Variable Pitch Turbine ( A Sneak Peek)

Introduction

Small scale wind turbines are used to generate supplementary electricity for a range of applications and environments. Small scale wind turbines have several design considerations for improving power output as a function of modifying blade aerodynamics. Manipulating blade pitch as a function of speed and rotor speed can produce optimal angles of attack. Producing an optimal angle of attack for a given wind speed and rotor speed increases power output over a greater range of wind speeds. The objective of this project is to design and analysis a wind turbine rotor that self-optimizes the pitch angle of its blades, achieving maximum conversion efficiency from wind to electricity over the range of operating wind speeds. The Variable Pitch Rotor team is developing a new variable pitch rotor to be retrofitted on a 300 W Air Breeze small-scale wind turbine. The new variable pitch rotor self optimizes the pitch angle passively by using centripetal force to pitch the blades as a function of the rotor speed. In order to prevent damage from high rotational speeds, a fixed pitch turbine must reduce speed considerably or shut down. Variable pitch turbines offer a solution to both these problems. A variable pitch design adjusts to an optimal blade pitch in order to continuously maintain an optimum aerodynamic efficiency through angle of attack. The result is more efficient generation of power across a wider range of wind speeds, including speeds that would be undesirable to a fixed pitch turbine

Design Requirements

The following design requirements are made to verify the performance of the new variable pitch rotor turbine:

•  The new design must demonstrate an increased power output over the wind speed range of 4-7 m/s. 
• The blades should be able to pitch a total of 15° at a minimum rate of 3° per second (VP Turbines, 2010). 
• The mechanism must be able to operate in typical weather conditions, and be waterproof.

Design Analysis

1. Shaft Assembly

Blade bending moments are present and are designated as either flapwise moment or edgewise moment The flapwise bending moment will cause the blades to bend downwind. Edgewise moments are parallel to the rotor axis and give rise to the power-producing torque. In addition, torque due to the wind on the blades is also present

    

Conclusion

We conclude that this system can be used for practical applications. It is observed that though the power output is low over a designated wind speed but as the wind speed increases the power generated by the rotor increases and efficiency increases on increasing of the angle of attack. It is a safe, simple but expensive system to be fabricated it out. It is pollution free and low maintenance is required if it is install. This could prove to be the solution for the current energy crisis. . 

CAM operated Luggage Lifter

INTRODUCTION:

CAM one of the only mechanisms i have never seen before i actually encountered it in the kinematics textbook in my 4th Semester fascinated me and I promised myself that i would do a project with this mechanism and thus born out of this promise is this project which attempts to fabricate a innovative luggage lifting mechanism using multiple CAM's.

A cam is a rotating or sliding piece in a mechanical linkage used especially in transforming rotary motion into linear motion or vice-versa.
It is often a part of a rotating wheel (e.g. an eccentric wheel) or shaft (e.g. a cylinder with an irregular shape) that strikes a lever at one or more points on its circular path. The cam can be a simple tooth, as is used to deliver pulses of power to a steam hammer, for example, or an eccentric disc or other shape that produces a smooth reciprocating (back and forth) motion in the follower, which is a lever making contact with the cam

Fig  2 : Working of a CAM

PROJECT SUMMARY

• Cam Mechanism is studied and a suitable model is designed.
• The material to be chosen such that it can carry optimal load, cost is less and strength and fatigue life is more.
• The components are first machined and mechanically tested for fatigue and strength in strength of machinery lab for different components.
• The load that can be carried by the lift is determined.
• The model is done manufactured and tested for application.
• The observed readings are then submitted along with the model.



MATERIALS USED

Fig 3 : Materials Used

TESTING OF MATERIALS

The following tests were done in order to determine the suitable material to be used for the various parts of the cam.

• Izod Impact Test of MS Square rods

• Tensile test for MS rods using UTM

• Tensile test for Aluminium rods using UTM

•Izod Test of the Square rods

• These square rods are used to support the structure of our project.

• We tested the hardness of these rods in different sizes and lengths using Rockwell Hardness test.

