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Abstract

In the paper it is proposed and described in detail a mathematical model that is able to assist in the design of cycloidal rotors. The method is formulated on a semi-empirical way including unsteady aerodynamic effects that are based on first principles. It is able to predict the overall generated thrust and the power required by the operation of the cycloidal rotor. The model also includes a kinematic package that can provide an instantaneous design and animation of the cycloidal rotor under different regimes of operation. For validation it was addressed three different rotor configurations where it was varied several rotor parameters, namely: pitch amplitude; pitching axis location; blade chord; airfoil thickness; phase angle of eccentricity. It was shown that the proposed model is able to provide a good estimation of thrust and power when compared with the experimental data from these different sources, showing that the semi-empirical approach could be applied in a more general way.

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... The dynamic pitching provided by the four-bar linkage mechanism is expressed by the following equations [13]: ...
... This mechanism, which has proved well for cyclogyros used in aeronautical propulsion [13][14][15][16][17][18], is simple, reliable, and has the ability to self-adjust the turbine dynamics as a function of the rotating speed of the rotor and also on the direction and magnitude of the incoming wind. It is noted that the system kinematics also allows for an asymmetric pitching schedule of the blades, which could be beneficial since the frontal area of the rotor operates at a different angle of attack than the rear region. ...
... To this end, data for a cyclogyro of similar dimensions as the wind turbine, operating in propulsion mode (V wind ¼ 0), are used. This configuration, here denominated IAT21-L3 rotor, was analyzed as a part of an European research project, which aimed to develop the cyclogyro technology as a mean of propulsion for small and medium size aircraft [13,18,[20][21][22][23]. It is obvious that the results obtained for the IAT21-L3 rotor do not faithfully represent the features of a VAWT, since in propulsion mode energy is being provided and not extracted from the flow. ...
Article
In this paper, four key design parameters with a strong influence on the performance of a high-solidity variable pitch vertical axis wind turbine (VAWT) operating at low tip-speed-ratio (TSR) are addressed. To this aim, a numerical approach, based on a finite-volume discretization of two-dimensional (2D) unsteady Reynolds-averaged Navier–Stokes (URANS) equations, on a multiple sliding mesh, is proposed and validated against experimental data. The self-pitch VAWT design is based on a straight-blade Darrieus wind turbine with blades that are allowed to pitch around a feathering axis, which is also parallel to the axis of rotation. The pitch angle amplitude and periodic variation are dynamically controlled by a four-bar linkage system. We only consider the efficiency at low and intermediate TSR; therefore, the pitch amplitude is chosen to be a sinusoidal function with a considerable amplitude. The results of this parametric analysis will contribute to define the guidelines for building a full-size prototype of a small-scale wind turbine of increased efficiency. [DOI: 10.1115/1.4032794]
... The airfoils depict an increase in C p with t/c as seen through Fig. 19(b), and this observation suggests that for a given k, upon increasing the blade thickness, the performance of the rotor seems to be promising. Apart from this, they have also examined the effect of b through a controlled pitching mechanism as suggested by Leger et al. 94 Their findings suggest that using the proposed pitching mechanism, the rotor generates a relatively higher torque compared to fixed b while operating a low k. Furthermore, it is to be noted that the rotor with six blades produces a higher torque compared to lesser number of blades. ...
... 59 At low k, the pitching mechanism for VAWT generates higher torque. 94 ...
Article
The utility of small wind turbines (SWTs) covering horizontal and vertical-axis types as off-grid, standalone, and decentralized energy supplement systems has gained market attention. Such turbines primarily operate at low Reynolds number ( Re) and low tip speed ratio ( λ) conditions. Under such circumstances, the design, development, and testing of SWTs have become a tedious task, mainly due to the lack of precise aerodynamic knowledge of SWT. The present article reviews the fundamental aspects of SWT, including airfoil selection criteria, blade design, and aerodynamic improvement through passive flow control and augmentation techniques. The article also reports several classes of potential airfoils that can be employed in the design of SWTs. The airfoils considered operate mainly in the range of Re = 0.3 x 10 ⁵ to 3 x 10 ⁵ and λ = 0.5 to 6. Besides the classical approach, the article showcases the prospects of several bioinspired profiles/shapes that are meant for SWTs operating at low Re and λ conditions. Towards the end, various design constraints and applicability of SWTs are summarized.
... A European Union project entitled "CROP" was developed with the intention to work on aerodynamic efficiency, optimizations and designing the most promising configurations of cyclorotors as propulsion systems. Under this project, Leger et al. [17][18][19] made detailed analytical studies to detect the optimal mechanical dimensions under specific operating conditions. Their model was able to compute the dynamic and kinematic behavior of a UAV-scale cyclorotor operating at hover. ...
