SpaceX的猛禽发动机这样的“全流量“—“分级燃烧”—“闭式循环”火箭引擎究竟是什么?What exactly is a full-flow closed cycle staged rocket engine like the SpaceX Raptor?

【翻译自quora,回答者 Jeffrey Naujok 】

(A Raptor engine — SN-001 — on the test stand at McGregor, Texas. If you look carefully at the right side, you can see someone standing behind it for scale.)

(猛禽引擎 – SN-001 – 得克萨斯州麦格雷戈试验台上的规模,如果你在右侧仔细看,你可以看到有人站在它背后的规模)

Well, this gets a bit complex, since to understand what the sentence means you have to understand how a rocket engine works. I’m going to try to go from the basics up…

解释起来有些复杂,因为你得了解火箭引擎是如何工作的。我将试试一步步解释清楚。

I mean, it’s not like it’s rocket science, right?

Just as a fair warning, this gets a little bit… long.

(For those who hate reading… why not try out Everday Astronaut’s video instead? Is SpaceX’s Raptor engine the king of rocket engines? – Everyday Astronaut)

(如果你不大想阅读,为什么不去看看“SpaceX的猛禽引擎是火箭引擎之王吗?”)

(A pressure-fed rocket engine. Yes, it’s that small, including the tanks and valves. Photo: Nadir Bagaveyev)

(一个挤压式液体火箭发动机。对的,它很小,但仍然包括了燃料箱和阀门)。

The simplest (liquid-fueled) rocket engines work by having two pressurized tanks, one with fuel, one with oxidizer, with pipes that feed through a valve into a combustion chamber. Add an ignition source, open the valves, and you have a rocket engine.

最简单的(液体燃料)的火箭发动机由具有两个加压罐,一个装燃料,一个装氧化剂,可以通过管道和阀门到燃烧室。用单触发火药装置打开阀门,然后你就有了个火箭引擎。

【补图】

However, there’s a lot of disadvantages to this “pressure-fed” rocket system. First, the tanks have to be at a higher pressure than the combustion chamber, or, obviously, the pressure will push the fuel and oxidizer back into the tank rather than the fuel and oxidizer pushing into the combustion chamber. That severely limits how powerful of an engine you can build, but this was the first real liquid rocket engines as built a little after the turn of the 20th century by guys like Robert H. Goddard.

然而,这种“压力输送”火箭系统有很多缺点。首先,燃料箱必须比燃烧室压力更高,或者否则压力将推动燃料和氧化剂流回燃料箱,而不是进入燃烧室。这严重限制了它。但这是第一款真正的液体燃料引擎,是在20世纪由 Robert H. Goddard这样的人建造起来的。

These kind of engines are still used today on things like the reaction control system rockets on most spacecraft, like the Draco engines on the SpaceX Dragon capsule.

这些类型发动机的至今仍在使用,如大多数航天器反应控制系统(Reaction control system,RCS),和SpaceX公司的龙飞船的Draco引擎。

But, like I said, these are limited by tank pressure, to make a more powerful engine, you need a higher-pressure tank, which needs to be built thicker and stronger, and you quickly run into diminishing returns.

但是,正如我所说,这会被燃料箱压力限制,如果要做更强力的引擎,你就要更高压的燃料箱,就需要更厚更强,这很快就会让你不堪重负。

If only there were a device to take a low pressure fluid and turn it into a high pressure fluid…. Oh wait, there is: a pump.

如果有个设备能把东西从低压流体变成高压流体就好了…..哦,有了:泵。

Even your car has pumps in it. One for taking the low pressure oil and pressuring it up to flow through all the places in the engine that need lubrication, a second for pumping the gas from the gas tank to the engine, and third, a water pump for pumping cooling water around the engine.

