Capstone Final Report. (1) Adam

FACULTY OF MECHANICAL ENGINEERING

CAPSTONE PROJECT: SMART AIRFOIL BLADE

END OF SEMESTER REPORT

TEAM MEMBERS

Kosi Ndubisi

Adam Jasek

Christian Clavijo

Abhishek Nayaar

Druhmihl Mehta

Luis Varon

TEAM SUPERVISOR

Dr Vesselin Stoilov

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ContentsABSTRACT....................................................................................................................................................3

INTRODUCTION...........................................................................................................................................4

DESIGN METHODOLOGY..............................................................................................................................5

T.S.R (Tip speed Ratio).........................................................................................................................5

SMART TRUSSES..................................................................................................................................6

ACTUATORS.........................................................................................................................................7

SHAPE MEMORY POLYMER (S.M.P).....................................................................................................8

CONNECTORS/JOINTS..........................................................................................................................9

FINAL DESIGN....................................................................................................................................10

SCHEDULED DATE OF COMPLETION..........................................................................................................11

TESTING AND REDESIGNING..............................................................................................................11

BUDGET.............................................................................................................................................13

CONCLUSION.............................................................................................................................................14

REFERENCES..............................................................................................................................................15

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ABSTRACT

The motivation behind this project is to improve the overall efficiency of conventional wind turbines by improving the arms of each turbine with the use of S.M.P (shape memory polymers) to alter the shape of the arms during the different temperature changes and in so doing improve their output efficiency.

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INTRODUCTION

A lot has been done in the field of green energy to design airfoil shapes and turbine blades for

better efficiency and cheaper costs. In this paper one such method is discussed in developing an

airfoil blade that utilizes the uniqueness of the shape memory polymer and smart trusses. The

power output of a wind turbine depends upon its efficiency or power coefficient, the swept

area, the diameter of the turbine blades, and the wind speed. To maximize the power output,

blades with improved efficiency and thus higher power coefficient can be employed. However

this can often be accompanied by increased cost of manufacture and thus negating any

benefits. Larger blades can be used to sweep large area but require more money and

maintenance. The camber of an airfoil is the curve of its upper and lower surfaces. This curve is

measured by how much it departs from the chord of the airfoil. Some airfoils have very little

camber, i.e., the airfoil looks flat, while others have a higher degree of camber—the airfoil has

more curve. When the curve is away from the chord, the camber is said to be positive. When

the curve is toward the chord, the camber is said to be negative. The camber of an airfoil causes

an increase in velocity and a consequent decrease in pressure of the stream of air moving over

it.

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DESIGN METHODOLOGY

T.S.R (Tip speed Ratio)TSR is the ratio of the blade's tip speed to the actual wind speed. We emphasize the word blade because

TSR is applied to lift type turbines, such as a three bladed turbine or Darrius VAWT.

Fig 4.2 Fig 4.3

Fig 4.2 Shows the direction of the tip speed vector in a three dimensional plane i.e. u(x), u(y) and

u(z).

Fig 4.3: Pictured above is a graph showing the power coefficient for different values of tip speed

ratio. As engineers we are aware that efficiency is measured by the ratio of extracted energy

from the wind to the available energy in the wind.

This design will implement an operation at an optimal wind tip speed ratio in order to extract as much

power as possible from the wind stream. Wind tip ratios depend on particular rotor airfoil profile as well

as number of blades used.

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Fig 6.1 Rotor Airfoil Profile

SMART TRUSSESAs a consequence of studying the benefits of variable geometry truss in the field of robotics it is amazing

to see how an individual truss can develop adaptive features by actively controlling the current passed

through linked actuators.

The design consists of smart trusses made of aluminum spokes coupled with actuators, which are hinged

so as to allow free movement in the direction as desired. For example if the actuators near the trailing

edge are made to expand the nearby trusses adapt and lower the tail thereby increasing lift.

6.2 The figure is a 3-d model, showing internal trusses showing the location of actuators marked as yellow axis.

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ACTUATORS

An actuator is a device that converts energy into motion. It also can be used to apply a force. An

actuator typically is a mechanical device that takes energy usually energy that is created by air,

electricity and converts it into some kind of motion. That motion can be in virtually any form, such as

blocking, clamping or ejecting.

In this project piezoelectric actuators will be used. These devices produce a small displacement with a

high force capability when voltage is applied. Some advantages may include precise movement, small

compact size, low energy consumption and quick response. These actuators will be placed strategically

to stipulate maximum displacement across the wingspan using less actuation energy. The choice of

actuators will depend on a full analysis of the drawing and will be made in regards with the stroke i.e.

the amount of displacement the actuator can instigate and size to reduce as much weight as possible.

