance ratio) is extremely important. A novel blade pitch mechanism has been developed, which is passively driven by centrifugal force, and could potentially be adapted to generate the required pitching schedules for efficient operation over a range of advance ratios. A simplified flightworthy version of this mechanism was implemented in the present cyclogyro. The mechanism was able to generate the appropriate blade kinematics and the thrust required for the vehicle to hover. Also, the present mechanism is designed such that it is possible to vary both amplitude and phasing of the cyclic blade pitching. A novel control strategy was developed using blade pitch amplitude (thrust magnitude) control for roll, phasing (thrust direction) for yaw and tail rotor for pitch control. The control strategy was implemented using a three gram onboard processor, which was used to stabilize the vehicle without a pilot, through a closed-loop feedback control system. This is the first flight-capable cyclogyro reported in the literature to utilize cycloidal rotors having both pitch amplitude and phase control. The successful flight for the present vehicle also validates the flightworthiness of this completely passive pitch mechanism design, which has great potential for efficient forward flight. NOMENCLATURE µAdvance ratio V ∞ Freestream velocity Ω Rotational speed r Rotor radius 145

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Novel Cyclorotor Pitching Mechanism for Operation at Curtate and Prolate Advance Ratios

Cited by 4 publications

References 4 publications

Parametric Analysis of a Large-Scale Cycloidal Rotor in Hovering Conditions

Parametric Analysis of a Large-Scale Cycloidal Rotor in Hovering Conditions

Optimal pitching schedules for a cycloidal rotor in hovering

Design, Development, and Flight Test of a Small-Scale Cyclogyro UAV Utilizing a Novel Cam-Based Passive Blade Pitching Mechanism

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