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P14651: Drop Tower for Microgravity Simulation

P14651: Drop Tower for Microgravity Simulation . Adam Hertzlin Dustin Bordonaro Jake Gray Santiago Murcia Yoem Clara. Project Summary. Problem Goals Design & Build Drop Tower Vacuum Piping Structure Cost Effective Effective Cycle Time Aesthetically Pleasing Precision in Measurements

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P14651: Drop Tower for Microgravity Simulation

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  1. P14651: Drop Tower for Microgravity Simulation Adam Hertzlin Dustin Bordonaro Jake Gray Santiago Murcia Yoem Clara

  2. Project Summary • Problem Goals • Design & Build Drop Tower • Vacuum Piping Structure • Cost Effective • Effective Cycle Time • Aesthetically Pleasing • Precision in Measurements • Educational User Interface • Access for Object Transfer • Adaptability for Future Development • Constraints • Location and design approval from the dean(s) • Material availability/size (ex. tube, pump) • The device is aesthetically pleasing • The tower 6” – 12” Diameter • The device can be operated year round. • The system is safe to operate. • The project budget is $3,000. Team must justify the need for additional funds. • The project must be completed in 2 semesters.

  3. Project Deliverables • Installed drop tower • Detailed design drawings and assembly manual • Bill of materials • User’s Guide for operation • Designed Lab Experiments • Determine gravity in the vacuum within 1% error • Compare drag at different pressures and drag vs. acceleration • Additional vacuum related experiments • Fun and Educational Experience for Middle School Students • Technical Paper • Poster

  4. Week #6 Review Open Items • What are the engineering requirement values? • How is external pressure accounted for? • Does Temperature Affect Calculations?

  5. Agenda • Customer Meeting Updates • Customer Requirements • Engineering Requirements • Proposed Concept Design • Isolation Valve Cost Analysis • List of experiments • Concept and Architecture Development • System Block • Sub-systems • Summary • Risk Assessment • Test Plan • Bill of Materials

  6. Customer Meeting Notes • Account for Pipe Fitting Leaks in calculations • How does Ultimate Pressure change with Leak Rate? • Limit design to one tower • Simple Prototype • Fit two objects in one tower • Allow for lift mechanism • Design Concepts to Future Tower Development • Go with 6-8 in. Diameter, approx. 10-15 ft. Tall Tower • Measure new location heights • Dr. K Lab • Talk with Mark Smith about using MSD space • Does Ultimate Pressure Effect object drop times • Feather vs. Ball Bearing • Use only one laser when dropping items to measure gravity • Keep the educational aspect in mind

  7. Customer Requirements

  8. Engineering Requirements

  9. Isolation Valve – Cost vs. Time Analysis • Assumptions: No losses due to connection points, 10 cubic foot per meter pump, 15 micron ultimate pressure, 2ft above & below valves, single tower

  10. - Isolation Valves Pros and Cons + Quicker cycle time The air needed to be taken out of the pump is independent of tower heightCan use less costly pump (Lower pump speed) • Our Conclusion: Although isolation valves would save a substantial amount of time, the time benefit does not outweigh the cost for the tower height we are considering. At this scale it would be more beneficial to increase the pump size instead. • Costly • Disrupts view of items falling • Can not alter for a continuous system in the future • More pipe / pump sections  need more parts • More chance of pressure leak

  11. List of Experiments • Dropping two objects simultaneously • Measure Gravity • Measure Drag • Balloon Expansion • Marshmallow Expansion • Sound Insulator • Plastic Bottle Compression Note: The following slides will attempt to justify the required tower pressure and size to complete these experiments

  12. CONCEPT & ARCHITECTURE DEVELOPMENT

  13. Proposed Concept Designs

  14. Proposed Base Structure

  15. Selected Concept Designs (part 1)

  16. Selected Concept Designs (part 2)

  17. Continuous Lift Concept #1

  18. System Block Diagram

  19. Sub-Systems Release Mechanism • Release system Calculations Air Control • Ultimate Pressure • Evacuation time • Leak Rate Analysis Catching Mechanism • Energy dissipation Calculations Piping system • Critical external Pressure Sensors Structure • Tower height calculations • Support Buckling

  20. Engineering Analysis Release Mechanism

  21. Base Specifications Polycarbonate Diameter = 6.0 in Thickness = 0.375 in ρ = 1.22 g/cm3 (0.0441 lb/in3) Hatch Doors Length = 1.5 in Width =4.0 in Thickness = 0.375 in 6.0” 0.375” 4.0” 0.375” 1.5” 1.5”

  22. Electrical Specifications 12 VDC Operating temperature of -40F to 140F Holding Force 4.5lbs Physical Specifications Weight – 0.06lbs Diameter – 0.75in Height – 0.62in Other Specifications Quick Release Mechanism Electromagnet Specifications

