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Videos uploaded by user “JoshTheEngineer”
In a Nutshell: Afterburners
 
03:01
Let's talk about what afterburners are, when they're used, and how they work. In my first 'In a Nutshell' video, I'm testing the waters on giving simplified explanations for complicated topics. Let me know what you think. ===== RELATED VIDEOS ===== → Detailed Afterburner Video https://goo.gl/nt9KBp ===== REFERENCES ===== ► "Afterburners" in The Aerothermodynamics of Aircraft Gas Turbine Engines, Zukoski ► Mechanics and Thermodynamics of Propulsion, Hill and Peterson ► Aerothermodynamics of Gas Turbine and Rocket Propulsion, Oates ► Aircraft Propulsion, Farokhi ► Aerospace Propulsion Systems, Ward ► Fundamentals of Jet Propulsion with Applications, Flack ===== THUMBNAIL PHOTO CREDIT ===== By United States Navy, Mass Communications Specialist 2nd Class Michael D. Cole [Public domain], via Wikimedia Commons
Views: 9941 JoshTheEngineer
Explained: Slider GUI [MATLAB]
 
03:48
This video explains how to code a slider in a MATLAB GUI. It also shows how to change the 'Min', 'Max', and 'Value' arguments to alter the range of the slider.
Views: 17923 JoshTheEngineer
Explained: Linspace [MATLAB]
 
03:26
In this video I show you how to use the linspace function in MATLAB to easily create arrays.
Views: 9887 JoshTheEngineer
How To: Build Your Own Schlieren Setup
 
21:00
In this video, I go through a step-by-step process for how to build your very own Schlieren setup. First, I go through the basic theory and overview. Then I describe all the materials you'll need. Finally, I walk you through the full setup. By the end of the video, you should have no problem getting some nice pictures or videos with your at-home system. However, if you feel you need some more direction, don't hesitate to get in touch with me! Note: I will sometimes say 'laser' when I actually mean 'LED'. You will have to forgive me; I work with lasers in my research and have become accustomed to saying 'laser' whenever talking about some sort of source. Below are some website links that I found useful/referenced while going through my own setup. General Schlieren Knowledge http://goo.gl/gI1YQq http://goo.gl/pLwii8 http://goo.gl/uonkOt https://goo.gl/RFCSuG http://goo.gl/hegJHF http://goo.gl/YD0i0c Interesting Mirror Articles (slightly advanced) http://goo.gl/t16ePi http://goo.gl/BAL6Bj Want some more theory? Here's a video with some great visuals to aid your understanding. https://goo.gl/b31aOS Other Papers (you can search on Google for these) "Hypersonic Application of Focused Schlieren and Deflectometry" "Flow Visualization for Supersonic Flow Past a Wedge" "An Overview on Schlieren Optics and its Applications" "Design, Assembly, and Calibration of a Focusing Schlieren System" "Introduction to Shadowgraph and Schlieren Imaging" Below are little sections about the materials and where to find them (Amazon affiliate links). LED Light Source (https://goo.gl/bPbJx9) You can find tons of LEDs on Amazon. You will only need one, and I prefer a bright white LED, as seen in the link above. If you buy these, you'll end up with 49 extra, and who doesn't want an extra 49 LEDs lying around their house? I personally bought a single white LED from Radio Shack before the store closed at the mall. Resistors (470 Ohm) (https://goo.gl/XNH8u9) To build your own LED circuit, you'll need this particular resistor. The value comes from the fact that you are using a 9 volt battery, and that the white LED has a forward voltage of about 2 V and a current rating of about 20 mA. Using these values, you would need a resistor of 350 Ohms, but I've found it is better to be on the higher resistance side, and 470 Ohms is the next highest resistor you can use without having to wire together a series or parallel circuit to get the most accurate value. It's a compromise between simplicity and efficiency. Above is a link to a pack on Amazon, although you'll only need one. Circuit Board (https://goo.gl/tKNaFH) If you're making your own circuit (like I did), you'll want a circuit board to solder all your materials together. This one from Amazon seemed like a good bet. I bought mine straight from the Radio Shack at the mall. 9V Battery Connector (https://goo.gl/oL7M3g) To finish off the circuit, you'll need some way to connect the 9V battery. Above is a link to a 9V battery connector. Knife Edge (Single Edge Razor Blade) (https://goo.gl/zCyNt1) This is again one of those items where you only need one, but you'll end up buying a thousand. Above is a link on Amazon, but they sell them at any store like Target. Mirror (Spherical Concave) It looks like the mirror that I use has officially been fully sold out (from both Anchor Optics and now Edmund Optics). I'll be looking for an inexpensive alternative with the same quality, and will update this section if I find one. If you find an option, please leave a comment letting me know so I can update this section! Small focal length mirrors won't give you the sensitivity you need, so make sure to get a longer focal length mirror. Note that Z-type systems will use two parabolic mirrors, while this double-pass system uses one spherical concave or parabolic mirror. Camera (https://goo.gl/KmPwy7) I personally use my Nikon D3200 DSLR camera with its 18-55mm f/3.5-5.6 kit lens. I use this lens so I can zoom in on the mirror. I also have a 35mm f/1.8 prime lens, but it can't zoom (obviously), so I don't see that being as useful. Above is a link for the camera I have on Amazon (newer model). I have used my point-and-shoot camera and Samsung S6 phone to get videos and pictures as well. I mention this just so you realize you don't absolutely need to buy a DSLR camera. However, I will say the quality of the DSLR videos/images was much better than the other two. It gives you more control over settings, and will make your life much easier. Tripod (https://goo.gl/oKmyU8) I use two tripods during the video. The tripod that I use to mount the LED and knife-edge is a cheap plastic one that I got a while ago. I don't even know the name of it, but it's pretty terrible as far as photography goes. I purchased a higher quality tripod recently, and if you're looking for a low-cost, good quality tripod, I would recommend the one provided in the link.
Views: 85631 JoshTheEngineer
Explained: Popup Menu GUI [MATLAB]
 