For this project, we would be utilizing the L12-P linear Actuator which has a horizontal stroke of 30mm

and gear ratio of 100:1. It is also evident that for this project, we will be trying to use as little actuators

as possible to cut down cost seeing as this is where most of the expenses originate.

FIG 7.1 Showing a 1in displacement actuator

SHAPE MEMORY POLYMER (S.M.P)

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Polymers are capable of shape memory effect with basic principle that elevated temperature

deformations caused by applied load can be fixed during cooling. Work performed on the sample is

stored as latent strain energy if the recovery is prohibited by crystallisation, i.e. cooling and fixing. Shape

memory polymers undergoing deformation at higher temperatures, "Retain" the deformed shape when

cooled and return to their original configuration when heated above "Glass transition temperature".

Such types of materials capable of undergoing thermal shape-transition are a division of smart or

intelligent materials. Figure 4.6 depicts the shape memory polymer acting as a “skin” with convex shape,

allowing optimal airflow. A wire mesh is to be sandwiched between two layers of the polymer and

heated to the polymers phase transition temperature, which will then allow the airfoil to take desired

shape, predetermined by the underplaying frame.

Figure 8: Some physical properties of S.M.P

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CONNECTORS/JOINTS

Throughout the design process we had two completed prototypes. Due to simplicity, weight and cost,

we had opted in using the three dimensional, mirrored cross section structure. This design provides a

rigid structure that is capable of enduring repeated forces without fatiguing.

Because the frame needs to be light weight and durable, it will be constructed using 2mm steel spokes

which will be fabricated in a rectangular fashion and properly triangulated to increase its strength. To

allow the actuators to alter the camber of the airfoil, the structure needs to be able to rotate freely

along the z axis, thus a basic pin joint has been designed as shown in the figure below. This design shows

a clear improvement in terms of weight and simplicity compared to the original connector as shown in

Figure 9.1. The Actuators will be connected to the frame using a custom bracket design which will have a

fixed joint at the actuator and a pin joint at the contrasting side.

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e

Figure 9.1: Picture showing the connections between trusses.

FINAL DESIGNThis design here will allow us to modify the geometry of the airfoil by the use of carefully positioned

actuators located along the top side of the structure. With these actuators, we will be able to adjust the

camber and cord length which in turn would alter the lift and drag forces of the wing, improving the

overall aerodynamic efficiency. Shown below is a schematic of what the tail section of the final design

would look like after all parameters have been taken into account.

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Figure 10.1: Schematic of a section of the Arm

SCHEDULED DATE OF COMPLETION

TESTING AND REDESIGNING

After this prototype design has been completed, we would look to see if any improvements could be

made to further increase the efficiency results that will be obtained and also see if it will be feasible to

make a complete turbine with the allocated funds remaining. For the simulation of this design we will be

make use of fluent, Abaqus and Xlfr5 to either compute the computational fluid dynamics or to see what

kind of deflections can be obtained with the use of finite element analysis (F.E.A)

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Figure 11: Benjamin-Goldberg Low Speed Wind Tunnel

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Figure 12: Project completion timeline.

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BUDGETShown below is the final budget for the completion of this project.

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CONCLUSIONThis report discusses the current progress achieved through the first month of the design phase of the

smart airfoil blade. It has also outlined the design methods and implementation stages involved in the

completion of airfoil blade prototype. The fundamentals and knowledge gained have been documented

in this report over the course of the first four months. The second four months of the design phase is

when the extensive construction and testing of the prototype then begins and the final report, with

calculations will include our final observations and room for improvements to be made.

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REFERENCES

[1] Journal of intelligent material systems and structures. Justin K. Strelec, Dimitris C. Lagoudas,

Mohammad A. Khan, John Yen. Design and Implementation of a Shape Memory Alloy Actuated

Reconfigurable Airfoil. From: http://jim.sagepub.com/content/14/4-5/257.short.

[2] Yunus A. Cengel. Heat and Mass Transfer: A Practical Approach Mc Graw Hill series.

[3] "Aeronautics - Principles of Flight - Level 2." Aeronautics Learning Laboratory for Science Technology,

and Research (ALLSTAR) Network. Web. 23 Feb. 2012. <http://www.allstar.fiu.edu/aero/flight30.htm>.

[4] R.N. Sharma and U. Madawala, The Concept of a Smart Wind Turbine System, Renewable Energy

v.39, pp.403-410, 2012.

[5] Andreas Lendlein and Steffen Kelch, Shape-Memory Polymers, Angewandte Chemie International

Edition, v. 41, Issue 12, pp. 2034-2057, 2002.

[6] Michael D. Skillen and William A. Crossley. “Modeling and Optimization for Morphing Wing Concept

Generation. “NASA/CR-2007-214860”.

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