@article{elfering_metoyer_chatterjee_mazzoleni_bryant_granlund_2023, title={Blade element momentum theory for a skewed coaxial turbine}, volume={269}, ISSN={["1873-5258"]}, url={https://doi.org/10.1016/j.oceaneng.2022.113555}, DOI={10.1016/j.oceaneng.2022.113555}, abstractNote={A coaxial turbine under skew with significant rotor spacing has the potential for increased power output compared to a flow-aligned turbine due to a portion of the downstream rotor experiencing freestream velocity, referred to as a fresh flow region. A lab-scale prototype was designed and built to investigate the skew-to-power relationship of a coaxial turbine system as it compared to a blade element momentum theory model with multiple, sheared streamtubes representing the downstream rotor fresh flow region. The inclusion of the downstream rotor fresh flow region in the theoretical analysis is compared to the experimental data. The results support that the torque and power performance of the downstream rotor and overall skewed coaxial turbine system are predicted more accurately.}, journal={OCEAN ENGINEERING}, author={Elfering, Kelsey and Metoyer, Rodney and Chatterjee, Punnag and Mazzoleni, Andre and Bryant, Matthew and Granlund, Kenneth}, year={2023}, month={Feb} }
 @article{metoyer_chatterjee_elfering_bryant_granlund_mazzoleni_2021, title={Modeling, simulation, and equilibrium analysis of tethered coaxial dual-rotor ocean current turbines}, volume={243}, ISSN={["1879-2227"]}, DOI={10.1016/j.enconman.2021.113929}, abstractNote={Tethered multirotor axial flow turbines have been proposed to overcome the many challenges associated with extracting ocean current energy where deep waters render seabed mounting strategies infeasible. However, flexible systems are inherently more susceptible to perturbation than fixed systems. The effects of flow misalignment on the hydrokinetic energy conversion of multirotor coaxial turbines have been investigated recently; however, the spatial dynamics and equilibrium behaviors of tethered coaxial turbines have not been well characterized, limiting the ability of designers to explicitly tailor the device behavior. In this work, a computational model of a dual-rotor coaxial turbine is presented, and the model is employed to explore the equilibrium behavior of the turbine with variations in parameters. A complete characterization of the hydrostatic state of the system and a comparative study of representative tethered turbine simulation cases is also presented. Two important findings are presented. First, that a positively buoyant dual-rotor turbine that is anchored to a surface-dwelling platform can operate where the turbine is located at some desired depth below the surface. Second, that more than one turbine system may be anchored to a single point while maintaining the desired orientation and position of each turbine to avoid collision and maximize energy production. The results and methods presented in this paper may be used to inform application-specific coaxial turbine design and to develop additional targeted empirical and simulation studies.}, journal={ENERGY CONVERSION AND MANAGEMENT}, author={Metoyer, Rodney and Chatterjee, Punnag and Elfering, Kelsey and Bryant, Matthew and Granlund, Kenneth and Mazzoleni, Andre}, year={2021}, month={Sep} }
 @article{chatterjee_bryant_2019, title={Analysis of tension-tunable clamped-clamped piezoelectric beams for harvesting energy from wind and vibration}, volume={30}, ISSN={["1530-8138"]}, DOI={10.1177/1045389X19862390}, abstractNote={ This article presents a nonlinear structural modeling framework to analyze a tensioned doubly clamped energy harvesting device. The device is investigated for energy harvesting under base excitation loading, where the structure undergoes bending motion and aerodynamic loading, where the structure undergoes combined bending–torsion motion. Transfer-matrix method for analyzing torsional motion is modified to include the effects of applied axial preload tension. The tension-modulated mode shapes and natural frequencies of the structure, obtained using transfer-matrix method, are found to be in good agreement with the results obtained using a commercially available Finite Element software. Under base excitation loading, it is shown that the effects of tension on electromechanical coupling and stiffness create competing influences on the power efficiency of the system. For aerodynamic loading, increasing preload tension increases the cut-in wind speed of the device. However, beyond the cut-in wind speed, with proper selection of the preload tension, the tensioned structure can produce an order of magnitude more power than the untensioned case at the same flow speed. }, number={16}, journal={JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES}, author={Chatterjee, Punnag and Bryant, Matthew}, year={2019}, month={Sep}, pages={2405–2420} }
