wind turbine design report

7/30/2019 Wind Turbine Design Report

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The Pennsylvania State University

Department of Mechanical and Nuclear Engineering

Wind Power Generator Project Proposal

Jonathan Matteson

Joseph Manginelli

Jeff Irwin


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Table of ContentsExecutive Summary (Joseph Manginelli) .................................................................................................... 43

Problem Statement (Joseph Manginelli) .................................................................................................... 43

Project Objectives (Jeff Irwin) ..................................................................................................................... 43

Customer Needs (Jeff Irwin) ....................................................................................................................... 54

Design Process Summary (Jonathan Matteson) ......................................................................................... 54

Design Concepts .......................................................................................................................................... 76

Design Concept 1 (Jonathan Matteson) .................................................................................................. 76

Design Concept 2 (Jonathan Matteson) .................................................................................................. 87

Design Concept 4 (Jeff Irwin) .................................................................................................................. 98

Design Concept 5 (Joseph Manginelli) .................................................................................................. 109 CAD Drawing of Wind Turbine (Jonathan Matteson) ............................................................................. 1110

Design Specifications (Joseph Manginelli) .............................................................................................. 1412

Summary of Analysis (Jeff Irwin) ............................................................................................................. 1412

Discussion For Teachers (Joseph Manginelli) ......................................................................................... 1614

Project Management Plan (Jonathan Matteson) .................................................................................... 1715

Fabrication Process: (Jonathan Matteson) ............................................................................................. 1816

Testing Results and Design Revisions (Jeff Irwin) ................................................................................... 1917

Budget and Materials (Jeff Irwin)............................................................................................................ 2018

Team Reflection: (Jonathan Matteson) .................................................................................................. 2220

Appendix A: Gantt Charts ....................................................................................................................... 2321

Appendix C: Design Specifications .......................................................................................................... 2623

Executive Summary (Joseph Manginelli) ...................................................................................................... 3

Problem Statement (Joseph Manginelli) ...................................................................................................... 3

Project Objectives (Jeff Irwin) ....................................................................................................................... 3

Customer Needs (Jeff Irwin) ......................................................................................................................... 4

Design Process Summary (Jonathan Matteson) ........................................................................................... 4

Design Concepts ............................................................................................................................................ 6

Design Concept 1 (Jonathan Matteson) .................................................................................................... 6

Design Concept 2 (Jonathan Matteson) .................................................................................................... 7

Design Concept 4 (Jeff Irwin) .................................................................................................................... 8

Design Concept 5 (Joseph Manginelli) .................................................................................................. 910

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CAD Drawing of Wind Turbine (Jonathan Matteson) ............................................................................. 1112

Design Specifications (Joseph Manginelli) .............................................................................................. 1112

Summary of Analysis (Jeff Irwin) ............................................................................................................. 1213

Discussion For Teachers (Joseph Manginelli) ......................................................................................... 1415

Project Management Plan (Jonathan Matteson) ...................................................................................... 910

Fabrication Process: (Jonathan Matteson) ............................................................................................. 1516

Testing Results and Design Revisions (Jeff Irwin) 1617

Appendix A: Gantt Charts ....................................................................................................................... 1718

Appendix B: Bill of Materials ................................................................................................................... 1920

Appendix C: Design Specifications .......................................................................................................... 2021

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Executive Summary (Joseph Manginelli) The contents of this report include the project proposal and design process by Group 58 of ME 340 forthe development of a Teaching Teachers Engineering (TTE) wind turbine kit. The group was challengedto produce a working model of a TTE kit within 7 weeks and on a budget of $100. In order to determinethe customer needs for the TTE kit, section 5 of ME 340 interviewed Susan Stewart of the AerospaceEngineering and Architectural Engineering Departments. In addition to staying within the budget, theprimary drivers for the design were reusability, ease of assembly, stability of the base and variability interms of what the user can change on the kit. The quality of blade design in terms of the power outputof the turbine was also important.

Through internal and external research, a final design was chosen that satisfied the primary drivers mosteffectively. The TTE kit is meant to be used with a box fan which creates a swirling wind which doesnot move in directions completely perpendicular to the fan assembly. . Blades, which can be set at anyangle thanks to the hub design, catch the wind and rotate the fans shaft, which in turn causes the entiregear assembly and the generators shaft to rotate. Two banana plug receivers are connected to thegenerator so that a multi-meter can take any necessary measurements. The wind turbine allows foreasy assembly and repair due to its use of standard components and lack of permanent connectionssuch as welds and press-fits. The cost for this turbine was approximately $50.

