wind turbine detailed design report
TRANSCRIPT
Chris Carreo, Carlye Lauff, Mike Scardina | Confidential
11/04/12
Wind Turbine Kit ME 340: Design Methodology Detailed Design Report Spring 2012
Team 10 Chris Carreo, Carlye Lauff, Mike Scardina
4/11/2012
Team 10
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Executive Summary
This report discusses the final project proposal and detailed design analysis for a wind turbine generation kit aimed at educating elementary and middle school children. With the constant increasing demand for energy, renewable energy sources have become more prominent in industry. Additionally, there currently exists a market to use the wind turbine kits to stimulate the minds of children in elementary and middle school. By sparking their interest in renewable energy and engineering and science, it could change the course of their academics and cause them to be on the forefront of renewable energy. The members of Team 10 have used design methodology as defined in ME 340 this semester to systematically develop a system level design concept that has been adapted for mass production to be used across the nation.
After researching, external searching, and benchmarking, many concepts were generated by the team. These concepts were narrowed down to three main concepts. Through further evaluation using design matrices, the main ideas from several concepts were selected and combined to create a final design. This final design consists of several key features such as varying blade designs, a gearbox with varying gear ratios, a LED power output, and interactional materials for educational value. The beta prototype has been adapted for mass production and accurate SolidWorks renderings have been created. Preliminary economic analysis predicts that the wind turbine kit can be mass-‐produced for under $56.09 per kit at a rate of 25,000 kits per year. This cost is much less than most products in the market today and therefore makes Team 10’s wind turbine kit an extremely competitive product. The Net Present Value from a five-‐year NPV analysis is $1,266,072. Not only are their economic benefits to furthering development on the wind turbine kit, but there is also an area to develop educational value to change the course of engineering in the world as we know it.
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Table of Contents 1. Introduction ................................................................................................................................... 5
1.1. Problem Statement ................................................................................................................. 5
1.2. Background Information ......................................................................................................... 5
1.3. Project Planning ...................................................................................................................... 5
2. Customer Needs and Specifications ............................................................................................... 6
2.1. Identification of Customer Needs ........................................................................................... 6
2.2. Design Specifications ............................................................................................................... 7
3. Concept Development .................................................................................................................... 7
3.1. External Search ........................................................................................................................ 7
3.2. Problem Decomposition .......................................................................................................... 8
3.3. Design Concepts ...................................................................................................................... 9
3.4. Concept Combination ............................................................................................................ 10
3.5. Concept Selection .................................................................................................................. 10
4. System Level Design ..................................................................................................................... 12
4.1. Overall Description ................................................................................................................ 12
5. Detailed Design ............................................................................................................................ 14
5.1. Modifications to Proposal Sections ....................................................................................... 14
5.2. Theoretical Analysis ............................................................................................................... 14
5.3. Component and Materials for Mass Production ................................................................... 14
5.4. Fabrication for Mass Production ........................................................................................... 15
5.5. Industrial Design .................................................................................................................... 15
5.6. Detailed Drawings ................................................................................................................. 16
5.7. Economic Analysis ................................................................................................................. 17
5.7.1 Unit Production Cost ....................................................................................................... 17
5.7.2 Business Case Justification .............................................................................................. 18
5.8. Safety ..................................................................................................................................... 18
5.9. Test Procedure ...................................................................................................................... 18
6. Conclusions .................................................................................................................................. 19
7. References ................................................................................................................................... 20
Appendix A: Project Management ....................................................................................................... 21
A.1 Team 10 Description and Roles ............................................................................................. 21
A.2 Gantt Chart ........................................................................................................................... 22
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Appendix B: Customer Needs .............................................................................................................. 23
B.1 Customer Survey .................................................................................................................... 23
B.2 Sample Customer Responses ................................................................................................. 24
Appendix C: Concept Development ..................................................................................................... 26
C.1 Patent Search ......................................................................................................................... 26
C.2 Benchmarking: KidWind ......................................................................................................... 27
C.3 Benchmarking: Horizon .......................................................................................................... 29
Appendix D: Design Concepts .............................................................................................................. 30
D.1 Concept A .............................................................................................................................. 30
D.2 Concept B ............................................................................................................................... 31
D.3 Concept C ............................................................................................................................... 32
Appendix E: Mass Production Final Design .......................................................................................... 33
E.1 SolidWorks Drawings ............................................................................................................. 33
Appendix F: Material Properties .......................................................................................................... 35
F.1 Rapid Prototyping Properties ................................................................................................. 35
Appendix G: Business Case Justification .............................................................................................. 36
G.1 Five-‐year projected NPV economic analysis .......................................................................... 36
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1. Introduction
1.1. Problem Statement
In the world today, energy is a valuable resource. The harnessing of energy to produce power has become a booming and expanding industry. Currently, there has been a push for renewable energy since the world is quickly depleting the coal and natural gas resources [1]. This leads engineers to use other methods to generate energy, such as wind power. The team was assigned the task of designing, constructing, and testing a wind power generation kit. In doing so, the team will also use the kit to educate and motivate children ages 8-‐14 about the principles of wind power generation. The kit will allow the children to easily assemble and disassemble the wind turbine on their own. The final design will be critiqued in areas such as industrial design, performance, educational value, safety, and compactness, among other criteria. There will also be certain constraints the team must adhere to such as building an alpha and beta prototype using a Jameco motor and fitting the unassembled parts into a provided storage container. Once the wind turbine kit has been assembled, it must operate in varying winds speeds and directions. Two banana plug jacks must be used to allow instrument testing and to provide a signal indicating the power generated. In construction, no borrowing of parts from other turbines or fans will be accepted. All of this must be completed by the team under a budget of $100 and with the task of educating 8-‐14 year olds about wind power generation.
