Design and Simulation of a Lift-Mode Crosswind Kite Power System
A very brief summary of my work towards designing and analyzing a wind-energy system that is driven by a kite. Design parameters, challenges, and results are presented, as well as the underlying motivation for the research.
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[00:00:02.605]Hello, everyone, my name is Nick Swerczek.
[00:00:05.360]I am a Senior Mechanical Engineering Major
[00:00:07.700]here at Lincoln.
[00:00:11.020]And my sponsoring professor is Dr. Wei Qiao.
[00:00:14.090]My project was over
[00:00:15.033]"Design and Simulation
[00:00:16.610]of a Lift-Mode Crosswind Kite Power System".
[00:00:21.070]This, in this presentation,
[00:00:22.580]I'll try to quickly go through all these,
[00:00:24.580]but I get into a little bit
[00:00:26.060]of the background on the theory
[00:00:27.550]of as to why I'm doing the-
[00:00:29.000]I wanted to do the research that I did.
[00:00:31.610]Some of the pre-design analysis that I did,
[00:00:34.840]the final design that I created
[00:00:37.140]and the some of the conclusions
[00:00:38.520]and future recommendations that I would make.
[00:00:42.613]So, for theory and background,
[00:00:44.440]this is mostly motivated by the limitations
[00:00:47.200]of current wind turbines.
[00:00:50.210]They basically, they're built on very strong,
[00:00:53.100]heavy steel towers.
[00:00:55.570]These towers are extremely expensive to manufacture,
[00:00:58.440]purchase and transport, and install.
[00:01:01.030]And it also limits their height
[00:01:03.580]which means that they have to operate
[00:01:04.770]within the Atmospheric Boundary Layer.
[00:01:08.540]Basically, the Atmospheric Boundary Layer,
[00:01:10.990]very quickly, is the region of the atmosphere
[00:01:14.860]that is affected by effects with interactions
[00:01:18.620]with the surface.
[00:01:19.630]That could be thermal effects,
[00:01:21.080]it could be friction effects.
[00:01:23.120]It makes just when more, much more chaotic
[00:01:27.000]And above this, this layer, wind does a lot steadier
[00:01:30.670]and more constant and reliable.
[00:01:33.410]And as it happens,
[00:01:34.800]the thickness of this layer is directly correlated
[00:01:36.650]to how flat the surfaces
[00:01:39.460]and as it happens in Nebraska,
[00:01:40.900]is a very flat surface relative to a lot of the earth, so.
[00:01:45.630]So, in 1980, or yeah, in 1980,
[00:01:48.860]this guy proposed using kites
[00:01:51.510]as an alternative to a wind turbine
[00:01:53.570]as a way to convert wind into mechanical work.
[00:01:57.330]And his initial calculations actually estimated roughly
[00:02:01.430]3 to 20 times power output from an equivalent turbine.
[00:02:06.630]And that range is, it's a very large range
[00:02:09.290]but that's supposed to basically accounting,
[00:02:11.300]for really conservative design and optimistic opportunity.
[00:02:17.790]Some of the detailed, notable details of his paper,
[00:02:21.300]he proposed two different methods of,
[00:02:24.700]using a kite to generate power.
[00:02:26.710]The first actually mounts generators
[00:02:30.200]to the kite, it's called Drag mode or, or Fly-gen.
[00:02:34.070]Second one, uses the tension from the tether
[00:02:36.740]and the spinning of a spool to actually generate the power.
[00:02:39.890]And that's called Fly-gen,
[00:02:41.100]or excuse me Ground-gen or Lift mode.
[00:02:45.060]He also said, showed that the peak power
[00:02:48.160]is around 30% generation.
[00:02:50.810]And it also increases with the square
[00:02:53.480]of your lift to drag ratio.
[00:02:55.690]So my project,
[00:02:56.810]I wanted to basically determine the parameters
[00:03:01.360]I was getting into the science for the first time.
[00:03:03.450]There was a lot to learn.
[00:03:06.040]I simulated some of the basic building blocks
[00:03:08.690]of the system, design a buildable model
[00:03:11.990]and then, actually tried to build
[00:03:13.430]and test the system.
[00:03:14.570]As a bit of a spoiler,
[00:03:15.440]I did not make it to the fourth stage, unfortunately.
[00:03:18.830]With COVID-19 and this being my senior year of college,
[00:03:21.730]I just did not have the time, but yes.
[00:03:24.840]So, some of the parameters for a Ground-Gen System,
[00:03:28.027]its system basically has to cycle
[00:03:29.520]between two alternating stages.
[00:03:31.930]One stage, you basically allow the kite
[00:03:34.030]to pull the tether out.
[00:03:36.520]And the other stage, you're pulling the kite back in
[00:03:40.490]with the tether.
[00:03:41.840]For net-positive power, the tension in the cable,
[00:03:43.860]it needs to be greater than,
[00:03:46.300]when you're allowing the kite to pull it out.
[00:03:48.260]The tension needs to be greater than
[00:03:49.840]when you're pulling it back in.
[00:03:51.980]And you can do this by messing
[00:03:53.480]with the kite's Angle of Attack and velocity ratio.
[00:03:59.640]So, I did a quick analysis on this.
[00:04:01.750]The biggest takeaway from all this,
[00:04:03.920]is that you can control the velocity
[00:04:07.270]of the, the rotational system
[00:04:09.480]that is connected to the generator
[00:04:11.060]by controlling how fast you're damping the energy out of it
[00:04:15.790]as a representative by that constant B.
[00:04:18.550]So you can use gearings or something like that
[00:04:20.290]to step up or step down how fast that shaft is rotating
[00:04:23.480]and dispersing energy from the system.