Problem Statement (Joseph Manginelli) Group 58 was challenged to design, construct and test a table-top windmill kit that will be used inteacher workshops. The goal of these workshops is to prepare teachers to get their students interestedin wind energy and allow them to learn about it as well. The kit must be able to be used by youngstudents and must fit in a small container. The TTE kit must be able to operate in winds up to 20 mph. Itwas originally requested that the turbine be self-aligning, but it must only be able to handle winds from

a head-on direction. This removed a significant degree of difficulty from the design because it does nothave to be self-aligning.

Project Objectives (Jeff Irwin) Our teams objective for this project is to design, construct and test a table-top windmill kit that will beused in teacher workshops. The kit will:

cost less than $100 be aesthetically pleasing perform as efficiently as possible be durable and require minimum maintenance have educational value

be easy to repeatedly assemble and disassemble be safe be compact allow for creativity and fun

Comment [TAL1]: you can drop the prnow.

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After making improvements to this design, we will construct a functional beta prototype by the end of the

project to be tested against other student prototypes. If our teams design is judged to be the best in theclass, then we will advance to the Learning Factory Showcase.

Customer Needs (Jeff Irwin) The team was able to interview Dr. Stewart, who works with the Pennsylvania Wind for SchoolsProgram, which currently uses KidWind kits. Dr. Stewart had several recommendations. First, KidWindkits only allow voltage to be measured, not power as in the real world. Second, a set of instructionswould be helpful, especially for the multimeter which has caused confusion in the past. Third, studentsand teachers should be able to design and make their own blades for the kit. Finally, a gear box whichallows for changing of gear ratios would be interesting.

The team was also provided a number of evaluation criteria and design constraints by Dr. Litzinger.These criteria included cost, aesthetics, performance, durability, educational value, ease of assembly/disassembly, safety, compactness, and creativity/fun. Additionally, the product wasconstrained to ideally be assembled without tools and to contain at least one part made by rapidprototyping or water jet.

From the information provided by Dr. Stewart and Dr. Litzinger, we concluded that the followingcustomer needs must be satisfied:

kit needs to include instructions/lesson plan kit needs to allow measurement of voltage and power kit needs to include a base and allow for interchangeable blades kit needs to fit inside an 11.5 in 6 in 4 in container kit needs to be assembled with no tools repeatedly kit needs to be educational for children of age 8 14 years kit needs to operate in varying wind speeds up to 20 mph kit needs to operate untended kit needs to include standard interface for test instrumentation kit needs to use permanent magnet DC motor for generator kit needs to include at least one part fabricated by FDM, water jet, CNC, or casting methods kit needs to cost less than $100

Design Process Summary (Jonathan Matteson) After the team met with Dr. Stewart to develop customer needs ;, the team moved on developingvarious different design concepts. The team held meetings in order to get everyone on the same page.In these meetings, it was discussed what component would be rapid prototyped, what materials wouldbe consider for building the turbine, as well as any initial turbine ideas. The team went to 23 Reber in

order to get a sense of what materials were available to use and what materials might need to beordered. The next step was for each team member to develop two different designs and share themwith all team members.


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Once all group members had seen each design, a Selection Matrix was used in order to narrow the

design ideas. The matrix, presented in Table 1, incorporates the following selection criteria determinedto be most critical: size, reusability, assembled without tools, ease of assembly, allows for multiple gearratios, and structural stability. After scoring completed by all team members, it was decided to continueworking on designs #1 and #6. The two designs were analyzed, and modified in order to come up with adesign everyone agreed on.

Table 1: Selection Matrix:

Design Number

Selection Criteria: 1 2 3 4 5 6

Unassembled Size 0 + 0 0 + 0

Reusability 0 - 0 0 - 0Assembled without tools 0 0 0 0 0 0Ease of Assembly 0 - 0 0 - 0Allows for multiple gear ratios 0 - 0 - - 0Structure Stability 0 0 - - 0 0

Plus 0 1 0 0 1 0Minus 0 3 1 2 3 0

Same 6 1 5 4 2 6Net 0 -2 -1 -2 -2 0

Rank 1 3 2 3 3 1Continue ? yes no no no no yes

All team members took part in external search efforts in order to generate their design concepts. Thewebsite http://learn.kidwind.org/ was used , which was suggested by Dr. Stewart, in order to get ageneral sense of what one of these wind ki ts typically entailed. The team explored the site and foundsome videos depicting different designs of wind turbines. The hub design idea was developed from afew of the designs found on this website. The design allows for easy addition of blades, as well as theflexibility to change blade pitches and number of blades very easily. Multiple Google searches on windturbine kits provided a number of ideas for gear box designs. Several designs were found that allowedfor a variety different gear sizes to be used, and this inspired some of our design concepts to allow fordifferent gears to be used when testing the turbine. All team members used online parts catalogs inorder to research different parts that could be used to construct the turbine. Sites such aswww.jameco.com and www.mcmaster.com were used for this purpose. When selecting the bearings touse there was extensive search done in order to pick the correct bearing for this application. Since no

team member was familiar with self-lubricating sleeve bearings, the team did some research online inorder to see if they would balancemitigate thrust from the shaft. After watching videos and looking attechnical drawings online the team determined that ball bearings would be more suitable for thisapplication.