你的车上也有泵。其中一个将低压状态下的油加压让它流过引擎里所有需要润滑的地方。第二个泵把气体箱中的气体送到引擎,第三个泵把水送到引擎周围以冷却引擎。

Let’s look at this last pump, the water pump. It works by simply spinning. You add low pressure water in the center, and as the pump spins, the water is thrown to the outside edge at high pressure, where it leaves the pump casing and flows through the system. This is known as a centrifugal pump, and it’s driven off a shaft or pulley directly from the spinning of the engine itself.

来看看最后一个泵,水泵。它工作时只是旋转而已。你把低压下的水加到中心,然后这个泵旋转,然后水以高压甩到叶轮周边的蜗壳通路,这叫 离心泵 ,它只驱动一个轴或者只旋转自身。

But, some cars have one more pump, used for pumping pressurized air into the engine. This pump looks a lot like the water pump, and is also connected to a shaft, but rather than the shaft going to the engine, it goes to a turbine.

但是,有些车多了一个泵,用于抽送加压空气进入发动机。这个泵看起来很像水泵,它也连接到一个轴,但是这个轴并未连到发动机,而是进入了涡轮机。

A turbine is sort of an “anti-pump”. It take high pressure fluid, and uses it to turn a set of blades, and thus spin a shaft, resulting in low pressure exhaust. In a car, the hot exhaust of the car feeds into this turbine, and cooler, low-pressure exhaust feeds out of it, after spinning the turbine to high speed.

涡轮是那种“反式泵”。它让高压流体流过它的叶片,因而带动轴的旋转,然后产生低压废气。在车上,高热量气体进入这个涡轮,然后冷的低压气体离开这个涡轮,让这个涡轮能高速度旋转。

That turbine drives the pump that compresses air to feed into the engine. The combined turbine and pump is known as a turbopump, or, on most cars, a turbocharger.

这涡轮机驱动把压缩空气送入引擎的泵。将合并的涡轮机和泵称为涡轮泵,在大多数汽车中,叫涡轮增压器。

(A car turbocharger — diesel in this case — used to compress air to get better performance from the engine. Photo: www.dieselnet.com)

(汽车涡轮增压器 – 柴油在这种情况下 – 用压缩空气从而得到从性能更好的发动机。照片www.dieselnet.com)

So, why did I just go through all those car parts? Because rockets use turbopumps to drive the fuel and oxidizer into the engine.

所以为什么说这么多有关汽车的部分呢?因为火箭使用涡轮泵把燃料和氧化剂送入引擎。

And that’s where we end up with all the complicated nomenclature.

现在我们不用再去管那些复杂的名称了。

Even the very first rockets, the German A4 — known in the west as the V2 rocket, used a turbopump.

就算是世界上第一款火箭,German A4——西方国家通常叫V2火箭,也使用涡轮泵。

(The A4 rocket engine. Yes, it says Calcium-Permanganate, but Z-Stoff was Sodium Permanganate. I guess it was the fog of war? Photo: www.v2rocket.com)

To drive the turbine, it used super-heated steam, derived by adding sodium permanganate (German term: Z-Stoff) to highly pure hydrogen peroxide (German term: T-Stoff). This caused the peroxide to instantly decompose into super-heated steam.

为了驱动涡轮,需要使用超热的蒸汽,这需要把高锰酸钾(德语:Z-Stoff)加到高纯度的过氧化氢(德语:T-Stoff)中。这让过氧化物瞬间变为过热蒸汽。

The turbine, spun by the decomposing T-Stoff, would drive the shaft that connected the turbine to a pair of pumps. One pump was for liquid oxygen (A-Stoff) and the second was for a 75% ethanol, 25% water mix called B-Stoff.

被分解后的T-Stoff驱动旋转的涡轮,也将驱动把涡轮和两个泵连接到一起的轴上。一个泵用于液氧(A-Stoff),另一个泵用于75%酒精25%水的混合物,叫做B-Stoff。

These two pumps were manufactured at different sizes so that each would pump the proper amount of fuel and oxidizer to the engine.

