Counter Rotating Vertical Axis Wind Turbine

Project Title

Counter Rotating Vertical Axis Wind Turbine

Project Area of Specialization Mechanical EngineeringProject Summary

With the depletion of non-renewable energy sources coupled with the ever-rising demand for power, the quest for alternate sources of energy has assumed an imperative significance. Wind energy is considered to be amongst the leading sources of renewable energy expected to aid in bridging the supply-demand gap in terms of energy. Despite its high potential and considering that it has been researched upon for a long time, wind energy has failed to completely take over the energy scenario in the country. In order to achieve the full potential of wind energy, it is imperative that innovative solutions are incorporated to the existing knowledge regarding wind turbines. 

The opportunity for innovation in the this highly lucrative market has driven us to propose our solution towards overcoming the shortcomings that restricts wind from becoming the single largest solution in the energy problem. We propose a counter rotating Vertical Axis wind turbine which takes the principle of a conventional vertical axis wind turbine towards the creation of a hybrid system in order to incorporate two turbines in the space of one for maximum extraction from wind energy. 

Project Objectives

A vertical-axis wind turbine (VAWT) is a type of wind turbine where the main rotor shaft is set perpendicular to the wind (but not necessarily vertically) while the main components are located at the base of the turbine. This arrangement allows the generator and gearbox to be located close to the ground, facilitating service and repair. VAWTs do not need to be pointed into the wind, which removes the need for wind-sensing and orientation mechanisms.

There are 2 types of vertical axis wind turbines: The Savonius model and the Darrieus model.

Savonius is a drag-type device, consisting of two or three scoops. Looking down on the rotor from above, a two-scoop machine might resemble the letter "S" in cross-section. Because of the curvature, the scoops experience less drag when moving against the wind than when moving with the wind. The differential drag causes the Savonius turbine to spin.

Darrieus turbines have long, curved wings with each end attached to the top and bottom of the rotor shaft. Another model of the Darrieus turbines has three straight wings connected to the shaft parallelly, forming the “H” shape.

In terms of operation, Darrieus utilizes the “lift” aerodynamic force to rotate. By flowing around the structure, the wind creates a suction on the front side of the turbine, driving the wings to rotate. Because of the shape of the wings, they do not experience as much drag as Savonius turbines do. Once the rotation starts, Darrieus wind turbines are able to accelerate to rotate faster than the wind speed.

Our Objective is to couple both turbines, savonius and darrius,  to get the maximum energy output. the project also aims to test the countr rotating arrangement of the hybrid model which promises better results as compared to the simple co-rotating arrangement aided by the additional turbulence. 

Project Implementation Method

In accordance with the widely used method, the project was initiated by conducting an in-depth literature review aiming to collect alll relevant information and existing knowledge on the subject. This knowledge was essential to achieve a headstart and ensure that lessons were learnt rom previous researches and taken into consideration in the design of our project. On the basis of of the information collected an initial design was proposed which was amended with time to achieve the final design. 

The first design decision in terns of the project was the selection of the airfoil of the blades which was done on the basis of results from Q Blade. Computational fluid dynamics (CFD) analysis was conducted on the selected blde profile which gave us our first simulation results. An iterative process was conducted towrads the finalistaion of the blade design which concluded when the CFD results appeared to fall within the expected range of results. 

Upon the completion of the blade geomety, the design of the structural and power transmission elements was performed which included the inclusion of shafts, bearings, bolts, nuts, pulleys, belts, and the project frame. A CAD model was developed on Solidworks to analyse the model in 3D form.

The structural design was validated by performing a Finite Element Analysis (FEA) on the design to ensure the stresses induced on the structure were within the tolerable limit. Once the design was validated, the fabrrication phase of the project was initiated.

The fabrication was completed by procurement of all the parts and components which was then assembled in phases to complete the final model..

A performance testing plan was then set up to deduce the performance parameters of the project. The plan consisted of tetsing throgh the wind tunnel method in addition to the endurance testing of the model.

Finally, the literature of the project was compiled and performance results were tabulated to compare with the simulation results achieved earlier.  

Benefits of the Project

VAWTs offer a number of advantages over traditional horizontal-axis wind turbines (HAWTs):

• Omni-directional VAWTs may not need to track the wind. This means they don't require a complex mechanism and motors to yaw the rotor and pitch the blades.
• Gearbox replacement and maintenance are simpler and more efficient, because the gearbox is accessible at ground level instead of requiring the operator work hundreds of feet in the air. Motor and gearbox failures generally are significant operation and maintenance considerations.
• Some designs can use screw pile foundations, which reduces the road transport of concrete and the carbon cost of installation. Screw piles can be fully recycled at end of life.
• VAWTs can be installed on HAWT wind farms below the existing HAWTs, supplementing power output.
• VAWTs may operate in conditions unsuitable for HAWTs. For example, the Savonius rotor, which can operate in irregular, slow wind ground-level contexts, is often used in remote or unattended locations although it is the most 'inefficient', drag-type, VAWT

 Among the advantages of a vertical axis Savonius wind turbine are :

• low noise level
•  the ability to operate with low wind speeds and relative independence on the wind direction
• simplicity of maintenance and manufacture of the turbine

The advantages of the Darrieus Wind Turbine include the following.

• The rotor shaft of this turbine is vertical. So it is feasible to situate the load similar to a generator otherwise a centrifugal pump at earth level. When the generator is not turning, then the wire toward the load is not bent & no brushes are necessary for huge twisting angles.
• The rotor receives the wind from each direction.
• Easily arranged in the buildings
• The arrangement of the windmill over a building might be bigger as compared to a horizontal-axis windmill.
• Scalability
• Safety for workers
• Very easy to operate, so they don’t upset people in housing neighborhoods.
• Portable from one place to another.

Technical Details of Final Deliverable

Technical details of our final deliverable are given below;

Turbine Blades( Darrieus):

• NACA 0018 airfoil for darrieus turbine.
• Number of blades; 6
• Material : PVC
• 31.5 in blade length
• Swept diameter: 30 inch
• 1mm thickness

Turbine Blades( Savonius):

• S shaped savonius blade
• Material: PVC
• Length: 26 in 
• Diameter: 10 in

 Bearings:

• Deep groove ball bearings
• Main bearing outer dia: 63mm, inner dia: 25mm
• Small bearing outer dia: 22mm, inner dia: 8mm

 Pulley system:

• 2 pulleys of 9 in diameter

 Shafts specifications:

• Darrieus shaft diameter; 25mm
• Savonius shaft diameter: 8mm

Final Deliverable of the Project Hardware SystemCore Industry Energy Other IndustriesCore Technology OthersOther TechnologiesSustainable Development Goals Affordable and Clean EnergyRequired Resources

Item Name	Type	No. of Units	Per Unit Cost (in Rs)	Total (in Rs)
			Total in (Rs)	48120
Lamination Sheets	Equipment	1	3000	3000
Thread Rod	Equipment	1	2200	2200
PVC Pipe fittings	Equipment	2	2000	4000
Acrylic Sheets	Equipment	2	4000	8000
Silicon Bonding Agent	Equipment	1	220	220
PVC Pipes	Equipment	1	2000	2000
Iron Pipe	Equipment	1	800	800
Main Bearing	Equipment	4	700	2800
Small Bearing	Equipment	2	400	800
Stud Bearing	Equipment	8	200	1600
Nuts and Bolts	Equipment	1	700	700
Wooden support	Equipment	2	1500	3000
Pulleys and Generators	Equipment	2	4500	9000
Logistics and travel	Miscellaneous	1	10000	10000