Comment [TAL2]: balance

Comment [TAL3]: Nice work!
http://learn.kidwind.org/http://learn.kidwind.org/http://www.jameco.com/http://www.jameco.com/http://www.mcmaster.com/http://www.mcmaster.com/http://www.mcmaster.com/http://www.mcmaster.com/http://www.jameco.com/http://learn.kidwind.org/


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Design ConceptsEach design Concept doesnt None of the design concepts take into consideration any blade designsbecause they will be designed by the students. These designs allow for students to create their ownblade designs, change the number of blades, as well as change blade pitch. Teachers can make it into acompetition to see which turbine will generate the most power. By plugging a multi-meter into thebanana plug jacks , power can be measured to you can determine which turbine generates the mostpoweris the best .

Design Concept 1 (Jonathan Matteson)

This design incorporates a base made from PVC pipe and connecting T-joints. It is assembled into asquare geometry with one tower leading up to the gear box. The gear box is made from two machinedaluminum platforms held together using bolts and wing nuts. The gear box is bracketed onto the PVCpipe. The generator is bracketed onto the bottom plate. The hub is rapid prototyped and is connected a

metal shaft supported by two bearings. The shaft is then connected to the generator using a system of gears. This design does not take into account the blade designs because this will be up to the student todesign.

Comment [TAL4]: don't switch personpower can be measured to determine ....


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One advantage of this design is that everything is fastened together using bolts and wing nuts, this

allows the entire turbine to be assembled by hand. It features an adjustable gear box so that thestudents can raise or lower the top platform to experiment with different gear ratios. The hub isdesigned to allow students to experiment with different blade angles and number of blades.

Design Concept 2 (Jonathan Matteson)

This design features a base made entirely from PVC pie and connecting T-joints. This base features twolegs for stability, as well as a tower that connects to the shaft casing. The shaft itself sits in a piece of PVC pipe, attached to the base using a T-joint. The shaft is supported by two bearings glued into the PVC


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pipe, and features the same rapid prototyped hub as in design #1. The other end of the shaft connects

to the gearing that transfers power to the generator. The generator is zip-tied to the PVC piping andwire leads go to the banana plug jacks

Design Concept 4 (Jeff Irwin)

This design features a rapid-prototyped hub, with two halves held together by washers and wing nuts ona shaft threaded on one end. The other end of the shaft is machined to a 3 mm diameter to fit thegear. The shaft passes through two flange-mounted bearings which are attached to two aluminumplates. The plates are held together by bolts and wing nuts. The gear connected to the shaft drives aworm gear which is connected to the generator, which is clamped to one of the plates. The entiresystem is clamped to a base made of PVC pipes.


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Design Concept 5 (Joseph Manginelli)

This design very much resembles Concept 1. The gear box is identical in that is uses the same concept of two aluminum plates to be used as platforms that can be raised and lowered so that gears can bealigned if multiple gears were available. The hub is also rapid prototyped, but only has 6 slots for fanblades as opposed to twelve. The only significant difference is the base design. The base is more table-like, with a half-section cut out of two ends of the PVC pipe so that the gear box can sit neatly on a flatsurface.

This design allows for some more security in terms of tipping. Compared to a vertical tower base, thisdesign minimizes some of the moment that is caused by the force of the wind on the system becausethere is no vertical shaft that rotates freely. However, this design does not take into account the methodwhich the height can be adjusted so that the blades are not hitting the ground. There is also no stabilitybetween the two table legs to prevent them from slipping out from underneath the gear box. It mayalso prove to be too large to fit into our container.

Comment [TAL5]: I can't quite see thisdesign?


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CAD Drawing of Wind Turbine (Jonathan Matteson)

Full Model

Comment [TAL6]: You need to have sodiscussion of your model, which looks goodway. You should discuss key features of the

You should include the drawings for your hualso detailed drawings to show your bearingarrangement as well as your gears.


