Problem Statement: Renewable energy such as wind can be inefficient and unpleasant to look at, our purpose will be to engineer more efficient, smaller scale wind energy production that will not impede local landscape views.

Specifications and Requirements:

The design must be of competitive cost and superior production capacity to comparable generation methods, be easily serviceable, have a 10+ year lifespan, withstand 100mph sustained wind, and have a more desirable appearance.  The system will need to generate on average 28.9 kWh per day and will require a base operating wind load of 5mph.

Assumptions:

The user wants an aesthetically pleasing, autonomous, on-site renewable energy production system.

Link to Matrix: Decision MatrixLinks to an external site.Links to an external site.

Relating the information to the Matrix:

Ease of Use and Installation: A vertical windmill is mounted at ground level, so a small cement block or anchors can be used to mount to the ground, in some cases a guy wire is needed to secure the tower. Some smaller premade units can be installed with limited special tools giving the Vertical a (5). The Shrouded horizontal wind turbine was given a (2) because of the height requirements. The Tower, at least 100ft high, requires on average 8 cu. Yards of cement to secure the turbine, creating a permanent fixture. This also requires the use of a large crane for installation.

Generation efficiency: A vertical wind turbine is not as refined as a horizontal at this current stage and leads to lower operating efficiencies, however the turbines work better at lower ground level and are omnidirectional. This means no matter which way the wind is blowing it will be generating power. Typically, the cut in windspeed is 2.5m/s. With all of this factored it gives the vertical a rating of (3). The Shrouded Horizontal turbine is the ideal candidate for efficiency. The shroud is bell mouthed directing more air into the inlet of the turbine, thus giving a score of (5)

Life span: The vertical wind turbine lives on the ground so this means that maintenance is much more accessible and can be repaired much easier giving a score of (4). The horizontal unit while in the air at over 100ft, does not have as much rotating mass due to smaller rotors, meaning less maintenance, however it is still suspended leaving a score of (4).

Aesthetics: One of the main factors in design is that surrounding skyline views would not be impeded, this leaves the horizontal wind turbine is a difficult spot, because in order to have reliable performance the turbine needs to be suspended at least 100ft in the air, this leads to a (3). A vertical however can be mounted under 50ft and while the real-estate is somewhat substantial it carries a smaller foot print than a horizontal unit. To power a typical house at 28.9Kw/Hr a day (the avg for American households) it would take a unit 4.4m in diameter and 15m high where as a horizontal unit would require a large amount of cement and a large tower carrying the turbine. The fact the vertical will not block neighboring homes and views is why it has earned (5) in the rankings.

Design and Production Cost: Vertical wind turbines are less expensive to build because they do not require the same level of exotic materials needed in a horizontal unit carrying the load 100ft above the ground. The shear forces contained in a vertical unit are much less due to not having a side loaded support tower, which means less expensive manufacturing, this earns the vertical a (5). Whereas a horizontal unit requires lightweight and strong materials that are guaranteed to last years and years which drives the overall cost up, this leads to a (3).

Considerations During Design Process: When designing the parameters for the vertical turbine the safety factor for some items was incredibly high for some components, but was necessary for clearance for other working components. For example, the outer shaft that carries the weight and rotational energy of the rotors has a safety factor of 400 during average operation, but the inner stationary support shaft has a safety factor of 80 during normal operation. This was designed incase of hurricane force winds in excess of 100mph, at 100mph the system has a safety factor of 1.5 at the weakest link.

Module 1: Pulley Driven Generator

This module is about translating the motion from the turbine shaft to the generator. A pulley system is both quiet and efficient and requires low maintenance, however a serviceable item in this module would be the belt, pulleys and bearings. This has 1 degree of freedom. The serviceable items make this a lower tiered choice as maintenance is required. The system would consist of a stepped pulley system to create a mechanical advantage and lower the speed of the generator to a specified 1500 rpm nominal rate. The starting ratio would be a 100” diameter pulley to a 4” diameter pulley with an attached 62.4” pulley driving a final pulley of 4”. Effectively this will yield a 390:1 ratio, this will invoke a high slip force due to the arc angle, this can be rectified with a tensioner to increase the belt contact area. Without a tensioner the belt was calculated to a Safety Factor of 1.5 due to the max allowable stress on the belt, this was calculated by the max wind force rated at 150mph or 65m/s which yields 50750N-m of force on the shaft of the turbine. Using the surface area and the diameter of the pulleys, taking into account the arc length of the pulleys a belt of 3” wide, 14mm thick with a ribbed pattern was chosen. The PSI of stress on the belt was 83.3psi while the max allowable is 125psi leaving a S.F. of 1.5

