1. 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 ……

2. Mechanical Power Extraction :The fundamental Aerodynamic Phenomena
The type of aerodynamic forces used for generation of change in tangential velocity across a rotor greatly influences the actual power developed by a wind turbine.
All bodies exposed to an airflow experience an aerodynamic force.
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 real power coefficients obtained vary greatly in dependence on whether aerodynamic drag or aerodynamic lift is used for power generation.
A significant enhancement in power generation can be achieved in lift machines when compared to and drag machine.
This is due to the fact that much higher relative wind velocities can be achieved with lift machines.

3. Basic Principle of Changing Angular Momentum
Lift driven WT
Drag driven WT

4. 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.

5. 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:

6. Capacity of Drag Device
Instantaneous Power Developed by a drag device
Average Power Developed by a drag device

7. Power Coefficient of A Drag Wind Turbine
The instantaneous power coefficient
Maximum instantaneous power coefficient
Define Blade Speed Ratio, 
Condition for maximum value of CPmax,

8. Efficient Drag devices
The aerodynamic drag coefficient of a concave surface curved against the wind direction can hardly exceed a value of 1.3. V0 vr

9. Cup anemometer
V0 +Vb R V0
V0-Vb

10. Maximum Torque Generated by A Cup Anemometer

11. Selection of Cup Geometries

12. Instantaneous Drag Coefficient 

13. Cup Anemometer as An Wind Speed Measuring Devices-1

14. Cup Anemometer as An Wind Speed Measuring Devices-2

15. Cup Anemometer as An Wind Speed Measuring Devices-3

16. Savonius Rotor Wind Turbine

17. Creative Designs

18. Lift Devices

19. Lift Based Blade in Wind Turbine

20. Flow past an airfoil