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The Solidworks drawing showed above is the complete representation of Team 58s wind turbine. Thedesign above is the final design concept as members would envision it. The model consists of severalcomponents. There is the base made from 7 sections of PVC piping and 3 T-joints. There are the gearbox plates, on which the generator, gearing, shaft, and bearings are mounted. There is also the hubdesign into which there is the option of inserting 12 blades.

Gear Box Assembly


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Depicted above is a representation of the gear box assembly for this wind turbine. Here there are twoaluminum plates that slide up and down on four 3 bolts. The reason they slide up and down is to allowfor different sized gears to be experimented with. For larger gears on the shaft or generator the topplate can be adjusted upwards in order to provide for appropriate gear meshing. Other features visiblein this picture are the generator, which is mounted to the bottom gear box plate. The banana plug jackscan also be seen mounted to the bottom gear box plate. Mounted to the top plate are the two bearings,which allow the shaft to spin level and with minimum friction.

Hub Design

Banana Plug Jack

Motor andMount

Pinion

GearBearing

Shaft

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Depicted above is the hub designed in Solidworks. This hub design was taken to the Learning Factory

where it was rapid prototyped into an actual part. The picture above only depicts half of the part, sothat the inside is visible, in reality this part is two identical halves that close together in order to securethe created blades. This design has 12 identical slots for a dowel rod to be inserted into. Anotherunique feature of this design is the ridges, which can be seen in each of the 12 holes. These ridges havebeen incorporated in order to help grab the blades so that they wont fly out of the hub when theturbine spins.

Design Specifications (Joseph Manginelli )The team established design specifications based upon the performance of our alpha-prototype and thecustomer needs statements , which we formed earlier in the design process. The performance

specifications are baselines for the final design. The final model should either equal or surpass itspredecessor in most categories. A complete bill of materials and list of specifications can be found inAppendix B and Appendix C, respectively.

The customer needs statements which we focused on the facts that the TTE kit has to be small enoughto fit our container and that assembly must be easy and uncomplicated. Focusing on the fact that theentire kit has to fit into a box 11.5x6x4, we were able to construct a base that is wide enough toprovide stability while still small enough to fit into the container. We chose to make the base out of PVCpiping because it was easy to manipulate and also light enough for teacher to transport withoutdifficulty.

Focusing on the idea of ease of manufacturing, we chose to create a gear box which that utilized justlong spade-head bolts and wing nuts. Choosing to go with wing nuts over the conventional hex nut

allows the user to make alterations and repairs without the use of hand tools. We also chose to create agear box which that utilizes pre-bracketed ball bearings and a bracket for our engine. Compared to adesign which has a permanently mounted engine and press-fitted bearings, our design allows for botheasier replacement and less repair time if either the bearings or engine were to fail.

Summary of Analysis (Jeff Irwin) One of the objectives of this project is for the kit turbine to perform as efficiently as possible. Asidefrom minimizing frictional losses in the bearings and gears, the only components which that affectefficiency are the blades, motor/generator, and gear ratioEfficiency can be improved by minimizingfrictional losses in the bearings and gears, changing the blade design, using a different motor/generator,and changing the gear ratio . The key blade variables affecting efficiency are:

N = number of bladesRt = tip radiusRi = inner radius

Comment [TAL7]: Small and importanthat it should be in the main report.

Comment [TAL8]: This is not a senten

Comment [TAL9]: A nice find!

Comment [TAL10]: turbine built from

Comment [TAL11]: but what you list, generator, gear box is pretty much the entireturbine?

Comment [TAL12]: gear ratio is not acomponent, the gearbox is.


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= blade pitch

w = chord (width of blade)

Angle of attack is also important , but. Tt his variable is dependent on wind speed, angular velocity,radius, and blade pitch. An angle of attach of 10 provides a good balance of lift coefficient and dragcoefficient. For our analysis, we make the following assumptions:

Rt = 0.235 m

U = 4.2 m/s (incoming wind speed)

= 20.9 rad/s = 200 rpm (angular velocity)a = 0.2 (axial induction factora = 0 (tangential induction factor)

Blade Element Velocities and Forces

p. 59 Wind Turbine Handbook

From geometry in the above figure:

Substituting the values of the variables and taking r = 0.1 125 m (half radius), we find = 54.42.1 .Again, from geometry:

Substituting the ideal angle of attack = 10, we find = 44.442.1 . Ideally, would vary with along theradius of the blade to keep constant. However, this is not practical with cardboard blades. Thus, ourblades have a constant pitch of around 42.145 , which results in an angle of attack less than 10 at thetip, and greater than 10 at the inner radius.

Comment [TAL13]: why but?

Formatted: Keep with next

Comment [TAL14]: Should provide a for this figure.

Comment [TAL15]: 42.1 degrees is noapproximate, 40 degrees is.