这两个泵在建造时尺寸不同,但在工作时能把适量的燃料和氧化剂送入引擎。

In the engine was, basically, a firework that was ignited to provide a combustion source. Once the engine ignited, it was throttled up to 100% and then the rocket was released.

在这个引擎就是用火花塞点火引燃燃料,燃烧室就能工作了。一点引燃,引擎立马100%工作然后火箭升起了。

This system used two completely separate fuel cycles to power the engine, with gas generator driven by one fuel cycle, and dumping the waste steam overboard, and the two pumps were fed off one shaft, with no fuel or oxidizer mixing until they reached the combustion chamber.

这个系统使用了完全独立的燃料循环来驱动引擎,其中一个燃料循环将产生高压气体来推动燃料与氧化剂进入燃烧室,然后排出废气。另外的两个泵是共轴的,燃料和氧化剂在到达燃烧室之前都不会接触到。

【补图】

To put that in perspective, that would be an “Open-cycle, dual fuel gas-generator rocket”. Open-cycle meaning that the exhaust from driving the pump is just wasted. It does nothing to aid the rocket in flight. The “gas-generator” portion means that there is an entirely separate system being used to generate the gas to push the turbine. The dual-fuel is sort of a weird outlier. Most modern rockets don’t carry a separate fuel to run a gas-generator cycle, they just use the same fuel that powers the rocket.

严格来说,这将是一个“开放式循环,双燃料燃气发生器。”开放式意味着排出的废气只能白白浪费,不能再帮助火箭飞行了。有一个“气体发生器”部分意味着一个完全独立的系统被用来产生气体以推动涡轮。双组元是有点奇怪。大多数现代和火箭都不会携带需要独立燃料的燃气发生器循,但他们也是使用相同的燃料为火箭提供动力。

(The Rocket Lab Rutherford engine being held by their CEO, Peter Beck. The engine is actually 3-D printed, and the pumps are driven by an electric motor. It may look small, but it generates almost three tons (24 KN) of thrust. Photo: India Times)

(Rocket Lab的Rutherford引擎被他们的CEO Peter Beck拿着。这个引擎是3D打印出来的。泵被电动马达驱动。也许它看起来很小,但可以产生三吨(24KN)的推力。图片:India Times。)

One exception to that would be the Rocket Lab Electron rocket, which uses an electric motor instead of a turbine to power the pumps. Technically, this would be an open-cycle engine, since the chemical reaction of the lithium in the battery is driving the pumps, but the exhaust (which stays in the battery) is not aiding the thrust of the rocket. So, in that way, the Electron rocket has more in common with the 70 year old V2 rocket design than with the Raptor. Weird but true.

有一个例外,那将是 Rocket Lab 的电子火箭,其使用电动马达,而不是涡轮。从技术上讲,这将是一个开放式循环发动机,由于在电池中的锂的化学反应驱动了泵,替代了涡轮驱动泵,但废气依然不为火箭提供推力。所以,与猛禽相比,电火箭与70年历史的的V2火箭设计更接近。很奇怪但却是事实。

So, the first step is obviously to get rid of the separate fuel system. This means that you need to have a combustion chamber inside the engine to generate the gas to turn the turbine. In other words, inside your turbo-pump rocket, you have a pressure-fed rocket driving the turbine. This is called the gas-generator in a rocket engine, and it can actually be quite powerful. The gas-generator on the F-1 engines of the Saturn V generated about 55,000 horsepower each.

所以,第一步显然是要摆脱分离的燃料系统。这意味着你需要有发动机内部的燃烧室,就要产生气体来驱动涡轮,而不是用独立的高压气体泵。换句话说,就是把燃烧后的富燃料燃气重新导入燃烧室,加上氧气继续燃烧。这叫做“燃气发生器循环”。它可以很强大。在土星号5的F-1的发动机里的气体发生器每个产生约55,000马力。【译注:此段并未完全按照原文翻译】

(The Open-Cycle Gas Generator engine. Photo: Wikipedia)

(开式燃气发生器循环引擎)

The exhaust from this gas generator is then fed to the turbines that turn the pumps. The exhaust is still dumped overboard — on the F-1 it was used to cool the exhaust nozzle, but that actually ever-so-slightly reduced the thrust, it didn’t help it.

