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  • Hey, it's me Destin. Welcome back to Smarter Every Day (SED).

  • So excited about this video

  • In the last episode of SED

  • I showed you my transparent potato gun,

  • at 3,000 fps during the day.

  • 3, 2, 1

  • But this episode it's going to be the same transparent potato gun,

  • meaning we can look directly into the science

  • at night, at 20,000 fps.

  • Google up! Science is about to happen.

  • What happens, if I start the ignition of the potato gun

  • from the back?

  • vs. What happens, if I start it from the middle?

  • I always thought it would have worked better

  • if you go from the middle,

  • 'cause you get even expansion of those gases.

  • But, let's record it in high-speed, and let's see what the difference is, between the two.

  • We'll go from the back first!

  • We got some potato juices in there.

  • 3, 2, 1

  • (laughter)

  • It's like 9 o'clock.

  • Alright, let's see it in high-speed.

  • It's completely awesome.

  • We saw that it started at one end and went all the way to the end.

  • Now, I'm gonna take this, it's a grill-ignitor,

  • You can see the little zaps there.

  • I've got electrodes, set up in the center of the potato gun

  • and we're going to zap it from the center

  • and we should get a more even combustion, right?

  • So, let me hook it up and then we'll give it a shot.

  • literally.

  • Loading the potato gun again.

  • 3, 2, 1

  • (laughter)

  • It doesn't get old!

  • Was that cool, or what?

  • Ok, so check it out, so this is my combustion chamber, right?

  • The first time I shot this thing, it was a flint-sparker on the end of this thing, right?

  • If I hold it, you can see a twist

  • and I get the spark.

  • What you saw on the second time - here are my electrodes that I told you about

  • going to hit this button you can see down in there. Can you see what I'm

  • sparking right there in the middle?

  • That's how I fired that thing. When we first start the combustion from the end

  • it's a wave

  • you've got an oxygen/fuel mixture that goes all the way down to the combustion

  • chamber; when we start right in the middle,

  • we start to expand, we start using that fuel and using that oxygen, but we run

  • out of oxygen before we burn all the fuel. We're going to shoot this thing

  • from the end, we're going to zoom in with a high-speed directly on the combustion

  • chamber and we're gonna see if we can see that flame front moving one

  • Mississippi two Mississippi three Mississippi four Mississippi three two

  • one

  • Ok, before i show you the next slow mo, I want you to understand that it has

  • enough information in it to provide for several phd's ,so I want you to be on the

  • lookout for a couple of key things that I find interesting.

  • #1 When the explosion moves towards the closed off into the

  • combustion chamber, unless the fuel/air mixture is just perfect,

  • sometimes you'll run out of oxygen and have unburned fuel

  • this creates a compressed pocket of fuel, that stays unburned until it turns into

  • a rarefaction and pulls more oxygen back in through the barrel, to burn it up

  • #2 There's something that happens in combustion chambers called

  • "sidewall cooling" basically the pipe itself cools the gases down below the

  • combustion point, so it can't burn right next to the wall

  • this leaves more unburned fuel and actually counts for most of the

  • pollution products caused by the engine in your car

  • The slow-motion you're about to see is real. I haven't ran the speed, to make it

  • look more interesting,

  • It's just pure awesome footage. Straight out of a high-speed cameras.

  • Watch what happens, as the explosion over expands, the system has to equalize so it

  • pulls air back in through the barrel ,into the combustion chamber, which causes

  • that fresh oxygen in the air to meet up with the remaining fuel and start the

  • burning process all over again.

  • It's a pretty inefficient way to burn a fuel rich mixture;

  • so I think my original hypothesis might be wrong.

  • I think it's cool that when the gas squeezes down into the barrel from the

  • combustion chamber, it has to speed up so that it can maintain the exact same flow

  • rate

  • One of the things I love about science, is the ability to look at a complex

  • dynamic system like this and try to understand every physical phenomenon

  • that's occurring, but equally important to me personally is the ability to look at

  • footage like this and say "you know, that's pretty."

  • To summarize, what we've learned tonight, think about this: when you have a

  • combustion chamber

  • we've learned that it depends not only on the localized chemistry or the

  • stoichiometry, the fuel/air mixture at any point inside that combustion chamber;

  • it also depends on how its vented it's really fascinating the dynamics of

  • venting a combustion chamber effect directly the ability to create localized

  • pressures and rarefactions sometimes at the end of the video when the add part

  • comes up you kind of roll your eyes ,because you're not excited about it.

  • Well, this time is different, you see, SED is supported by

  • audible.com and they have supported me for a really long time and it's a really big deal

  • because it's kind of expensive to afford videos like this.

  • So, what I'm going to do is I'm going to create an audible event so that you can

  • remember to support SED at audible.com/smarter.

  • We're going to create the same flame front that we did before, only we're not

  • going to contain both sides of it we're going to vent one side

  • I want you to listen to this huge audible vent and then we'll look at high

  • speed ready? 3, 2, 1... It's on fire!

  • If you want to support SED, feel free to go to audible.com/smarter.

  • That's a very audible event, I hope you agree, anyway they have tons of free

  • audio books.If you get a free trial at audible.com/smarter

  • I'm super stoked that they have chosen to support smarter every day for so long

  • they've been a very valuable partner and I am very appreciative so if you want to

  • support SED directly go to audible.com/smarter get a free trial

  • of audiobooks you're going to get smarter and you're going to like it.

  • So there you go, I hope you feel like this video on your subscription if not

  • that's it.

  • I'm Destin you're getting smarter every day have a good one

  • (inaudible) i ... going at watermelons. Yeah and I'm record in slow

  • motion

  • You are?

  • Yeah. Is that cool? - That's what they all say... You don't do it at night too?

  • Is that all right? - It's your property, do what you want to do on it. You do anything

  • you want to do over here! You ain't going to bother me

  • I think it's time to go to bed

Hey, it's me Destin. Welcome back to Smarter Every Day (SED).

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B1 中級

エクスプロージョンを20,000 fpsで保持する - Smarter Every Day 156 (HOLDING AN EXPLOSION at 20,000 fps - Smarter Every Day 156)

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    簡宇謙 に公開 2021 年 01 月 14 日
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