1.2. Background Information
Constructing the wind power generation kit will require the team to use both past and present knowledge and resources. The team’s education thus far will have a large effect on the completion of tasks. Core engineering classes such as Statics and Dynamics will be utilized in building the prototypes. Electrical engineering, manufacturing processes, machine design, and physics are other areas of study that will be used to complete the project. In the construction of components like the hub, blades, and nacelle, the team will use both Statics and Dynamics. Statics will be used to determine the forces on the shaft, and Dynamics will be used in the motion of the blades. Electrical engineering concepts will be used in wiring LEDs to the generator to indicate the power output. Manufacturing process and machine design will be implemented when fabricating parts of the turbine that must fit together as well as in the overall manufacturing of the kit. Most of the technology and resources necessary will be available in the Learning Factory and the Reber Building. To better understand how wind power generation works, the team has researched vertical and horizontal axis wind turbines. This has helped in the design of the wind turbine and understanding the similarities and differences between the two types. Also, the team has acquired electrical parts and LEDs to display the output power. To construct the light sequence, the team will need to research electrical circuits in order to construct the lights. Whenever an unfamiliar topic presents itself, the team is ready to take on the challenges head on. There is a growing market for the wind power generation kits. As mentioned in the problem statement, the need for renewable energy is constantly increasing [2]. This means that there is a market for educating the next generation of scientists and engineers. Through the wind turbine kit, students can become excited about wind energy and consider the topic in their future studies.
1.3. Project Planning
During the spring 2012 semester, the team will follow the design methodology as presented in ME
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340, adapted from Ulrich and Eppinger’s Product Design and Development, 4th edition [3]. The team developed a Gantt chart within the first week to ensure that all tasks could be completed in a timely manner. This Gantt chart can be viewed in Appendix A.
The three members of Team 10 used their strengths to focus on certain tasks throughout the design process. The breakdown of the project titles and roles for the group members are found in Appendix A. Each group member used their strengths in completing milestones in the design project per the Gantt chart schedule. The team has open communication and always uses democracy in making decisions, such as choosing the top three concepts. This mindset has allowed the team to excel thus far in the design process and makes the team strongly believe that there will not be any setbacks in the final milestones of the project.
2. Customer Needs and Specifications
2.1. Identification of Customer Needs
A clear and concise customer survey was developed to gain insight into what the team should focus on when developing the wind turbine kits. The questionnaire the team developed can be viewed in Appendix B. This questionnaire begins with an overview of the project followed by a series of questions that teachers from pre-‐school to eighth grade answered. The team sent this survey via email to over 30 teachers and received feedback from 10. From the feedback, the team developed several criteria to consider in the design. This feedback can be seen in Table 1 below.
Another way the team identified customer needs was through personal interviews with middle school students. The team talked to five students between the ages of 11-‐13. The main feedback the students gave was to make the wind turbine kits as interactive as possible. One important statement that was repeated multiple times was that the students wanted to know why the wind turbines existed and how it would benefit them. From this, the team decided to include additional materials in the kit such as a PowerPoint presentation that can be altered slightly for each class, a short video showing the purpose of wind turbines and the team actually building the model, and a handout that can be copied and dispersed to the students in the class.
Table 1. Customer responses from the surveys.
Option # Mentions Percentage Build out of easily replaceable material or
recyclables (i.e. PVC, Balsa wood) 8 80%
Incorporate learning about different energy forms (i.e. KE, PE) 5 50%
Allow simple prototyping for students 9 90% Have students compete against one
another 6 60%
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2.2. Design Specifications
From the wind generator problem description and the customer needs seen in Table 1 above, a Quality Function Deployment matrix was created in Table 2 below. These nine metrics were used in creating the design specifications.
Table 2. Product Specification based off customer needs in QFD.
Metric No. Metric Importance Units
1 Prototype for under $50 4 US $
2 Industrial Design for under $15 4 US $
3 Efficiency of 15% 5 kW 4 Durable for 3 years 2 yr.
5 Adaptable for many grades 1 -‐
6 Built under 5 minutes 3 s
7 No sharp edges or dangerous parts 2 -‐
8 Fits in a tuber wear container 1 In.
9 Simple yet complete design 3 -‐
From the customer needs and translated metrics, the team decided on ten criteria to be used in the concept selection phase. These criteria can be seen in Table 4 and Table 5 in Section 3.5 further below. The criteria chosen to analyze the design concepts came from the needs and customer responses. These criteria are cost, industrial design, performance, durability, educational value, ease of assembly, safety, aesthetics, compactness, and simplicity. These criteria were then weighted based off of the importance to the team. Criteria like educational value (25%) and performance (15%) were the most important and therefore held more weight in the decision process. On the other hand, criteria such as durability (5%), simplicity (5%), and cost (5%) were not the main factors in the decision making and received much lower weighted values. These values are outlined in Table 6 and described more in detail in that section.
