慢镜头下的消音器纹影冲击波 - 每天变聪明一点点 204：英语精读讲义

A quick caveat before we get started here. 表達脈絡

在我们开始之前，我先简单声明一下。

I do not want Smarter Every Day to be observed 語氣意圖

我不希望 Smarter Every Day 被看作是

as a channel that glorifies weaponry.

一个吹捧武器的频道。

I am just fascinated by fluid dynamics, ballistics, 語法

我只是对流体力学、弹道学、

optics,

光学、

uh mechanics, aerodynamics,

呃，力学、空气动力学很着迷，

all this stuff is just fascinating to me.

所有这些东西都让我非常着迷。

And I am hard pressed to find one singular thing that I can study 習語

此外，我很难找到任何其他单一的研究对象，

that wraps all these physical phenomena into like the perfect Venn diagram 文化背景

能够把所有这些物理现象像一个完美的维恩图一样结合在一起，

that tickles my brain 習語

让我感到如此绞尽脑汁、

quite like firearms.

又像枪械这样有趣的。

So that's why you will see me studying firearms so often.

所以这就是为什么你们经常看到我研究枪械。

And um I hope you realize that I'm doing it

而且嗯，我希望你们能意识到我正在尽可能

as intelligently and respectfully as I can. 語法

理智并且充满敬意地做这件事。

That being said, 表達脈絡

话虽如此，

I've made some observations in the last episode 短語搭配

我在上一集中做了一些观察，

and I've learned some stuff.

并且学到了一些东西。

And I've also decided to push a little bit further 習語

而我也决定再深入一点，

by studying suppressors.

来研究一下消音器。

So let's look at this

所以让我们来看看这个，

and try to get smarter every day.

并且努力每天变聪明一点（Smarter Every Day）。

First, let's revisit what we learned in the last episode. 表達脈絡

首先，让我们回顾一下我们在上一集中学到的内容。

Using a Phantom camera with a clever photography technique called schlieren, 用詞

使用一台 Phantom 摄像机，以及一种叫做纹影（schlieren）的巧妙摄影技术，

which is German for streak,

这在德语里是条纹的意思，

by the way,

顺便说一句，

we observed that the supersonic bullet creates an angular shock cone

我们观察到超音速子弹会产生一个有角度的激波锥，

and the angle of that cone can be used to determine the Mach number. 講解

而这个锥体的角度可以用来确定马赫数。

We also learned from Dr. Konigstrasse at UAH

我们也从 UAH 的 Konigstrasse 博士那里学到，

that a bullet traveling in the transonic regime can create supersonic flow around it 用詞

在跨音速区域飞行的子弹可以在其周围产生超音速气流，

because the air has to speed up 短語動詞

因为空气必须加速

and rush around the outside of the surface of the bullet.

并冲过子弹表面的外围。

This is a connection I didn't make at the time, 短語搭配

这是我当时没有联系起来的一点，

but we've all seen these awesome pictures of like a fighter jet

但我们都见过那种战斗机的炫酷照片，

with this cone of vapor behind it.

它的后面跟着这样一个蒸汽锥。

This is totally why that happens.

这完全就是它发生的原因。

The jet is flying along in the transonic regime,

喷气式飞机是在跨音速区域飞行的，

just like that bullet.

就像那颗子弹一样。

And just like the normal shock wave that occurs on the side of the subsonic bullet,

就像亚音速子弹侧面发生的正常激波一样，

that's happening on the jet.

这种现象也在喷气式飞机上发生。

And it does two things. 表達脈絡

它导致了两件事。

Number one,

第一，

it makes this cone of vapor form on the jet.

它让这个蒸汽锥在喷气式飞机上形成。

And number two,

第二，

it makes me all tingly inside.

它让我内心一阵激动。

Okay, so I think we have a good understanding at this point

好的，我认为我们现在对

of shock waves created by a bullet itself.

子弹自身产生的激波有了很好的了解。

You may have heard someone talk about the crack of a bullet as it passes. 用詞

你可能听人谈论过子弹飞过时的爆裂声。

That's created by this shock wave.

那就是由这种激波产生的。

But if you think about the bang of a gunshot,

但是如果你想想枪声的轰鸣声，

like it's all those rapidly expanding gases out the front of a muzzle, right?

