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# Current System
[[File:Wind-turbine-system-diagram-v1.png|850px]]
[view and comment on system diagram](https://whimsical.com/RTwJtGcE62ijqnrpdg2m85)
__Equipment manuals__
__Aurora 3kW inverter__ - [data sheet](https://drive.google.com/file/d/1b_QylTKJzde8saR7A5cHfEcUz2PQZ7JJ/view?usp=sharing)</br>
__Aurora wind interface box/rectifier__ - [manual](https://drive.google.com/file/d/1YciYcLJHPdqsU5kGbLKZFx5bYpHzk-JD/view?usp=sharing)</br>
__TCMG-3kW Taechang N.E.T. Generator__ - [online specs](https://tcnet.en.ec21.com/3kW_Small_Wind_Turbine--1105310_1105312.html)</br>
__3kW Discharger Breaker - 3K-DIS-001__ - can't find online manual - </br>
__3kW Dynamic Braking Resistor__ - [instruction manual](https://drive.google.com/file/d/1u_LV9H5tyxtQRk8UA6zT45W3fTitwZu3/view?usp=sharing)</br>
__Anemometer__ </br>
__Wind direction meter__ </br>
## Tower, shaft, bearings
__Shaft tubes__
The diameter of the generator's shaft is 1.22 in. It's rated RPM is 360 at 12 m/s.
The shaft consists of an 8 ft section and a 4 ft section of [1.5" OD x 0.134" Wall x 1.232" ID stainless seamless round tube](https://www.onlinemetals.com/en/buy/stainless-steel/1-5-od-x-0-134-wall-x-1-232-id-stainless-round-tube-304-seamless/pid/14789) made out of the 304 stainless steel alloy. The two pieces of the shaft are connected with a slightly wider tube that of [1.75" OD x 0.12" Wall x 1.51" ID](https://www.onlinemetals.com/en/buy/stainless-steel/1-75-od-x-0-12-wall-x-1-51-id-stainless-round-tube-304-welded/pid/483).
__Bearings__
The shaft is held in place by two [Mounted Ball Bearing with Nickel-Plated Iron Housing
for 1-1/2" Shaft Diameter](https://www.mcmaster.com/6494K19/).
### Forces on the shaft[^ncyuMaterials]
## Tower
## Blades
## Anemometer - wind speed measuring
[[File:PorchAnemometer-anemometerroof.jpgjpeg|border|thumb|Anemometer data logger prototype on porch400px]] We are using a Vortex wind sensor. One revolution per second equals 2.5 mph. Since our anemometer has a relay (a mechanical switch), it creates a _switch bounce_switch bounce. Therefore, we need a debounce circuit. Please refer to [[Electrical Control Unit]] for the repository and more information. # Prototyping ### Twisted Savonius V1 [[File:CAD-v1-savonius.png|border|thumb|CAD of twisted Savonius prototype]][[File:Savonius-prototype-v1.jpg|border|thumb|V1 of twisted Savonius prototype]]We attempted to prototype a twisted Savonius turbine to allow a more continuous application of force when the wind turbine spins. Ideally, both sails would be slightly offset to each other to allow airflow from one airfoil to the other. Such an offset can be seen in the following picture that inspired our design. As the Savonius turbine is based on drag, it has a high starting torque, which will allow for lower self-starting speeds. [[File:Savonius-twisted-airfoil.png|frameless|border|]] With our next prototype, we seek to combine a twisted Savonius turbine with a Gorlov turbine (Rajdeep Nath Dr. John Rajan; How to Design and Fabricate a Vertical Axis Wind Turbine: Design, Analysis, and Fabrication using Gorlov and Savonius Blades (p. 75)). We can 3D print the blades but might want to scale down the prototype to decrease printing time. [[File:Savonius-gorlov-waterpump.jpeg|frameless|border|]]
# Research and background knowledge
## Tower design
We considering building a wooden structure on top of the house to elevate the wind turbine. A tripod design that attaches to the two bump-outs and the gable would make the tower accessible. We are currently considering a tower height of 15 feet up to 22 feet.
[[File:Anemometer-house.jpeg|border|thumb|The tower could be mounted in between the two bump outs]]
Guy wires are an option to secure the turbine as it will be quite large to account for low wind speeds. However, a pole that is merely held up by guy wires is not accessible enough.
## How to charge our batteries
We seek to charge our battery system with the energy obtained from the wind turbine. However, our current system diagram connects the AC rectifier to the inverter, which outputs 110 V alternating current (US outlets). As the energy output from the wind turbine will vary quite a lot, we need to charge the batteries with direct current (DC). For that purpose, we might have to acquire a wind turbine battery charge controller that can handle high voltages (0-600 V from the AC rectifier) to charge our 24 V battery system. Tae Chang offers a [Battery Charge Controller](https://tcnet.en.ec21.com/Battery_Charger_Controller--1105310_1105320.html). We probably need a _600 VDC 24v wind turbine MPPT charge controller 2500W_. Most charge controllers seem to be in the range of 200-300 VDC ([example](https://www.grainger.com/product/55HX52?cm_mmc=PPC:+Google+PLA&ef_id=CjwKCAiA4o79BRBvEiwAjteoYOv_peCpu8ur8vgakfuuD9tEog_f5FFEEgu7gsxPleKhCmGqSbyKoRoCkEUQAvD_BwE:G:s&s_kwcid=AL!2966!3!264955915673!!!g!461787465034!&gucid=N:N:PS:Paid:GGL:CSM-2295:4P7A1P:20501231&gclid=CjwKCAiA4o79BRBvEiwAjteoYOv_peCpu8ur8vgakfuuD9tEog_f5FFEEgu7gsxPleKhCmGqSbyKoRoCkEUQAvD_BwE)), which might be enough considering wind speeds in our area.
## Research papers, articles, media
Battisti, L., Brighenti, A., Benini, E., & Castelli, M. R. (2016, September). Analysis of different blade architectures on small VAWT performance. In Journal of Physics: Conference Series (Vol. 753, No. 6, p. 062009). IOP Publishing. https://iopscience.iop.org/article/10.1088/1742-6596/753/6/062009/pdf
### Small Scale Wind Turbines Optimized for Low Wind Speeds
Letcher, T. (2010). [Small scale wind turbines optimized for Low Wind Speeds](https://drive.google.com/file/d/1ZQyqHlQZY_gyVylVg2PHsEZCPJwZ3cGe/view?usp=sharing).
### 10 Wind Turbines That Push the Limits of Design
https://www.popularmechanics.com/science/energy/a4428/4324331/
### Design and Manufacture of a Cross-Flow Helical Tidal Turbine
Anderson, J., Hughes, B., Johnson, C., Stelzenmuller, N., Sutanto, L., & Taylor, B. (2011). [Capstone Project Report: Design and Manufacture of a Cross-flow Helical Tidal Turbine](https://drive.google.com/file/d/110NNrJwMsjzH_Jbfal9jF5kHzRMOwEfB/view?usp=sharing). University of Washington, Washington.
## General wind turbine knowledge
- integral length scale; from time series, we compute the auto-correlation function
- turbulence spectra
- averaging periods of 10 min are commonly used; 30 min period for turbulence studies; the larger integral time scale, the larger should be averaging period; sampling frequencies should be much smaller than the integral time scale- you have to detrend te the time series to get rid of high-frequency fluctuation # References [^ncyuMaterials]:http://web.ncyu.edu.tw/~lanjc/lesson/C3/class/Chap03-A.pdf
