AERO DYNAMO

"I will get a better grade on these social media posts, even if I just end up writing my garbage thoughts on the internet, at least the garbage is out"    -Kyle O'Connell

[kyledoconnell-blog1]

Final Reflection

Wow, that was my Wind tunnel Lab, 10 weeks in the tunnel can do a number on you but I think I came out a better engineer in the end.  I will be honest though, the first few weeks of the quarter were difficult for me because of the workload, the reflections twice a week, homework of other classes as well as the labs, and extracurricular that I was doing.

But also, I felt like I was not doing enough for some of the group project. During the 4412 project Matlab was a big part of the lab, and Matlab isn't really a collaborative effort therefore some people were saddled with a lot of the coding or the difficult parts of the coding. While I did do a portion of the work, there was no practical way of helping code and complete the coding that was required.  This was something that I was thinking about the whole duration of the 4412 airfoil.

Another thing that was on my mind during the 4412 airfoil was the pressure of finding the right numbers and the correct answers. Knowing that research existed that might contradict our findings was difficult to think about. Although these past experiments were useful to compare and check if our code was correct, we were still in constant anxiety that maybe our calculations aren't correct. I'm not sure if there is anything that can be done about this, but the transition from getting exact numbers in the labs that we had in previous labs to the level of uncertainty that the wind tunnel has was something that I believe was a transition that was hard to get used to.  Fortunately, the lecture about  error was extremely helpful in the confidence and the legitimacy of our tests and work. And I suppose thius fits into the idea that science never has an objective and fixed position on any experimentation. The experiments define the theory, and the math that is created is only serves as a tool rather than defining absolute truths.

This may sound like an obvious revelation but it give me confidence that the results that we collected are not something that I'm bad at but rather part of the process of the experiments we run.

Out of all the labs/ experiments we ran the NACA 4412 and the Lab Hack were my favorite parts of the lab because we were able to design and were given a lot of liberty with what we wanted to pursue. I get excited even thinking about it because it think it's exactly what I love to do. I find the most satisfaction out of going after an objective but with the freedom of pursuing the objective in a way that I see fit.  And although that is what Matlab allows for, seeing an actual  product come out of the effort that was put forth is satisfying.

To answer a prompt from the email that Dr. Doig sent out, I think I'll choose this one.

What did you find to be the most memorable "moment" of 307?

My favorite moment in the 307 Lab would definitely have to be the blue dye explosion, but I feel like that is way too generic, I wasn't even a part of that experiment and I can think of something better.

It would have to be Harrison drilling  pilot holes in the diffuser. For some reason, Harrison was perfectly proportioned to be in the diffuser, and working around the diffuser cone was one thing that made it even more comical. We didn’t take a photo but nonetheless, the flexibility of Harrison was quite impressive. And it will probably be something I hold over his head for a while.

Overall, I really enjoyed how this Lab ended and the work that we did in the tunnel. I cannot wait to work in the tunnel this summer, even if it is unpaid, the ability to work in an environment that is similar to the lab hack project will be something that I cannot wait to do.

[kyledoconnell-blog1]

Foam Insert Installation

To deal with the gap between the debris screen and the fan housing we decided to cut blue foam inserts to smooth the transition between the  test section octagon and the fan housing.

Using the cad model of the tunnel we created inserts that continued the polycarbonate inserts that we used to blend the corners of the tunnel. The small extrapolation of the inserts were then used to create a file that the CNC machine can convert into g-code.  For this project  we decided that if we had the CNC hotwire available , then we should use it accordingly.

With the help of Kurt from DBF we completed the inserts in about two hours, which was for 10-12am of this Thursday. The hotwire snapped once so that was a delay that ended up costing about 30 minutes of reassembly and re-zeroing. All in all, it’s a fantastic machine that was fun to watch as it worked on our parts.

The parts turned out great, the finish along the curve was excellent and much better and faster than anything we could have done by hand. The edges did get messed up but nonetheless, the parts looked great. The finished forms were twice as thick as needed so I was volunteered to cut the pieces down in the hangar as I was the only one wearing pants that day. The others in my group finished installing the diffuser plastic inserts. they turned out great. 

