1 A R E S A eroelastic R enewable E nergy S ystem David Chesnutt, Adam Cofield, Dylan Henderson, Jocelyn Sielski, Brian Spears, Sharleen Teal, Nick Thiessen

2 2 Project Goals and Objectives Increase performance characteristics and knowledge database of Aeroelastic Energy Device (AED), through research, mathematical modeling, and experimentation. Mathematically model AED and its power generation Design and build functional prototype of AED Test AED to obtain voltage readings and thus power Generate database of information on AED to examine power generated

3 3 Coils Magnets on Either Side of Membrane Wires to AC/DC Converter Vibrating Membrane Clamped End WIND Windbelt ™ Concept

4 4 Project Specifications Generate power for small electronic devices –Device must produce 60 mW (8.05 × hp) of power Determine relationship between wind speed and belt tension for various belts; optimize tuning of AED for maximum power –Device should produce power in wind speed range of 1.2 m/s to 4.9 m/s (4 ft/s to 16 ft/s)

5 5 Project Specifications Device should be tunable to operate at maximum efficiency under most common wind speed –Manufacture belt to withstand a 4.9 m/s (16 ft/s) constant wind Device should withstand wind gusts –Manufacture belt to withstand a 16.8 m/s (55 ft/s) gust

6 6 Tentative Project Specifications Electromechanical System –Reduce losses of converting mechanical power to electrical power Power Conditioning System - Minimize losses in electrical signal to transmit most power possible

7 7 Project Calculations Overview Aerodynamics –Flutter, vortex shedding, natural frequency Electromechanical –Magnetic flux, AC current, voltage Power Conditioning –AC to DC converters

8 Project Organization

9 Project Organization Aerodynamics

10 Project Organization Electromechanical

11 Project Organization Power Conditioning

12 Project Organization Final Concept

13 Calculations Aeroelasticity and Flutter Aeroelasticity: The study of structural deformation due to aerodynamic loading Flutter: Vibration of structures due to oscillating fluid motion.

14 When flow separates in oscillating manner around structure near structure’s natural frequency, lock-in effect occurs –Usually ± 10% the natural frequency of structure Shedding frequency forced to match natural frequency in this region, also with multiples or sub-multiples of natural frequency Design intent: create lock-in effect. Calculations Flutter and Resonance Lock-In

15 String Theory Natural frequency depends solely on tension. Beam Theory Natural frequency depends on both tension and EI term. Calculations Characterizing Natural Frequencies

16 E=3.1GPa t=50 microns b=2.5 cm Calculations Belt Vibration Model b t y x String theory is almost identical to beam theory when A<<1m^2 How close?

17 Accuracy of String Theory E=3.1GPa t=50 microns b=2.5 cm Calculations Can the String Model Be Used? Allows modeling of vibrations as string Simple equations save time

18 Match natural frequency to shedding frequency in order for resonance lock-in to occur. Strouhal Number is usually determined experimentally. Dependent upon Reynolds number. For 300<Re<30000, S~.2 Flow Induced Vibrations, Robert Blevins. Calculations Strouhal Number

19 Calculations Alpha Prototype Example 19 Flow-Induced Vibration, Robert Blevins. Approx. Values *Small D values mean small amplitude wakes- once angle of attack is established due to torsional motion, wake grows in width (larger effective D value), increasing minimum velocity required for flutter.

20 Calculations Wake Oscillator Model Single degree of freedom in y- direction Allows calculation of structural displacement function. Applicable when 300<Re<30000 Assumptions: a)Inviscid flow can be assumed outside, near wake. b)Well formed vortex sheet with well defined shedding frequency. c)Vorticity generated only in boundary layer, vortices move downstream. d)Flow is 2-D. e)Force exerted on cylinder depends only on velocity and acceleration of averaged flow relative to cylinder. 20 Flow Induced Vibration, Robert Blevins.

21 Calculations Calculating Displacement Amplitude Flow Induced Vibration, Robert Blevins. Determined experimentally

22 Alpha Model Equation –N is number of coils –A is area of coils normal to flux –B is experimental flux density equation –x, sinusoidal displacement function –K is shape factor which contains permeability and magnet intensity –n is set to fit function to experimental data Calculations Electromechanical Model - Alpha

23 Alpha Model –Use Faraday's law to establish magnetic flux density equation –Use voltage and current readings to establish flux density equation –Model will help establish a "shape factor" to predict magnetic flux density –Neglect radial motion of magnets and Lorentz Force Calculations Electromechanical Model - Alpha

24 Beta Model –Aeroelastic force input function –Elastic restoring force function –Lorentz Forces of coils acting on magnets –Neglect radial motion of magnets –Use previous model's flux density relation with respect to magnet displacement Calculations Electromechanical Model - Beta

25 Gamma Model –Collaborate with aeroelastic model Calculations Electromechanical Model - Gamma

26 Model displacement, velocity, and acceleration curve –Need maximum amplitude estimate. –Model forcing function belt will apply to magnet(s) Model torsional frequency –Important for belt life, determines its importance for power generation Incorporate electromagnetic forces on belt as information becomes available. Calculations Next Steps

27 Calculations Next Steps Develop expressions for y(x,t), θ(x,t), and γ(x,t) –Experimentally verify

28 Belt Design Using composite materials (thin fabric lamina) special behaviors can be achieved By laying-up 2 or more laminae in certain directions, couples behaviors are produced in laminate (bend-twist, extend-twist, etc.) Potential control of twisting of belt

29 Present Hardware Tightening Screw L-Bracket Base Membrane Core Metal Inductor Fret Magnets Mounting Blocks Bolt Holes Electromechanical Alpha Model

30 Present Hardware Magnetic Induction Coils Setup

31 Present Hardware Proof of Concept Model

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