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 Lift driven WT Drag 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 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 : V0 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:

Savonius Rotor Wind Turbine

Design of Blade for Savonius Rotor Wind Turbine

Local Static Coefficient of Torque

The cyclic torque coefficients with the time for modify 4 rotor at different

Ensemble Average torque coefficient versus the instantaneous location of the rotor at different tip speed ratios.

Savonius Turbine : Average Coefficient of Torque

Savonius Turbine : Average Power Coefficient

Cup anemometer V0 +Vb R V0 V0-Vb

Maximum Torque Generated by A Cup Anemometer

Selection of Cup Geometries

Instantaneous Drag Coefficient  

Cup Anemometer as An Wind Speed Measuring Device -1

Six Cup Anemometer as An Wind Speed Measuring Device 

Three Cup Anemometer as An Wind Speed Measuring Device- Polysterin Arm 

19th Century lift Devices

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, Samarangana Sutradhara, 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 in 1 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

Superiority of Zero Weight Balloon

Development of an Ultimate Fluid machine

Can We Identify the Cause?

The Natural Genius & The Art of Generating 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.

The Potential of C-Start

Motorcontrol strategies : Multiple Skills of Natural Genius Larva of Chinook Salman Larval Lamprey Northern Pike