比如枪口前面所有快速膨胀的气体，对吧？

So it's time to hone in on that area right there 短語動詞

所以现在是时候集中注意力在那个区域上，

and study that with super slow super slow mo suppressor schlieren.

用超慢速、超慢速消音器纹影摄影来研究它了。

There you go.

终于说出来了。

It's hard to say. 習語

这话真难念。

In a past episode of Smarter Every Day,

在 Smarter Every Day 的往期节目中，

I asked a company to fabricate a see-through suppressor 用詞

我请一家公司制造了一个透明的消音器，

so we could see the flame front propagate through the baffles

这样我们就能看到火焰前锋在挡板中传播，

and try to understand what was going on. 短語動詞

试着了解到底发生了什么。

That was effective in showing what happens on the inside of their particular suppressor design,

这有效地展示了他们特定消音器设计内部发生的事情，

but what I want to see is exactly what happens on the outside of the suppressor.

但我想要看的是消音器外部到底发生了什么。

After all, that's where all the noise is. 表達脈絡

毕竟，所有的噪音都在那里。

Here's my friend Coop firing his rifle chambered in 300 Blackout, 用詞

这是我朋友 Coop 在用他的 300 Blackout 口径步枪开火，

both suppressed and unsuppressed. 用詞

包括装消音器和不装消音器两种情况。

I'm going to show you a full minute of slow motion video

我要给你们看整整一分钟的慢动作视频，

because I believe it does the best job of explaining the physics of what's going on. 短語搭配

因为我相信它最能解释发生这些情况的物理原理。

On the left, we have a suppressed weapon,

在左边，我们有一把装了消音器的武器，

and on the right, we have the same weapon unsuppressed.

而在右边，我们有同一把没装消音器的武器。

When they're first fired,

当它们刚开火时，

you can see straight away that the weapon on the right seems to have a larger,

你可以立刻看到右边的武器似乎有更大、

dirtier blast.

杂质更多的冲击波。

But after 4 milliseconds,

但是在 4 毫秒之后，

there doesn't seem to be any more shock waves. 語法

似乎就没有更多的激波了。

We're just venting the exhaust gases at that point.

那个时候我们只是在排出废气。

The weapon on the left, however, is still chugging away. 短語動詞

然而，左边的武器还在继续“喷吐”。

It's like this initial blast has been bouncing around on the inside of the suppressor

就像是这种最初的冲击波一直在消音器内部来回反弹，

and just a little bit of the gases are being leaked out with every reverberation.

然后每次混响都只有一点点气体泄漏出来。

Watch what happens next, though.

不过，请看接下来发生了什么。

On the right,

在右边，

the echo from the unsuppressed weapon is huge and very distinct.

没装消音器武器的回声巨大且非常清晰。

You can see how powerful and singular that initial blast was 語法

你可以看出最初的爆炸是多么强大和集中，

by how sharp the echo is when it returns.

因为它返回时的回声非常尖锐。

Imagine that echo entering your ears. 語法

想象一下那回声进入你的耳朵。

Meanwhile, you can still see that the suppressed weapon is dissipating that acoustic energy slowly.

同时，你仍然可以看到装了消音器的武器在缓慢耗散声能。

This is like the clearest example I can show of that energy being dissipated differently.

这可能是我能展示的这种能量被不同方式耗散的最清晰的例子了。

On the right, the unsuppressed version,

在右边，不装消音器的版本，

the whole thing's over in like a millisecond and a half. 語法

整个过程大概一毫秒半就结束了。

But on the left,

但在左边，

the same acoustic energy is dissipated over 15 milliseconds.

同样的声能被耗散了超过 15 毫秒。

That is a direct comparison showing you

这是一个直接的对比，向你展示

that it almost acts like a capacitor in a circuit. 表達脈絡

它几乎就像电路里的电容器一样起作用。

It's like slowly filtering the energy as it exits.

就像在它退出时慢慢过滤能量。

Anyway, that energy dissipation does not come for free. 習語

无论如何，这种能量的耗散是有代价的。

Suppressors heat up very, very quickly.

消音器升温非常、非常快。

All that thermal energy is captured because it doesn't dissipate away from the weapon.