3. Concept Development
3.1. External Search
In order to develop a competitive wind turbine kit, the team completed a patent search. There was one patent found that incorporate several of the team’s ideas for the kit, such as an adjustable hub for variable blade design [4]. The patent publication number is US 2011/0116932 A1. It was published on May 19, 2011 and is entitled “Miniature Wind Turbine Having Variable Blade Pitch.” This patent, which can be viewed in Appendix C, allowed the team to see a way to develop the hub to incorporate varying blade designs. No patent infringements are anticipated because the design the team will be using varies the length and diameter as well as pitch of the blades.
The team also benchmarked competitive products in the market to ensure a complete understanding of wind turbine kits. The two products the team looked at were the KidWind’s Wind
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Energy Kit and Horizon’s WindPitch Educational Kit. Both of these products are currently being used in many educational institutions and have developed credentials in academia. Both of these designs can be viewed in Appendix C. In Table 3 below, KidWind and Horizon have been analyzed by the biggest pros and cons from each design.
Table 3. Pros and Cons for two benchmarked products.
Design Pros Cons
KidWind
Pre-‐assembled gearbox Expensive Blade variation Set gear ratio
Cheap blade materials -‐ easy to replace Limited students/model
Interactive videos and handouts
Horizon
Hardware, software, and curriculum material Very Expensive
Learn about more than one renewable energy
Not much variation for interaction
Creative energy output Materials hard to replace
KidWind is an excellent wind turbine kit that has received excellent reviews. Two of the middle school science teachers the team spoke with have actually used science grant money to purchase kits from KidWind to implement into their curriculum. There are four levels of comprehensive kits all ranging in the amount of materials included. The price range is from $36 for a KidWind Mini to $149 for a Geared Turbine. The level of complexity would determine which kit the teachers would need to purchase. The Geared Turbine is developed to run blade design experiments using a multi-‐meter to record power output as well as testing amount of LED bulbs they light up or water they pump. The gearbox is fixed at 6:1 and comes preassembled for ease to use. The drawback is that this kit can only be used for a small group of students. If a teacher needed to teacher a class of 50 or more, then they would have to purchase Classroom Pack for $384. These kits are rather expensive for containing such basic materials and the team believes a less-‐expensive equivalent can be created. Some images of KidWind designs can be viewed in Appendix C. [5]
Horizon has developed two kits for wind energy production. The one is a WindPitch Energy Kit that is sold for $120 and allows students to reconstruct the number of blades between one and twelve. The rest of this kit cannot be altered, however. The other kit sold is a Hydro-‐wind Educational Kit. This kit is $190 and comes with optimal educational materials including software programs as well as many power outage tools like an LED voltmeter, music maker module, and the ability to store the wind energy in fuel cells. These materials are rather hard to replace, but the concept of the power outage is quite unique to other kits. Some images of Horizon designs can be viewed in Appendix C. [6]
3.2. Problem Decomposition
In designing the wind turbine kit, this complex problem was decomposed in order to gain a greater understanding of the several different subproblems and probable solutions to them. In completing this problem decomposition, a functional model was used incorporating ideas from the “black box”
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model. The overlaying problem for this class is to create a wind turbine kit. However, this problem can be broken down into three subproblems: energy production from the wind turbine, limited space for building the model, and the overall educational value of the kit. Each of these subproblems can be seen in Figure 1 below. All of these problems can be answered by choosing the best materials for the design in order to create a full functioning wind turbine kit.
Figure 1. Functional diagram of the problem decomposition.
3.3. Design Concepts
From the background needs, customer specifications, and benchmarking, the team developed many concepts. In the first round of generated concepts, the team employed the 3-‐3-‐7 method. This is where the three team members produced three concepts every seven minutes for three rounds. The entire process took 21 minutes and produced 28 concepts. Then, the team voted on the best qualities found in those 28 models. Next, brainstorming was implemented to combine all of the best ideas into more refined concepts. Each team member came up with three well-‐defined concepts. At a team meeting, the members voted democratically for the three concepts to move forward. They can be viewed in Appendix D. Those three concepts were then critiqued against one another to further develop the best final design.
Concept A was a very educational based design that was built with the intention of teaching students about wind energy and topography. There would be a fold out board of land where the students could place the miniature HAWT, VAXT, or Wind Ribbon designs. This would allow the students to visually see where wind turbines might be located on the various terrains. It would be reusable and be connected to a built in voltmeter to see out the power production. This concept was very bulky and did not allow students to learn more about the wind turbines in general. Instead, it gave an overview of wind turbines across the land. Concept A can be viewed in Appendix D.
Concept B was a rather unique design in that it was the only vertical axis wind turbine. The team wanted to keep a VAWT design until the last three concepts because it was unique to the other
Energy Producmon
Store or produce power output
Convert mechanical to electrical energy
Limited Space
Store all components of
turbine Easy to construct
turbine Choose the best
materials Create full
funcmoning wind turbine kit
Educamonal Value
Teach students principles of wind energy
Simple design for students to test
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groups. However, a vertical design requires intense calculations and is something the team would spend tedious hours understanding instead of refining a concept. Concept B would be able to be constructed out of majority recyclable material, and the students could enjoy using objects like small Dixie-‐cups as the blade design. Concept B can be viewed in Appendix D.
