Engineering Design

1. Engineering Design Day 2: NSE 6th grade MSTA Region 11 Teacher Center

2. Engineering Design Goals 1. Teachers will explore redesign in engineering. 2.Teachers will explore wind energy and applications through gears and generators. 3.Teachers will connect engineering activities across the standards.

3. Day 2 Agenda – Engineering Design • Connecting to the standard • Pre-assessment • Engineering Design Cycle activity • Connecting engineering standards and physics standards • Connecting to mathematics • Post-assessment

4. Connecting to the Standards • What standards were covered in the “save the penguins” activity? • How well did this activity address the engineering standards? Which specific standards were addressed?

5. Connecting to the Standards

6. Connecting to the Standards

7. Connecting to the Standards Nature of Science & Engineering

8. Pre-Assessment

9. Electricity Generation • Where does the electricity comes from to power this device? • Write at least five words that come to mind when thinking about fossil fuel electricity generation.

10. Electricity Generation • When will fossil fuels run out?

11. Electricity Generation • How will we heat our homes, make electricity, transport ourselves as fossil fuels run out? • What sustainable energy source makes the most sense for Minnesota?

12. Wind Energy • Where should wind turbines be built?

13. Wind Energy • How can we generate electricity using wind?

14. Design Cycle: Blade Design

15. Design Cycle: Blade Design You are working for a power company that harnesses alternative forms of energy. Your boss has asked your team to design the wind turbine blade unit to get high power output.

16. Step 3: What are the design criteria and constraints? Brainstorm possible solutions Step 2: How have others solved this? Design Cycle: Blade Design • What factors related to the blade unit design influence the power output of a wind turbine?

17. Step 3: What are the design criteria and constraints? Brainstorm possible solutions Design Cycle: Blade Design You are working for a power company that harnesses alternative forms of energy. Your boss has asked your team to design the wind turbine blade unit to get high power output. However, there are costs involved in testing, so you must plan carefully! (Next slide has costs) You must keep track of your expenses in a way that is easily understandable and explainable.

18. Step 5: Build a prototype Step 4: Which of the possible solutions do you choose? Design Cycle: Blade Design Budget: $10,000 for today’s testing • each test you run (turning on the fan and using multimeter) costs $800, • initial costs for each white plastic blade is $200 • initial costs for each balsa blade is $400 • to change the shape of a set of blades costs • $100 for 1-3 blades in the set • $200 for 4-6 blades in the set • $300 for 7-9 blades in the set • $400 for 10-12 blades in the set

19. Step 6: How does it work? Try it and test again. Step 7: How do you learn from the designs of others? Gallery Walk • On a post-it poster: • Summarize what you have learned so far about blade unit design. • What would be your next steps? • Post on the wall • Walk around to get ideas about how other teams addressed this engineering challenge

20. Step 8: How can you use your new ideas to improve your design? Design Cycle: Blade Design • What did you learn from other groups that will be useful in improving your design? • What is your hypothesis for improving design (what will you change and why?)  • What variable(s) will you keep constant for this re-design process? • What variable(s) will you investigate next?

21. Design Cycle: Blade Design Budget: $15,000 for today’s testing plus residual budget from day 1 • each test you run costs $800, • initial costs for each white plastic blade is $200 • initial costs for each balsa blade is $400 • to change the shape of a set of blades costs • $100 for 1-3 blades in the set • $200 for 4-6 blades in the set • $300 for 7-9 blades in the set • $400 for 10-12 blades in the set

22. Redesign Gallery Walk • On a post-it poster: • Include your data table • Summarize what you have learned about optimizing the blade unit. • Post on the wall • Walk around to get ideas about how other teams addressed this engineering challenge • Create a summary data chart as you look at other team’s data (number of blades, angle of blades, cost etc.)

23. Redesign Summary • Which turbine produced the largest current? • How do you think that design was able to produce more power than other designs? • What is the “best design”?

24. How much power is in the wind?

25. How much power is in the wind? • Treat the problem as a mass of air moving through an area (A) defined by the turbine diameter in a given time (dt) • Mass (m) = rV = r(Audt) Distance = udt

26. How much power is in the wind?

27. How much power can be extracted?

28. How much power can be extracted? • How does length of blades impact power output? • What does our data tell us? (optimal blade length is proportional to fan diameter) • What does the physics tell us? (power is directly proportional to R so the longer the blade the better) • Can you explain the discrepancy between our data and the physics?

29. How much power can be extracted? • How many blades are best? • What does your data say? • Wall vs. fewer, small blades • Aerodynamic efficiency increases with number of blades but with diminishing return • So why do most turbines use three blades?

30. How much power can be extracted? • What angle/shape of blade is best? • What does our data say? • The role of lift: • What will happen when you blow between the index cards?

31. How much power can be extracted? • How is lift generated from an airplane wing? • http://www1.eere.energy.gov/windandhydro/wind_how.html

32. Generators • Attach the GenPack to your turbine. Adjust the GenPack and gears so you can get a voltage reading

33. Generators What did you observe using the GenPack? How does a generator work? http://www.walter-fendt.de/ph14e/generator_e.htm http://phet.colorado.edu/simulations/sims.php?sim=Generator

34. Generators • Why is the voltmeter readings changing from negative to positive?

35. Generators • To run most electrical devices we convert AC to DC. In the GenPack we use a rectifier to accomplish this conversion.

36. Generators • What variables impact the output from a generators?

37. Generators • What is the relationship between number of coils and voltage?

38. Gear Ratios • What do your students know about gears? Where have they encountered gears? • Gears are used to create mechanical advantage in a machine in which speed and force can be made greater or less and the direction of application can be changed.

39. Gear Ratios What is the gear ratio between the yellow and red gears? Why might it be useful to string several gears together?

40. Gear Ratios • String all four gears together. • What is the gear ratio between the first gear and last gear on the line? • If the yellow gear rotates at 6 revolutions per minute, how many revolution per minute does the red gear rotate?

41. Engineering Challenge - Modeling Engineers working on wind turbines must decide what gears to use in their wind turbine. They know that the blades turn at one speed and the generator needs to turn at a different speed. What they don’t know is how to figure out how fast gears rotate when linked based on their size.

42. Engineering challenge Please provide a general procedure for the engineers to use that will help them with their problem. Use the question below as a prompt. • If you have any two gears and the primary gear is rotating at x rpm, how fast does the secondary gear rotate? Be prepared to present your solutions to the engineers.

43. Wind Turbine Gear Ratios • What is the gear ratio between the smallest gear and the three larger gears? • How would you explain to the engineers which gear should be put in the wind turbine for maximum power output? • Considering each gear size, what do you predict will happen to power as we increase the gear ratio?

44. Post-Assessment

45. Characteristics of Good Engineering Curricula • Context • Science/Math Content • (even better if there are other content too) • Scientific Inquiry • Could include design of experiments • Engineering Design • Design cycles • Redesign

46. Summarize and Share • What standards were covered in the wind turbine activity? • How well did this activity address the engineering standards? Which specific standards were addressed? • Discuss more directions that you could take these activities on wind energy. • Compare and contrast the “penguins” and wind turbine activities

47. Exit Slip • Please share your thoughts on • The wind turbines lessons we worked on today • Your current thoughts about how you will integrate engineering into your science class.