  23. Physical Specifications Height – 3.5in Width – 1.5in Depth – 0.21in Radius – 5/16in (0.3125in) Pin Specifications Length – 3.5in Radius – 9/16in (0.5625in) Hinges Specifications

  24. FBD

  25. Given Values

  26. Equations

  27. Force of Magnet in y-direction

  28. Force of Pin in the x and y Direction

  29. Shear Stress

  30. Factor of Safety

  31. Engineering Analysis - Air Control Ultimate Pressure & Gravity Error Effect

  32. Gravity Calculation with 1% Error • Constant Acceleration Equations • Assumes no air resistance / perfect vacuum • , where x is position and t is time • Assume 0.XX% Error due to pressure

  33. Free Body Diagram of Object • Force Balance • At Terminal Velocity • Acceleration = 0 • At Vacuum Pressure, drag force = 0 • , where a is downward (negative)

  34. Drag Force (Air Resistance) • FD = Drag Force • ρ = Air Density • V = Velocity of Object • CD = Drag Coefficient (Fudge Factor) • A = Projected Area of Object • P = Air Pressure (Pa) • R = Specific Gas Constant = 287.05 J/kg*K • T = Air Temperature = 21°C = 274K

  35. Objects to calculate gravity • Based on a certain vacuum pressure and other parameters, center objects will be suitable of calculations while others are not • Objects vary by their mass, projected area and drag coefficient • Assumptions: • Allowable Error in Gravity due to Pressure = 0.01% • This can increase if the error from the position and time measurements are minimized • Pressure = 0.015 Torr = 2 Pa • This can be decreased if a more efficient pump is available (cost / benefit) • Max Tube Height = 5 meters • Max Velocity • Ideal Gas • Room Temperature • Standard Gravity

  36. Results • For the assumptions: Gravity Error = 0.01% Base Pressure = 2 Pa • m/(CD*A) >= 1.19 kg/m^2 Where: m = mass (kg) CD = Drag Coefficient A = Projected Area Note: Error % and Pressure can be adjusted to change this threshold

  37. Ping Pong Ball Threshold

  38. Engineering Analysis - Air Control Evacuation Time

  39. Conductance • The flow of air in a tube, at constant temperature, is dependent on the pressure drop as well as the cross sectional geometry. • Viscous Flow: Pressure (micron) * Diameter (in) > 200 • Transitional Flow: 6.0 < Pressure (micron) * Diameter (in) < 200 • , • Molecular Flow: Pressure (micron) * Diameter (in) < 6.0 • C = Conductance (cfm) • F1 = Viscous/Transitional Flow Scale Factor = 0.52 • F2 = Transitional Flow Scale Factor = 12.2 • F3 = Molecular Flow Scale Factor = 13.6 • D = Pipe Diameter (in) • L = Pipe Length (ft) Viscous Molecular

  40. Equivalent Pipe Length • Pipe fittings can cause losses within a piping system • These include: elbows, tees, couplings, valves, diameters changes, etc. • Tabulated values for Le/D can be used to adjust L in the conductance equations • D = Diameter of Pipe • Le = Equivalent Length • Total Length = L + Le1 + Le2 + Le3 + ….

  41. Effective Pump Speed • SEff for each flow regime • Viscous, Transitional, & Molecular • n = number of pipe diameters • C = Conductance (cfm) • = Given Pump Speed (cfm) • = Effective Pump Speed for Tube Dimensions

  42. Evacuation Time • = 760 Torr (Atmospheric) • = Viscous–Transitional Pressure • = Transitional-Molecular Pressure • = Ultimate Pressure • Example: Single 6” x 15’ Tube • Pump used on left • See Spreadsheet for: • Fittings • Individual conductance • Individual flow regime time VP6D CPS Vacuum Pump 2 Stage Rotary Pump 15 micron Ultimate Vacuum Pump Speed – 6.25 cfm Price: $268.92

  43. Results • For the tube and pump size listed, the evacuation time is 5.25 minutes • This will increase if: • Tube diameter increases • Tube length increases • Pump speed decreases • Ultimate pressure decreases

  44. Engineering Analysis - Air Control Leak Rate

  45. Chamber Leak Rate • Constants: • Chamber Volume • Temperature • Atmospheric Pressure • Leak Area • Time Variables: • Mass Flow Rate • Chamber Pressure • Throughput, Q Units: (Pressure * Volume) / Time • Pump Throughput, QP Where: Seff = Effective Pump Speed P = Pressure • Leak Throughput, QL Where: dP/dt = Differential Pressure V = Chamber Volume Leak V Pump

  46. Flow Regime Change

  47. Engineering Analysis - Catching Mechanism Energy Dissipation

  48. Energy Dissipation In process …

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