The foam inserts that I cut were installed shortly afterward with gorilla glue 5 minute epoxy that was found in the tunnel. After the cure, the pieces were sanded down to ensure the proper fit in the tunnel. To install these, the tunnel diffuser had to be moved. Which was no problem, the getting it back in was the challenging part. It was annoying because we spent nearly all the time that we intended to test trying to get the diffuser section back in the tunnel.

The weird thing was that we removed and put back the tunnel so many times last  Friday with more ease, you would think that this would be a snap! We don’t know why it was giving us so much trouble. Either way, the tunnel was installed properly, and then we began our tests, except the dynamic pressure  readout was not working.

I was looking forward to this day when we would get an answer whether all that we did was in vain or for triumph . Oh well, all thing in time, I was just looking forward to the satisfaction of something that I helped make and design working.  Sometimes I feel that is a feeling that I haven't had in a long time.

The good news is that I destroyed some scrubs on Xbox live later that day, so that was nice but, it's not quite the same.

[kyledoconnell-blog1]

Final Cuts and Installation Prep

Yesterday our progress was halted in by an overcrowding of the hangar shops, and although we were able to make some crude cuts with the super mileage jigsaw, it was too slow for us to complete all of the necessary cuts in the plastic we needed. Luckily, today we were able to get all of our cuts done in mustang 60 which was a considerable less of a walk.

After all the parts were cut, we measured, and marked the position of all of the panels in the wind tunnel. For my own sake we used a 1-8 naming convention that started on the lower left side of the tunnel and progressed in a clockwise  fashion. While the cuts were simple and straightforward we had a lot of difficulty in the tunnel boring pilot holes  in the tunnel. Not to mention the fact that  the led paint was a real pain in the ass.

It made me think of the how difficult things are to reverse when you are working with a something so ubiquitous as paint. Not only that but its hard to believe that only sixty years ago or even less, gasoline was leaded.  Its hard to believe that even when we used this dangerous chemical in an everyday use that the environment didn't kill itself after such a  trauma. Even crazier was the fact that we vaporized the crap.

I don't even want to think about it. It's disgusting. back to the project , we still have a lot to do but with what we have now, I believe that we will be able to deliver our improvements also. One of the things I was not expecting was how good the end result looks.  See the picture below.

Next up we will install all the panels in the diffuser and hopefully get started on the test section side of the octagon. I cannot wait to finish this project, and hopefully, we'll have some  improvement in tunnel performance!

Also, I've been trying to upload an interesting video of a phenomenon that took place two weeks ago. The weather This May has been quite temperamental, and  often we will get a rolling marine layer that runs up the Los Osos valley and happens to flow right into my backyard.  On a Friday two weeks ago I was lying in a hammock in my  and managed to capture this video of what appears to be a vortex created by bishop peak.  I believe this is the fact because  Bishop peak is the only outstanding structure that lays in the path of the prevailing wind. Therefore, I believe that these vortices  were caused by  the onshore  flow  of moisture and the  sheer height and prominence of bishop peak. Here is a map of the surrounding area that details what I believed I observed.

The video is above and was taken with an iPhone, the effect is best observed by watching at two times speed which can be activated by pressing the settings icon in the toolbar of the player. Although it is not exceedingly clear like that of satellite images  or time lapses, I believe that it is adequate footage of the effect.

[kyledoconnell-blog1]

Chop Chop

Today in the lab we  learned that we have an in house option for the  plastic inserts that would be placed in the tunnel. It’s a material called mackrolon made by bayer plastics and it is essentially a polycarbonate sheet that is stiff enough to hold its own in the tunnel and flexible enough to be placed in the tunnel and be a smooth transition between the plastic and the fan inlet/ outlet

Harrison and Eric cut down the plastic that we had marked on and we were able to place the triangle in the wind tunnel and test the fit. With two wood screws in each, and possibly some silicon caulking , the plastic should work beautifully.

One thing that we did notice that there is a gap between the fan and the debris screen in the rear of the tunnel. We are wondering if that will be a problem with the insert as the insert on the test section do not sit flush with the fan housing. What I'm worrying about is if we need to have a continuous blend into the fan, we need to make sure that it doesn’t  freaking fall into the fan. That would be bad.