• The results are as following:

Sample 1: the hardness in different places are 33, 28, 27 HRC
Sample 2: the harnesses are 33, 32, 35 HRC
Sample 3: The harnesses are 30, 19, 20 HRC
• The lengths of the sample square rods are 75x10 mm

Fig 4 : Square Rod after IZOD test

TENSILE test – Aluminium

TENSILE test – Mild Steel

TESTING OF MATERIALS CONCLUSION

Thus it was concluded that

1. Mild steel was a better choice for making the roller follower as :
 It could withstand higher loads
 The tensile test showed that it had higher tensile strength
 It was cheaper and easier to get in the market

2. The Mild Steel Rods could withstand high impacts without breaking hence it was to be used in the making of the cam rod. A square rod is chosen so that the drilling of the holes is easier. The rods were found to be more ductile and less brittle thus preventing a complete breakdown of the cam at higher loads.

Fig 5 : Tensile Test Specimens

MANUFACTURING PROCEDURE

The manufacturing Process can be divided into the following sections

• Frame
• CAMs
• Roller Followers
• Crank rod
• Wooden blocks
• Assembly


FRAME :

1. The Hollow GI Rectangular tubes were cut as follows :
25 cms-1no
75cms -2nos
50cms-2nos

2. Holes of diameter 13mm were drilled with their centres 40 mm apart on the 25 cm tube and holes of 15 mm diameter were drilled 9cms from one edge of the 75cm tubes.

3. The 75 and 50 cm rods were welded together to form two T – Shaped Structures.

4. The T-Shaped Were then Welded together with the 25 cm rod in between.

Fig 6 : Frame in two different views

CAMs :

1. The GI Hollow Circular Pipe was cut 5 into cylinders of 35 mm height

2. A 6mm hole was drilled 10 mm from one edge of the cylinder

3. This process is was repeated for all cylinders

4. The nut and bolt were checked with the drilled holes

Fig 7 : (top) A Single CAM with a nut and bolt

(right) CAMs with nuts and bolts

Crank Rod :

1. The Solid Rectangular MS rods were into 25 cm, 5cm , 5cm rods

2. Holes of diameter 6mm were 40 mm apart on the 25 cm rod

3. The rods were then welded together as shown in the figure

Fig 8 : Crank Rod

Roller Followers :

1. The Mild steel Circular rods were welded with the bearings in such a way that the centre of the bearings were fixed to the rods while the outer wheel was freely rotating

2. The follower edge was then grinded so that the mild steel rod will not touch the cams

3. The bearings were lubricated for free movement

Fig 9 : Roller Followers

Wooden Blocks :

• The wooden blocks were cut into 30x40x150 mm blocks

• 12 mm holes were drilled in the center of the base with varying depths of 2,3,4,5,6 cms.

• The blocks were then sanded and checked with the follower rods for goodness of fit

Assembly :

• The individual parts made were then assembled and lubricated for free movement

• The working of the cam was then checked

• Any problems encountered were noted and fixed



Problems Faced and Sources of error

• The holes were not of uniform diameter and improper allignment initially which resulted in the jamming of the cam
• Welding without compromising on the alignment of the frame was difficult
• Weld heat would melt the rods when too much current was given to the weld in arc welding
• The bearing expanded on fast welding which stopped its rotary motion
• The cam pipes got deformed when held in the bench wise for cutting if held too tight.
• The cam pipes cut were not cut perfectly cylindrical if the bench wise was too loose.
• The follower rods were not of uniform orientation during the rotation of the cam mechanism.

Scope for improvement

• The crank rod can be replaced with a cylindrical rod to reduce friction and easier movement. (if we can drill holes in cylindrical rods)
• Grooving on the cam will help the roller follower maintain its path.
• A motor attached to the crank rod can help in applications in real life as perhaps a luggage carrier or an alternative for conveyor belt mechanism.

CONCLUSION

CAM mechanism was studied and was applied to make a luggage carrier model. The parts were tested for the required strength based on which a suitable material was chosen. The components were machined and welded to form the parts of the CAM model. Welding, machining concepts were studied and used accordingly. The CAM was then assembled and its working was tested and studied. Real time application of model was also researched.