03:48
Pop-up menus can be used to make a selection from a list of items. This video shows how to get the user's input from a pop-up menu in a MATLAB GUI. Tip: The method described in the video gives you a little bit more information to work with when extracting data from the popup menu, but if you want the most efficient code, you can use the code below. popVal = get(hObject,'Value'); assignin('base','popVal',popVal); In this code, you're simply getting the selected value. The first choice is 1, the second choice is 2, and so on. You can then immediately assign this variable back into the base workspace. This code is much simpler, but you also won't have a variable with the strings of all the choices available. In most of my applications, I don't care about the actual strings, just about the value that's selected.
Views: 28357 JoshTheEngineer
Schlieren Knife-Edge Placement
 
03:55
How do you know where to place your knife-edge for your Schlieren setup? In this video, I'll show you what happens when you put the knife-edge in front of, behind, and exactly at the focus point. After watching, you'll be able to place your knife-edge in the best possible position for your own setup. ===== RELEVANT VIDEOS ===== How To: Build Your Own Schlieren Setup https://goo.gl/TzM8vr How To: DIY Laser Schlieren https://goo.gl/ERghgJ
Views: 3454 JoshTheEngineer
Explained: Linear Interpolation [Math]
 
05:20
In this video, I explain how to obtain the equation for linear interpolation between two points. I then go through a simple example. Linear interpolation can be useful when you need data at points where data does not exist. This happens a lot when looking at tabulated data. Here are some examples of tabulated data where linear interpolation can come in handy: - Steam/vapor tables in thermodynamics - Property tables in heat transfer - Normal shock tables and isentropic relations tables in gas dynamics In the video linked to below, I show you how to program this equation into a graphing calculator (TI-83), so you can use it on exams or whenever you need a quick estimate. https://goo.gl/ntTuKl
Views: 16568 JoshTheEngineer
Explained: Edit Text Box GUI [MATLAB]
 
02:22
Edit text boxes can be used to input numbers or strings in your GUI. This video explains how create an edit text box and retrieve both string data and double data from it.
Views: 16858 JoshTheEngineer
Explained: Aligning Torque
 
06:05
Why does your steering wheel feel like it wants to straighten out when you're in a turn? In this video, I'll explain what aligning torque is, and where it comes from. ===== NOTES ===== ► I'm not including any mechanical trail in this description. ► The tire has no inclination angle/camber. ===== RELATED VIDEOS ===== → Explained: Aligning Torque Simulation https://goo.gl/NwVJjb → Explained: Tire Axis System https://goo.gl/Q3w7Br → Explained: Tire Slip Angle https://goo.gl/rjUcYG ===== THUMBNAIL IMAGE ===== By J.H. Sohn from Melbourne, Australia (2014 Australian F1 Grand Prix) [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons
Views: 2347 JoshTheEngineer
Explained: NACA 4-Digit Airfoil [Airplanes]
 
10:16
The NACA 4-digit airfoil series is described by equations that use the maximum camber, position of maximum camber, and maximum airfoil thickness as variables. These three variables are given in the 4-digit description. This video covers a basic definition of each of the four numbers (technically three), and then goes through the equations that are used to generate the (x,y) coordinates of the airfoil for use in plotting or simulation codes. The next video in this series is a MATLAB code that implements the equations seen in this video, and will return a plot of the airfoil of your specification, as well as a text file with the coordinates. Here is the link to that video: https://goo.gl/r6pK7f For the MATLAB GUI code that I wrote, head over to my GitHub account, linked to here: https://github.com/jte0419/NACA_4_Digit_Airfoil If you like this video and want to see more, please subscribe! Chord Length Video: http://goo.gl/zIeO7u References: "Theory of Wing Sections", Abbot and von Doenhoff http://www.amazon.com/Theory-Wing-Sections-Aeronautical-Engineering/dp/0486605868 http://airfoiltools.com/airfoil/naca4digit#calculation http://www.dept.aoe.vt.edu/~mason/Mason_f/CAtxtAppA.pdf
Views: 17125 JoshTheEngineer
Explained: Tire Slip Angle
 
07:12
Let's talk about tire/tyre slip angles! I'll go through two ways of thinking about it. The first is the mathematical description, which will be useful for my later videos on vehicle dynamics. The second is the physical description of what is happening in the tire contact patch when a tire is operating at a finite slip angle. ===== NOTES ===== ► One thing I forgot to make a note of is that even though the terminology calls it a 'slip' angle, the rubber in the footprint is rarely slipping. In my foot-on-a-treadmill example, you can see that the only time the rubber starts to slip is towards the rear of the print. This is because towards the rear of the print, the normal (vertical) force pushing the rubber onto the road, and the friction coefficient between the road and the rubber, are no longer able to keep the rubber from sliding back to its undeflected position. It's more complicated than this, but that's the general reason. ===== RELEVANT VIDEOS ===== → Tire Axis System https://goo.gl/W4Y9iR ===== SEMI-RELEVANT VIDEOS BUT NOT REALLY ===== → How to Calculate Top Speed https://goo.gl/T4UvN4 → F1 Aerodynamic Drag at Top Speed https://goo.gl/oyStsp ===== THUMBNAIL PHOTO CREDIT ===== By Phil Guest (Flickr: [1]) [CC BY-SA 2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons
Views: 4660 JoshTheEngineer
How To: Build Your Own Rubens' Tube
 