 @article{khatri_chatterjee_metoyer_mazzoleni_bryant_granlund_2019, title={Dual-Actuator Disc Theory for Turbines in Yaw}, volume={57}, ISSN={["1533-385X"]}, DOI={10.2514/1.J057740}, abstractNote={No AccessTechnical NotesDual-Actuator Disc Theory for Turbines in YawDheepak N. Khatri, Punnag Chatterjee, Rodney Metoyer, Andre P. Mazzoleni, Matthew Bryant and Kenneth O. GranlundDheepak N. KhatriNorth Carolina State University, Raleigh, North Carolina 27695*Graduate Research Assistant, Department of Mechanical and Aerospace Engineering.Search for more papers by this author, Punnag ChatterjeeNorth Carolina State University, Raleigh, North Carolina 27695*Graduate Research Assistant, Department of Mechanical and Aerospace Engineering.Search for more papers by this author, Rodney MetoyerNorth Carolina State University, Raleigh, North Carolina 27695*Graduate Research Assistant, Department of Mechanical and Aerospace Engineering.Search for more papers by this author, Andre P. MazzoleniNorth Carolina State University, Raleigh, North Carolina 27695†Associate Professor, Department of Mechanical and Aerospace Engineering. Associate Fellow AIAA.Search for more papers by this author, Matthew BryantNorth Carolina State University, Raleigh, North Carolina 27695‡Assistant Professor, Department of Mechanical and Aerospace Engineering.Search for more papers by this author and Kenneth O. GranlundNorth Carolina State University, Raleigh, North Carolina 27695§Assistant Professor, Department of Mechanical and Aerospace Engineering. Senior Member AIAA.Search for more papers by this authorPublished Online:23 Jan 2019https://doi.org/10.2514/1.J057740SectionsRead Now ToolsAdd to favoritesDownload citationTrack citations ShareShare onFacebookTwitterLinked InRedditEmail About References [1] Betz A., “Das Maximum der theoretisch möglichen Ausnützung des Windes durch Windmotoren,” Zeitschrift für das gesamte Turbinenwesen, 1920, pp. 26, 307–309. Google Scholar[2] Newman B. G., “Actuator Disc Theory for Vertical Wind Turbines,” Journal of Wind Engineering and Industrial Aerodynamics, Vol. 15, Nos. 1–3, 1983, pp. 347–355. doi:https://doi.org/10.1016/0167-6105(83)90204-0 JWEAD6 0167-6105 CrossrefGoogle Scholar[3] Rosenberg A., Selvaraj S. and Sharma A., “A Novel Dual-Rotor Turbine for Increased Wind Energy Capture,” Journal of Physics: Conference Series, Vol. 524, 2014, Paper 012078. doi:https://doi.org/10.1088/1742-6596/524/1/012078 JPCSDZ 1742-6588 CrossrefGoogle Scholar[4] Adams Z. and Chen J., “Flux-Line Theory: A Novel Analytical Model for Cycloturbines,” AIAA Journal, Vol. 55, No. 11, 2017, pp. 3851–3867. doi:https://doi.org/10.2514/1.J055804 AIAJAH 0001-1452 LinkGoogle Scholar[5] Anderson M., “Horizontal Axis Wind Turbines in Yaw,” Proceedings of the First British Wind Energy Association (BWEA) Wind Energy Workshop, 1979, pp. 57–67, http://adsabs.harvard.edu/abs/1979wien.work...57A. Google Scholar[6] Grant I., Parkin P. and Wang X., “Optical Vortex Tracking Studies of a Horizontal Axis Wind Turbine in Yaw Using Laser-Sheet, Flow Visualization,” Experiments in Fluids, Vol. 23, No. 6, 1997, pp. 513–519. doi:https://doi.org/10.1007/s003480050142 EXFLDU 0723-4864 CrossrefGoogle Scholar[7] Newman B. G., “Multiple Actuator Disc Theory for Wind Turbines,” Journal of Wind Engineering and Industrial Aerodynamics, Vol. 24, No. 3, 1986, pp. 215–225. doi:https://doi.org/10.1016/0167-6105(86)90023-1 JWEAD6 0167-6105 CrossrefGoogle Scholar[8] Howland M., Bossuyt J., Martinez-Tossas L., Meyers J. and Meneveau C., “Wake Structure in Actuator Disk Models of Wind Turbines in Yaw Under Uniform Inflow Conditions,” Journal of Renewable and Sustainable Energy, Vol. 8, No. 4, 2016, Paper 043301. doi:https://doi.org/10.1063/1.4955091 CrossrefGoogle Scholar Previous article Next article FiguresReferencesRelatedDetailsCited byPool-Based Tow System for Testing Tethered Hydrokinetic Devices Being Developed to Harvest Energy From Ocean CurrentsMarine Technology Society Journal, Vol. 57, No. 1Blade element momentum theory for a skewed coaxial turbineOcean Engineering, Vol. 269Closed-Loop-Flight-Based Combined Geometric and Structural Wing Design optimization Framework for a Marine Hydrokinetic Energy KiteDemonstration of a Towed Coaxial Turbine Subscale Prototype for Hydrokinetic Energy Harvesting in SkewCharacterization of the Steady-State Operating Conditions of Tethered Coaxial TurbinesIncreased Energy Conversion with a Horizontal Axis Turbine in TranslationModeling, simulation, and equilibrium analysis of tethered coaxial dual-rotor ocean current turbinesEnergy Conversion and Management, Vol. 243Experimental analysis of dual coaxial turbines in skewOcean Engineering, Vol. 215 What's Popular Volume 57, Number 5May 2019 CrossmarkInformationCopyright © 2018 by the authors. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. All requests for copying and permission to reprint should be submitted to CCC at www.copyright.com; employ the eISSN 1533-385X to initiate your request. See also AIAA Rights and Permissions www.aiaa.org/randp. TopicsAerodynamicsAeronautical EngineeringAeronauticsConservation of Momentum EquationsEnergyEnergy FormsEnergy Forms, Production and ConversionEquations of Fluid DynamicsFlow RegimesFluid DynamicsFluid Flow PropertiesTurbinesTurbomachineryWind EngineeringWind Turbine KeywordsTurbinesYawConservation of MassHorizontal Axis TurbineFree Stream VelocityConservation EquationsTwo Dimensional FlowNavier Stokes EquationsKinetic EnergyFluid DensityAcknowledgmentsThis work was funded by a grant from the North Carolina Coastal Studies Institute. The authors would like to thank undergraduate research assistants Tyler Farr and Kyle Weiner for their contributions to these results.PDF Received27 August 2018Accepted2 December 2018Published online23 January 2019}, number={5}, journal={AIAA JOURNAL}, author={Khatri, Dheepak N. and Chatterjee, Punnag and Metoyer, Rodney and Mazzoleni, Andre P. and Bryant, Matthew and Granlund, Kenneth O.}, year={2019}, month={May}, pages={2204–2208} }
 @article{chatterjee_bryant_2018, title={Aeroelastic-photovoltaic ribbons for integrated wind and solar energy harvesting}, volume={27}, ISSN={["1361-665X"]}, DOI={10.1088/1361-665x/aacbbb}, abstractNote={This letter investigates the energy harvesting capabilities of a novel hybrid wind and solar transduction device. The proposed device is an inverted-U shaped structure with a pair of piezoelectric benders connected by a flexible, tensioned photovoltaic ribbon. The tensioned photovoltaic ribbon member undergoes aeroelastic flutter limit cycle oscillations (LCOs) at low wind speeds, leading to time-varying tension forces applied to the piezoelectric benders, producing cyclic deflections and output voltage. Experimental characterization of the proof of concept energy harvester indicates that it is possible to obtain several milliwatts (mW) of power using the centimeter scale device, with an output power of ∼12.1 mW at a combination of 12 m s−1 wind speed and 100 W m−2 of solar irradiance, for indirect solar applications. It is shown here that an optimal combination of applied tensile preload and preset angle of attack exists which produces the highest wind power output of the system. An explanation of this behavior is also provided through the analysis of data collected on the photovoltaic ribbon velocity, piezoelectric voltage signals, and high-speed imagery, providing further insight to the motion kinematics of the highly nonlinear system response. Interestingly, the solar power output has been observed to remain invariant with increasing vibration velocity. This suggests that the gain in solar power efficiency from vibration-induced convective cooling negates any losses from the deflected incidence angle of the photovoltaic ribbon. These results illustrate that there is a negligible performance penalty in adding wind energy harvesting capability to the solar cells with this device concept.}, number={8}, journal={SMART MATERIALS AND STRUCTURES}, author={Chatterjee, P. and Bryant, M.}, year={2018}, month={Aug} }
 @article{chatterjee_bryant_2016, title={Aeroelastic modeling of a Piezo-Solar tensioned energy harvesting ribbon}, volume={9799}, ISSN={["1996-756X"]}, DOI={10.1117/12.2222109}, abstractNote={A multifunctional compliant structure is proposed that can harvest electrical power from both incident sunlight and ambient mechanical energy including wind flow or vibration. The proposed energy harvesting device consists of a slender, ribbon-like, flexible thin film solar cell that is laminated with piezoelectric patches at either ends and mounted in the cross flow of wind in a clamped-clamped end condition with an adjustable axial preload. Taking this motivation forward a system model of the energy harvester is developed which captures the structural response of the solar ribbon and couples it with Theodorsen unsteady aerodynamics to predict the flutter boundary conditions as a function of applied axial preload tension. The model also accounts for geometric and material discontinuities, by effective use of Transfer Matrix Method (TMM) modeling technique both in bending and torsional degrees of freedom. This paper also derives TMM technique for torsional vibrations with an applied axial load from first principles, verifies the method and presents its applicability for the proposed energy harvester. The paper also points out that the flutter instability arises out of different structural modes at different values applied axial tension, with the help of a sample modal convergence plot. The analysis also presents the possibility to tune the solar ribbon to operate at an optimal reduced frequency by adjusting the applied axial preload.}, journal={ACTIVE AND PASSIVE SMART STRUCTURES AND INTEGRATED SYSTEMS 2016}, author={Chatterjee, Punnag and Bryant, Matthew}, year={2016} }
