Design Report Expectations Sophomore Engineering Clinic I November 24, 2014

Design Report Basics  Definition: Documents a solution to a unique problem  Purpose: To communicate the solution to a problem  Audience: Someone who may need to use, understand, or reference your design

Overview of Design Report Sections  Cover Letter  Title Page  Executive Summary  Table of Contents  Problem Definition  Design Description  Evaluation  References  Appendix

Front Matter  Cover Letter  Each members contributions to the design and report  Title Page  Project title, names of the design team, name(s) of the client, and date  Executive Summary  Problem definition, design description, evaluation of results  One page  Table of Contents  Heading and subheadings

Problem Definition  Scope  Fully describe the problem given to you by the eng. faculty!  Technical Review  Why is solving the problem important?  Review of how the turbine design effects performance  5-10 Sources  Design Requirements  What are the physical constraints?

Design Description  Overview of Final Design  General characteristics of turbine & result (blades, pitch, chord)  Detailed Description  Your description must be detailed enough so I could make it myself!  Exact descriptions of all aspects of the wind turbine  Results from test day & code  Design Use  How does the turbine interface with the gearbox to produce power?

Evaluation  Overview of Design Evaluation  How did you evaluate each design?  Prototypes  Earlier designs  How was max Cp obtained?  Testing and Results  Overview of design process (no story telling!)  Plots: Max C p vs pitch, # of blades, chord  Explain how each parameter effected the final design

Evaluation  Assessment  Strengths and weaknesses  Final design C p vs omega  How did final results compare to MATLAB results (explain)  Next Steps  What would you did if you had an entire semester?  How could you make your design better?

End Matter  References  IEEE – Same format as literature review  Number citations in the order in which they appear in the paper  Appendices  Contains supporting information  Ex. max C p data for every run, MATLAB code

Other Notes  Be direct and to the point (quality over quantity)  Be specific  Be quantitative  Don’t use “I, We, The team, Our”  No bulleted lists  Check your significant figures  Past tense for experiments that were performed  Revise your work!

Questions?  Cover Letter  Title Page  Executive Summary  Table of Contents  Problem Definition  Design Description  Evaluation  References  Appendix

Wind Turbine Efficiency and Losses Sophomore Engineering Clinic I November 24, 2014

Wind Turbine System: Efficiency & Losses  Single metric to measure success  Amount of electricity generated during final testing  The Amount of Available Wind Power  60 Watts  Can you expect to generate 60 W of Power with your optimized Wind Turbine?  No…   Betz’ Law—No turbine can capture more than 60% of the wind energy  Efficiency Loss  2 Primary Sources of Efficiency Loss  Mechanical  Electrical

Mechanical Losses  Frictional Loss  Moving equipment creates some level of friction  Turbulence  Leading Edge  Trailing Edge – Fan Velocity Dependence  Wind Tunnel (Edge Effects)  Interference due to lack of uniform undisturbed wind across the entire area  Tolerances  Blade construction  Blade adhesion to dowel  Blade Rigidity

Generator Operation N S ω V ~ ω BA A

Generator Efficiency  Generator efficiency increases as a function of speed until it reaches a maximum value  About 35% for the generator/ motor we will be using  After it reaches a maximum it decreases due to losses in the motor /generator

Generator Outputs  The output voltage of the generator is proportional to the armature rotational speed  However, as the rotational speed of the armature increases, in an opposing electromotive force (back emf) increases  This causes decreased current which reduces the generator efficiency  This results in a maximum value for the power and the output voltage as a function of armature speed

Net Efficiency  The available wind power for our setup is 60 W  The Betz limit ( maximum) is ~60% or 36 W  More realistic numbers are less than 20% or 12 W  From efficiency plot, a maximum of 35% of the mechanical power input will be converted by the generator to usable electrical power  Less than 4 W  So the net efficiency of the turbine-generator system is 7% or less