12:02
In this video I'll show you how to build a DIY Rubens' Tube! All the parts and steps are shown in the video and in the description below. Should you have any questions, feel free to leave a comment! If you want a detailed written document to follow, check out my blog post on the build at the link shown below in the LINKS section. If you want to see my tube in action, check out the songs listed in the SONGS section below. ================ ===== LINKS ===== ================ → My blog post https://goo.gl/ZfNiAP → Engineering Toolbox NPT https://goo.gl/N9cQNf ================= ===== SONGS ===== ================= → Lensko - Circles https://goo.gl/cROa5P → Unknown Brain - Saviour https://goo.gl/ldjdbR → K391 - Earth https://goo.gl/8n4Cj1 → Lensko - Cetus https://goo.gl/3UQlOj → Lensko - Let's Go https://goo.gl/VR7E17 ============================= ===== WHAT YOU WILL NEED ===== ============================= - [1] Propane tank (grill LP 15 or 20 lb) ($30 empty + $18 fill) - [2] Char-Broil Universal Propane Regulator with Nut (female 3/8" NPT) ($15) - [3] Brass hex pipe nipple 3/8" MIP x 3/8" MIP ($3) - [4] Gas ball valve 3/8" brass ($6.45) - [5] Male Hose Barb Adaptor - 3/8" ID Hose Barb x 3/8" MIP ($3.79) - [6] Vinyl tubing 3/8" ID x 1/2" OD ($0.39 per foot) - [7] Nylon 3/8" barbed adaptor 90 degree elbow ($2) - [8] 3" x 60" galvanized steel duct ($7.25) - [9] 3" galvanized steel duct cap ($3.41) - [10] Latex glove or balloon - [11] Speaker (any kind you want) - Duct/Aluminum/Foil tape ($3) - PTFE thread seal tape ($1.50) - Masking tape - Ruler/tape measure - Writing utensil - 1/16" drill bit - Drill - Matches or a lighter Total Cost = $50 (if you have a filled propane tank) Total Cost = $100 (if you don't have a propane tank) ================= ===== NOTES ===== ================= ► I don't have links to the parts in the list above, because I got everything at Lowes or Home Depot. If you go to the store, you will be able to find everything. ► The one thing the store didn't have in stock (but you can order it and have delivered to the store at no extra cost) is the 3" tube cap. ► Some songs might work better than others. The music needs to be in the correct frequency range for you to see the waves, so anything with frequencies that are too low or high probably aren't going to look special. ► I switch between calling it a Rubens Tube and a Rubens' Tube because I've seen it both ways. It was invented by a guy named Heinrich Rubens, so the second naming style is the possessive, calling it his tube. But I also think the first naming style is fine and makes more sense if you precede it with an article (e.g. A Rubens Tube). If John Smith invented it, I feel like it would make sense to call it a Smith Tube, instead of a Smith's Tube. If you have strong feelings about this, let me know.
Views: 12472 JoshTheEngineer
Explained: Load CSV Data [MATLAB]
 
04:59
This video explains how to load CSV files into MATLAB using textscan.
Views: 15296 JoshTheEngineer
Explained: Converging-Diverging Nozzle
 
22:31
Why do rocket engines look the way they do? In this video, I'll be explaining what a converging-diverging (CD) nozzle is, and how the flow changes as it passes through it. See the Relevant Videos section below for some more in-depth videos on each of the flow states, including examples! ================= ===== NOTES ===== ================= ► At 11:28, I say "so far, we have subsonic flow throughout the nozzle for all these cases." I meant to say that we have isentropic flow throughout the nozzle for all these cases. ========================== ===== RELEVANT VIDEOS ===== ========================== Pressure Ratio Delineations https://goo.gl/VQnH1n Normal Shock in the Nozzle Calculations Coming soon! Overexpanded Flow Calculations Coming soon! Underexpanded Flow Calculations Coming soon! Area-Mach Number Relation https://goo.gl/j4FwQX Sonic State (Critical, Star) https://goo.gl/vhjESy Normal Shock Relations https://goo.gl/bhw6Ln Isentropic Relations https://goo.gl/mkdNHd Stagnation Relations https://goo.gl/hBY2AV ============================== ===== RELEVANT BLOG POST ===== ============================== http://www.joshtheengineer.com/2016/11/16/solving-the-area-mach-number-relation/ ====================== ===== REFERENCES ===== ====================== ► Notes by Matt MacLean ► Modern Compressible Flow, Anderson Amazon Link: https://goo.gl/9B7F8H ► Elements of Gasdynamics, Liepmann and Roshko Amazon Link: https://goo.gl/brfScu ► Gas Dynamics, Zucrow and Hoffman Amazon Link: https://goo.gl/mwLk8L =========================== ===== THUMBNAIL IMAGE ===== =========================== By NASA (NIX #: MSFC-0201422. [1], Alt. URL.) [Public domain], via Wikimedia Commons
Views: 14211 JoshTheEngineer
Explained: TI-83 Linear Interpolation Program [Math]
 
05:19
In this video I show you how to program a linear interpolation equation into your TI-83 graphing calculator. If you would like to see how the equation is derived, click the link below to my other video. https://goo.gl/7OA0UU Here is the code if you already know how to input it into your calculator: PROGRAM:INTERP Input "X1=",A Input "X2=",D Input "X= ",I Input "Y1=",N Input "Y2=",S Disp (((S-N)/(D-A))(I-A)+N)
Views: 3272 JoshTheEngineer
Explained: Sonic State (Critical, Star)
 
