发射台会被火箭发射时喷射出的巨大火焰毁坏,并且之后需要修补吗?

【继续翻译。quora网址。

Great question, because it often goes overlooked, along with the many other components, teams and systems that must work properly in order to deliver humans or equipment to space.

这是一个很好的问题,因为它经常被忽视,而其他许多组件,团队和系统则必须正确运行才能将人员或设备运送到太空。

We’ll go through what the parts are, how they interact, and then into the actual effects, damage and repairs.

我们将详细介绍零件的含义,它们的工作方式,然后介绍实际的效果,损坏和维修。

Imagine, if you would, a very slow motion solid rocket booster igniting and launching into the air. The ground underneath the pad (or at the bottom) would have to be angled, so that the flames don’t “bounce” back up, and cause additional heat or vibrations to that very rocket. Notice how right away, we introduced a couple new dangers to any healthy rocket plume:

想象一下,如果有的话,一个速度非常慢的固体火箭助推器会点燃并向空中发射。发射台的下方(或底部)的地面必须倾斜,以免火焰回弹,并给该火箭造成额外的热量或振动影响。请注意,我们将介绍一些对正常的火箭羽流的新危险:

  • We already had FLAME / FIRE / PLUME (PRESSURE!)
  • 我们已经有火焰/火/烟气(压力!)

And because of it, we must add the following two as main dangers during a rocket launch:

因此,在火箭发射期间,我们必须介绍以下两个主要危险:

  • HEAT / TEMPERATURE
  • 热/温度

(To give you an idea, I’ve posted a photo of thermite. The hottest man-made substance, reaches almost 4000 °F (2200 °C), and burns through asphalt and most everything else… The Shuttle’s SRBs burned at the same or a bit hotter temperatures… more on this below)

(为了让您体会到这一点,我发了一张铝热剂的照片。最热的人造物质,可以达到约4000°F(2200°C),可以在沥青和大多数其他物质种燃烧。航天飞机的固体燃料推进剂燃烧时和这一样甚至温度更高…更多的请看下面)

  • VIBRATION / SOUND
  • 振动/声音

So as we said, the first thing we need to do is deflect that mean hot flaming machine at an angle.

正如我们所说,我们要做的第一件事是使发火机倾斜一定角度。

Enter the Launch Pad Trench

走进发射台下的沟渠

The pad’s trench was designed not only to be a stable launch platform for rockets (from Apollo to the Shuttle and on), but in being so it contains components that help maintain and improve that stability.

发射台的沟渠不仅设计成是火箭(从阿波罗号到航天飞机等)的稳定发射平台,而且还包含有助于维持和改善火箭稳定性的组件。

The MFD (Main Flame Deflector): This is a ramp-like structure, at two different angles. One to deflect the Orbiter’s three SSME’s (Space Shuttle Main Engines), and the other side for the SRBs (Solid Rocket Boosters). These angles are based on studies, calculations, and the meat and potatoes of engineering, in order to help with the three dangers we’ve identified above.

MFD(主挡火板):这是一种类似两个不同角度的斜坡状结构。一种是偏转轨道飞行器的三种SSME(航天飞机主引擎)喷出的火焰,另一种是偏转SRB(固体火箭助推器)喷出的火焰。这些角度基于科学研究研究,计算以及工程的实质而得出的,目的是帮助解决上面已经确定的三种危险。

Here is an Apollo Era MFD:

这是阿波罗时代MFD:

As mentioned above, the MFD photos shown from this point on will be for the Space Shuttle program, which will show one side of the Flame Face differently shaped/angled than the other.

如上所述,此张照片上的MFD将用于航天飞机项目,显示火焰面的一侧形状/角度与另一侧不同。

Watch NASA work super-fast at building the Shuttle-era MFD:

观看NASA在构建航天飞机时代的MFD方面的工作: https://www.youtube.com/watch?v=9matDigB2w4

How does the Trench and MFD look together as a whole in the pad?