Concept C was deemed the swift energy design based on a company that developed a similar product. This design was extremely safe and efficient as seen with the circular ring encompassing the blades as well as the two tailfins used to direct the wind turbine into the wind. This design would not allow students to change the blades or alter the design in any way possible due to the constraints. Another unique feature on this design would be that students could be exposed to a common wind turbine that can be located on the tops of houses or businesses. This could let the students take the design and bring it outside and put it on their playhouses and actually observe what that wind turbine would look like in real life to scale. Ultimately, this model did not give enough flexibility that the team desired for the final design. Concept C can be viewed in Appendix D.
3.4. Concept Combination
The team developed three unique concepts that were all compared to one another. The screening and scoring matrices found in Tables 4 and 5 below under Section 3.5 show the criteria that ultimately allowed the team to move forward with ideas from Concept A and Concept B. Using ideas from Concept A and Concept B, the team used a concept classification tree to see which parts of each design were the most promising. The team took the best subsystems from those two concepts along with a few new innovative ideas to develop the final design. The best ideas from Concept A included the basis of an educational valued model and the fully functioning build in voltmeter. The best ideas from Concept C included the tailfin, the gearbox, and the cheap yet sturdy materials. When combining these features, the team felt as if there was something missing to set the team apart. After brainstorming again, the team decided to implement varying gears within the gearbox. This would allow students flexibility in both blade and gear design, making their experience the most rewarding.
3.5. Concept Selection
In deciding upon the best possible design for the wind turbine, the team constructed decision matrices to determine which concepts to pursue. Since each concept had unique characteristics, the team made a screening matrix to find which concepts to continue developing. This screening matrix can be seen below in Table 4. The matrix consists of criteria that each concept was judged on. These concepts were then decided to be better or worse than the chosen reference. Based upon the net score of the concepts the team decided what parts of each concept to include in the final design. Concept C had the highest net score of 2 based upon its performance, design, educational value, and aesthetics. Concept B was the least desired with an overall net score of -‐2. Concept A also had some positives that were incorporated into the design selected. Another helpful tool the team used was making a concept scoring matrix to aid in the design. This matrix can be viewed below in Table 5. The same criteria were used as the screening matrix but each was weighted a certain percentage. Based upon this percentage, each concept was giving a rating and ranked according to the total weighted score. In determining the weight for each criterion the team thought about which areas of the project to focus. For the team, educational value was most
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important and was weighted the highest. Performance was also deemed important and given an appropriate weighting. Less relevant criterion such as cost and durability were given lower weight values. Using these weights, each concept was rated between 1-‐5 with 1 being the least desired rating and 5 being the most. For example, Concept A had a low cost and was given a 5/5 for the rating but was determined to be somewhat aesthetically displeasing and was therefore given a 2/5 rating.
Selection Criteria Concept A Concept B Concept C Class Reference
Cost + 0 -‐ 0 Industrial design -‐ 0 + 0
Performance (efficiency) -‐ 0 + 0 Durability, low maintenance 0 -‐ 0 0
Educational value 0 0 + 0 Ease of assembly + -‐ 0 0
Safety 0 0 0 0 Aesthetics -‐ 0 + 0
Compactness 0 0 -‐ 0 Simplicity + 0 0 0
Sum +'s 3 0 4 0 Sum 0's 4 8 4 10 Sum -‐'s 3 2 2 0
Net score 0 -‐2 2 0 Rank 2 4 1 2
Continue? Combine No Combine n/a
Selection Criteria
Weight (%)
Concept A Concept B Concept C
Rating Weighted score Rating
Weighted score Rating
Weighted score
Cost 5 5 0.25 3 0.15 2 0.1 Industrial design 8 2 0.16 4 0.32 5 0.4
Performance (efficiency) 15 2 0.3 3 0.45 4 0.6
Durability, low maintenance 5 4 0.2 3 0.15 3 0.15 Educational
value 25 2 0.5 3 0.75 4 1 Ease of assembly 10 5 0.5 3 0.3 3 0.3 Safety 10 4 0.4 2 0.2 3 0.3
Aesthetics 7 2 0.14 3 0.21 4 0.28 Compactness 10 4 0.4 2 0.2 2 0.2 Simplicity 5 5 0.25 3 0.15 3 0.15
Total score 3.1 2.88 3.48
Rank 2 3 1
Table 4. Concept Screening Matrix.
Table 5. Concept Scoring Matrix.
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By using decision matrices, the team saved time with testing and decision-‐making. Completing the matrices allowed the team to quickly view the most important aspects of each concept and eventually decide which concept was best and should be pursued further. This permitted further development of a more detailed design that can more actively engage children in wind power generation.
4. System Level Design
4.1. Overall Description
The final concept for the wind turbine incorporates every aspect the team sought out to achieve. Keeping in mind the goal of designing for educational value the design has various parts that teach students the fundamentals about wind turbines. A main theme behind the design is self-‐experimenting through changing different parts of the turbine on a mission to find the best design. With a little guidance of the included CD we hope to show the students why a change does or does not increase performance or efficiency. For part specifications and exploded drawings please see Appendix E.