[00:04:28.530]Also did an Angle of Attack Analysis.
[00:04:31.090]I, this actually, the Aerodynamic Analysis that I did
[00:04:34.730]took the longest
[00:04:37.181]out of anything.
[00:04:38.230]I used XFOIL, which is an old 4th gen program
[00:04:41.870]and I tied it into MATLAB
[00:04:43.800]to sort of calculate all these, the coefficients.
[00:04:47.250]I used the NACA 4412 Airfoil
[00:04:50.920]because it has a really good lift to drag ratio.
[00:04:53.970]Basically, take away from this is that you want the,
[00:04:56.800]during the power cycle, you want it to be in the peak area.
[00:05:01.860]And then when you're pulling it back in,
[00:05:03.930]you want it to be oriented in a way
[00:05:05.180]that this is as low as possible.
[00:05:09.870]This is also sort of a sample.
[00:05:12.520]I did a lot of simulations just to determine the effect
[00:05:16.060]of a fin
[00:05:18.030]on the system
[00:05:18.863]so that I can make sure my control system,
[00:05:20.890]control surfaces would work properly.
[00:05:24.980]So, generally what I was going for
[00:05:27.690]when I was modeling this system is I wanted to model it
[00:05:30.520]like the other kind of powerless flight system glider.
[00:05:36.630]So that means long, long wings with a,
[00:05:41.120]very thin profile
[00:05:42.260]or a short profile, excuse me, and a thin fuselage
[00:05:46.350]and just everything being as light as possible.
[00:05:50.200]I also had to make a decision between a soft,
[00:05:51.940]Soft-Shell Kite versus a Hard-Shell Kite.
[00:05:54.530]Soft-Shell Kite would be something
[00:05:55.620]that's made out of fabric or plastic.
[00:05:57.250]Hard-Shell Kite would have like a,
[00:05:59.430]rigid rods or something like that,
[00:06:00.790]that's holding it together.
[00:06:03.070]Soft-Shell Kites have a big advantage
[00:06:05.420]in terms of their lightness and their simple, simplicity.
[00:06:09.600]So there, you're gonna be able
[00:06:10.433]to get a lot more power out of them technically
[00:06:12.510]but they're also, because of their softness,
[00:06:16.060]it's hard to analyze a design.
[00:06:18.110]It's basically the opposite
[00:06:19.040]for Hard-Shell Kites are heavier
[00:06:20.290]but they're easier to design and analyze.
[00:06:21.730]So, that's what I went with.
[00:06:25.290]This is my final SOLIDWORKS model.
[00:06:28.120]It's version four.
[00:06:29.930]I think I went through like five different iterations
[00:06:32.040]of all this.
[00:06:33.660]It took a while to come on this
[00:06:34.700]but this is basically what it is.
[00:06:38.709]It uses carbon-fiber tubing to provide a structure
[00:06:41.990]and then that tubing holds a bunch of a 3D printed ribs
[00:06:47.290]which actually provide the shape
[00:06:48.570]to the wings and then stretched over those ribs.
[00:06:50.810]So it would be some sort of thin plastic
[00:06:53.780]which would actually create the surface.
[00:06:55.810]And then of course housed within this
[00:06:57.610]is all the electronic parts that you need
[00:07:00.090]for controlling and monitoring the behavior of the kite.
[00:07:05.240]Talking about the electronics,
[00:07:06.780]this is the, the basically the simplest control system
[00:07:09.330]I could come up with.
[00:07:10.700]You have a 6DOF Sensor there
[00:07:13.400]to basically track its position in space,
[00:07:17.120]You have an Atmospheric Sensor to sort of track pressure
[00:07:20.953]You can get density readings from that.
[00:07:24.660]You have a Radio Transceiver
[00:07:26.220]or a MircroSD Card,
[00:07:27.440]basically they store all the sensor information
[00:07:29.470]that you're getting.
[00:07:31.060]Obviously, a battery and your control board.
[00:07:32.880]And then you have all the servos that handle
[00:07:35.790]and actuate the control surfaces.
[00:07:40.140]The conclusions I got from all this,
[00:07:43.410]I've come, come through this rather quickly
[00:07:45.330]but you could control the velocity ratio of the,
[00:07:49.800]of the kite with respect to the wind
[00:07:51.960]via how fast you damp the energy
[00:07:53.790]out of the rotational system
[00:07:55.290]that's hooked up to the generator.
[00:07:57.910]You could likely accomplish quite a lot with a very cheap
[00:08:02.630]and simple kite design,
[00:08:05.310]and empirical methods and experimentations
[00:08:07.350]are needed for the best analysis.
[00:08:09.510]You can't really analyze this kind of system
[00:08:11.660]without actually going out and doing testing.
[00:08:13.850]So for future study,
[00:08:14.910]the next step would be to actually build
[00:08:16.810]and test a simple system.
[00:08:18.720]You want to run test to quantify the power-output ratio
[00:08:23.640]and actually test your control system,
[00:08:26.130]make sure everything's working correctly.
[00:08:28.760]You also, it would be good to optimize the path
[00:08:31.750]that you take on the power stroke versus the reload stroke.
[00:08:36.620]And also finally, the biggest thing actually,
[00:08:39.850]really of all these bullet points
[00:08:41.760]is to compare the output power
[00:08:43.350]of this kind of system to an equivalent turbine system.
[00:08:47.160]Just to make sure that your cost per kilowatt-hour ratio
[00:08:50.610]is comparable or better.
[00:08:53.520]And if so, how much better?
[00:08:58.749]Yeah. So thank you for listening to me.
[00:09:01.060]And I think I'm overtime now.
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