05:18
Here's the next video in our quest to understand jet engine and rocket nozzles (among other things). We will be talking about the sonic state, which is also called the critical state or the star state. These values are useful for determining whether flow through a nozzle is choked. If the nozzle is indeed choked, then the sonic state values (P*, rho*, T*, etc.) are the actual static quantities at the throat of the nozzle. ===== RELEVANT VIDEOS ===== → Stagnation Relations https://goo.gl/FMFUBA → Area-Mach Number Relation https://goo.gl/Hp6uGQ ===== REFERENCES ===== ► Notes by Matt MacLean ► Modern Compressible Flow, Anderson ► Elements of Gasdynamics, Liepmann and Roshko ► Gas Dynamics, Zucrow and Hoffman ===== THUMBNAIL ===== By Ad Meskens (Own work) [Attribution, GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY-SA 4.0-3.0-2.5-2.0-1.0 (http://creativecommons.org/licenses/by-sa/4.0-3.0-2.5-2.0-1.0)], via Wikimedia Commons
Views: 1421 JoshTheEngineer
Explained: Tire Axis System
 
11:44
In this video, I will explain how to define the tire axis system, along with definitions for the forces and moments acting on a tire (or tyre) in this coordinate system. After the definitions, I'll go through a little example of why it's important to understand sign convention when talking about how tires generate their forces and moments. The example goes through the relationship between lateral force (cornering force) and slip angle (which are topics for a few other videos that I'm currently making). ===== WHAT TO WATCH NEXT ===== → Tire Slip Angle https://goo.gl/9hyb9T ===== THUMBNAIL IMAGE ===== The picture in the thumbnail is someone's rendering of my SolidWorks model of a tire and wheel (from GrabCad). I picked this particular rendering (and not mine) because it was an isometric view so I could add the axes, and because I didn't feel like doing another rendering.
Views: 3327 JoshTheEngineer
Explained: Afterburners
 
10:35
What are afterburners, and how do they work? In this video, I'll go into some detail on how different parts of the afterburner work, and why they are designed that way. ===== NOTES ===== ► I always speak pretty quickly in my videos, so if you need to take it slower, you have the option of slowing down the video speed to 0.75x or even 0.5x the normal speed. I don't have any plans to slow down my speech in the future (the videos get way too long), so if you need it, definitely take advantage of the speed settings. ► Apparently since YouTube got rid of annotations, I have no way of letting you know in the video that I made a mistake, so I'll just have to hope that you read my video descriptions. ► At around 4:49, I say that "droplet evaporation times are higher for higher temperatures". I meant to say that droplet evaporation times are higher for LOWER temperatures, which is why the cold bypass flow takes longer to evaporate droplets. Another way of saying this is that for the same droplet diameter, it will take longer to evaporate in a colder flow than in a hotter flow. ===== RELEVANT VIDEOS ===== → In a Nutshell: Afterburners https://goo.gl/fCxCqs → Area-Mach Number Relation https://goo.gl/yNuu2t ===== REFERENCES ===== ► "Afterburners" in The Aerothermodynamics of Aircraft Gas Turbine Engines, Zukoski ► Mechanics and Thermodynamics of Propulsion, Hill and Peterson ► Aerothermodynamics of Gas Turbine and Rocket Propulsion, Oates ► Aircraft Propulsion, Farokhi ► Aerospace Propulsion Systems, Ward ► Fundamentals of Jet Propulsion with Applications, Flack ===== THUMBNAIL PHOTO CREDIT ===== By United States Navy, Mass Communications Specialist 2nd Class Michael D. Cole [Public domain], via Wikimedia Commons
Views: 50084 JoshTheEngineer
Explained: Waitbar [MATLAB]
 
04:34
A waitbar (or progress bar) allows you to visualize when a program will finish. The argument to the waitbar fills up the bar with the percentage specified. While it's a fun way to see how long you have to wait until everything is done computing, it is extremely time consuming, and I would probably recommend just outputting data to the command window using fprintf.
Views: 3826 JoshTheEngineer
Explained: Supercritical Airfoil [Airplanes]
 
09:59
At transonic speeds, shocks waves form on the wings of an aircraft. Wave drag due to the presence of shocks can become a large portion of the overall drag on the aircraft. A supercritical airfoil can be used to delay the onset of shocks, and thus enable faster cruising speeds. If you would like some more background on the subject, feel free to watch the following videos. http://goo.gl/hCKHgf http://goo.gl/iFxmXs There are a couple things I want to mention briefly regarding drag. I mentioned the critical Mach number in the video, but neglected to include the drag divergence Mach number. Nothing particularly special happens at the critical Mach number. The shock wave or pressure wave that is formed is actually fairly weak because the flow doesn’t need to slow down too much through the shock wave. There is, however, a freestream Mach number at which the drag starts to "suddenly" increase quite a bit. This Mach number is the drag divergence Mach number, and is actually more important than the critical Mach number when designing planes. Wave drag occurs due to the presence of shock waves, and as the Mach number increases, wave drag also increases. If you’d like to read some more about the drag divergence Mach number, here are some references to get you started. "Modern Compressible Flow," John D. Anderson, pg. 345 http://en.wikipedia.org/wiki/Drag_divergence_Mach_number http://www.adl.gatech.edu/research/extrovert/classes/hispd/hispd_notes06.pdf http://adg.stanford.edu/aa241/drag/cdcintro.html http://naca.central.cranfield.ac.uk/reports/1947/naca-tn-1396.pdf (pg. 6 under Drag Characteristics)
Views: 9842 JoshTheEngineer
3D Printing: How To Level the Bed
 
07:59
In this video I go through how to level the bed of your MP Select Mini 3D printer. I'll show you how I do it from startup to finish. I'm new to the whole 3D printing thing, so if you have better methods of doing this, I'd love to hear them and learn something new.
Views: 4342 JoshTheEngineer
Explained: Area-Mach Number Relation
 
