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Advanced Design Applications Power and Energy © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications Teacher Resource Primary Challenge – What About All This Wind?
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The BIG Idea Big Idea: Knowledge of energy and power technologies along with the transfer and manipulation of those technologies will be essential for student success in the design of the Primary Challenge device. © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Multi-Task Windmill Competition It’s All About Energy and Power! “LIFTING” TEST - Greatest Average Power mgh / t = mgv AVE (g=9.8 m/s, h =.75 m) ELECTRICAL POWER - Greatest average power V 1 A 1 + V 2 A 2 = Average Power © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Multi-Task Windmill Challenge Lakewood 101 Box Fan ~1/2m x 1/2m 3.1 m/s air speed © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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© STEM Center for Teaching and Learning™ Example of Device © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Motion An object’s motion is fully described by translation of its Center of Mass and rotation about its Center of Mass (CM) © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Motion Continued Translation Can Occur in 3 Dimensions Rotation Can Occur in 3 Dimensions Full Description of Motion is referred to as 6 Degrees of Freedom (6- DOF) © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Forces and Motion Forces Acting through CM only causes translation Forces acting a distance (torque ) from CM will also cause rotation F F r = rF F=ma = I © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Translation and Rotation for Challenge Generally center of mass is pinned for rotating elements so motions are either pure translation or pure rotation in this challenge Trick is to convert Power and Energy from Translation to Rotation, vice-versa, and to other forms © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Energy Energy is required to do Work Work is done when an object is moved a distance against a force Lift a 1 kg mass 1 m against gravity Force = mg = 1 kg x 9.8 m/s 2 = 9.8 Newtons Work = Force x Distance = 9.8 N-m = 9.8 Joules Work = mgh = Energy Not Surprisingly an object h meters off ground has Gravitational Energy = mgh If dropped will convert to kinetic energy Kinetic Energy on Ground = ½ mv 2 = mgh © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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© STEM Center for Teaching and Learning™ 1 kg g = 9.8 m/s 2 F = 9.8 N © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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© STEM Center for Teaching and Learning™ 1 kg g = 9.8 m/s 2 F = 9.8 N h = 1 m Work = Fh = Energy = 9.8 Joules © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Rotational Work Its takes energy to rotate an object against a torque Work = Energy = F, h © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Power Power is Required to Work Quickly Power = Energy / Time Power is required to sustain a velocity against a force If we want to raise the rock at 1 m/s then Power = Force x Velocity = Fv = mgv = 9.8 N-m/s = 9.8 Joules/s = 9.8 Watts Rotational Power Power is required to sustain an angular velocity against a torque Power = Torque x Angular Velocity, P= © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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© STEM Center for Teaching and Learning™ 1 kg g = 9.8 m/s 2 F = 9.8 N © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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© STEM Center for Teaching and Learning™ 1 kg g = 9.8 m/s 2 F = 9.8 N © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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© STEM Center for Teaching and Learning™ 1 kg g = 9.8 m/s 2 F = 9.8 N © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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© STEM Center for Teaching and Learning™ 1 kg g = 9.8 m/s 2 F = 9.8 N © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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© STEM Center for Teaching and Learning™ 1 kg g = 9.8 m/s 2 F = 9.8 N 1 m/s Power = Fv = Energy/s = 9.8 Watts © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Power – Rotating Shaft to Move a Mass r F=mg = Fr = mgr =v/r P = = Fr = Fv = mgv © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Electrical Power Power = Voltage x Amperage, P=VA Voltage = Energy / # of Electrons Joules / Coulomb of Electrons Amperage = # of Electrons / s Coulomb of Electrons / s Voltage x Amperage = Joules / s = Watts Measure V = 1 Volt, A = 1 Amp P = VA = 1 Watt © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Energy and Power are Convertible Gravitational Potential to Kinetic Energy mgh -> ½ mv 2 Rotational Power to Mechanical Power -> Fv = mgv Torque x Angular Velocity = Force x Velocity Rotational Power to Electrical Power -> VA Without losses replace -> with = Want to eliminate losses due to friction, drag etcetera © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Windmill Design Two Components Power Generation Convert wind power to mechanical power Wind -> Pushes Wind Mill Blades -> Wind Mill Shaft Turns Power Distribution Use power of rotating shaft to Transfer power by moving mass Generate Electricity © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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How Much Power in Moving Air? Power is Energy / Time How much Energy in Moving Air? © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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© STEM Center for Teaching and Learning™ Fan ½ m 3.1 m/s 1/8 m 3 Density of Air - 1.225 kg/m 3 Mass = 1.225 kg/m 3 x 1/8 m 3 =.153 kg © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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© STEM Center for Teaching and Learning™ Fan ½ m 3.1 m/s.153 kg Kinetic Energy = ½ mv 2 = ½ x.153 kg x 3.1 m/s x 3.1 m/s =.74 Joules 3.1 m/s © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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© STEM Center for Teaching and Learning™ Fan ½ m 3.1 m/s.75 Joules.74 Joules t = ½ m / 3.1 m/s =.16 s ½ m 3.1 m/s Power = Energy / Time =.74 Joules /.16 s = 4.6 Watts © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Betz’s Law Windmill Deflects Air © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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© STEM Center for Teaching and Learning™ Cowling? © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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© STEM Center for Teaching and Learning™ Cowling Used on a Device for the MESA Competition © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Two Windmill Types Horizontal Rotating Shaft Vertical Rotating Shaft © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Simplified Horizontal Wind Mill Lift Force distance r Lift Force rL = = I r-distance, L-Lift, -torque, I-Moment of Inertia, -angular acceleration Side View Wind Front View © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Factors for a Good Turbine Blade Airfoil Design – “Design from the Side” Planform – “Design from the Top” Aspect Ratio – “Squat or Elongated” Blade Twist © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Airfoil – Design from the Side Airfoil works by redirecting moving air downward (Action) resulting in Lift (Reaction). The Bernoulli Effect - Loss of Pressure with increase in velocity is a small effect. © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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© STEM Center for Teaching and Learning™ The key effect contributing to Lift is Leading Edge Suction due to turning off moving air about leading edge of wing without increase in speed. The so called “Coanda Effect” results from the Viscosity of Air. Airfoil © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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© STEM Center for Teaching and Learning™ A key airfoil characteristic is angle of attack . This allows the airfoil to redirect moving air downward. Thus even a flat plate can generate lift. Airfoil © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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© STEM Center for Teaching and Learning™ Camber or curvature of the wing allows more effective redirection of the air without flow detaching. Airfoil © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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© STEM Center for Teaching and Learning™ Thickness about camber is also a Factor. A blunt leading edge with Maximum thickness ~1/3 way back and tapered trailing edge maximizes lift and minimizes drag. Airfoil © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Planform – Design from the Top Rectangular Tapered Elliptical © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Induced Drag High Pressure Low Pressure Wing Tip Vortex © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Wing Tip Vortex © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Minimizing Induced Drag Rectangle Maximizes Induced Drag Although easy to construct Ellipse Minimizes Induced Drag But can be hard to construct Tapered Planform Frequently Chosen Almost as good as ellipse in minimizing drag Reasonably easy to construct © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Aspect Ratio Aspect Ratio Length of Wing / Average Width (Chord) Low Aspect Ratio High Aspect Ratio © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Best Aspect Ratio? Low Speed High Aspect Ratio* High Speed Low Aspect Ratio © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Windmill Blade Twist Angle of Attack is dependent on the speed of the blade with respect to the air If the blade is moving perpendicular to the wind the angle of attack will change © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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© STEM Center for Teaching and Learning™ Rotor Aerodynamics Blade must be twisted maintain optimum angle of attack Electricity Generating Wind Turbines Use an odd number of blades to avoid harmonics Problem – Won’t know rotational speed until windmill is built. So twist should be adjustable! © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Blade Twist Diagram © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Typical Horizontal Windmill © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Blade Design Materials Pink or Blue Foam Board 3-D Printer Balsa Wood / Shrink Wrap What other materials can you use? © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Vertical Windmills Drag Type Vertical Windmill Lift Type Vertical Windmill © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Vertical Wind Turbines Have not caught on in the commercial market Drag Type has low efficiency Lift Type efficiency better Optimal Design is not Clear However May be well matched for this contest Insensitive to Wind Direction Flow Field is Rectangular © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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© 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Weight Lifting Challenge h = 75 cm Want to maximize Power = Weight x Velocity Weight = mg, Velocity = h/t Mass is team’s choice Windmill is intrinsically a high torque, low- speed device Best strategy is to lift large Weight at low speed Attempt to increase speed leads to power losses © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Weight Lifting Challenge © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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© STEM Center for Teaching and Learning™ Wind Changing Electric Power © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Generating Electrical Power © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Electrical Power Generation High rotational speeds are required for efficient electrical generation Windmills are high torque – low- speed devices How can rotational speed be increased. Proper gearing! © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Step Up Gearing 12 Teeth 8 Teeth © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Kid Wind Gear Kit 8:1 Rotational Speed Gain © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Step Down Pulleys © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Power Losses Must carefully watch for power losses in every stage Rotating Shaft, Pulleys, Rotating Bearings Must Minimize Rotational Inertia I in Rotating Elements Eliminate unneeded mass © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Performance Scoring Mass Lift Electrical Power © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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Parts to the Challenge The design of your device Operation of your device Measurements (power and weight) for the two tasks Documentation Design process, ideas, selection of ideas, cost, drawings/sketches Presentation © 2014 International Technology and Engineering Educators Association STEM Center for Teaching and Learning™ Advanced Design Applications
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