Article
The present study demonstrates an improved performance of cycloidal rotors by actively controlling the pitching oscillations and rotational speeds. The computational fluid dynamics (CFD) coupled with artificial neural network (ANN) were the methodologies used in the optimization analysis for the hover-state operation rather than the take-off mode under ground effects [1]. The former is carried out to obtain numerical predictions at various operating conditions for an UAV-scale cyclorotor. The oscillating-rotating blades and the corresponding flowfield is computed unsteadily along the complete circular trace for performance considerations. From CFD simulations, the optimum operational state is predicted for a 30∘ and 500 (rpm) pitch angle and rotating speed, respectively. On a second step, by training the ANN with the CFD database at various operating conditions and parameters, the ANN was then capable of analyzing the optimum states for operating at different conditions. The pitching oscillation schedule is then optimized for each rotational speed by using ANN and for each azimuthal location over the traversing trace. This will imply to perform on-board control in active mode for the blades, rather than assigning constant pitching oscillations for all operating states. This active control concept showed to be a potential approach to enhance the cyclorotor efficiency by 12 percent in average.
... A European Union project entitled "CROP" was developed with the intention to work on aerodynamic efficiency, optimizations and designing the most promising configurations of cyclorotors as propulsion systems. Under this project, Leger et al. [17][18][19] made detailed analytical studies to detect the optimal mechanical dimensions under specific operating conditions. Their model was able to compute the dynamic and kinematic behavior of a UAV-scale cyclorotor operating at hover. ...
Article
The present study demonstrates an improved performance of cycloidal rotors by actively controlling the pitching oscillations and rotational speeds. The computational fluid dynamics (CFD) coupled with artificial neural network (ANN) were the methodologies used in the optimization analysis for the hover-state operation rather than the take-off mode under ground effects [1]. The former is carried out to obtain numerical predictions at various operating conditions for an UAV-scale cyclorotor. The oscillating-rotating blades and the corresponding flowfield is computed unsteadily along the complete circular trace for performance considerations. From CFD simulations, the optimum operational state is predicted for a 30◦ and 500 (rpm) pitch angle and rotating speed, respectively. On a second step, by training the ANN with the CFD database at various operating conditions and parameters, the ANN was then capable of analyzing the optimum states for operating at different conditions. The pitching oscillation schedule is then optimized for each rotational speed by using ANN and for each azimuthal location over the traversing trace. This will imply to perform onboard control in active mode for the blades, rather than assigning constant pitching oscillations for all operating states. This active control concept showed to be a potential approach to enhance the cyclorotor efficiency by 12 percent in average.
... The Cycloidal Rotor Optimized for Propulsion (CROP) project (CROP 2013b), a project under the European Union FR7 framework license, held cyclorotors as the optimizing target. Leger et al. (2015Leger et al. ( , 2016 studied the different operating principles of a cyclorotor at a hovering state using an analytic approach. Furthermore, in another numerical work, they predicted the presence of threedimensional effects, tip leakage, and main flow structure considerations when equipped with endplates (Xisto et al. 2014b). ...
... The blade numerical domain exchange information with the rotor domain through a sliding mesh as well as the rotor and the environment domains. Each blade region moves according to Eq. (3) [33] which describes the blade pitch angle variation [ ] imposed by the mechanical system shown in Fig. 6. ...
Conference Paper
Full-text available
Cycloidal rotors have the inherent ability to provide vectorized thrust with fast reaction times. However, their present efficiency levels restricts their routinely use as propulsion elements for air-vehicles. Efforts have been made to improve the performance of cycloidal rotors through the optimal combination of its geometric parameters. In the present work the performance improvement of cycloidal rotors is demonstrated using a different approach, namely by imposing an unsteady change on the dynamics and structure of the vortices developed around the blades. This required change on the flow field, around the blades, was applied by adding an harmonic vibration to the traditional cycloidal movement of the blades, thus causing the blades to vibrate as they describe their oscillating pitch movement. This research on the effect of harmonic vibration, on lift and drag coefficients, was done first for a single blade profile, and later for a full cycloidal rotor, and is based on the Takens reconstruction theorem and Poincaré map. Therefore, diverse test cases and conditions were considered: a single static airfoil, an oscillating blade profile, and a complete cycloidal rotor. We concluded that the optimal combination of harmonic vibration parameters, specifically; amplitude, phase angle and vibration frequency, under adequately tuned design conditions, can have a beneficial effect on cycloidal rotor performance.