07:43
Ever wonder why rocket nozzles have an hourglass shape, or why fighter jets use something called a converging-diverging nozzle? This video goes through one of the most fundamental concepts in compressible flow, and shows you why you need to first shrink down the area, and then expand the area to get supersonic flow. ===== NOTES ===== ► When I talk about the choked flow, I didn't make it clear that you can increase the choked mass flow rate through the nozzle by increasing the stagnation pressure upstream of the nozzle. The mass flow rate will not increase only if you keep the same geometry and upstream stagnation conditions. That is, you can't increase the mass flow rate when the flow is choked by only decreasing the throat area and/or decreasing the back pressure. ► The flow will be sonic at the throat for isentropic flow (see the assumptions used in the derivation). This is not the case for real flows. ===== RELATED VIDEOS ===== → 1D Mass Conservation https://goo.gl/Wo8mcV → 1D Momentum Conservation https://goo.gl/YJypbz → 1D Mass Conservation in Differential Form (Blog Post) https://goo.gl/Q4ac2t → Speed of Sound https://goo.gl/HPtH16 → Sonic State https://goo.gl/eou3aC ===== REFERENCES ===== ► Notes by Matt MacLean ► Modern Compressible Flow, Anderson ► Elements of Gasdynamics, Liepmann and Roshko ► Gas Dynamics, Zucrow and Hoffman ===== THUMBNAIL PHOTO CREDIT ===== By NASA [Public domain], via Wikimedia Commons
Views: 2906 JoshTheEngineer
Explained: Load Excel Data into Tecplot [Tecplot]
 
01:53
This video shows how to take data from Excel and load it into Tecplot. One reason to do this is to generate more professional looking plots. Remember that equations won't load into Tecplot, and that it must be saved as a 97-2003 file.
Views: 5450 JoshTheEngineer
How To: Schlieren in Color!
 
06:29
Want to upgrade your normal Schlieren setup to a color Schlieren setup? In this video, I'll show you how to quickly make a three-color filter out of flash filter gels (~$12, see link below) so you can get pretty pictures and videos. Try experimenting with different color combinations (or number of colors) and post your pictures or videos! ===== NOTES ===== ► I said that you'll see the green in parts that are undisturbed by any refraction, but you'll also see green when the gradient in index of refraction is zero. That's why the middle of the heat from the flame is green; you can think of it like the peak of a bell curve, where the derivative is zero because it's changing from positive to negative slope (or vice versa). ► The ideal size to make the middle filter (in my opinion as I'm writing this) is the exact width of the beam spot. This way, when there is nothing in the beam path, you'll only see green. If you make your middle filter too small, then your beam spot will be partly into the outer filters as well. By making the middle filter the exact size of the beam spot at the focus, you can be sure that any colors you see from the outer filters is due to an index of refraction gradient. ===== FLASH FILTER GELS ===== https://goo.gl/kv8tGd ===== RELEVANT VIDEOS ===== How To: Build Your Own Schlieren Setup https://goo.gl/TzM8vr How To: DIY Laser Schlieren https://goo.gl/ERghgJ Schlieren Knife-Edge Placement https://goo.gl/vtbC9X
Views: 3172 JoshTheEngineer
Explained: Hydrogen Burnoff Igniters [Space Shuttle]
 
03:26
What are the sparks seen beneath the space shuttle's main engines just before launch? These sparks come from the hydrogen burnoff system that makes sure there is no excess hydrogen near the engines before ignition. The sparks from the igniters can be seen in the video below at 1:09. http://www.youtube.com/watch?v=T7vGqQUhciE
Views: 3713 JoshTheEngineer
Explained: Stagnation Relations
 
09:00
In this video we will derive the stagnation-to-static relations for pressure, density, and temperature. Specifically, these derivations will be carried out in a form that is valid for compressible flow. ===== RELEVANT VIDEOS ===== → Turbofan Inlet https://goo.gl/0s7nSR → 1D Energy Eqn https://goo.gl/RSXVyc → Thermally Perfect Gas https://goo.gl/maElnm → Specific Heats https://goo.gl/kdf1B7 → Isentropic Relations https://goo.gl/Q8Rv9O ===== REFERENCES ===== ► Notes by Matt MacLean ► Modern Compressible Flow, Anderson ► Elements of Gasdynamics, Liepmann and Roshko ► Gas Dynamics, Zucrow and Hoffman
Views: 2802 JoshTheEngineer
How To: Import Airfoil into Gmsh
 
04:43
In this video I'll show you how to export an airfoil coordinate file so that it can be read into Gmsh. You'll still need to create the mesh once the data is in Gmsh, but this is the first step you will need. ====== MY GITHUB ===== → https://github.com/jte0419/NACA_4_Digit_Airfoil ===== RELATED VIDEOS ===== → GMSH: Unstructured Rectangular Mesh https://goo.gl/5cqz5f → GMSH: Structured (Transfinite) Rectangular Mesh (4 Pt) https://goo.gl/1hpF9m → GMSH: Structured (Transfinite) Rectangular Mesh (5 Pt) https://goo.gl/RAebxS
Views: 3359 JoshTheEngineer
Explained: Continuity Equation, Fixed Control Volume [Fluid Dynamics]
 
07:36
This is the third of four derivations of the conservation of mass equation. I derive it using a finite control volume fixed in space (fluid moving through it), which results in the integral, conservative form of the equation. The other three videos (in the order I recorded them) can be found in the links below. 1: https://www.youtube.com/watch?v=AbbD8Xs-8E4 2: https://www.youtube.com/watch?v=-8beM4Y4pP4 4: https://www.youtube.com/watch?v=uXPRyYAHvZk The derivation of the conservation of momentum equation is reviewed using a fluid element moving with the flow. This results in a partial differential equation, and is in non-conservation form. Reference(s): "Computational Fluid Dynamics" by John D. Anderson, Jr.
Views: 5698 JoshTheEngineer
GMSH: Structured (Transfinite) Rectangular Mesh (4 Pt)
 