然后从该燃气发生器产生的废气被供给涡轮机来转动泵。废气仍然被排放到外面 。在F-1中 它被用于冷却排气喷嘴,但实际上它几乎对推力降低没有影响。

In order to keep the turbine from melting, these gas-generators are usually run “fuel-rich” meaning that all the oxidizer gets burned, and the remaining cool fuel keeps the downstream turbine from melting. It’s eating rocket exhaust after all, right? So when you dump that exhaust overboard, it never goes to help push the rocket, and the fuel is lost.

为了保持涡轮持续转动,这些燃气产生器使用“富余的燃料”,这意味当所有的氧化剂被用完时,剩下的冷却燃料仍然让下游涡轮持续转动。【??】这些废气白白消耗了,对不对?所以,当你把排气排掉时,它永远没法助推火箭,然后燃料就没了。

So this is a single-fuel, open-cycle, gas-generator engine. A lot of the engines you actually see in use, like the Merlin engines, are actually this type.

所以这是一个单燃料开式循环,燃气发生器引擎。很多你实际看到引擎,像梅林引擎,其实都是这种类型。

Whew. Hang in there, I’m about a third of the way done.

奥,到了这里,你大概已经弄清楚三分之一了。

So, if you really want to squeeze everything you can out of an engine, the first thing you want to do is to use all that extra fuel you’re tossing overboard in an open-cycle engine. Well, if you do that, you get a closed-cycle engine.

所以,如果你真的想把所有能用东西都不要排放到引擎外白白浪费,你要做的第一件事,就是把 在一个开放式循环发动机里所有因排出而损失的燃料都回收起来,。好吧,如果你这样做,你会得到一个闭式循环发动机。

Yes, that’s right, 1,000 words into the answer and I finally have the first term in your question.

对了,这1000个单词的答案终于回答了问题你的里的第三个名词。

(The Closed-Cycle engine. Now all of the fuel and oxidizer goes through the combustion chamber.)

(闭式循环发动机。现在所有的燃料和氧化剂都经过燃烧室。)

The closed-cycle engine ensures that every drop of fuel and oxidizer run through the engine will go through the combustion chamber and aid in the act of producing thrust for the rocket.

闭式循环引擎保证了通过引擎的每一滴燃料和氧化剂,都将到达燃烧室并对推力做出贡献。

To do this, we usually have to make changes to the turbopump design. The first thing is that the exhaust of the turbine has to feed back into the intakes of the pump. The exhaust was fuel rich if you’ll remember, which is why we have to send it to the fuel side pump.

要做到这一点,我们通常要进行更改涡轮泵的设计。第一件事是,涡轮的废气需要回到泵的输入处。如果你还记得,就知道废气中还有很多燃料,这就是为什么我们必须把它送到侧燃油泵。

The leftover fuel in the exhaust is re-pressurized by the pump and fed into the combustion chamber where it meets the oxidizer, and you get a closed-cycle engine.

排气管中的剩余燃料通过泵再加压,并送入燃烧室与氧化剂,你会得到闭式循环引擎。

One problem, however.

然而有个问题。

Most fuels in rocketry contain carbon, meaning if you mix hot exhaust with cryogenic fuel, the carbon drops out as soot, and you get “coking” of the pumps. That’s bad.

火箭的大多数燃料含有碳,如果你用的低温燃料混合热废气的意思,碳会变成滴出的烟,泵就“焦化”了。不好。

The turbopumps on rockets spin insanely fast. Turbochargers on most cars run at 80,000 RPM or more, but they’re 3–4 inches across. Turbines in rocket engines are typically 16–18 inches across and spinning at 36,000 RPM. By my math, that means the outside edges are moving at more than twice the speed of sound. Even the slightest imbalance in weight and they’ll tear themselves apart. Turbopump failures are the most common failures in rocket engines.