所有的热能都被捕获了，因为它没有从武器上散去。

So the problem with suppressors is if you fire enough rounds through them, 用詞

所以消音器的问题是，如果你通过它们发射了足够多的子弹，

they heat up very, very fast

它们升温非常非常快，

and they can cause malfunctions and even damage to the weapon.

可能会导致故障，甚至损坏武器。

Now let's look at subsonic ammunition being fired from a suppressor.

现在让我们看看从消音器发射的亚音速弹药。

This is absolutely fascinating.

这绝对令人着迷。

Okay, first observation.

好的，第一个观察结果。

The first thing that leaves the suppressor is unburnt powder. 用詞

离开消音器的第一样东西是未燃烧的火药。

And look at that.

看看那个。

There's little baby shock waves. 用詞

有微小的激波。

They're supersonic.

它们是超音速的。

Now whether this is gunk coming loose from previous shots or whatever, 短語搭配

现在，这是不是之前射击松动的污垢或者其他的什么，

I don't know.

我不知道。

But it's clearly supersonic.

但它显然是超音速的。

Second, did you see that little vortex ring poot out the end? 用詞

第二，你看到末端喷出那个小涡环了吗？

Okay, here we go.

好的，开始吧。

Bullet time. 文化背景

子弹时间。

We know this is a subsonic round,

我们知道这是一种亚音速弹，

so we're expecting normal shock waves on the sides of the bullet.

所以我们预计子弹侧面会有正常的激波。

But look at that.

但看看那个。

They're not there until the bullet is several inches away from the muzzle. 語法

直到子弹距离枪口几英寸的时候它们才出现。

It is crazy to think about how complicated this flow environment is,

想到这种流动环境有多复杂就很疯狂，

but it's really fun to make these observations and try to figure it out. 短語動詞

但是做这些观察并试着弄清楚真的很有趣。

What are these little squirrely things that come out of the suppressor? 用詞

这些从消音器里钻出来的奇形怪状的小东西是什么？

Okay, so what you're seeing here on this Blackout cartridge is

好的，关于这种 Blackout 子弹你在这里看到的是

you're seeing unburnt propellant leaving the muzzle before the bullet does. 語法

你看到未燃烧的推进剂比子弹先离开枪口。

And so for 300 Blackout,

所以对于 300 Blackout 来说，

optimally you get complete burnout around 9 and a half to 10 inches of barrel length. 用詞

最理想的情况是在 9.5 到 10 英寸的枪管长度时完全燃烧。

And so this is a 10.2 inch barrel length.

而这是一个 10.2 英寸长的枪管。

And so we're right on the threshold of burning all the propellant out before the bullet leaves the muzzle. 短語搭配

所以我们刚好处于子弹离开枪口前烧光所有推进剂的临界点。

Well, look, there was a supersonic piece of powder.

嗯，看，有一块超音速的火药。

See that?

看到了吗？

Woah.

哇哦。

This is insane.

这太疯狂了。

We're just like learning like important stuff. 用詞

我们感觉就像是在学习重要知识一样。

All right.

好的。

Well, that was delightful.

刚才真是太开心了。

What did we learn, John?

约翰，我们学到了什么？

Propellant outruns bullets sometimes. 用詞

推进剂有时候跑得比子弹快。

You may have grains of propellant that exit the muzzle faster than the bullet supersonically.

你可能会有颗粒状的推进剂以超音速比子弹更快地退出枪口。

That's crazy.

太疯狂了。

And there's a shock wave on those grains of propellant.

而且这些推进剂颗粒上还有激波。

Exactly.

完全正确。

That's uh I never would have thought that. 語法

那个，呃，我从来没想过。

Neither would I. 語法

我也没想过。

I hope this episode earned your subscription. 語氣意圖

我希望这一集能赢得你的订阅。

You can also click the bell to be notified anytime I upload something

你也可以点击小铃铛，这样我每次上传视频你都会收到通知，

or not. 語氣意圖

或者不点。

Whatever.

无所谓啦。

You're a smart person.

你是个聪明人。

You can make your own decisions.

你能自己做决定。

I'm Destin, you're getting smarter every day.

我是 Destin，你正在每天变聪明一点（Smarter Every Day）。

Have a good one.

祝你愉快。