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This article explores the fundamental aerodynamic phenomena and basic methods of solid-fluid interactions in wind power extraction. It covers the principles of changing angular momentum, drag-driven and lift-driven wind turbines, and the design of Savonius rotor wind turbines.
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Fluid Dynamic Principles to Generate Axial Induction P M V Subbarao Professor Mechanical Engineering Department I I T Delhi Basic Methods of Solid Fluid Interactions to Extract Wind Power ……
Mechanical Power Extraction :The Fundamental Aerodynamic Phenomena • All bodies exposed to an airflow experience aerodynamic force. • This force generated on a wind turbine rotor is responsible for • generation of change in tangential velocity across a rotor & • Axial induction in upstream wind. • The components of which are defined as • aerodynamic drag (in the direction of flow), and • as aerodynamic lift (at a right angle to the direction of flow). • The component of force responsible for above effects, greatly influences the actual power developed by a wind turbine.
Basic Principle of Changing Angular Momentum/ Axial Induction Drag driven WT Lift driven WT
Drag Translator • Drag results from the relative velocity between the wind and the device. • The power extracted by an elementary drag is the product of the drag force and the translation velocity.
Simple Drag Device V0 • The simplest type of wind energy conversion can be achieved by means of pure drag surfaces. • The air impinges on the surface A with velocity V0. • The instantaneous power capture P from the aerodynamic drag D, and the velocity Vblade with which it moves is expressed as : Define coefficient of drag:
Capacity of Drag Device Instantaneous Power Developed by a drag device Average Power Developed by a drag device
Power Coefficient of A multi-Cup Drag Wind Turbine The instantaneous power coefficient of reference cup: The instantaneous power coefficient of multi cup turbine: The instantaneous torque coefficient of multi cup turbine:
The cyclic torque coefficients withthe time for modify 4 rotor at different
Ensemble Average torque coefficient versusthe instantaneous location of the rotor atdifferent tip speed ratios.
Cup anemometer V0 +Vb V0 R V0-Vb
Three Cup Anemometer as An Wind Speed Measuring Device- Polysterin Arm V0
Engineering of Newton's Third Law • What we enjoy/need is the reaction of some action. • The action to create a reaction has to be invented. • The action must be techno-economically viable. • It must lead to construction of a light hardware for flying.
India : The land of flying machines Flying machines described in many ancient texts like Yajurveda, Mahabharata, SamaranganaSutradhara, Rigweda, Ramayana and even older ones.
The Shocking News in The New York Times • 1 million to 10 million years they might be able to make a plane that would fly ?!?!?! • People had dreamed of flying for many years. • The United States Army was trying to develop an airplane in 1903, but the plane wouldn't fly. • The New York Times wrote that maybe in1 million to 10 million years they might be able to make a plane that would fly. • Only eight days later two men were successful in flying the first manned plane. • Controlled, powered flight had seemed impossible until Orville Wright took off on the 17th December 1903. • They were Wilbur Wright and his younger brother, Orville.
Kate Carew Interviews the Wright Brothers • “Are you manufacturing any racing machines?” • “Not just now, but we intend to.” • “How much can I buy one for?” • “Seven thousand five hundred-dollars.” • “Is that all? It doesn’t seem like an outside price for a perfectly good airship?” • “Airship!” shouted the Wright brothers indignantly. • “Is that the wrong word?” • “An airship,” said Wilbur contemptuously, “is a big, clumsy balloon filled with gas.” • “Well, I don’t see why your biplane shouldn’t be called an airship, too.”
A Ship Can’t Fly • “It’s a flying machine,” said Wilbur. • “The name we prefer is ‘flyer,’” said Orville. • “An airship would cost $50,000,” said Wilbur. • “More like $150,000,” said Orville, and they argued the question. Right Action to generate Lift
Hydrodynamics of Prey & Predators • Flying fish can be seen jumping out of warm ocean waters worldwide. • Their streamlined torpedo shape helps them gather enough underwater speed to break the surface, and their large, wing-like pectoral fins get them airborne. • Flying fish are thought to have evolved this remarkable gliding ability to escape predators, of which they have many.
Motorcontrol strategies : Multiple Skills of Natural Genius Larva of Chinook Salman Larval Lamprey Northern Pike