Today, we went over packing or efficiency of packing the triangular inserts, unfortunately the polycarbonate sheet is at odds with the dimensions that we need and that means that we will unfortunately have some unusable plastic left over after we make all of our inserts. We also need more plastic because of this fact, in total we will be able to squeeze 10 triangle inserts out of the entire sheet. So if you ask me that's pretty good.

During the last hour of lab we performed a simple test of the tunnel diffuser using tufts. WE wanted to see the actual recirculation or any other strange aerodynamic effects in the diffuser. The video documents these problems in the tunnel and confirms our theory of recirculation within those very small pockets.

we tested at multiple speeds the first being  15 m/s  approximately. We then tested at a range of speeds, however, as we expected the pocket of recirculation was formed even at 15 m/s. This Test confirms that our project will have an effect although the exact performance metric and magnitude is not known. If all goes well, this simple modification will produce a result that increases the  speed of the flow for a given rpm.

One of the worries that I have about this project is the aesthetics that will come out of it, I hope that we aren't too rushed come finals week and we are able to make the inserts look nice. WE might have to discuss painting or other installation considerations to make sure that our project is something that makes the wind tunnel not only perform better, but also look better.

Overall today was a productive day , and I look forward to completing the rest of the inserts and installation.

[kyledoconnell-blog1]

Final Thoughts: Flow Visualization

Aside from some hiccups,  this lab was a though exercise  in how I can get frustrated and upset when things aren't going perfectly. It one of the  things that I believe makes me thoughtful in the design process or planning process but extremely liable to anger when things aren’t going well.  This happened a lot when I played sports in high school and even in college. My hot head would get in the way of performing well and actually making good decisions on the court.  I think that this is probably one of my failings and although it give me room to get better, it is also the reason why we work together in a lab. Our combined strengths make us better as scientists and experimenters. (don’t know if that's a real word). One of the things I am glad about is the fact that we didn’t try to make this test overly complicated or difficult, the difficulties came out of things that we didn’t have control over and that is something that we dealt with and I am proud of that.  

I learned a lot from this lab and it showed me that sometimes when things don't go your way, all is not lost, you can still produce meaningful results. Our experiment showed this, that the even when we didn’t get all that we hope for, all was not lost and we still got what we came for. I am looking forward to the lab hack challenge next week as the quarter comes to a close, it seems that this lab hack will give us a greater degree of freedom, something that I've been looking for in this lab.

[kyledoconnell-blog1]

Interesting Visualization

I was browsing my favorite link sharing website, Reddit the other day and was amazed by this video of an microorganism bloom that happened in the sea of Cortez of Mexico. This video shows bio-luminescent organisms called Dino-flagellates or extremely small phytoplankton that are common through the sea. A recent bloom of these small organisms has created an amazing light show in the ocean. But what really caught my eye was the movements of dolphins through the water. I’ll link the video below.

Never mind, I can’t find it, the link got taken down :(

But this did get me thinking, if these small creatures illuminate when disturbed perhaps they can show where turbulence occurs on a body in the water tunnel, it would be pretty neat to see  just exactly where the flow turns turbulent instead of relying on a constant locus of dye or coloration. While a lot of technical considerations still must be ironed out before this is a legitimate idea, I think that I has the potential to be a powerful visualization tool.

[kyledoconnell-blog1]

Testing day NACA Flow Viz

This was quite possibly the most rage inducing day thus far. We started out fine, we planned ahead, everything was ready and yet everything that was important to our experiment ended up failing on us It was a day of learning the meaning behind murphy's Law.

We arrived early to tape the tufts on the wing and prepare the tunnel for our testing. Taping went very smoothly. tim figured out a way to mass produce the tufts and although we didn’t end up using aluminum tape for the tufts, we were able to produce tufts consistently  using the making tape and although it is somewhat rougher, it shouldn’t matter as much, due to the tufts create far more of an effect than tape ever would.