在火箭的涡轮泵旋转速度飞快。在大多数汽车涡轮增压器速度是80,000PRM以上,但它们的尺寸只有3-4英寸。在火箭发动机涡轮机通常有36,000 RPM以上,尺寸是16-18英寸。这意味着外边缘的移动速度是音速的两倍。即使重量丝毫不均衡,它们也会毁坏自己,涡轮泵损坏是火箭引擎中常见的损坏。

Thus, building up lots of sooty carbon on the pumps or turbines is bad, so, fuel-rich cycles are out on most engines; instead we see oxidizer rich closed-cycle engines.

因此,让泵或涡轮上有太多的积碳不好,所以,这种富燃料循环不被大多数发动机使用;因此我们有了富氧化剂的闭式循环引擎。

The idea is the same, but instead of adding extra fuel, you add extra oxidizer, and the exhaust goes through the oxidizer pump.

想法与之前一样,但这次不是添加多余燃料,而是添加多余氧化剂,而让废气通过氧化剂泵。

Of course, now you have red-hot oxidizer inside a metal pump. Red hot pure oxygen tends to do things like set metal on fire. Have you ever seen an oxy-acetylene torch cut right through plate steel? You heat the steel with the acetylene, but the cutting is done by blasting hot oxygen into the hot steel — it actually burns the steel away.

嗯,那么你现在有了一个在金属泵里的红热氧化剂。红热纯氧极有可能让金属起火。你看见过氧乙炔焰切割钢板吗?你用乙炔加热钢板,而把热氧气送到热钢上来切割——它确实把钢烧开了。

So, the metallurgy had to catch up to create an alloy like Inconel that can handle super-hot oxidizer without burning. The Russians spent years perfecting this and built some amazingly powerful engines like the NK-33 and the RD-170. It was so hard to do this, the American space program said that the Soviets were just lying about their engine technology until after the Soviet Union fell and they actually managed to look at some of those engines in person.

所以,我们只好依靠冶金来创造出像 铬镍铁合金 这样让超热氧气烧不起来的合金。俄罗斯人花了很多年来完善,并建造出了像NK-33和RD-170这样强力的引擎。这样做太困难了。美国航天项目说苏联依靠他们的火箭引擎技术保持领先直到苏联解体,他们设法以个人名义去观察这些火箭引擎。

And if you do all this you finally have a closed-cycle engine.

如果你做到了所有这些你就有了个闭式引擎。

Whew…

Of course, the Americans cheated — they just put the turbines after the pump, and used the already pressurized fuel and oxidizer to run their gas-generator… which, since it was no longer generating gas was renamed the pre-burner. This meant they had to do things like install a pre-start helium injector to spin up the turbine before they ran the engine. It was a small issue compared to having to invent new forms of metal.

当然,美国人作弊了 – 他们只是把涡轮放在了泵后,并用已经加压的燃料和氧化剂来启动他们的燃气发生器……因为它已不再产生气体,所以更名为预燃器。这意味着他们还得做一些事情,如安装预喷注管将两种燃料均匀混合并且喷入燃烧室。【??】 。与重新发明一种金属相比,这只是个小问题。

【补图】

Pre-burning the fuel means that you are burning the fuel once in the pre-burner, and again in the combustion chamber. That’s two stages of burning…

预燃烧意味着你现在预燃器里燃烧一遍燃料,然后在燃烧室里燃烧一次燃料,这是两级燃烧。

Thus the term, staged-combustion. Yay! We have our second term.

于是我们有了“分级燃烧”。诶呀,我们终于解释了第二个名称。

However, these engines all still used a single-shaft from the turbine to the pumps. This causes it’s own problems.

然而,所有这些引擎仍然涡轮泵使用单轴。这将导致一些的问题。

You have to have a shaft, spinning at more than 30,000 RPM, yet that can still hold a seal against 300–500 atmospheres (Bar) of pressure. Because the last thing you want is fuel and oxidizer mixing inside the pumps.