The first distinct aspect of the design is the students will be able to change the blades on the turbine. The blade hub is easily dis-‐assembled from the turbine and separated to remove the blades. The hub is composed into two sections made of ABS Plus plastic manufactured from a rapid prototyping machine (for material properties see Appendix F). The hub is set up in a way that students can experiment with one, two, three, and six blade configurations. Using ¼ inch wooden dowel rods the students can change the design, number and pitch of the blades in a simple design. Installation of blades is easily done by a clamping mechanism that tightens on the wooden dowels and prevents them from becoming a safety hazard.
With all types of teaching schedules in mind, the team chose to incorporate three standard blades made of ABS Plus plastic. In the event a teacher does not have time to have students conduct experiments they can still use the product to teach the fundamentals of wind turbines.
Connecting the blade hub to all of the other moving parts of the turbine is a hardened tool steel rod.
Figure 2. Full view of the wind turbine.
Figure 3. HUB extended view
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This rod runs the length of the nacelle and is connected to the different gears and the lifting attachment. The shaft is supported by two ball bearings mounted in the clear acrylic sides. A great feature of the wind turbine is students will be able to see the insides of the nacelle. While the teacher explains the operation of the turbine to the students for the audio learners, the visual learners will also benefit from watch the turbine operate. The top, sides, front, and back of the nacelle are made out of a strong impact-‐resistant clear acrylic. This ensures that no student has a bad point of view during any lesson involving the turbine.
Inside of the nacelle lies the gearbox and generator of the wind turbine. During ideation methods the team felt the turbine would not succeed unless a gearbox was incorporated. The gearbox design utilizes a movable motor along tracks machined in the acrylic. Students can change the gear ratios of the turbine by moving the motor, almost like a transmission, teaching about the importance of gear ratios in generator designs. Each gear is press fit onto the turbine shaft to ensure a correct coupling with the pinion gear and motor.
The motor is mounted in a holder that will guide it to the correct location. The holder is bent out of steel sheet with handles made out of tool steel. The motor mount will have stops located on the inner walls of the nacelle to ensure the motor does not slide off of the gears one way or the other. The wires soldered to the motor will be mounted out of the way of any moving parts so they do not become damaged or destroyed.
At the back of the nacelle is the directional fin and weight lifting attachment. The weight lifting attachment gives the students and the teacher more resources to experiment. Instead of generating power the students can have competitions to see whose design will lift the most weight. To set up the turbine for this type of experiment the gearbox can be put into “neutral” by moving the motor to the neutral slot located at the front of the turbine minimizing power loss.
The directional fin attached to the nacelle replicates the automated turning mechanisms in modern day wind turbines. This is intended to teach the students about nacelle orientation relative to the wind and show why it is important. The whole turbine up till now sits on a flange bearing attached to the tower. The acrylic sides and ends of the nacelle are attached to a sectioned piece of PVC with a shaft connected to the inner race of the flange bearing. In order to increase friction on the flange bearing and stop unnecessary rotations the flange bearing will be packed with grease. The outer race of the flange bearing will be supported by the tower but not rigidly connected so that the nacelle and tower can be separated for storage.
The tower of the turbine is a piece of PVC pipe that houses the wires coming from the motor. They are spliced at the banana jacks for easy digital multi meter readings. The wires continue down into
Figure 4. Gears and motor in the gearbox.
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the hollow base which house the electronics. The electronics inside the base will be created to take the voltage from the motor and convert it to light up an LED bar on a 10 segment LED bar graph. This indicator will show the students how much power their configuration of blades, pitches, and gear ratio will produce.
5. Detailed Design
5.1. Modifications to Proposal Sections
Due to revelations for prototyping and design constraints, changes have been made in the design, process, and schedule. In design, the team has moved forward with a gearbox design. This gearbox has five gears that allow the students to easily move the motor to test how gear ratios affect the overall efficiency of the wind turbine. Also, a tailfin blade was added to the rear of the turbine so that it could always move
towards the wind. These changes can be seen in Figure 5 to the right. In changes in the process of the project, the team has decided to break up tasks based on certain strengths. Since the team has many aspirations in completed the beta prototype, this break up of tasks is necessary. Lastly, the team has made alterations in the schedule. The building of the beta prototype has been pushed back ten days due to a wait for new parts. Additionally, the team had to move certain deliverables up in date a week such as the PowerPoint and video so that these tasks can be completed in a timely manner.
5.2. Theoretical Analysis
With the ability to design infinite configurations of blades and gear ratios analyzing each would be impossible. This section will focus on the included blade length of 7.5 inches and varying gearing ratios.
The equation ! = !!!"!! will estimate the maximum power available in the wind where A is the
sweep area of the turbine, v is the velocity of the wind, and ρ is the air density. The sweep area of the turbine is simple a circle, therefore area ! = !!!. With a radius of 7.5 inches, a wind velocity of 3 m/s, and an air density of 1.204 kg/m3 at 20° C the available power for the turbine is .205 Watts.