沟渠和MFD放在发射台下一起看是什么样子的?

These are made of multi-layered reflective concrete, thermal tiles, and other materials. Of main concern is not just damage to the Trench for re-usability, but also the potential for FOD (Foreign Object Debris) or “chunks of stuff” flying out and potentially damaging the vehicle at its most critical stage.

它们由多层反射混凝土,导热砖和其他材料制成。主要关注的不仅是对沟渠的损伤,可重复使用性,而有还可能导致FOD(异物碎片)或“杂物”飞出,并可能在最关键的阶段损坏车辆。

Now while that solution may help deflect the super-hot flame to the side, it sure does nothing to mitigate the pressure and sound/vibrations during the approximate four seconds that the Shuttle Assembly (commonly known as the stack) will spend in its influence.

现在,尽管该解决方案可以帮助将超热火焰偏转到侧面,但它确实无法减轻航天飞机(通常称为stack)在起飞时受到的大约四秒钟巨大声音/振动的影响。

The study:

此研究:

After NASA failed to convince a lot of people and a few chimpanzees to stand under there with a thermometer during a shuttle launch, modifications to the MFD were made in order to be able to measure this amount of force affecting various areas of the MFD and trench.

在航天飞机发射期间,NASA由于无法说服人类和黑猩猩拿着温度计站在那里,于是对MFD进行了修改,以便能够测量到MFD和沟渠各个区域的影响。

(this is probably a good time to notice the orbiter’s SSME flame face on the right, vs the much steeper angle of the SRB’s on the left). Shown also are the sensors that detected the amount of force during launch.

(这可能是个不错的时机,请注意轨道器的SSME火焰面在右侧,而SRB的倾斜角则在左侧)。还显示了传感器在发射过程中检测到的巨大的力。

The results were something like this.

结果就像是这样:

Heat rate after one second of launch (SRB’s):

发射一秒钟后的加热速率(固体燃料推进剂):

In terms of pressure, this is what was recorded after launch:

从压力来说的话,这就是发射后的记录:

What is 3660 psi (25.2 MPa) in terms of pressure? About 250 bars, or atmospheres. About 7 full-size elephants standing on an area the size of the palm of your hand. Except it would be 7 elephants for each time the palm of a hand fits in that center area pictured above.

什么是3660 psi(25.2 MPa)?约250巴,或250大气压。大约7头大号大象站在您手掌大小的区域。除非每次将手掌放在上图所示的中心区域中,否则将是7头大象。

So 4000–5000 °F (2200–2800 °C) temperatures, 250 bars of pressure… what about vibrations?

这是4000–5000°F(2200–2800°C)的温度,250个大气压的压力……振动又如何呢?

Another study tells us “Intense acoustic noise and vibration are unavoidable and undesirable by-products generated by the launching of a spacecraft, such as Space Shuttles. The generated noise during firing of rocket engines manifests itself to launch vehicle, sensitive spacecraft and launch pad in the form of airborne acoustics and structure-borne vibration. Therefore, a successful space mission requires thorough consideration of complex sound and vibration interaction of vibro-acoustics effects.

另一项研究告诉我们:“强烈的声噪声和振动是不可避免的,这是航天器的发射产生的不良副产品,例如航天飞机。火箭发动机点火过程中产生的噪声,以空气传播的和结构传播的振动的形式表现出来,影响着发射的飞行器,敏感的航天器和发射台。因此,成功的太空飞行需要彻底考虑复杂的声音和振动的相互作用。

The noise and vibration caused by spacecraft rocket engines on launch pads is extremely intense (approximately 180–190 dB) and produces vibration not only of the spacecraft vehicle but also of the launch tower and related support facilities. These vibration levels can be of sufficient magnitude to cause fatigue and eventual failure of some parts.