 @article{chatterjee_bryant_2015, title={Structural modelling of a compliant flexure flow energy harvester}, volume={24}, ISSN={["1361-665X"]}, DOI={10.1088/0964-1726/24/9/094007}, abstractNote={This paper presents the concept of a flow-induced vibration energy harvester based on a one-piece compliant flexure structure. This energy harvester utilizes the aeroelastic flutter phenomenon to convert flow energy to structural vibrational energy and to electrical power output through piezoelectric transducers. This flexure creates a discontinuity in the structural stiffness and geometry that can be used to tailor the mode shapes and natural frequencies of the device to the desired operating flow regime while eliminating the need for discrete hinges that are subject to fouling and friction. An approximate representation of the flexure rigidity is developed from the flexure link geometry, and a model of the complete discontinuous structure and integrated flexure is formulated based on the transfer matrix method. The natural frequencies and mode shapes predicted by the model are validated using finite element simulations and are shown to be in close agreement. A proof-of-concept energy harvester incorporating the proposed flexure design has been fabricated and investigated in wind tunnel testing. The aeroelastic modal convergence, critical flutter wind speed, power output and limit cycle behavior of this device is experimentally determined and discussed.}, number={9}, journal={SMART MATERIALS AND STRUCTURES}, author={Chatterjee, Punnag and Bryant, Matthew}, year={2015}, month={Sep} }
 @inproceedings{chatterjee_bryant_2015, title={Transfer Matrix Modeling of a Tensioned Piezo-Solar Hybrid Energy Harvesting Ribbon}, volume={9431}, DOI={10.1117/12.2086138}, abstractNote={This paper proposes a multifunctional compliant structure that can harvest electrical power from both incident sunlight and ambient mechanical energy including wind flow or vibration. The energy harvesting device consists of a slender, ribbon-like, flexible thin film solar cell that is laminated with piezoelectric patches. The harvester is mounted in longitudinal tension and subjected to a transverse wind flow to excite flow-induced aeroelastic vibrations. This paper formulates an analytic model of the bending dynamics of the device. We present a Transfer Matrix formulation that also accounts for the changes in natural frequencies and mode shapes of the system when subjected to axial loads in a beam. It also observed that mode shape obtained using TMM formulation shows numerical stability even for very high tensile loads providing results consistent with the geometric boundary conditions applied at the ends of a beam. This article also discusses about structurally modeling a piezo - solar energy harvester using TMM methodology, where a thin clampedclamped solar film is bonded with piezo patches having a much higher bending stiffness. Additionally, the effect of axial tension on the mode shape of the thin host structure of the piezo-solar ribbon is presented and it is shown how this tension can be used advantageously to affect the strain distribution of the entire structure and introduce higher strains at the piezo patches.}, booktitle={Active and passive smart structures and integrated systems 2015}, author={Chatterjee, P. and Bryant, M.}, year={2015} }
 @inproceedings{chatterjee_bryant_2014, title={Design of a compliant flexure joint for use in a flow energy harvester}, DOI={10.1115/smasis2014-7503}, abstractNote={This paper presents an initial experimental and computational investigation of a flow-induced vibration energy harvester with a compliant flexure mechanism. This energy harvester utilizes the aeroelastic flutter phenomenon to convert the flow energy to vibrational energy which can be converted into useful electrical power using piezoelectric transducers. However, unlike previous flutter-based flow energy harvesters [1] which require assembling multiple components to create the necessary aeroelastic arrangement, the device described here utilizes a monolithic, compact design to achieve the same. In this paper, we propose a flexure design for this device and model it using analytic methods and finite element simulations. A proof of concept energy harvester incorporating this flexure design has been fabricated and experimentally investigated in wind tunnel testing.}, booktitle={Proceedings of the ASME Conference on Smart Materials, Adaptive Structures and Intelligent Systems, 2014, vol 2}, author={Chatterjee, P. and Bryant, M.}, year={2014} }