05:38
In this video, we will create a rectangular, structure mesh that can be used in a CFD simulation. This is also called a transfinite mesh. In this particular video, we will be sticking with a simple rectangle defined by 4 points, defining a single zone. In my next video, we will add an extra point along one of the sides so that we can change the grid density along that side (see video below). If you're interested in how to use this mesh in a CFD simulation, stay tuned for some future videos. ===== GMSH AND SU2 ===== → http://gmsh.info/ → https://su2code.github.io/ ===== RELEVANT VIDEOS ===== → Gmsh: Unstructured Rectangular https://goo.gl/5cqz5f → Gmsh: Structured (Transfinite) Rectangular Double Zone https://goo.gl/RAebxS ===== NOTES ===== ► For this video, I was using version 2.13.2 ► The newest stable version is currently 3.0.6, and may behave slightly differently than seen in this video ===== REFERENCES ===== ► Tutorial by Matthew MacLean
Views: 3589 JoshTheEngineer
3D Printing: MP Select Mini Overview
 
12:22
I'm new to 3D printing, and couldn't pass up on this relatively inexpensive printer! In this video I'll go through the basic components included in the box. This is sort of a post-unboxing video, as the box has already been recycled. I'm looking forward to making some really cool parts, and if you'd like to keep up-to-date with my 3D printing adventures, make sure to subscribe! 3D Printing: How To Level the Bed https://www.youtube.com/watch?v=9qzPearLJ8c
Views: 25963 JoshTheEngineer
Explained: Flap Track Fairings/Whitcomb Area Rule [Airplanes]
 
06:58
What are flap track fairings and what purpose do they serve on an airplane? These canoe-shaped pieces house linkages and mechanisms that connect the flaps to the wing. As an added bonus (if designed correctly), they can help decrease the wave drag by something known as area-ruling. Reference(s): http://www.aerospaceweb.org/question/aerodynamics/q0240.shtml
Views: 7361 JoshTheEngineer
Explained: NACA 4-Digit Airfoil MATLAB Code [Airplanes]
 
13:48
This video goes through a step-by-step description of the coding of a program to calculate the coordinates of a NACA 4-digit airfoil. If you would like to know where the equations come from, please see my previous video, located here: http://goo.gl/FcufZh To download a GUI I made from this code, visit my GitHub linked to here: https://github.com/jte0419/NACA_4_Digit_Airfoil
Views: 10789 JoshTheEngineer
Explained: Static Text GUI [MATLAB]
 
02:06
Static text fields can be used to indicate the status of your program, or simply to write text or numbers. This video describes how to set the static text field in a MATLAB GUI.
Views: 4522 JoshTheEngineer
How To: Build a Double-Bottle Magic Wine Bottle Holder
 
16:52
In this video I'll show you how to up the ante by designing and building a double-bottle magic wine bottle holder! If you're interested in keeping it simple with a single-bottle magic wine bottle holder, check out my other video: https://goo.gl/S3tXtA If you're interested in the code, you can download it from my GitHub by clicking the link below. There are instructions on how to use them in the README file, but I will also be posting videos about how to use each code individually. https://github.com/jte0419/Magic_Wine_Bottle_Holder A quick note about using the dimensions given in this video: These dimensions are calculated for my specific wood type, density, thickness, and width. The dimensions will change (by how much I can't say) if you are using a different wood. This is why I've made the design tools for you to use. If you want to be sure the design will work, download the code/spreadsheet and get the correct values. More videos will become available as I make them. Here is a list of those I intend to make (with links if I've completed them): 1) Single-bottle magic wine bottle holder https://goo.gl/S3tXtA 2) Mathematics behind the code (single-bottle) 3) Mathematics behind the code (double-bottle) 4) How to use the single-bottle MATLAB code 5) How to use the double-bottle MATLAB code 6) How to use the single-bottle C++ code 7) How to use the double-bottle C++ code 8) How to use the single- and double-bottle Excel spreadsheet 9) How to find the CG of a wine bottle https://goo.gl/8PvgbD 10) How to calculate the density of your wood https://goo.gl/Cz1rzL Please like and subscribe if you enjoyed the video!
Views: 22189 JoshTheEngineer
How To: Calculate Wood Density
 
02:29
In this video we will calculate the density of a piece of wood that we can use to build the Magic Wine Bottle Holder (see videos below). 1-Bottle Magic Wine Bottle Holder https://goo.gl/S3tXtA 2-Bottle Magic Wine Bottle Holder https://goo.gl/mnP9rY
Views: 5547 JoshTheEngineer
Explained: Axes GUI [MATLAB]
 
01:49
Axes can be used to display data on a plot, or even to display an image. This video shows how to display a plot with data in a MATLAB GUI.
Views: 3645 JoshTheEngineer
How To: Calculate a Car's Top Speed
 
08:16
Let's calculate the theoretical top speed of a Bugatti Veyron Super Sport! This method will work for any car as long as you have the necessary information. What information do you need? Here's a quick list: 1) Engine power 2) Density of air that you're driving through 3) Drag coefficient of your car 4) Frontal area of your car That's it! We've neglected rolling resistance, and are assuming that the car is drag limited, meaning that all of listed engine power is being used to overcome the drag force acting on the car. We also assume that the engine power given is the power delivered at the wheels, and that the car is driving on a level surface (not going uphill or downhill). The frontal area ends up being an approximation as well. In reality, everything is an approximation because I'm taking data from different sources online, so you have to take the results with a grain of salt. I took data from a variety of sources, and forget exactly where each one comes from, but here's a list of some. They aren't necessarily all for the Bugatti. https://en.wikipedia.org/wiki/Bugatti_Veyron http://www.auto-data.net/en/?f=showCar&car_id=23277 http://ecomodder.com/ ===== THUMBNAIL PICTURE ===== © M 93 / Wikimedia Commons, via Wikimedia Commons
Views: 3816 JoshTheEngineer
How To: DIY Laser Schlieren
 
