Placeholder Image

字幕列表 影片播放

  • Airplane jet engines have gotten bigger and bigger over time - and it’s not just because

    飛機的噴射引擎隨時間越變越大─這不只是因為

  • planes are getting bigger: the Airbus A350 is a smaller plane than the Boeing 747 but

    飛機變大了:空中巴士A350體積比波音747小,

  • has bigger engines. The reason? Bigger engines are simply more efficient, up to a point.

    引擎卻更大。 為何?更大的引擎在一定範圍內更有效率。

  • Modern jet engines actually consist of two propulsion systems working together: the jet

    現代噴射引擎包含了兩組動力系統:

  • core, which provides the power and a small amount of thrust, and the fan, which is just

    核心,提供動力和少量推力;與風扇,其實只是個

  • a big propellor driven by the jet core that provides most of the thrust.

    被核心帶動的大型螺旋槳,提供大部分動力。

  • Pure jet engines can be incredibly powerful (which is why theyre used for fighter jets),

    純引擎核心力量極大(所以用在戰鬥機上),

  • but theyre also horribly inefficient because they shoot out their exhaust at super high

    但它們效率極低,因為會將廢氣以超高速噴出,

  • speeds, which equates to huge amounts of kinetic energy, since kinetic energy is proportional

    製造大量動能,由於動能與速度平方成正比,

  • to the speed squared, so accelerating exhaust to twice the speed takes 4 times the energy.

    因此廢氣噴速加倍時,需要消耗四倍能量。

  • In exchange for power, they literally blast energy away as a bunch of hot air.

    為了提供動力,這類引擎根本是用噴射熱氣燒能源。

  • Of course, you do have to shoot some air out of the back of an engine to generate thrust,

    當然,你的引擎一定要往後噴氣才能產生推力,

  • but it doesn’t have to have lots of energy. Instead of accelerating a little bit of air

    但它不需要燒那麼多能量。與其猛烈加速一小撮空氣

  • a lot, you can achieve your desired thrust by accelerating a lot of air a little bit

    你可以稍微加速大量空氣達到同樣速度─

  • - you get the same momentum boost but save a ton of energy.

    單位時間內推力相同但省下一堆能源。

  • Essentially, if you make an engine too small, it has to accelerate the air so much as to

    然而,若你把引擎做太小,它得把空氣加到極高速

  • be a waste of energykind of like using a machine gun to propel your car. But if you

    而顯得浪費能量─好比用機關槍讓車前進。但若你

  • make the engine too big, then it starts to cause too much drag. An ideal engine is somewhere

    把引擎造太大,又會增加太多阻力。理想的引擎大小

  • in betweenrough estimation puts the ideal engine somewhere around 4 meters in diameter,

    介於中間─大致估計直徑在四公尺上下,

  • which is just slightly bigger than the current largest engines.

    大約只比現行的最大型引擎大一點。

  • So you can expect jet engines to continue growing in size... but not forever.

    因此你能想見噴射引擎會繼續變大......但非永遠。

  • I’d like to thank Audible.com for supporting this video. As you may have heard, Audible

    感謝 Audible.com支持本片。你也許聽過,

  • has audiobooks of all sorts, including fiction, non-fiction and periodicals. You can try Audible

    Audible擁有各式有聲書,包含故事、非故事和期刊。 你可以免費試用Audible

  • free for 30 days by going to audible.com/minutephysics, and if you do so I recommend the book Ender’s

    30天,只要前往audible.com/minutephysics,我推薦

  • Game by Orson Scott Card, it was one of the pivotal sci-fi novels I read as a teenager

    Orson Scott Card寫的Ender’s Game,這是我青少年時

  • and I can’t recommend it enough. Remember, the enemy’s gate is down. And you can try

    讀過最重要的科幻小說,誠心推薦。 記住,敵人的大門已經關上。

  • Audible free for 30-days by going to audible.com/minutephysics.

    你可以上audible.com/minutephysics 免費試用Audible30天。

Airplane jet engines have gotten bigger and bigger over time - and it’s not just because

飛機的噴射引擎隨時間越變越大─這不只是因為

字幕與單字

影片操作 你可以在這邊進行「影片」的調整,以及「字幕」的顯示

B1 中級 中文 澳洲腔 引擎 推力 動能 飛機 空氣 能量

為什麼飛機發動機這麼大? (Why Are Airplane Engines So Big?)

  • 1269 113
    Ken Lo 發佈於 2021 年 01 月 14 日
影片單字