Blade element theory
About: Blade element theory is a(n) research topic. Over the lifetime, 1537 publication(s) have been published within this topic receiving 22517 citation(s).
18 Dec 2009-
Abstract: Preface Acknowledgements Introduction: Modern wind energy and its origins Modern wind turbines History of wind energy Wind characteristics and resources Introduction General characteristics of the wind resource Characteristics of the atmospheric boundary layer Wind data analysis and resource estimation Wind turbine energy production estimates using statistical techniques Overview of available resource assessment data Wind measurements and instrumentation Advanced topics Aerodynamics of wind turbines General overview One-dimensional momentum theory and the Betz limit Ideal horizontal axis wind turbing with wake rotation' Airfoils and general concepts of aerodynamics Momentum theory and blade element theory Blade shape for ideal rotor without wake rotation General rotor blade shape performance prediction Blade shape for optimum rotor with wake rotation Generalized rotor design procedure Simplified HAWT rotor performance calculation procedure Effect of drag and blade number on optimum performance Advanced aerodynamic topics Mechanics and dynamics Wind turbine rotor dynamics Detailed and specialized dynamic models Electrical aspects of wind turbines Basic concepts of electric power Power transformers Electrical machines Power converters Ancillary electrical equipment Wind turbine design Design procedure Wind turbine topologies Materials Machine elements Wind turbine loads Wind turbine subsystems and components Design evaluation Power curve prediction Wind turbine loads Wind turbine subsystems and components Design evaluation Power curve prediction Wind turbine control Overview of wind turbine control systems Typical grid-connected turbine operation Supervisory control overview and implementation Dynamic control theory and implementation Wind turbine siting, system design and integration Wind turbine siting Installation and operation issues Wind farms Wind turbines and wind farms in electric grids Offshore wind farms Operation in severe climates Hybrid electrical systems Wind energy system economics Overview of economic assessment of wind energy systems Capital costs of wind energy systems Operation and maintenance costs Value of wind energy Economic analysis methods Wind energy market considerations Wind energy systems: environmental aspects and impacts Avian interaction with wind trubines Visual impact of wind turbines Wind turbine noise Electromagnetic interference effects Land-use environmental impacts Other environmental considerations Nomenclature Problems Index
15 Apr 2002-The Journal of Experimental Biology
TL;DR: A standard quasi-steady model of insect flight is modified to include rotational forces, translational forces and the added mass inertia, and the revised model predicts the time course of force generation for several different patterns of flapping kinematics more accurately than a model based solely on translational force coefficients.
Abstract: We used a dynamically scaled model insect to measure the rotational forces produced by a flapping insect wing. A steadily translating wing was rotated at a range of constant angular velocities, and the resulting aerodynamic forces were measured using a sensor attached to the base of the wing. These instantaneous forces were compared with quasi-steady estimates based on translational force coefficients. Because translational and rotational velocities were constant, the wing inertia was negligible, and any difference between measured forces and estimates based on translational force coefficients could be attributed to the aerodynamic effects of wing rotation. By factoring out the geometry and kinematics of the wings from the rotational forces, we determined rotational force coefficients for a range of angular velocities and different axes of rotation. The measured coefficients were compared with a mathematical model developed for two-dimensional motions in inviscid fluids, which we adapted to the three-dimensional case using blade element theory. As predicted by theory, the rotational coefficient varied linearly with the position of the rotational axis for all angular velocities measured. The coefficient also, however, varied with angular velocity, in contrast to theoretical predictions. Using the measured rotational coefficients, we modified a standard quasi-steady model of insect flight to include rotational forces, translational forces and the added mass inertia. The revised model predicts the time course of force generation for several different patterns of flapping kinematics more accurately than a model based solely on translational force coefficients. By subtracting the improved quasi-steady estimates from the measured forces, we isolated the aerodynamic forces due to wake capture.
01 Jan 1926-
Abstract: 1. Introduction 2. Bernoulli's equation 3. The stream function 4. Circulation and vorticity 5. The velocity potential and the potential function 6. The transformation of a circle into an aerofoil 7. The aerofoil in two dimensions 8. Viscosity and drag 9. The basis of aerofoil theory 10. The aerofoil in three dimensions 11. The monoplane aerofoil 12. The flow round an acerofoil 13. Biplane aerofoils 14. Wind tunnel interference on areofoils 15. The airscrew: momentum theory 16. The airscrew: blade element theory 17. The airscrew: wind tunnel interference Appendix Bibliography Index.
Abstract: Rotating instabilities (RI) have been observed in axial flow fans, centrifugal compressors as well as in low-speed and high-speed axial compressors. They are responsible for the excitation of high amplitude rotor blade vibrations and noise generation. This flow phenomenon moves relative to the rotor blades and causes periodic vortex separations at the blade tips and an axial reversed flow through the tip clearance of the rotor blades.The paper describes experimental investigations of RI in the Dresden Low-Speed Research Compressor (LSRC). The objective is to show that the fluctuation of the blade tip vortex is responsible for the origination of this flow phenomenon.RI have been found at operating points near the stability limit of the compressor with relatively large tip clearance of the rotor blades. The application of time-resolving sensors in both fixed and rotating frame of reference enables a detailed description of the circumferential structure and the spatial development of this unsteady flow phenomenon, which is limited to the blade tip region.Laser-Doppler-Anemometry (LDA) within the rotor blade passages and within the tip clearance as well as unsteady pressure measurements on the rotor blades show the structure of the blade tip vortex.It will be shown that the periodical interaction of the blade tip vortex of one blade with the flow at the adjacent blade is responsible for the generation of a rotating structure with high mode orders, termed as rotating instability (RI).Copyright © 2000 by ASME
01 Oct 1990-
Abstract: Basic Helicopter Aerodynamics is widely appreciated as an easily accessible, rounded introduction to the first principles of the aerodynamics of helicopter flight. Simon Newman has brought this third edition completely up to date with a full new set of illustrations and imagery. An accompanying website www.wiley.com/go/seddon contains all the calculation files used in the book, problems, solutions, PPT slides and supporting MATLAB® code. Simon Newman addresses the unique considerations applicable to rotor UAVs and MAVs, and coverage of blade dynamics is expanded to include both flapping, lagging and ground resonance. New material is included on blade tip design, flow characteristics surrounding the rotor in forward flight, tail rotors, brown-out, blade sailing and shipborne operations. Concentrating on the well-known Sikorsky configuration of single main rotor with tail rotor, early chapters deal with the aerodynamics of the rotor in hover, vertical flight, forward flight and climb. Analysis of these motions is developed to the stage of obtaining the principal results for thrust, power and associated quantities. Later chapters turn to the characteristics of the overall helicopter, its performance, stability and control, and the important field of aerodynamic research is discussed, with some reference also to aerodynamic design practice. This introductory level treatment to the aerodynamics of helicopter flight will appeal to aircraft design engineers and undergraduate and graduate students in aircraft design, as well as practising engineers looking for an introduction to or refresher course on the subject.