你必须有一个轴,在超过30,000转速每分的速度旋转,你还要用特殊的密封装置来让它能在300-500个大气压下工作。你想要的最后一件事是泵内的燃料和氧化剂混合。

Not to mention, you still end up with needing different sized pumps for the oxidizer and the fuel to maintain the correct ratio of injection for the most efficient combustion. And that ratio is “hard-coded” into the pumps themselves. If you have a pressure leak, you can’t adjust fuel pressure separate from oxidizer pressure.

更何况,你还需要不同尺寸的泵分别用于燃料和氧化剂,以让喷注管在正确的速率工作,这样才能保证有效燃烧。这种速率“难以编码”来让泵自己保持。如果有压力泄露,你没法在不影响氧化剂压力的情况下而调整燃料压力。

Also, throttling gets tricky. Most engines can only be throttled through a small range of output because of this. The Merlin engines can only go between 70 and 100% thrust reliably. That’s because the combustion chamber always burns at the same temperature and the same heat, but when you spin-down the turbopump, the pressure drops, meaning that sometimes the pressure will drop below the pressure in the combustion chamber, and fuel/oxidizer will stop flowing until the combustion chamber pressure drops, which will allow more fuel/oxidizer in, it will ignite, chamber pressure will go up, and the cycle will repeat.

此外,节流问题很棘手。【译注:节流就是控制燃烧速率的意思,节流范围越大,燃烧速率可变化的范围越大】大多数发动机节流范围很小。梅林引擎只能做到70%到100%推力变化范围。这是因为燃烧室总是在相同的温度和相同的热量下燃烧,但是当你让涡轮泵旋转速度下降,压力下降,有时压力将下降到燃烧室的压力之下,燃料/氧化剂将停止流动。直至燃烧室压力也下降,更多的燃料/氧化剂将会流进,燃烧室内的压力又会上升,周期将重复。

This is known as chugging, and most throttle-able rocket engines suffer from it. Even the amazing RL-10 engine with it’s 17.5:1 throttle (5%-104%) suffers from chugging at the low end.

这被称为chugging,节流能力大的火箭也会遇到这个问题。即使是RL-10引擎,它的节流比是17.5:1,(5%~104%),也在低处遇到chugging问题。

So, how do you have separate control of fuel and oxidizer? Simple, you have two completely separate turbopump assemblies.

那么,你怎么单独控制燃料和氧化剂?很简单,你只需要两个完全独立的涡轮泵组件。

Yeah. You might be noticing this is getting complex…

对,可能有点复杂。

【补图,J-2引擎的示意图】

Now you have a separate gas generator on each turbine, and you can separately control the throttle of each. This is, in fact, how the J-2 engine that powered the second and third stage of the Saturn V was built.

现在你的每个涡轮都有独立燃气发生器,所以你可以独立控制它们的节流。这就是土星5号上J-2引擎为第二和第三级提供动力的方式。

The difference with the J-2 is that, since it burns hydrogen, which has no chance of coking since it has no carbon, they run a fuel-rich cycle rather than an oxygen rich cycle.

但是与J-2不同的是,它燃烧氢,所以没有燃烧碳所带来的的焦化问题,它们使用富燃料循环而不是富氧气循环。

So, the J-2 is, therefore, a fuel-rich, dual-shaft, closed-cycle staged-combustion engine.

所以,J-2是,富燃料,双轴,闭环,分级燃烧火箭。

(Note: I originally used the RL-10 as my example here, but as Duncan Oliver pointed out in the comments, I was lying by saying it was a gas-generator cycle engine. The RL-10 is actually a totally different kind of cycle called an expander cycle engine, but this was getting too long as it is. I suppose I could have picked the Russian made RD-180 used on the Atlas, but I was trying to stick to US made engines. Thus, I switched it to the J-2… which was the basis for the more complex Space Shuttle Main Engine, also known as the RS-25.)