航天器火箭发动机在发射台上引起的噪声和振动非常强烈(大约180–190 dB),不仅会让航天器产生振动,还会让发射塔和相关支持设施产生振动。这些振动水平可能足以引起零件疲劳并最终导致某些零件损坏。

The noise at launch (also during the two-minute liftoff and trans-sonic climb phase through the atmosphere from rocket exhaust and the turbulent boundary layer excitation, separated flows, wake flows and shocks) causes an hostile noise and vibration environment not only for the spacecraft itself but also for the delicate electronics and payload packages aboard. Then, the primary source of structural vibrations and internal loads during launch is due to these acoustic loads.” (Credit Revista chilena de ingeniería).

发射时的噪声(也在火箭排气和湍流边界层激发,分离的气流,尾流和冲击波穿过大气层的两分钟升空和超音速爬升阶段)不仅对飞行器造成不利的噪声和振动环境,航天器本身,也会于船上精密的电子设备和有效载荷造成影响。然后,发射过程中结构振动和内部负荷的主要来源就是这些声负荷。”

Above we can see the typical vibration time history during a Space Shuttle launch.

在上方,我们可以看到航天飞机发射过程中典型的振动时间历史。

Above is a diagram describing the main noise and vibration response of pad structures induced by rocket launch.

上图描述了火箭发射引起的对发射台结构的主要噪声和振动响应。

So to help mitigate some of these vibrations, the following is then introduced:

因此,为了减轻这些振动中的一部分,下面介绍了以下内容:

The Water Sound Suppression System:

水声抑制系统:

Goes something like this (test, without the launch platform).

像这样(测试,没有启动台)进行。 https://www.youtube.com/watch?v=LNkmwrTjKuo

Bubbles have the ability to absorb a remarkable amount of sound. As sound waves propagate through the water and encounter an air bubble, it causes the bubble to compress. The compression converts the sound energy into heat, substantially dampening the noise.

气泡具有吸收大量声音的能力。声波在水中传播并遇到气泡时,气泡会压缩。压缩将声能转化为热量,从而大大降低了噪音。

NASA makes use of the effect by spraying water molecules into the surrounding air at the Mobile Launcher Platform. Similar to the compression of the bubbles, when water molecules encounter a sound wave, they begin to vibrate, converting the sound energy into heat.

NASA通过在移动发射平台上将水分子喷洒到周围的空气中来利用这种效果。类似于气泡的压缩,当水分子遇到声波时,它们开始振动,将声能转化为热量。

The water system protects massive rockets during launch. Seconds before launch, 16 nozzles create a cascade of water which absorbs most of the sound energy. The system is effective enough to reduce the noise by half. It reduces acoustical levels within the orbiter payload bay to about 142 decibels, below the design requirement of 145 decibels.

供水系统在发射期间保护大型火箭。发射前几秒钟,有16个喷嘴产生大量水,吸收了大部分的声能。该系统足以将噪声降低一半。它将轨道有效载荷舱内的声级降低到约142分贝,低于145分贝的设计要求。

At the time of liftoff, the flow rate at the Launch Pad exceeds 900,000 gallons a minute (3.4 ML/min or 57 kL/s).

发射时,发射台处的流速超过每分钟900,000加仑(3.4 ML / min或57 kL / s)。

Repairs of the Trench after an average Shuttle launch:

一般在航天飞机发射后进行的沟渠维修:

May, 2008. Space Shuttle Discovery lifts off on its way to the International Space Station. On the meantime, there is nothing but damage and debris on the launch pad, Complex 39A.

2008年5月。发现号航天飞机升空前往国际空间站。同时,发射台Complex 39A上只有损坏和碎屑。

Inspectors show up post launch to check out the trench, based on video and evidence that shows that debris and construction material flew about 1500 ft (500 m), almost reaching the perimeter fence.

检查人员在发射后检查沟槽。 根据视频和证据显示,碎片和建筑材料飞出约1500英尺(500 m),几乎到达外围围栏。

NASA then wrote “With its protective bricks torn away by the recent space shuttle launch, the flame trench at Launch Pad 39A will be given a new layer of protection in time for the next space shuttle liftoff.