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After blades, the next components to consider are the motor and gear ratio.

Motor Specifications

We chose this motor because it had the angular velocityrotational speed at maximum efficiency closestto what our prototype was outputtingproducing . This way, we can keep the gear ratio as low aspossible. From the motor specifications shown above, the angular velocity needed for maximum motorefficiency is 2180 rpm. For a blade angular velocity of 200 rpm, this gives an ideal gear ratio of 2180/200

11. The smallest gear available has 10 teeth, while the largest has 50 teeth. Thus, the closest of thepossible ratios to the ideal ratio of 11 is 5.

Discussion For Teachers ( Joseph Manginelli )Everyone is familiar with the concept of energy in some shape or form. In its most raw understanding,energy is something that is needed to perform an action. Therefore, everything we do is somehowrelated to energy. When we make toast in the morning, we are using thermal energy. When we throw aball, we are using mechanical energy. And even as you are reading this sentence, you are using someenergy. But when it comes to providing energy to perform these actions, we may not know how thatenergy is created. We all know that toasters run on electricity, but the secret is how that electricity iscreated. While there are many ways to create it, for our sake we will only analyze the wind turbine.

Use of Ww ind turbines are is a growing trend in the world. They can be built on land and or anchored atsea, and use a virtually untapped source of energy: wind. A wind turbine takes wind energy andconverts it into electrical potentialenergy . More specifically, wind is a form of kinetic energy, as are allmoving masses. The wind hits a fan blade, causing kinetic energy to convert into a torquerotationalenergy . This torquerotational energy , which is manipulated through the use of gears, rotates a shaft inan electrical generator and electrical potential energy is created. The more wind there is, the greaterthe spin rotational energy of the shaft and the more energy that is produced.

Therefore, the most important concept regarding wind turbines is how we make the fan blades movefaster. There are several things to take into consideration here. The first is gear ratios. If the turbine wasconnected directly to the blades, it would rotate at the same speed as the blades. By utilizing gears,however, the turbines rotation can be changed to a desired level. Imagine a gear set up where a gearedattached to the blade had 20 teeth and the turbine gear had ten. Simple math tells us that the turbinewill spin twice as fast, and thus will produce twice as much electricity as its un-geared counterpart. Wecan manipulate gears to get a gear ratio (i .e., 2:1) which will provide an optimal turbine shaft speed.

Comment [TAL16]: it is really the rotaspeed that you are matching (RPM), not angvelocity.

Comment [TAL17]: This not really trupeople have no idea what conservation of en

Comment [TAL18]: poorly constructedsentence

Comment [TAL19]: electrical?

Comment [TAL20]: what kind??

Comment [TAL21]: why this phrase?

Comment [TAL22]: more complicated- rotational speed is governed by load.

Comment [TAL23]: But it is??

Comment [TAL24]: meaning what?


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Another factor is the design of the blades, which can vary by pitch, size, and shape. In nature, winds are

usually going to blow in a completely linear fashion perpendicular to the wind turbine. However, oursmall scale models are stimulated by box fans which produce a swirling wind at close range. Thereforewhen we consider the pitch of our blades, we must understand that the winds angle of attack is notnecessarily perpendicular to the base and factor that into figuring out at which angle the blades will bestcatch the wind.

The size and shape of our blades are also limited by our box fan. If we were in nature, our blades couldbe rather large and their entirety still be affected by the wind. However, the box fan will only create awind stream about 2 feet wide. If we have blades with a wingspan of 5 ft., a good amount of that will just be dead weight and will retard the energy producing process. Large blades also allow for a morecreative blade design. Most turbines you see today have blades which are air foils, which are designedto increase the lift produced by the wind and reduce the sound created. On a small scale, it is harder tomake such shapes, and you must be creative when utilizing materials to try to best mimic this concept.

One last thing to consider is the resistance to spin inherent in your design. Any time a bearing isnt welloiled, a gear isnt perfectly aligned or something is off balance, a frictional force is applied to your shaftreducing its speed and ultimately the energy created. Also, if the wind is strong enough, it can causeyour base to bend backwards and thus your blades wont be facing the wind in the direction youwanted it to. The easiest way to counteract this is make sure everything is engineered andmanufactured perfectly and create a sturdy base.

The gear box and base provided are an assembly which is very stable for classroom use. It is importantto note, however, that when swapping out gears, one must make sure that the four corners of the topplate are all level with one another and parallel to the bottom plate. If this is not the case, the gears willbe misaligned and the assembly will function poorly, if it functions at all. Also, make sure not to overtighten the hub or else it will crack. The hub is designed so that the two opposing faces do not have tobe flesh with each other in order for the blades to be held in place.