The Betz Law states that the maximum efficiency of any turbine is 59.3 percent. This would mean that the maximum power generation for the design is .122 Watts. With the added rotational inertia of the gears, bearings, and lifting attachment the estimated efficiency of the turbine is around 12 percent, making the estimated power output .0246 Watts. [7]
5.3. Component and Materials for Mass Production
The final design for the wind turbine kit can be broken down into a three main components: the
Figure 5. Alterations to the design of the wind turbine.
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base, the hub, and the nacelle. Each of these components will have several subparts that need to be manufactured as well. The three components and the several subparts along with the materials selected for manufacturing can be seen in Table 6 below.
Table 6. Components and Materials for Mass Production
Component Quantity Material Selection
Base
Tower 1 Metal Tower Base 1 Metal
LED 1 Epoxy
Alligator Clips 2 Metal plastic coated
Hub
Blades 15 Corrugated Plastic Weights 2 Plastic Gears 5 Plastic Rod Hub
6 in 1
Plastic Injection Molded Plastic
Nacelle
Motor 1 Metal DC Motor
Gearbox 1 Polycarbonate Sheet
Wires 1 ft Copper plastic coated
5.4. Fabrication for Mass Production
The alpha and beta prototypes differ from the mass production of the wind turbine kits. The SolidWorks rendering of the different components can be seen in Appendix E. In the fabrication of the wind turbine kits, techniques such as injection molding must be used for consistency. In order to produce a larger quantity of wind turbine kits, large-‐scale manufacturing techniques must be incorporated. The plastics and metals used in the design would be cut, shaped, and refined using large manufacturing machines. In mass production, certain subparts of the overall design such as the motor, LED light, and alligator clips could be purchased from a vendor in mass quantity. This would enable the production of the rest of the materials to be as quick and efficient as possible, allowing the kits to be shipped out in larger quantities.
5.5. Industrial Design
When designing the wind turbine, the team wanted to create a safe and easy to use product that also demonstrated educational value to children. The product also needed to be aesthetically pleasing while maintaining a low cost. All the features were implemented in the design of the wind turbine.
To allow easy assembly and disassembly of the turbine, it will be made it multiple smaller parts in order to fit the size constraint. Also, by having the children change the gear ratio allows them to
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interact with the product and understand the importance of gear ratios. In order to see the gears inside the nacelle, it will be constructed of 1/4” clear polycarbonate sheet. When changing gears, a ladder system attached will be used to move up and down gear sizes. This is to allow a smooth change between gears while still keeping it in place and safely housed in the nacelle.
In designing the hub, the team needed to find a way to allow interchangeable blades to be put in the hub while still be easy to use and safe. To achieve this, the blades each have an insert that goes into the hub and the hub can be tightened to fit around each blade. With this design, the children can make their own blades and decide how many to use. It also ensures the blades are secure to account for safety while also remaining easy to operate. The blades provided will not have any sharp edges to keep the product safe.
The base needs to be sturdy enough to not topple over in the roughly 20 mph winds they are to be designed to withstand. It will be made of metal but with no sharp edges to account for safety. As for the tower, it will be made of PVC pipe, along with part of the nacelle. The hub and directional fin will be made by rapid prototyping. Provided in the kit will be a template for the children to make their own blades out of their desired material. The design calls for similarly colored materials to add to the clean, aesthetic appeal of the wind turbine.
Upon first inspection of the kit, most parts should be readily recognizable, even to an 8-‐14 year old. This familiarizes them with the product and can help to get them interested. And since it’s designed to be easily assembled and disassembled, it is also easy to repair should a problem arise. With a transparent nacelle any gear problems will be easily spotted and able to be repaired. This will help to cut down on the cost associated with the product since repairs can be made to enable the turbine to last longer. The low cost of the materials needed for construction will also keep the price kits down to hopefully facilitate schools using the project. In turn, this would educate children nationwide about wind power generation.
5.6. Detailed Drawings
Here are several drawings of the final design that will be used for mass production in Figures 6-‐7 below. The rest of the images can be seen in Appendix E.
Figures 6-‐7. Detailed Drawings of the Final Design.
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5.7. Economic Analysis
5.7.1 Unit Production Cost
The cost of a product can greatly influence how well it will do in the market. To ensure a successful product, the cost should be kept relatively low to allow the consumer to choose the product while still making a profit. In determining the cost to develop the product, several factors were considered. The evaluated fields include parts, materials, tooling, labor and overhead.
Overhead accounts for marketing, development, labor, tooling, and distribution of the product. Marketing will be done to schools in order to show the product offered in addition to demonstrating its use and educational value. A website can be made and brochures as well to give to prospective customers and gain their business. Development costs include the gathering of materials and developing the design for sale as a viable product. This will take place in the first year of production in anticipation for sales after starting the company. Labor rates and tooling rates were estimated by determining what individual work will be completed and needed to construct each part. Distribution was also considered since the plan would be to sell nationwide. This would mean hiring laborers to deliver the product after fabrication. A complete bill of materials needed for the wind turbine can be found as Table 7 below. The overhead charges are also presented in Table 8 below.
Table 7. Bill of Materials for wind turbine kit.