14:00
In this video I will show you how to build a Schlieren setup using a laser pointer. There were quite a few questions on my first How To video, so I figured I would post a guide here. I use a little red laser pointer as my light source. To get the beam to diverge, I bought a plano-convex lens from Thorlabs (part number LA1213). Everything else in the setup is the same as the other setup. ===== RELEVANT LINKS ===== → Original DIY Schlieren Video https://goo.gl/dGSn23 → Thorlabs Plano-Convex Lens https://goo.gl/IfZu8d
Views: 10184 JoshTheEngineer
Afterburners: Why the Nozzle Opens Wider with Afterburner On
 
13:54
In this video I'll go through an example showing why the nozzle on a jet engine needs to open up wider when the afterburner is on. You can tell that an afterburner is on when you see the visible radiation in the afterburner/jet pipe. I'll be making some more in-depth videos about converging nozzles, converging-diverging nozzles, nozzle flow, choked flow, etc. If you haven't already, subscribe so you can be notified when I post them! ===== NOTES ===== ► Quick note regarding flow choking: You can increase the mass flow rate even when the flow is choked by increasing the upstream stagnation pressure. When I said you couldn't increase the mass flow rate anymore, it was for a fixed stagnation pressure, because that's what you usually have coming out of the turbine of the engine. So that plot on the board is valid for a fixed P_0, when we keep decreasing P. ===== REFERENCE VIDEOS ===== → Turbojet Thrust Equation: https://goo.gl/gyaalq → Stagnation Relations: https://goo.gl/yOSNeL → Isentropic Relations: https://goo.gl/vxhrLH → Speed of Sound: https://goo.gl/3qZhII ===== ASSUMPTIONS AND NOTES ===== 1) The nozzle is isentropic. - Adiabatic: no heat is added or removed. - Reversible: no friction, shocks, etc. 2) The working fluid is air. Of course the actual working fluid will be the mixture of air and combustion products. This assumption avoids extra calculations that can certainly be done, but are unnecessary for the outcome of this example. 3) The air is a calorically perfect gas (specific heats are constant). 4) The engine is fitted with a converging nozzle (not converging-diverging). 5) The direct result of turning the afterburner on results in an increase in the stagnation temperature of the fluid. 6) The flow is steady through the nozzle. 7) The flow is quasi-1D. 8) Mass flow rate and stagnation pressure do not change when the afterburner is turned on. 9) Values used are just characteristic numbers that might be valid for real engines. 10) If you do have a converging-diverging nozzle, then to get supersonic flow (higher exit velocities), you will still need to have choked flow. In order to increase subsonic flow to supersonic flow in a CD nozzle, the nozzle must be choked. ===== THUMBNAIL IMAGE ===== Photo: SAC Ben Stevenson/MOD [OGL http://www.nationalarchives.gov.uk/doc/open-government-licence/version/1/)], via Wikimedia Commons
Views: 11065 JoshTheEngineer
Explained: Taylor-Maccoll Conical Flow Overview [Taylor-Maccoll]
 
07:50
This is the first video in a series of videos about the supersonic flow over a cone at 0 degrees angle of attack. This is also known as Taylor-Maccoll conical flow, after the two guys that derived the equations and obtained solutions for this type of problem. This video aims to introduce the general problem description and lay out the basic steps for the derivation/solution. More videos will follow as described in the video.
Views: 1739 JoshTheEngineer
Explained: Maximum Thrust Nozzle Exit Pressure Condition
 
05:05
How can we get the maximum thrust from a nozzle? What exit pressure condition needs to met? In this video, we will go through a quick derivation showing that the ideal operating condition for a nozzle is when the exit pressure (at the exit plane of the nozzle) is equal to the pressure of the atmosphere that the nozzle is expanding into (also called the back pressure). This result is pretty interesting when doing some quick back-of-the-envelope calculations about different rocket nozzles, because we can deduce what their optimum operating altitude is. In one of my future videos, I'll be going through how to find the ideal operating altitude of the Space Shuttle Main Engine (RS-25). ===== RELEVANT BLOG POSTS ===== → Turbojet Thrust Equation http://www.joshtheengineer.com/2017/04/08/turbojet-thrust-equation/ → Quasi-1D Mass Conservation in Differential Form http://www.joshtheengineer.com/2017/02/26/differential-form-quasi-1d-mass-conservation/ ===== RELEVANT VIDEOS ===== → Converging-Diverging Nozzles https://goo.gl/sqj2qu → Sonic State (Critical, Star) https://goo.gl/qsDv3Y → Turbojet Thrust Equation Derivation https://goo.gl/434UST ===== REFERENCES ===== ►Gas Dynamics, Volume 1, Zucrow and Hoffman, ISBN-10: 047198440X
Views: 932 JoshTheEngineer
Calculating Shock Position in CD Nozzle
 
14:49
How do we calculate the position of a normal shock in a converging-diverging (CD) nozzle? In this video, we will go through the necessary calculations in order to compute the area ratio of the normal shock (and thus its position if you know how the nozzle's area changes with axial position). For the code used at the end of the video, check out the link below in the RELEVANT LINKS section. ===== RELEVANT VIDEOS ===== → Converging-Diverging Nozzle https://goo.gl/nC5hzb → CD Nozzle Pressure Delineations https://goo.gl/rQEA6S → Normal Shock Relations https://goo.gl/8BaJDH → Normal Shock Example https://goo.gl/HJfH3B ===== RELEVANT LINKS ===== ► Solving the Area-Mach Number Relation http://www.joshtheengineer.com/2016/11/16/solving-the-area-mach-number-relation/ ► CD Nozzle Pressure Delineations http://www.joshtheengineer.com/2017/12/17/converging-diverging-nozzle-pressure-delineations/ ► MATLAB Code http://www.joshtheengineer.com/2018/01/24/normal-shock-in-converging-diverging-nozzle/ ===== REFERENCES ===== → Modern Compressible Flow, John D. Anderson (https://goo.gl/tBPr9n) → Elements of Gasdynamics, Lipemann and Roshko (https://goo.gl/7mUFEi) → Gas Dynamics, Zucrow and Hoffman (https://goo.gl/cVAa2G)
Views: 3973 JoshTheEngineer
Explained: Listbox GUI [MATLAB]
 