Project Management Plan (Jonathan Matteson) The Gantt chart for this project can be located in Appendix A. The Gantt chart is broken down by thedeliverables required for this project. The main sections include progress memos, kit development,presentation, and written deliverables. Within the progress memos category there are completionperiods for each of the six required memos. The progress memos section This is included to ensure thatthe team wont forget about these while working on other more time consuming portions of the project.The kit development stage is broken down into subcategories of concept generation, concept selection,building, and testing. It was decided to budget the concept generation and selection time for the firstpossible availability. The team decided this would provide the most amount of time to obtain parts,

build and test the prototypes, and then make changes necessary without being rushed on time. Bygetting a head start on concept generation and selection, we gain a competitive advantage over manyother groups who will wait longer to choose a design and will therefore have less time to test and refinetheir designs. The building portion of the Gantt chart has been broken down into many subcategories,

Comment [TAL25]: this is too complicexplain easily to teachers. I would leave it o

Comment [TAL26]: this term is too notechnical, use friction.

Comment [TAL27]: ?? this is impossib

Comment [TAL28]: This is more approan assembly manual than discussion of princ

Comment [TAL29]: This section is beslater in the report. The sample report on ANprovides a possible model to follow.

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providing insight into the completion of each subsystem of the turbine. It has been broken down into

the following subsystems: hub, blades, platforms, base, shaft, wiring, and gears. The next category isPresentation, which is broken down into the subcategories of preparation and presenting. It is importantto include this into the project management plan because it is critical that a good sales pitch isdeveloped, so that the customer can see the true value and uniqueness of this product.

In order to complete the project there are several key tasks that must be completed. All materials mustbe purchased within the $100 budget. The base must be constructed by hand and fabricated to notallow for any structural flexibility ensure adequate structural stability when tested and handled bystudents . Fabrication will require some knowledge of power tools, which all team members alreadypossess. The hub must be designed in Solidworks and fabricated using rapid prototyping. All membershave knowledge of Solidworks for generating 3D parts. Team members have very limited knowledge of how to fabricate a part using rapid prototyping, for this the L learning Factory staff will be consulted. Forselection of turbine gearing, class notes and PowerPoints will be used, since no members have anyprevious experience choosing gears. Fabricating the gear box will require machining using large powertools, a drill press, and potentially a mill. All team members have experience using these machines andwill work together in order to fabricate these parts as quickly as possible in order to get a functioningprototype. The remaining assembly of the wind turbine can be completed by hand using standardhardware ; , so that the wind turbine is easy to put together for those with no technical background.

Fabrication Process: (Jonathan Matteson) The fabrication process can be split up into four major categories: turbine base, gear box platforms, huband blades, as well as shaft and gearing. To start the base, 5 of 1 OD PVC piping was taken and cutdown into six sections of length 5 and 1 sec tion of length 10. The next thing that was done tocomplete the base was using a drill press to drill a #8 thru hole, near the top of the 10 length PVC, in

order to mount two brackets to hold up the gear box platforms. Lastly, T-joints were used to connectthe six 5 sections in the form of an H supporting the 10 vertical column placed in the middle of thebase. The last thing that was done to complete the base was using a drill press to drill a #8 thru hole,near the top of the 10 length PVC, in order to mount two brackets to hold up the gear box platforms.After attaching the brackets with a #8 bolt and nut the next thing to do was tw o fabricate the two gearbox plates.

It was decided that the gear box plates were to be made out of metal in order to provide a rigidstructure for mounting the generator and shaft on. T wo identical 4x4 metal plates were cut using thesheet metal cutter. These were made out of 1/8 aluminum sheet metal. Next a drill press was used inorder to make a hole in each corner of the plates. These holes are used to house 3 bolts that theplates slide up and down on. T Next, t he generator/bracket assembly was centered on the edge of thebottom plate. The locations of the two holes that hold the generator bracket were marked off andmachined using the drill press. Next tT he locations of the #8 holes for the other side of the mountingbracket were marked off, and machined using the drill press. Now that theThe completed bottom platewas complete it was mounted to the base using #8 hardware. The generator/bracket assembly wasmounted to the bottom plate using two bolts and wing nuts. A 3 bolt was inserted into each of the

Comment [TAL30]: Still quite clear wmeans. You are merging two points - constrby hand and the need for a rigid structure - thnot really related.


Comment [TAL31]: Much too long to single paragraph.

Comment [TAL32]: You did this afterassembling the base?

Comment [TAL33]: You did this afterassembling the base?