Component Amount Purchase Cost ($) Assembly Tooling
Total Unit Variable Cost ($)
5/32" bearing 2 9.96 0.2 0 10.16 .157" steel rod 1 2.41 0.15 0.05 2.61
Clear polycarbonate sheet 1 14.01 1.5 0.4 15.91
Threaded knob 1 0.82 0.2 0 1.02 Jameco chip 1 2.75 0.5 0 3.25 LED bar graph 1 1.09 0.5 0 1.59 Breadboard 1 5.95 0.5 0 6.45
Motor 1 15 0.1 0 15.1 PVC pipe 1 0 0.1 0.2 0.3
Total Cost $56.09
Overhead Cost Marketing $40,000 Development $40,000 Labor $5,000 Assembly $5,000 Distribution $25,000
Total Cost $115,000
Table 8. Overhead Cost for Unit Production.
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5.7.2 Business Case Justification
While 1.5 million dollars seems like a large sum to spend on an investment, the returns can be even greater. In addition to providing education to children across the nation, there is also money to be made in the product. The total cost to produce one unit is roughly $50. At a production of 100,000 units over four years, this translates to an NPV of $1,566,072. This estimate is conservative, but still leaves plenty of room for profit. This NPV was estimating as shown in Table 9 below. The equation used for the present value was the period cash flow divided by (1+.1)^x with x being the number of quarters since the first. This value demonstrates the opportunity available in the selling the product to schools. The five-‐year projected NPV economic analysis can be viewed in Appendix G.
5.8. Safety
When designing the wind turbine, the team had safety as a priority due it being used for children’s education. Keeping this in mind, the team made sure to adhere to safety standards set forth by the governments where the turbine may be sold. The team also made sure to design the turbine in such a way that there are now sharp edges or parts that could possibly injure any children during its assembly and use. Being marketed towards children, the team used several safety standards. The American Society for Testing and Materials (ASTM) is a worldwide leader in the development and delivery of standards. To be available to children, the team followed standards set forth in ASTM F963-‐11. This standard lists important terminology and requirements for toys being marketed towards children. For sale in international countries the product must meet safety standards by the International Electrotechnical Commission (IEC). The team’s wind turbine satisfactorily complies with the safety set forth in the IEC 61400-‐1 standard for wind turbines. This includes the structural design of the turbine in addition to the mechanical and electrical systems of which the product comprises. For sale in the United States and also other nations Underwriters Laboratories uses safety standards to govern the products available. The team’s turbine adheres to the UL 3200, UL 6140, and UL 6141 safety regulations. These regulations ensure the satisfactory performance of wind power generating systems. By following the safety guidelines in the standards, the team can guarantee the safe operation of the turbine.
5.9. Test Procedure
When gathering data about the prototype the team will want to know what works about it and what does not. Once this is determined, the team can analyze what the data is telling them to make any necessary improvements. Also, a visual inspection of a test in progress will help show any defects in the prototype. To test the prototype, the team will use a box fan set up three feet away to try to spin the blades and generate some power. While testing, the team will use the prototype, the fan, and measuring tape.
On March 28th the alpha prototype was completed and tested at the Learning Factory. The team used the large fan at the factory, not a box fan. The prototype was placed three feet in front of the fan. Upon testing the prototype, it was a success with the blades spinning so fast they flew out of the hub at a certain point. This immediately raised a safety concern, especially for use around children.
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The blades were fixed and the testing was completed.
The next day on March 29th the team brought the alpha prototype in for more testing. This test used the standard box fan with prototype three feet in front. With the box fan the blades did not spin at three feet. The blades spun at roughly one foot away, but only if they were nudged to start off. Once given the needed help, the blades made several full rotations before coming to a stop. Several factors could have contributed to these results. The blades and hub were quite large and heavy which made rotation harder. Also, the hub was not completely balanced and it caused the blades to rotate irregularly and eventually cease. Lastly, friction between the shaft and the caps the team used may have reduced the rotational speed slightly. Some improvement the team need include making a smaller hub and blades while also balancing them to ensure even rotation. Bearings can also be used to reduce friction and allow free rotation and therefore more power.
6. Conclusions
The wind turbine kit that has been developed by Team 10 serves as an excellent educational model for all students ages 8-‐14. The wind turbine kit has taken into considerations the feedback from customers and lead users, competitive products, and the restricting factors in this design course. The team effectively learned how to implement the design process and used knowledge from other engineering classes to aid in the analysis and manufacturing. Overall, the team believes that all the nine criteria for this project were met and that the innovative design of the model can be competitive against the other students in this class and in the market as a whole. The economic analysis proved that one kit could sell for $56.09, which is incredibly competitive against the much more expensive models that are equally as capable. Although the team believes that the Beta prototype and mass-‐production design is excellent, there are always more improvements that can be made. The world is constantly changing and the minds of the team are constantly opening up to bigger and brighter ideas. If this project was to continue for another year, the team is confident that the cost could decrease, the efficiency increase, and the capabilities be even more astounding.
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7. References
[1] "Packing Some Power." The Economist. The Economist Newspaper, 03 Mar. 2012. Web. 6 Apr. 2012. <http://www.economist.com/node/21548495>.
[2] "Wind Power." Energy & Environment. The New York Times Newspaper, 27 Jan. 2012. Web. 4 Apr. 2012. <http://topics.nytimes.com/top/news/business/energy-‐environment/wind-‐power/index.html>.