Design of a Hydraulic Press

INTRODUCTION

Hydraulic machines had continued to fascinate me in the third semester and when i was given the oppurtunity to do a design project i pounced at the opportunity to do a hydraulic press

           

Background:

A hydraulic press is a machine using a hydraulic cylinder to generate a compressive force. It uses the hydraulic equivalent of a mechanical lever, and was also known as a Bramah press after the inventor, Joseph Bramah, of England.

Different types of Hydraulic presses are:

1. .      Deep Drawing Press- a flexible press used for advanced deep drawing.
2. .      Blanking Press– a press range for blanking,forming and coining operations, in fully automatic design.
3. .      Multi-Purpose Press-a versatile press for various forming operations.
4. .      Large Bed Press – a Press specially designed for forming of large components.
5. .      Hydroforming Press – forming of tube and sheet parts with the aid of fluid subjected to high pressure.
6. .      Transfer Press–a  compact, modular based press for complete production lines.

Product

The Hydraulic Press is an apparatus designed, built, and used for forging metal. This press was designed to be versatile and capable of producing up to 250 ton of force.

Model

The hydraulic press C250 is shown in Figure 1, ref 1.

LITERATURE STUDY

The Working Principle:

A hydraulic press is a machine that uses pressurized liquid to create force. These machines are composed of a simple cylinder and piston mechanism. The press consists of a large cylinder, with a large piston, and a small cylinder and a small piston. The large cylinder and the small cylinder are connected to one another by means of a pipe. The two cylinders, and the pipe connecting them, are filled with a liquid. At this point, the function of the hydraulic press depends on Pascal's Principle.Pascal's Principle states that when pressure is added to a liquid at rest, there is an identical increase in pressure at all points. Applying this principle to the hydraulic press means that any force that is added to the piston in the smaller cylinder will be transferred to the piston in the larger cylinder, in a proportionally increased level of force. This allows a hydraulic press to produce a great deal of force from the application of a small amount of force to the small piston.

As air enters the booster cylinder, oil is displaced in the hydraulic cylinder above. The displaced oil enters the ram cylinder and drives the ram down. Pressure is maintained throughout the entire stroke. When the valve is de-energized, the ram retracts to its home position.


Advantages:

Advantages of Hydraulic Press over a mechanical press:-

1.  Full power stroke  
2. Built-in overload protection  
3. Much lower original cost and operating costs  
4. Larger capacities at lower cost  
5. More control flexibility 
6. Greater versatility - A single hydraulic press can do a wide variety of jobs within its tonnage range. Commonly seen are deep draws, shell reductions, urethane bulging, forming, blank and pierce, stake, punch, press fits, straightening, and assembly. They are also used for powered metal forming, abrasive wheel forming, bonding, broaching, ball sizing, plastic and rubber compression, and transfer molding. 
7. Quiet  
8. More compact  
9. Lower tool costs  
10. Safety - No manufacturer will (or should) claim that hydraulic presses are safer than mechanical presses. Both types of machines are designed and built to be safe if the controls and safety features built in are used properly.
11. Less Heat.

Improperly used, all machines are potentially dangerous. But the factor of control of the ram movements makes hydraulic presses easy to make safe. Non-tie down, anti-repeat, dual palm button controls are used. The interlocking of guards, as well as other safety devices, is relatively easy because of the nature of a hydraulic press control system.

Isometric view of Hydraulic Press (Fig B):

Exploded view of Hydraulic Press (Fig E):

DETAILING AND MANUFACTURING INFORMATION

The various parts that were created for making the Hydraulic Press along with their manufacturing information are as follows.

1.      Base (Fig 1.1 and Fig 1.2): A base is a structural system that supports other components of a physical construction. It  is a building technique based around vertical structural members, usually called studs, which provide a stable frame to which interior and exterior wall coverings are attached. It is made of cast iron.