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corner holes and secured using wing nuts. It was aA t this point that we realized that the wing nuts

wouldnt sit flat on the base because it was running into the motor bracket. So a metal grinder was usedto grind down a portion of the generator bracket to allow the wing nuts to be flush with the bottomplate.

to tThe next task to be completed was the fabrication of the top plate. F our 1/8 holes needed to bedrilled to mount the bearings, but accuracy needed to be ensured so that the shaft wasnt misaligned, sothese four holes were machined using the digital readout on the mill. It was determined that thebearings should be offset towards the front of the plate in order to better support the weight of the huband blades, so these four holes were machined, and the two sets of holes were spaced 2 apart. Nowthat the top plate was completed it was slid onto the four 3 bolts and secured with wing nuts.

The next process was making the shaft and gearing. First, using 1/8 hardware the two ball bearings were mounted onto the top plate. T he shaft was then wrapped with tape in order for it to fit snuggly

into the bearings. The brass shaft was inserted through the bearings and then the team moved on togear fabrication. Since the gears have much smaller holes for the shaft, the gears provided were takento a drill press to machine the shaft hole to for the large gears. The large gear was hand twisted ontothe threaded end of the shaft. Next the pinion had to be drilled out in order to fit the bushing provided;this was done using the drill press. After pressing the bushing into the pinion, the bushing was pressedonto the generator and the distance between the two plates was ad jhusted using the wing nuts in orderto get the gears to mesh.

Last was fabricating the hub and blades. After drawing up a two piece clamping design in Solidworks,the hub design was taken to the learning Learning factory Factory for rapid prototyping. Once that wasfinished it was attached to the other threaded end of the shaft using washers and wing nuts. The oldblades made from cardboard and duct tapes were originally used, but after extensive blade testing,smaller, rounder blades were constructed from cardboard, glue, and dowel rods. The blade radius wasmade smaller in order to be in the middle of the airflow.The old blades made from cardboard and ducttape were used . These new blades were inserted into various slots in the hub and angled appropriatelyto allow the turbine to spin. After testing a few times, it was noticed that there was considerable rockingbecause of an uneven base. To fix this, rubber patches were put on the bottom of the base, in order toact as feet and stabilize the design. This is what has been done up to this point, but the design ischanging constantly to improve efficiency and functionality.

The final change made to the design was the addition of banana plug jacks. Two holes were drilled intothe bottom plate and then the two banana plug jacks were fastened in. Then wire leads were solderedbetween the generator and the banana plug jacks. This completed all the changes that were made tothe wind turbine.

Testing Results and Design Revisions (Jeff Irwin) Our alpha prototype was predominantly based on design concept #1, with a base structure similar todesign structure #2, and a hub connected to a shaft as shown in design concept #4. The motorThe




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voltage drop drop generated a voltag e across a 10. 06 resistor , which was measured with a digital

multimeter. With a blade pitch of around 10, a voltage of 1.5 V was achieved. After adjusting the bladepitch to around 40, a voltage of 2.6 V was achieved. With our initial blade design, a voltage of .48 V wasachieved. After changing the blade shape, a voltage of .70 V was achieved. After increasing the numberof blades from three to six, a voltage of .75 was achieved. After shortening the radius of the blades bytwo inches, a final voltage of .96 V was achieved. We can calculate power generated P as:

=

The power coefficient can be calculated as:

= density of air = 1.2 kg/m 3= incoming wind speed = 3.04.2 m/s

A = area swept out by blades =

Substituting the values of the variables, we find C p 0.0343731 .

There were several problems with the alpha prototype, which prompted design revisions. First, theshaft was slightly undersized compared to the bearings. By wrapping a piece of paper around the shaft,it was made to fita tighter fit was achieved securely in the bearings . Also, the platform's wobble on thePVC base structure. This problem was easily resolved by tightening the nut attaching the PVC pipe tothe L-brackets. Also, the entire structure wobbles, as it sits on the tees rather than the extending PVCpipes. By adding rubber foam cushions to the undersides of the PVC pipes, this unwanted motion waseliminated. Finally, we do not have a standard interface for test instrumentation. By drilling two holesin the lower platform and soldering wires to the motor leads, we can createcreated an input for bananaplugs.

