The flow resistance of the tunnel and the boosting capacity of jet fan in the tunnel are the foundation to calculate the tunnel ventilation, they are the first ascertained parameters.

隧道的流动阻力和风机在隧道内的升压力是隧道通风计算的基础，是进行通风计算首先要确定的参数。

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One way to increase the efficiency of a high-bypass jet engine is to turn the fan into an open rotor, a bit like returning to propellers, but using two rings of stubby counter-rotating blades.

提高高旁通飞机引擎的方法之一就是把风扇变成开放式旋翼，有点回归于螺旋桨的味道，但要使用两圈粗短的反旋桨叶。

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I’m a big fan of Jet Li。

我非常喜欢李连杰。 我是李连杰的超级影迷。

youdao

One way to increase the efficiency of a high-bypass jet engine is to turn the fan into an open rotor, a bit like returning to propellers, but using two rings of stubby counter-rotating blades.

ECONOMIST: A new way to build a greener jet engine

It seems that global preseason tours, driven by the need to boast revenue and satisfy the growing demand of an international fan base, shows no sign of ending soon even if jet-lagged players maybe a growing sight on the opening day of the European season.

CNN: Preseason football goes global

Whereas in the 1960s, jet engines were long and slim, today they have a vast opening at the front containing a giant fan.

ECONOMIST: A new way to build a greener jet engine