2. Piston (Fig 1.3): A piston is a component whose purpose is to transfer force from ‘pushed fluid’ in the cylinder to the crankshaft via a piston rod and/or connecting rod ; made of mild steel or cast iron.

     3.Ram (Fig1.4 and Fig 1.5):- It is the component which is used to apply pressure on the die ;usually made of cast iron or galvanised iron

     4.Clamps (Fig1.6):-They are used to provide rigid support to the pipes both in lateral and longitudinal directions, thus relieving stresses caused by unequal movements in the pipe line ; thus made of cast iron or Aluminium.

      5.Cylinders (Fig1.7):-It contains  the fluid, so is made of a rigid and insulating material like composite material.

7.Nuts(Fig1.9):- A nut is a type of fastener with a threaded hole. Nuts are graded with strength ratings compatible with their respective bolts; for example, an ISO property class 10 nut will be able to support the bolt proof strength load of an ISO property class 10.9 bolt without stripping. Likewise, an SAE class 5 nut can support the proof load of an SAE class 5 bolt, and so on. Nuts are made of mild steel.

       9.Pressure Gauge(Fig2.0):- It is used to measure pressure of the fluid. It is an external device.

METHODOLOGY

The Hydraulic Press was modelled using the drafting and modelling software ‘SolidWorks 2012 x64 edition’.

The whole project involves phases namely part modelling of the components of ‘Hydraulic Press’ followed by assembling them. Finally, 2-D drafting of the components was done.

Various tools included in the software which were used while modelling the components were ‘Revolve Base’, ‘Extrude Base’, ’Extrude Cut’, ’Circular Pattern’, ‘Hole Wizard’,

Angular Extrudes were made using tools like ‘Reference Geometry’

Basic motion analysis was done in solid works and animation wizard in Inventor Autodesk.

Conclusion

We were able to understand the structural and functional details of a C-250 similar Hydraulic Press and express it successfully as a SolidWorks project (along with motion analysis).In this process, the manufacturing details of various parts have also been seen.

             Thus, this project has helped to enhance our hands-on interface with the software.

Wooden Air Engine

1. INTRODUCTION

Air engine is a type of motor which does mechanical work by expanding compressed air. Pneumatic motors generally convert the compressed air to mechanical work through either linear or rotary motion. It has existed in many forms over the past two centuries, ranging in size from hand held turbines to engines of up to several hundred horsepower. Some types rely on pistons and cylinders, others use turbines. Many compressed air engines improve their performance by heating the incoming air, or the engine itself. Pneumatic motors have found widespread success in the hand-held tool industry and continual attempts are being made to expand their use to the transportation industry. However, pneumatic motors must overcome inefficiencies before being seen as a viable option in the transportation industry.

2. MATERIAL USED

S. No.	Item	Specifications
1	PLYWOOD	2 metre x .60 m x.10 m
2	ROSE WOOD	.60 m x .20 m x .30m
3	FEVICOL	200 ml
4	SUPER GLUE	10 ml
5	SCREWS	1 INCH-10 Nos
6	Nails	I INCH -1O Nos.

3. FABRICATION PROCESS

1.     CUTTING OF PARTS

Following Parts are prepared using carpenting BOSCH tools like jig-saw.sander,roter etc:

·         Flywheel                                      • Piston rod

·         Control rod

·         Crankshaft

·         Piston Housing

·         Bearing block

·         Cylinder mount

2.     ASSEMBLY OF PARTS

·        We assembled the piston housing using wood screw , super-glue and fevicol.

·        The valve slider was connected to crankshaft such that the control rod moves freely.

·        Fix the bearing block onto the base as per requirement.

·        Then ,we connect the flywheel to the crankshaft such that flywheel rotates with the crankshaft.

·        The connecting arm was attached to the piston such that it moves freely and other arm was connected periphery of the flywheel such that piston moves connecting arm rotates the flywheel.

·        Piston housing was mounted on the cylinder mount and cylinder mount was nailed on the base.

·        The bearing block was closed such that crankshaft was placed between two bearing block and crankshaft axis passing through the holes in the bearing blocks.