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Cycloidal rotors have shown to be susceptible to achieve larger efficiency enhancements while being subjected to various designs and operating conditions. In this work an improvement on the performance of a UAV-scale cycloidal rotor is demonstrated at hovering mode and for various operating conditions with three endwall designs. The novel concept of actively controlling the pitching oscillations at different rotational speeds is obtained from a coupled methodology of computational fluid dynamics (CFD) and artificial neural network (ANN). In this approach, rather than a free-sided rotor, the effects of employing single and double endwalls are targeted for optimizing the operation at hover-state, whereas, the previous work focused on forward-flight and lift-up phases (Habibnia Rami and Pascoa 2021). A detailed database from numerous combinations of operating conditions is obtained from CFD predictions. Over eighteen principal parameters are processed and computed along the continuous 360◦ circular trace, which is showing novel results. Subsequent to performing a precise database from the rotating-oscillating blades under various operating conditions for all the three designs, the ANN approach is trained from the CFD data for optimization analysis and to propose the optimum pitching schedules by using a parametric study on the cyclorotor performance at each operating condition. Since each design can be used in its specific application, the optimum operating state for each of the endwall designs is further illustrated and reported as a baseline data. The coupled analysis from CFD and ANN methodologies, reports the efficiency achieved with free-sides, doubled endwalls, and single-side endwall, respectively. Moreover, employing a single-side endwall results in 18.8% efficiency, and the doublesided model in 13.6% efficiency reduction as compared with the free-sided cyclorotor. The computations on horizontal and vertical force productions are revealing an 8% and 11% higher horizontal force for free-sides design than those of double-endwall and single-endwall models, and an average of 7% and 16% higher values in vertical force generation in double-endwall model compared with free-sided and single-endwall designs.
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Cycloidal rotor is a rotor whose blades pitch around the pitching axis and revolve around the rotor shaft that is parallel to blade. It can generate omni-directional thrust with high efficiency. In this paper, the numerical simulation models were validated by the wind tunnel experiments. Then physics of the cycloidal rotor in forward flight was studied. The effects of blade number and advance ratio were qualitatively discussed based on the numerical simulation results. Results of the analysis indicate that the rotor with more blades will result in smoother force curve, so that there will be lower vibration. However, the rotor with three or four blades will be the most efficient. The maximum forward flight efficiency is obtained from medium-to-high advance ratio. The efficiency is comparable with that of a screw propeller at the same Reynolds number. At low advance ratio, the peak lift on the blade can be observed when the blade is located at the lower left part of its trajectory. This is caused by positive blade pitch angle and relatively large inflow speed, which is similar to the downwash in the rotor cage under hovering status. From medium-to-high advance ratio, the thrust and lift primarily originated from the plunging motion of the blade. If the advance ratio is high enough, there will be negative horizontal force and positive torque, which means that the blade is taking energy from the inflow. Resultant force of the horizontal and vertical force does not vary too much with the advance ratio. But with the advance ratio approaching 1.0, the direction of the resultant force will point upwards and no horizontal force can be observed.
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Conference Paper
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In the following paper we introduce PECyT system for enhancing the aerodynamic efficiency of cycloidal rotors. For that purpose the incorporation of Dielectric Barrier Discharge plasma actuators for active flow control on a pitching airfoil, under deep-stall conditions, will be assessed using a numerical tool. Two different arrangements of DBD actuators will be analysed, namely single-and multi-DBDs configurations. For the single-DBD plasma actuator the effect of different modes of actuation on the lift coefficient will also be studied. We will show that the multi-DBD actuator, in a steady-actuation mode, could delay stall and allows for a faster reattachment of the flow. However during the downstroke phase of the pitching cycle the unsteady operation of a single-DBD gives us the best results in terms of lift coefficient.
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A cyclocopter propelled by a cycloidal blade system is a new concept of vertical takeoff and landing aircraft. The cycloidal blade system, which can he described as a horizontal rotary wing, offers powerful thrust levels and a unique ability to change the direction of the thrust almost instantly. This paper investigates the development of the cyclocopter with four rotors, file aircraft was designed through computational fluid dynamics and finite element structural analyses. Elliptic blades and a swash plate were applied to the rotor system to improve the rotor performance and control mechanism. Efficient dc brushless motors and lithium-polymer batteries were used for power transmissions. Almost all parts of the rotor blades and fuselage were manufactured out of composite material. Thrust and required power were measured experimentally on the test bed. The experimental result shows that the cyclocopter on produce sufficient thrust for both hovering and low-speed forward flight.