(注意:我一开始用的是RL-10作为例子,但正如Duncan Oliver在评论区指出的那样,我说它是燃料循环引擎确实说错了。RL-10的循环与之前提到的完全不同,叫做膨胀循环引擎,但要解释起来又要花很长篇幅,于是我想讲讲 Atlas上的俄制RD-180,但我仍然想要讲美制引擎。因此,我选择了J-2….这是许多航天飞船主引擎的基础,叫做RS-25。)

(This starts to show how complex the real piping gets in an engine when you have to cover all the needs. This is a logical diagram of the space shuttle main engine, a dual-shaft, closed cycle fuel-rich engine.)

(这个图显示了,如果你需要满足所有需求,你的引擎管道结构得多么复杂。这是航天飞机主引擎的逻辑图,双轴,闭式富燃料引擎。)

Yeah, still only two terms from your question in there.

对,仍然只解释了你的问题的后两个名词。

Which gets us to the last term. Remember when I said mixing fuel and oxygen inside the pumps was bad?

现在来说说最后一个名词吗。还记得我曾经说过在一个泵里混合燃料和氧化剂不好吗?

Wouldn’t it be great to have a fuel-rich turbine on the fuel side, and an oxygen-rich turbine on the oxidizer side, meaning that the seals really wouldn’t matter that much, since anything that leaked through would just be the same stuff you were pumping anyway?

如果一边用富燃料涡轮,把燃料送进一个预燃室,另一边用富氧化剂涡轮,把氧化剂送进另一个预燃室呢?这样密封的问题就不重要了。泄露进来的东西与自己一样,就不用太在意了。

Well, that would mean you’d have to take a flow of oxygen from the oxidizer side and pump it to the pre-burner on both the oxidizer side and the fuel side, and you’d have to pump a flow of fuel from the fuel side to the pre-burner on the fuel side and the pre-burner on the oxidizer side.

好,现在你在一个预燃烧室有了富燃料燃气,另一个预燃烧有了富氧化气燃气,然后你用泵把这两股高温燃气送到燃烧室。

This would mean you are flowing a full set of combustion goods to both sides of the engine pump system.

于是你就在燃烧室有了两股高温燃气,发生剧烈而稳定的气-气燃烧,效率大大提高。 【译注:为了解释清楚,这三段没有完全按照原文来。】

Hey, look, full-flow.

好了,你看,全流,即送入燃烧室的全是气体。

So, now you’re running a full-flow, closed cycle, dual shaft, staged-combustion engine.

所以现在,你有了全流,闭式,双轴,分级引擎。

(Finally, a full-flow, closed-cycle, dual-shaft, staged-combustion engine.)

And that’s what the Raptor is.

这就是猛禽。

In case you’re wondering, it’s only the third one ever built — really, only the second full engine since the “full-flow power-head demonstrator” never actually had a combustion chamber attached. The other is the Russian RD-270 engine.

如果你还不知道这是什么概念,这其实是世界上第三个建造的——真的,甚至是第二个完整的引擎,那个“ full-flow power-head demonstrator ”还没有装好燃烧室。另一个是俄罗斯的RD-270引擎。

It’s also the first full-flow, closed-cycle, dual-shaft, staged-combustion rocket to ever fly. So far, it’s only 20 meters or so, but it did fly. (Update: 150 meters now…)

这也是第一个可以真正起飞的全流,闭路循环,双转轴,分级燃烧火箭。到目前为止,这是只有20米左右,但它确实飞了起来。(更新:现在150米了…)

So there’s your answer.

Anyone still reading is now entitled to a cookie. You earned it.

任何读到这儿的人都有权吃块曲奇饼干。这是你应得的。

【注:翻这篇大概用了3,4个小时?翻译里错误仍然很多,但以我目前的水平也只能翻译成这样了。不过学到了好多,以后玩ksp就有东西可以吹牛逼了,嗯。翻译参考:】

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