TA的每日心情 | 擦汗 2019-6-16 23:34 |
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签到天数: 1277 天 [LV.10]大乘
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本帖最后由 冰蚁 于 2017-10-17 16:09 编辑 + X2 \: ]" A8 @0 E
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from wiki:
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0 B1 m! Q$ \! pIn gas dynamics, the Kantrowitz limit refers to a theoretical concept describing choked flow at supersonic or near-supersonic velocities.[1] When a fluid flow experiences a reduction in area, the flow speeds up in order to maintain the same mass-flow rate, per the continuity equation. If a near supersonic flow experiences an area contraction, the velocity of the flow will increase until it reaches the local speed of sound, and the flow will be choked. This is the principle behind the Kantrowitz limit: it is the maximum amount of contraction a flow can experience before the flow chokes, and the flow speed can no longer be increased above this limit, independent of changes in upstream or downstream pressure. ; O" N. l) @0 C0 K2 u. J
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musk 在他的 proposal 里提了两种方法来解决这个 limit。一个是速度降低,一种是极高速,也就是类似国内航天提的那个4000公里时速。但他随即否了这个极高速。他的计划书是围绕LA到SF的350英里线展开的。所以认为不适合这种高速度(加速/减速/弯道)。从LA到NY可能可以,但经济性不如研发超音速飞机。 |
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