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Among the purely aeronautical applications, near-horizontal axis as well as horizontal axis devices are considered. The former cover the radial-lift propeller or 'self-propelling' wing; the latter cover Magnus effect and related systems; cyclogiro systems and horizontal-axis propeller systems with cyclic pitch. A limited investigation of non-aeronautical applications of HARWAS is also made, which covers wing-rotor type windmills, cyclogiro windmill turbines, Magnus effect ship propulsion and cycloidal ship propulsion. Approximately 1200 references are listed. A series of cross-index tables is also included to provide a quick means for the reader to determine the content and availability of the references. An analysis of the various lift systems pertinent to the HARWAS field is made with a view to potential air vehicle applications. Over 20 original aeronautical applications are identified and evaluated in the light of recent advances in power plants, transmissions and lightweight structural techniques. This analysis points out the extraordinary variety of HARWAS and identifies promising new aeronautical systems. A preliminary performance and design study of two promising HARWAS concepts is also reported. The two concepts are the STOL logistics aircraft using a rotating airfoil flap and the amplified high-pitch cyclogiro for application to the composite aircraft mission.
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BOSCH Aerospace, Inc., (BOSCH Aerospace) and subcontractor MSU RASPET Flight Research Laboratory (RASPET) accomplished successful development and testing of a prototype Curtate Cycloidal Propeller during the SBIR Phase 1 effort which concluded on October 31, 1998. This propulsion concept holds significant promise for adaptation to UAV VTOL operations. Thrust levels demonstrated were substantially higher than achievable by the best screw type propellers, and approximately equal to those of high end helicopters. Vectoring of thrust through a 3600 arc, and low noise characteristics throughout the RPM range were demonstrated. Also accomplished was identification of efficiency gain techniques that may increase the overall thrust by approximately 30%.
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An experimental investigation was conducted to study the flow around a cycloidal propeller. Flow fields were obtained using a particle image velocimetry system whose data acquisition was synchronized with the propeller’s angular position. The chord-based Reynolds number was Re c = u rc/υ = 1.4 × 104, where u r is the rotational velocity of the propeller and c is the chord length of the airfoil. Flow characteristics such as mean velocity, vorticity and the RMS value of velocity fluctuation were derived from the measurements. The results demonstrated the presence of a downwash around the propeller during the generation of lift. Detailed observations around each airfoil visualized distinct vortex shedding and reattaching flow at certain phase angles of the propeller. Graphical Abstract
Article
Simplified unsteady aerodynamic and inertial force models were developed for a cycloidal propeller system operating at small forward speeds. These models were used to support the development of a VTOL concept demonstrator vehicle. The nature of the blade motion showed that interactions between the blades could be neglected to first order. The downwash through the rotor could not be neglected because of the induced angle of attack caused by the downwash. The total force was compared with wind tunnel data produced by Wheatley in the 30's and a ground test system developed for this project. It was found that the estimates produced by the model agreed with the total force and power to within 10% for the Wheatley data. Agreement between the model and the current tests was within 5% for the total force and power. The inertial loads were used to design the blade structure, the support structure, and the blade motion system. It was found that the inertial loads were much larger than the aerodynamic loads. The aerodynamic effect of forward motion or wind moving toward the propeller was defined. It was modeled as a constant velocity induced flow through the propeller that induced an angle of attack of the blades. It was found that the cycloidal propeller was very susceptible to wind gusts, but that the resultant force from the wind gust could be easily damped out. The same forward motion model was used to simulate downwash. By modeling the downwash as a constant velocity flow through the propeller, the lift and thrust of the propeller was linked to the induced flow velocity. The effect of the induced flow velocity was then linked back to its effect on the lift and thrust produced by the propeller. Mode of access: Internet via the World Wide Web. System requirements: Internet connectivity; World Wide Web browser software; Adobe Acrobat Reader. Title from title screen. Electronic book in PDF. Thesis (M.S.)--Mississippi State University. Department of Aerospace Engineering. Includes bibliographical references.
Article
This paper presents an experimental study on the development of a cyclogyro-based flying robot with a new variable angle of attack mechanism. A cyclogyro is a flying machine supported in the air by power-driven rotors that rotate about a horizontal axis, like the paddle-wheels of a steamboat. Machines of this type have been designed by some companies but there has been no record of any successful flights. Our design starts with a new variable angle of attack mechanism with an eccentric (rotational) point in addition to a rotational point connecting to a motor. The main feature of the mechanism with the eccentric rotational point is the ability to change attack of angles in accordance with the wing positions (as determined by the rotational angles of the cyclogyro) without actuators. The design parameters (wing span, the number of wings, and eccentric distance) of the flying robot are determined through a series of experiments. Experimental results show that the cyclogyro-based flying robot with the new variable angle of attack mechanism is capable of generating sufficient lift force for flying.