Budget and Materials (Jeff Irwin)Table 2. Materials Costs for Prototype

Item Notes CostGears $1.25 per gear 2.50Motors $3.00 motor 3.00Rapid Prototyped Hub $8 per cubic inch 12.00PVC Piping 5 of 1 pipe, and 3 joining

Ts 4.40

Bearings 2 at 15.14 each 30.28Shaft Brass Rod 1.84Motor Clamp Steel bracket 2.59Steel Brackets 2 at 0.35 each 0.70

Comment [TAL34]: Jon mentioned thi


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Spade Head Screws 4 at 0.58 each 2.29

Wing Nuts 16, free from InstrumentRoom 0.00

#8 Hex Nuts 3, free from Instrument Room 0.001/8 Hex Nuts 4, free from Instrument Room 0.00 Washers 2, free from Instrument Room 0.00 Screws 2, free from Instrument Room 0.00#8 Screws 3, free from Instrument Room 0.001/8 Screws 4, free from Instrument Room 0.004x4 Aluminum Sheet Metal 2, free from Learning Factory 0.00Cardboard From cereal box 0.00Rubber Foam Cushions 4, free from Instrument Room 0.00Total Cost 59.60

Table 3. Estimated Cost for Kit

Assume 5000 units produced and a labor cost of $10/hr. Further assume that the unit cost of materialsand components such as gears and motors will be reduced by 1/6 compared to the cost in Table 1. Forcomponents that must be manufactured, e.g., your hub or motor mount, please specify themanufacturing process that you assumed and the basis for your cost estimate.

Item Notes Cost/Price ($)Gears 0.42Motor 0.50Hub Rapid Prototyped Component 2.00

PVC Piping 0.73Bearings 5.05Shaft 0.31Motor Clamp 0.43Steel Brackets 0.12 Spade Head Screws 0.38 Wing Nuts 0.00#8 Hex Nuts 0.001/8 Hex Nuts 0.00 Washers 0.00 Screws 0.00#8 Screws 0.001/8 Screws 0.00

4x4 Aluminum Sheet Metal 0.00Cardboard 0.00Rubber Foam Cushions 0.00Total Materials Costs 9.94


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Hours required to produced

Kit

$10/hr 1.5

Cost to produce one kit Materials plus Labor 24.94

Price of Kit Price set to achieve a 20%internal rate of return

38.18

For the prototype, many pieces of hardware such as screws, nuts, and washers were acquired for freefrom the Instrument Room in Reber Building and the Learning Factory. Assuming 5000 units produced,the cost of these standard materials would be negligible compared to the cost of other componentssuch as the bearings and the hub.

Team Reflection: (Jonathan Matteson)

We felt that this project gave team members a great opportunity to experience what design is like in thereal world. This project was the first opportunity many people in the class have had to do any hands onwork with designing, choosing materials, and fabrication of a mechanical device. We believe that thisclass gave us invaluable experience when it came to choosing materials/parts. It taught us differentthings to look for when selecting parts, as well as expanded our horizons to the vast choices that areavailable in the world of hardware. We know this is something that often times we had to learn on ourown during internships, but this class gave some class members the experience they need for when they

are asked to do this in the work place. Fabrication wise, this class provided an opportunity to work witha variety of different power tools, saws, mills, lathes, drill press, rapid prototype machine, and soldering.These are all skills that we will carry with us into our profession careers and will help us be moreproductive engineers.

One very important professional skill everyone in the group learned was how to meet deadlines.Throughout the project there were many deadlines established more certain project components. Doingthis helped the team manage their time effectively in order to meet the due dates. This translates verywell to what we will do in a professional work place in meeting the deadlines given to us by our bosses.The other very valuable professional skill we all learned was how to assemble a professional technicalreport. Before this project we didnt have much practice assembling technical reports, but this projectprovided a very elegant way of teaching us how to do this step by step.

Formatted: Heading 1


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Appendix A: Gantt Charts

Original Gantt Chart


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Gantt Chart as of 4/15/2012


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Appendix B: Bill of Materials

Vendor Part # Quantity Description Unit Price Price

Lowes PVC 040100600

1 5'x1" PVC Schedule40 Piping

$2.48 $2.48

Lowes 401010RMC 3 1" PVC Schedule 40Tee

$0.64 $1.92

McMaster 4551K31 1 Brass Float Rod, 1/4"-20 threads, 8" long

$1.84 $1.84

McMaster 8600N3 2 Stainless steel ballbearings, for 1/4"shaft

$15.14 $30.28

McMaster 11355T29 1 Clamp for 11/4" OD

$2.59 $2.59

McMaster 90181A556 1 10-pk Spade Headthumb screws, 1/4"-20, 3" long

$5.72 $5.72

McMaster 1556A24 2 7/8" x 5/8" cornersteel bracket

$0.35 $0.70

Jameco RF-500TB-12560

1 Brushed DC Motor $3.95 $3.95

Stock 4 Rubber padding

Stock wiring

Stock 2 banana plug receptors

Stock 1 gear set

Stock 16 Wing nuts

Total Cost $49.48


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wind turbine design report

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