[3] Ulrich, Karl T., and Steven D. Eppinger. Product Design and Development. 4th ed. New York: McGraw-‐Hill Higher Education, 2008. Print.
[4] "Miniature Wind Turbine Having Variable Blade Pitch." Google Patents. United States Patent Application Publication, 19 May 2011. Web. 11 Apr. 2012. <http://www.google.com/patents?id=go_hAQAAEBAJ>.
[5] "Science Kits." KidWind. KidWind Prokect Inc., 2012. Web. 2 Apr. 2012. <http://learn.kidwind.org/>.
[6] "Education -‐ Horizon Fuel Cell Technologies." Educational Kits & Resources. Horizon Fuel Cell Technologies, 2010. Web. 2 Apr. 2012. <http://www.horizonfuelcell.com/education_kits.htm>.
[7] Johnson, Gary. Wind Energy Systems. 2004. PDF.
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Appendix A: Project Management
A.1 Team 10 Description and Roles
Team 10 consists of three mechanical engineering students currently completing their undergraduate degree at The Penn State University. The three students are currently enrolled in the ME 340 course entitled Design Methodology. Each team member brings their own unique skill set to the project, which has allowed the team to multitask efficiently. All members have worked hard during the semester to follow the design process methodology. The following will outline the roles and responsibilities that have been assumed and agreed upon by the team.
Chris Carrero is a junior mechanical engineering student with an interest in mechanical design. He is serving as the lead design engineer on this project. He will lead the SolidWorks drawing and manufacturing. Chris has a creative flare to his design work and is very detailed oriented, making him an excellent leader in his role as lead design engineer. Some of Chris’s tasks include:
• Creating and finalizing all SolidWorks renderings of design • Running the concept development section • Selecting and obtaining final materials • Ordering the parts for the prototypes • Leading manufacturing processes in the Learning Factory
Carlye Lauff is a junior mechanical engineering student minoring in engineering leadership. This specialty in engineering leadership allows her to be an effective leader in her role as the general project manager. Carlye’s strengths in communication and organization make her the ideal liaison between the design engineers, customers and course instructors. Some of Carlye’s tasks include:
• Creating and analyzing customer survey and external research • Being the main contact for the course instructors and other via • Send weekly updates and maintain the status of the Gantt chart • Compiling and formatting the reporting documents • Developing presentations and communicating the team’s ideas to others
Mike Scardina is a senior mechanical engineering student who will serve as the lead analysis engineer. Mike will use his strengths in understanding the root cause of problems to analyze both the concepts and the economic value of the kit. He has also played a large role in concept selection and system level design. Some of Mike’s tasks include:
• Generating the economic analysis • Designing and constructing the final prototype • Compiling the research and offering lead advice to discuss • Creating the screening and scoring matrices for concept analysis • Aided in completing the SolidWorks renderings
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A.2 Gantt Chart
Figure A.1. Team 10 Gantt chart
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Appendix B: Customer Needs
B.1 Customer Survey
GE Energy Wind Power Generator Design Project
Project Statement:
Wind is attracting considerable attention as a source of renewable energy. Our team is asked to design, construct and test a tabletop windmill kit to educate and excite elementary school children in the basics of wind power generation. Our kit must be easily assembled and disassembled repeatedly by children 8-‐14 years of age.
Expert/Customer Questions:
1. What is the best way that your students learn?
2. What excites your students in a classroom environment?
3. What are a few different learning methods and the positive/negative aspects of them?
4. What do students age 8-‐14 know about wind power or renewable energy?
5. What is currently covered in the sciences courses related to wind power or renewable energy?
6. How would you incorporate this project into your current curriculum?
7. If you were given this project, how would you go about completing it (in very general terms)?
8. Do you have any teacher-‐related resources or advice for our further research and investigation?
9. If you have any comments on this project that might help us at all, please feel free to leave them below.
Figure B.1. Customer Survey
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B.2 Sample Customer Responses
Figure B.2. Example Customer Survey Response from an Art Teacher
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Figure B.3. Example Customer Survey Response from a Science Teacher
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Appendix C: Concept Development
C.1 Patent Search
Figure C.1. Wind Turbine Patent
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C.2 Benchmarking: KidWind
Figure C.2. KidWind Mini
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Figure C.3. KidWind Geared Turbine
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C.3 Benchmarking: Horizon
Figure C.3. WindPitch miniature Educational Kit
Figure C.4. WindPitch Hydro-‐wind Educational Kit
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Appendix D: Design Concepts
D.1 Concept A
Figure D.1. Concept A
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D.2 Concept B
Figure D.2. Concept B
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D.3 Concept C
Figure D.3. Concept C
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Appendix E: Mass Production Final Design
E.1 SolidWorks Drawings
Figure E.1-‐2. Front and Side Wind Turbine Renderings
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Figure E.3. Top Wind Turbine Renderings
Figure E.4. Gear Renderings
Figure E.5. Nacelle Gearbox Renderings
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Appendix F: Material Properties
F.1 Rapid Prototyping Properties
Figure F.1. Rapid Prototyping Material Properties
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Appendix G: Business Case Justification
G.1 Five-year projected NPV economic analysis
Figure G.1. Five-‐year NPV economic analysis