The real trouble started in the actual wind tunnel during testing and our first problem was watching the sting not follow the instructions we gave it trying to use the auto angle.  We ended up having to use the manual control and the digital protractor. We communicated via some walkie talkies and we called out the angles. In addition we were running the tunnel too slow to begin with and we achieved inverted stall at only 3 degrees or so. WE increased the speed and saw that the tufts straightened out sure enough. We also did not have a dynamic pressure reading so the whole time we could only estimate how fast we were going.  Additionally, and unfortunately, the go pro that we used during the test to show a top down view died during the test but we were able to at least 3 clips of a full alpha sweep. Even when stalled, the yarn turfs didn’t seem to ocillate but instead curled one way or the other. While we started testing the second wing the blue wing we were unable to stop the wing from increasing the angle of attack even when in manual mode. And by then I believe that point in our testing our go pro on top of the wing was truly dead.  So it was a rough and upsetting day, as we worked pretty furiously beforehand to get everything ready and then everything sort of fell apart in the tunnel. Fortunately, we have enough to talk about and  we did see some consistent behavior of the tunnel.

also just before the force balance when to poop, we were able to take these photos of the blue airfoil before we had to shut down the tunnel

yay!

[kyledoconnell-blog1]

Flow Viz Planning

We are in the tunnel and testing the lengths of yarn and which tape to use while in the tunnel. I'm personally curious as to how much aluminum tape is used by the tunnel  over the course of the year. That would be interesting to see or investigate. I thought that that is was just silver colored and smooth gaffer tape or stage tape, but that is not the case.

We kind of want to use the aluminum, because it is so easy to make because of its backing that acts like a sticker rather than it being stuck to itself. I'm confident that using masking tape isn't going to make too much of a difference as the yarn tufts that we want to use are so big already. Kevin suggested that we use ribbon…

I feel like ribbon will just lay down flat. And only get up when there is separation, also who's to say that maybe the ribbons will just lay down the whole time? I trust the ribbons a little bit more but also, I don’t know that I'll have time to go get different material with the AERO 405 HW Approaching. Thank goodness it was pushed back.

We tried several different lengths of tufts and its funny that they seem to have a critical length where they start to act like string instead of little stiff rods. If they are under 1 inch they tend to not bend or give at all with a disturbance while tufts over 2 inches(5.08 cm) long seem to get wrapped around other tufts and also seem like they just sort of whip around too early. It's hard to talk about the two inch tufts because we just know that they are too long for this  experiment. They just don’t look right …… and that's the best explanation that I can give. Not very scientific but trust me, we think that the tufts of 1.5 inches or 3.81 cm will do just fine. And us standing behind the diffuser testing  the tufts on the red wing seems to reflect that.

Also, Jordan's Hair in the wind tunnel is absolutely majestic, I think he should just stand behind the diffuser for the whole lab bringing beauty to the world. See the video below

Overall, we came up with a plan to test, and planned to meet 2 hours before our test. So we could get everything squared away and ready. Until I have another great thought , Seeya !

also one of the group’s test s in section 1 looks really really cool, and also reminds me of the battlefield 3 loading title cards, pretty neat if you ask me!

The Test Section

Battlefield 3

[kyledoconnell-blog1]

Saturday meeting

Our group had the unfortunate experience of being first up  on Tuesday and therefore we met on Saturday night to discuss results from last section and the tests that we would need to do to get a set of data could possibly mop up any errors as well as prove repeat ability  in our experiment.

Our worst fears, come to life

Garret, having poured over the data on Thursday, was the first to discover that our high speed tests of the 4412 had gone awry. Although our test was nominal in some ways, and adverse in others, we discovered that we had not captured the stall in our high speed tests!

Even when we had exceed the expected stall angle of 11-15 degrees, we still had not managed to capture stall behavior even at 18 degrees. An odd fact, and something that we would have to revisit when we went back. When I was looking at the tunnel , I did not notice the buffeting of the airfoil like we saw at the lower speeds.  Although this seemed odd to me at the time, and it was indeed a mental note of mine, I thought nothing of it, and dismissed it as the increase of speed led to an increase in frequency of the buffeting that was either not superimposing upon itself or was too weak to buffet the airfoil.

At further analysis, however, these results make sense, as I was taught in glider school, the stalling of an airfoil is purely one of airspeed. And this was drilled into my head as I would approach final landing. There are too many stories of glider pilots being too slow too close to the ground attempting to make adjustments or maneuvers that would ultimately severely injure or kill them. It’s a fact that is all too real among glider pilots, and the 'one shot at landing' makes this fact of keeping up airspeed all too important.