FRDPARRC link: Module 1 https://docs.google.com/spreadsheets/d/1FT5RGsqIyA6vjCt9G5TkHKFe0o_OsVl_HCeKXWggnIk/edit?usp=sharing

Module 2: Gear Driven Generator

This module turns the generator by a set of gears coupled directly to the turbine shaft, this is the preferred choice of modules because it is the sturdiest and has the least number of consumable parts, it will however require annual servicing of the gear fluid to which the gears are incased. This system has 1 degree of freedom. The gear ratio will be a 390:1 ratio and will be split using a 100:4-62.4:4 gearset. This option is the middle of the road in terms of cost as a pulley system is initially cheaper, but will have more service costs. The gearset was designed with A36 steel with a shear stress of 14,400 psi. The max load under 150MPH or 65m/s wind conditions would be 50,750 N-m on the shaft of the turbine, this translates to 8320 psi on the 2^nd pulley where torque will be greatest on the system. The teeth mesh was calculated to be 1.5” of positive engagement with a 3” tall gearset. This leaves a S.F of 1.73:1 at 150mph.

FRDPARRC link: Module 2:

https://docs.google.com/spreadsheets/d/12vOkNHR1OOZ5j5z8wXnyj8_GjoZaxIlxVwDAif2oCXU/edit?usp=sharing

Module 3: Chain Driven and Gearbox Driven Generator

This module is the most complex and most expensive option, there is a chain drive that will create a ratio of 4:1 leading to a gear box where the rest of the multiplication will occur to a final drive ratio of 390:1; the gear box will have a ratio of 97.8:1. Under max loaded conditions (150MPH winds) the chain will experience 12687N-M of stress as well as the gearbox. This can lead to major failure, the solution is to oversize the components to reduce this risk, with a chain a double roller can be used and with the gearbox, hardened gears as well as oversized gears can be used. This however dramatically increases the price, leaving this option as the last choice due to the complexity and cost. This system has 2 degrees of freedom.

FRDPARRC link: Module 3:

https://docs.google.com/spreadsheets/d/1kFZ8oSab-dZPzJBbuJxVCl_OH3xaS6mxZX-j-uWUsq4/edit?usp=sharing

Lessons Learned:

• READ THE INSTRUCTIONS CAREFULLY
• Understand what you are making does not have to be complicated
• If something is misunderstood go back to the basics
• Over engineering is a necessity for some components that will see mother natures abuse.
• Inner components constrain outer components regarding size requirements in loaded situations
• Cold Coffee hits harder at 3am so do the tears

Partner:

Walker Bond ( https://uncc.instructure.com/eportfolios/2270 )

Activities Date and Time: 

9/17/2021 14:00-16:00 Create group/brainstorm ideas

9/20/2021 13:30-16:00 Create solidified purpose

9/29/2021 16:00-23:30 Add Info to E-profile, Create Gantt Chart, Sketch Ideas, Research Topics More In depth

10/04/2021 16:00-20:00 Create a defined decision matrix

10/06/2021 07:00-10:00 research different turbines

10/13/2021 12:15-13:00 Talk to Dr. Fagan regarding forces on wind turbines

10/13-14/2021 18:00-01:30- Complete research, sketches and canvas update

10/18/2021- 18:00-21:00-Start load calculations for projected height and width

10/25/2021-06:00-07:30 Sketch a semi-complete assembly

10/27/2021- 12:15-14:00 Dr. Fagan information session

11/03-04/2021- 18:00-04:00 Finalize load calculations for material, Create Cad model, update webpage

11/07-08/21-19:00-05:30 RE-design modules properly and update project

Resources: Generator model used in Cad thanks to Mei Rezki Rosi Pratama, https://grabcad.com/library/matari-15-kw-1Links to an external site.

Bearing assembly: https://www.mcmaster.com/7111N31/Links to an external site.

Below are the links for the CAD Model that is a completed unit: The individual modules will be listed below as well