NASA随后写道:“随着最近航天飞机的发射,保护砖被损坏掉,发射台39A的火焰沟将被铺上新的保护层,以便下次航天飞机升空。

The flame trench channels the flames and smoke exhaust of the shuttle’s solid rocket boosters away from the launching spacecraft.

火焰槽将航天飞机的固体火箭助推器的火焰和烟气从发射飞船引导开。

A swath of about 3,500 protective bricks tore away from the walls of the structure when space shuttle Discovery lifted off May 31 to begin its STS-124 mission. None of the bricks bounced back in the area of the shuttle. Preliminary computer models of the exhaust pattern suggest no likelihood of loose bricks coming back to the mobile launcher platform or the shuttle.

当发现号航天飞机于5月31日升空开始执行STS-124任务时,约有3500块保护砖从结构的墙壁上被扯下。航天飞机附近的砖块都没有反弹。排气模式的初步计算机模型表明,松散的砖块不可能弹回移动发射台或航天飞机上。

Just as a swimming pool is coated with a protective layer before it is soaked, the flame trench will be sprayed with Fondue Fyre, a fire-resistant concrete, to shield it from fire and smoke. Sections of the flame trench already are protected by Fondue Fyre. A shuttle program meeting was held Thursday to solidify many of the details of the repairs.”

就像游泳池在浸泡之前先涂上一层保护层一样,在火焰沟上也要喷上耐火混凝土Fondue Fyre,以保护其免受火灾和烟尘的侵蚀。火焰槽的各个部分已经受Fondue Fyre保护。周四举行了一次航天飞机程序会议,以确定许多维修细节。”

(Above: Repaired trench, using the Fondue Fyre coating, back in 2009).

(上图:使用Fondue Fyre涂层修复的沟槽,早在2009年)。

They continue, “ The bricks protect the reinforced concrete structure of the flame trench from 7 million pounds (31 MN) of thrust generated from the SRBs.

他们继续说:“砖保护着火焰沟的钢筋混凝土结构免受SRB产生的700万磅(31 MN)的推力。

NASA’s Perry Becker, who is leading the engineer investigation and repair effort, said it is too early to tell why the wall came apart during liftoff. The wall was built in 1965 and has endured 82 launches, including 12 liftoffs of the Saturn V rocket.

NASA的佩里·贝克尔(Perry Becker)负责工程师的调查和维修工作,他说,如果现在断言在升空过程中墙为什么会裂开,就为时过早了。隔离墙建于1965年,已经承受了82次发射,包括12次土星V火箭的升空。

Each of the bricks weighs about 19 pounds (8.6 kg) each and the tongue & groove design allows them to interlock with each other for additional support. The force of the shuttle’s solid rocket boosters carried some of the bricks approximately 1,500 feet (500 m) from the launch pad. “(credit NASA Spaceflight).

每块砖重约19磅(8.6千克),榫槽设计使它们可以互锁以提供额外的支撑。航天飞机的固体火箭助推器的力量将一些砖块带离了发射台约1,500英尺(500 m)。

In summary, after the Space Shuttle era, the trench in both Complexes 39 A and B have been overhauled to host the next generation of rockets.

总而言之,在航天飞机时代之后,Comlexes 39 A和B的沟渠都被进行了大修,以容纳下一代火箭。

(The renovation of the Launch Pad Trench)

(翻新后的发射台沟渠)

I leave you with this amazing footage of Michel Mephit, walking around the Endeavour Space Shuttle, and making his way down to the trench, able to stand directly below the SRBs.

我留下米歇尔·麦菲特(Michel Mephit)的这幅令人惊叹的镜头,在奋进号航天飞机旁行走,直奔沟渠,能够直立于SRB下方。 https://www.youtube.com/watch?v=dTAjGiZvI9k

Amazing!

All the best,

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