Here a pusher plane attempts to make an aggressive maneuver low to the ground, this photo most likely ended up in a crash.

When we return to the wind tunnel we will repeat this test except capture the lift from 17 to 25 and also if we have time, the pressure recovery of the wing from 25 degrees to 16 degrees AoA.

[kyledoconnell-blog1]

Lack of Stall

here this GIF shows our increasing AoA  and shows the velocity profile that the rake captured. as you can see, the faster, and therefore much more turbulent flow moves down the rake as angle of attack is increased. This expected as the higher the AoA, the greater the Lift, and a greater velocity of air moves downward. When stall occurs, almost the entire span should increase in velocity. This is shown in the last two frames of the gif on the left. It turns out that we were unable to capture stall for the high speed flow. this is what we will have to do mop-up testing on which is unfortunate, but necessary because we need to see the stall for the high speed flow. The maximum AoA of each is 18 degrees a still of the 18 degree AoA is shown below. 

the more distributed velocities indicate the lack of stall. Notice also how the velocities of the high speed flow begin to interfere with the boundary layer probes at the bottom of the wake. 

[kyledoconnell-blog1]

Wake Rake Experiment

Because were the second to last group to go for our pressure port experiment, we were consequently the last group to go on Thursday. Due to the difficulty of our last lab we were eager to be able to perform our high speed tests correctly and without slowing down the tunnel to move the airfoil.

Luckily, were able to move the angle of attack successful without slowing down the tunnel, although we do not know why the first experiment with the 4412 was so difficult to move, but without a doubt it was easier to move this week compared to last.

Additionally, the theory about pushing in the airfoil into the test section from the opposite side of the graduated side, will not work, that theory would only work with the cylinder lab. So nuts to that. There is a lip that sits in the way of doing so.

Of another note, there is a lip at the beginning of the rake that Is no doubt will have some effect on our readings of the experiment. We should see this show up on the plots that we get and thus we should be able to dismiss that as error. The boundary layer rake ports are simply there to report that the boundary layer exists.

Here is a picture of it…. Wow so original haven't seen this before.

Additionally, the wake rake is positioned almost exactly in the center of the tunnel.

Oooooooo …. symmetry!

That’s me measuring the lip that is present, with a high precision, high dynamic range, and most importantly, high speed low drag hood to prevent myself from the low speed flow that could be activated anytime while in in the test section.

And good news! We will have even more data because the pressure ports from experiment 1 are still hooked up! Yay, repeatability!

We were able to perform all of our tests nominally and moving the airfoil was a breeze this week. (puns)The pressure changed  little throughout the test, while we did see a decrease in temperature from 1330 to 1500.

[kyledoconnell-blog1]

NACA 4412 day 1

The is the beginning of our test. We started at -6 degrees to help us capture the zero lift angle of attack. 

Here, we are approacing the anticipated stall angle of 11-15 degrees, If the wing has not stalled already, it will soon.

In this picture, the airfoil is probably fully stalled, at 17 degrees, the airfoil was buffeting and vibrating. 

As a pilot, one of the signs of impending stall is buffeting or vibration of the aircraft. Similarly, during the wind tunnel test the airfoil began bouncing up and down and flexing within it’s mounts.  This effect is most likely caused because of the turbulence of the separating airflow. the turbulent effects disrupt the uniform distribution of lift , causing the airfoil to flex violently.

Stay tuned for the attack of the rakes!

[kyledoconnell-blog1]

The calculations above helped to determine the speed at which we should run tunnel to get similar results between the airfoil section and the finite wing, although the data the each produce will most likely not match up perfectly, it will be interesting to compare and consider the differences between them.

[kyledoconnell-blog1]

Procedure as outlined initially on Tuesday, April 12.

[kyledoconnell-blog1]

Experiment Planning

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LAB 1 Final Thoughts

[kyledoconnell-blog1]

the above photos illustrate the importance of knowing where and what  your pressure readings are. We discovered that the cylinder ports are not laid out in an intuitive numerical fashion. we were able to figure out which ports were doing what in the lab and then continue our tests. With the help of Jordan's Code, were were able to quickly modify and correct the problem. We were then getting good results however, one of the ports seemed a little troublesome so we ran some more experiments and were able to get the data we needed.