04:50
This video shows how to get data from a listbox in a MATLAB GUI.
Views: 4178 JoshTheEngineer
How To: 3D Print a Rocket Nozzle
 
10:46
In this video I'll go through how to design, model, and 3D print a rocket nozzle! For clarification, the design of the nozzle uses the 2D (or planar) method of characteristics, so it's technically not accurate to simply rotate the nozzle contour about its axis, but it's close enough for our purposes. For my Method of Characteristics code, check out my GitHub: → https://github.com/jte0419/Rocket_Nozzle_Design
Views: 3413 JoshTheEngineer
Explained: Continuity Equation, Moving Differential Element [Fluid Dynamics]
 
04:22
This is the first of four derivations of the conservation of mass equation. I derive it using an infinitesimally small fluid element moving in space, which results in the partial differential equation (PDE), non-conservative form of the equation. The other three videos (in the order I recorded them) can be found in the links below. 2: https://www.youtube.com/watch?v=-8beM... 3: https://www.youtube.com/watch?v=pf6Ue... 4: https://www.youtube.com/watch?v=uXPRy...
Views: 1686 JoshTheEngineer
How To: Build a Magic Wine Bottle Holder
 
16:00
Let's design and build a magic wine bottle holder! For my 100th video, I wanted to post something that I've been meaning to for over a year now. I've written some code and made a spreadsheet so that anyone can design and then build their very own single-bottle magic wine bottle holder (double-bottle link can be seen below). I will be posting links and resources related to this video here in the description. If something is missing (or links don't work), please let me know so I can fix them. ===== NOTES ===== Note about the sound: I apologize for the difference in volume level between video filmed on my camera and video filmed on my computer. ===== GITHUB ===== To access all the files necessary to get building, head on over to my GitHub repository. There is a PDF in there that explains all the math behind the code. https://github.com/jte0419/Magic_Wine_Bottle_Holder I'll be putting these files on my website as well, but for now they are only located on GitHub, so just download them there. Feel free to make your own improvements to the code. Make sure you read the README file first. ===== RELEVANT VIDEOS ===== More videos will become available as I make them. Here is a list of those I intend to make (with links if I've completed them): 1) Double-bottle magic wine bottle holder https://goo.gl/mnP9rY 2) Mathematics behind the code (single-bottle) 3) Mathematics behind the code (double-bottle) 4) How to use the single-bottle MATLAB code 5) How to use the double-bottle MATLAB code 6) How to use the single-bottle C++ code 7) How to use the double-bottle C++ code 8) How to use the single- and double-bottle Excel spreadsheet 9) How to find the CG of a wine bottle https://goo.gl/8PvgbD 10) How to calculate the density of your wood https://goo.gl/Cz1rzL
Views: 4225 JoshTheEngineer
How To: Install SU2 CFD Code in Linux
 
08:32
Let's install the open-source CFD program SU2 on your computer. In this video, I go through step-by-step how to install the code on Linux. My computer runs Windows, but I have VirtualBox installed and running Ubuntu, which is where I'm downloading and installing SU2 (see links below). If you have problems installing, or if this method doesn't work for you, I'm probably not the person to ask how to fix it. I would recommend Googling your issue, which is what I do when I get stuck. Everything listed in the LINKS section below is free. ===== NOTES ===== ► There are multiple ways to do what I do in the video. This video just shows you one of the methods. ► The newest version of SU2 is now at 6.0 (Falcon). ► I use version 4 for the video tutorials I'm making since I ran these simulations before version 5 or 6 were out. If you want to follow along with the exact same configuration files, download version 4. Configuration files might need to be slightly changed if you want to run in 5 or 6, since some options have been added or removed. ► I don't think you actually need to add the "SU2_CFD" line in the .bashrc file, as I do in this video. ► Apparently I like the word "currently". ===== LINKS ===== → SU2 Main GitHub Site https://su2code.github.io/ → SU2 Releases Page https://github.com/su2code/SU2/releases → Other SU2 Stuff https://github.com/su2code → VirtualBox https://www.virtualbox.org/wiki/Downloads → Paraview https://www.paraview.org/download/ → GMSH http://gmsh.info/ ===== ALIASES ===== ► Add the following to your alias file, which is called .bash_aliases in my case n. = nautilus. lsl = ls -l lsla = ls -la maxwindow = resize -s 1000 1000 ===== KEYBOARD SHORTCUTS ===== Alt + Tab → Switch between windows Win + S → Open workspace view Arrow + Enter → Switch to other workspace ===== LINUX TERMINAL COMMANDS ===== cd = Change directory ls = List files ls -l = List files in an ordered list ls -a = List files including hidden files nano = Text editing program without leaving terminal (can also use gedit, nedit, etc.)
Views: 1517 JoshTheEngineer
Explained: Substantial Derivative [Math]
 
12:36
The substantial (or total) derivative appears frequently when deriving the governing equations. We can imagine that we hop on a fluid element as it is moving through a flow field, and we look at how the properties of the fluid element change. This is fundamentally different than sitting still and watching the flow move through a fixed point, and then seeing how the properties change at that point. This is why we have a local derivative term as well as a convective term. Source: Modern Compressible Flow with Historical Perspective, John D. Anderson
Views: 5405 JoshTheEngineer

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