Overcoming stopovers in cyc-loidal rotor propulsion integration on air vehicles In: Proceedings of the A ˆ SME 2012 international design engineering technical conferences & computers and infor-mation in engineering conference
  • Pa´
Pa´ JC and llieva Gl. Overcoming stopovers in cyc-loidal rotor propulsion integration on air vehicles. In: Proceedings of the A ˆ SME 2012 international design engineering technical conferences & computers and infor-mation in engineering conference, Chicago, IL, IDETC/ CIE, 12–15 August 2012.
Design of two-rotored UAV cyclocopter
  • Lee
  • Ch
  • Min
  • Sy
  • Kim
  • Ys
Lee CH, Min SY, Kim YS, et al. Design of two-rotored UAV cyclocopter. In: 5th European Conference for Aeronautics and Space Sciences, Munich, Germany, 1–5 July 2013, Korea Aerospace Research Institute.
Experimental investigation of the cycloidal rotor for a hovering micro air vehicle
  • Benedict M I Chopra
Benedict M, Chopra I, Ramasamy M, et al. Experimental investigation of the cycloidal rotor for a hovering micro air vehicle. In: Proceedings of the 64th annual national forum of the American Helicopter Society, Montreal, Canada, 28–30 April 2008.
Experimental performance of a six-bladed vertical axis propeller
  • Bv Nakonechny
Nakonechny BV. Experimental performance of a six-bladed vertical axis propeller. Report No. 1446, Department of the Navy, January 1961.
A new way of simulating whale tail propulsion
  • Manen Jv
  • Terwisga Tv
Manen Jv and Terwisga Tv. A new way of simulating whale tail propulsion. In: Twenty-first symposium on naval hydrodynamics, 1997.
The Voith Schneider propeller current applications and new developments. G 1849 e Print Run 1500 aK
  • Bartels
Bartels J and Ju¨ D. The Voith Schneider propeller current applications and new developments. G 1849 e Print Run 1500 aK/Wo Printed in German, December 2006.
Simultaneous PIV and balance meas-urements on pitching aerofoi
  • Mk Heerenbrink
Heerenbrink MK. Simultaneous PIV and balance meas-urements on pitching aerofoi. Master of Science Thesis, Delft University of Technology, 30 May 2011.
Aircraft design: a conceptual approach
  • Dp Raymer
Raymer DP. Aircraft design: a conceptual approach. American Institute of Aeronautics and Astronautics, Inc., Washington, DC, 1989.
BRI cyclo-turbine for energy production
  • J H Boschma
Boschma JH. BRI cyclo-turbine for energy production. Brownsboro, AL: Boschma Research, Inc, 2011.
Cycloidal propulsion applied to aircraft
  • F Kirsten
Kirsten F. Cycloidal propulsion applied to aircraft. Trans Am Soc Mech Eng 1928; 50: AER-50-12.
The research on the performance of cyclogiro
  • Y Hu
  • K B Lim
  • W R Hu
Hu Y, Lim KB and Hu WR. The research on the performance of cyclogiro. In: 6th AIAA aviation technology, integration and operations conference, Wichita, Kansas, 25-27 September 2006.
Design of two-rotored UAV cyclocopter
  • C H Lee
  • S Y Min
  • Y S Kim
Lee CH, Min SY, Kim YS, et al. Design of two-rotored UAV cyclocopter. In: 5th European Conference for Aeronautics and Space Sciences, Munich, Germany, 1-5 July 2013, Korea Aerospace Research Institute.
Experimental investigation of the cycloidal rotor for a hovering micro air vehicle
  • M Benedict
  • I Chopra
  • M Ramasamy
Benedict M, Chopra I, Ramasamy M, et al. Experimental investigation of the cycloidal rotor for a hovering micro air vehicle. In: Proceedings of the 64th annual national forum of the American Helicopter Society, Montreal, Canada, 28-30 April 2008.
A new VTOL UAV cyclocopter with cycloidal blades system
  • C Y Yun
  • I K Park
  • H Y Lee
Yun CY, Park IK, Lee HY, et al. A new VTOL UAV cyclocopter with cycloidal blades system. American Helicopter Society International, June 2004.
Experimental performance of a sixbladed vertical axis propeller
  • B V Nakonechny
Nakonechny BV. Experimental performance of a sixbladed vertical axis propeller. Report No. 1446, Department of the Navy, January 1961.
Simultaneous PIV and balance measurements on pitching aerofoi
  • M K Heerenbrink
Heerenbrink MK. Simultaneous PIV and balance measurements on pitching aerofoi. Master of Science Thesis, Delft University of Technology, 30 May 2011.