Anatomy of Wind Turbines P M V Subbarao Professor Mechanical Engineering Department I I T Delhi Argons of a Machine to Generate Maximum Action …..

Learnings from Betz Theory A Rotor (energy converter) which can generate an axial induction factor greater than zero is capable of extracting the mechanical power from a free-stream wind. The extractable mechanical power increases with the third power of the wind velocity. The power increases linearly with the cross-sectional area of the (rotor) converter. Even with an ideal airflow and lossless conversion, the ratio of extractable mechanical work to the power contained in the wind is limited to a value of 0.593. When the ideal power coefficient achieves its maximum value cP = 0.593, the wind velocity in the plane of flow of the converter amounts to two thirds of the undisturbed wind velocity and is reduced to one third far behind the (rotor) converter.

The Power Extraction Analysis for Wind Turbines

Classification of Wind Machines The adjectives horizontal or vertical attached to the two major classes of wind machine. This classification refers to the geometrical aspect of the driving shaft on which the rotor/wheel is mounted. An oldtime wooden machine with four sails (a type typified by the term Dutch windmill) is now called a horizontal-axis wind turbine (HAWT). Past usage terms it as a vertical windmill, because the path of a point on a moving blade lies in a vertical plane. A machine with a central vertical axis and a number of straight or bent vanes arranged in a direction more or less parallel to the shaft is today called a vertical-axis wind turbine (VAWT). In past times this was called as a horizontal windmill.

Blade type, Number of Blades and Speed of Rotor Runs at high Speed Used for driving Generators Runs at Low Speed Used for driving Reciprocating Pumps

Speed of A Wind Turbine A rotor rotating at low speed will allow the wind to pass unperturbed through the gaps between the blades. A rotor rotating rapidly will appear as a solid wall to the wind. It is a challenge to design the blades of the rotor to make the rotor to run at an optimal blade speed to angular speed to extract highest power. This ratio is determined by the tangential velocity of the rotor blades in relation to the undisturbed axial airflow, the wind velocity. This is called as the Tip Speed Ratio λ, commonly referenced to the tangential velocity of the rotor blade tip.

My Exposure to Development of A Realtime Turbo-machine IIT Experience Vs Rural Invention…..

Samantara akSha-rekhA Jhal Chakra

Analysis of the Mangal Singh’s Design Diameter of the wheel : 4m. Speed of the wheel: 13 RPM. 24 blades ! Huge Diameter ! Very Low Speed! Weighing more than a ton! Huge material cost! The speed of A common pump or Generator is 1500 RPM. A gear box is required to Increase the speed 120 times! Very costly gear box.

Scientific Model of The Turbine Rp w Re 2j 1D hj, Vj 1A 1C 1B

Minimum Number of Buckets tj : Time taken bye the jet to travel lj tb: Time taken by first bucket to travel y q y Rp Re d hj, Vj lj w For better working tj < tb

Analysis of the Problem Water is falling form a height H, called Head. The velocity of the stream when reaches down most point is: Newton’s Second Law applied for present problem: Any Obstacle, which changes the direction of the stream (of given mass flow rate) will experience a force. If the agent is fixed to a shaft, it can generate a torque. The product of torque and speed of the agent is Power.

The Concept

Blade Geometry Blade Cross Section Kinematics of Blade & Jet Outlet Jet Inlet jet

Proposed Civil Construction Layout

Design of Barrier and Spillway

Scientific Model of The Turbine Rp w Re 2j 1D hj, Vj 1A 1C 1B

The New Design Blades and Assembly

The New Design of Wheel

IIT Delhi Design & Mangal’s Make

IIT Delhi Model

Design II : Krishi Vigyan Kendra ,Jagdishpur, Sonipat 5KW design with 3.7KW Irrigation Pump

Comparative study on development of Micro hydro water wheel $400 $320 $2700 Cost of gear box $170 $160 $1800 Cost of wheel impulse Principle 15 14 24 No. of blades 86%[t] 76%[p] 72%[t] 68%[p] 40%[t] 20%[p] Efficiency 22l/s 22 l/s Pump discharge 450l/s 400l/s 1800l/s Water Consumption run 5kw 6kw Power developed 1 1.5 Head at site in m 1.26 4 Diameter in m New Design II (KVK, Sonipat) Haryana New Design I (Semera Village) Lalitpur,UP Farmer ’ s version Bhailoni Village Specification

Uttaranchal A Land for Traditional Harvest of Hydro Power

Vertical Axis Over Shot Water Wheels Source of power in Rural Uttaranchal

Layouts for Uttaranchal Units : HESCO Penstock Water Wheel Main Shaft Bush Bearing Wooden Base Grinder adjusting lever Grinding Wheel 10” Pulley 12” Pulley Gear Box Generator Canal Forbay New Design

Specification of upgraded wheel for Garwhal area

Intersection of Wind & Blade

The Art of Time Scale Analysis There exist at least two important time scales in any fluid flow problem. Time taken for any given blade to move into the position occupied by its predecessor, tb. Time take for the disturbed wind to re-establish itself to natural state, tw.

The Skill of Group Co-ordination

Capacity Vs Number of Blades For a given efficiency , a wind turbine with large capacity will run at lower speed. What is the lowest RPM (Revolution Per Minute) a single bladed turbine can make without loosing its efficiency drastically? It is 60 RPM or one revolution per second. Why? Because it should sweep whole rotor area in one second. If turbine rotates slower than this, it will miss some air particles and it's output power will be low. However if it rotates faster than one revolution per second it will produce more power which is better. But faster rotating blades create more stresses on overall structure. Therefore one bladed turbine should run at highest possible safe rpm.

Low Speed for Higher Number of Blades A two bladed turbine can run at lower speed with high efficiency. This is because while one blade sweeping one half of the circle area, the other blade is sweeping the other half. By using same analogy a three bladed turbine can run much lower speeds with high efficiency. Low speed turbine increase the cost of electrical equipment. Higher number of large blades will increase wind turbine and civil structure costs. A techno-economically viable option is essential.

An Ultimate Art of Wind Turbine Design

Common Industrial Practice

Performing Under Highly Uncertain Conditions

Instantaneous Direction of Wind Rotor Plane (t) V0