🌊 弗劳德数Froude Number Calculator

使用说明与常见问题How-to & FAQ

「弗劳德数」是什么？What is the Froude Number Calculator tool?

Fr = v / √(g L)：v 流速，L 特征长度（明渠为水深）。Fr < 1 缓流（亚临界），= 1 临界，> 1 急流（超临界）。本地处理。Fr = v / √(g L): flow speed v and characteristic length L (water depth for open channels). Fr < 1 subcritical, = 1 critical, > 1 supercritical. Processed locally.

如何使用「弗劳德数」？How do I use the Froude Number Calculator tool?

填写流速、特征长度（明渠时为水深）和重力加速度，即可得到弗劳德数 Fr = v ÷ √(gL)，以及是缓流、临界流还是急流。结果会随输入实时更新。Enter the flow speed, the characteristic length (water depth for open channels) and gravity to get the Froude number Fr = v ÷ √(gL) and whether the flow is subcritical, critical or supercritical. The result updates as you type.

船舶？Ships?

船舶用水线长计算，Fr 约 0.4 附近兴波阻力急剧上升（船体速度）。For ships use waterline length; wave drag climbs steeply near Fr ≈ 0.4 (hull speed).

能举个计算实例吗？Can you show a worked example?

例如在「弗劳德数」中填 流速 m/s = 3，特征长度 / 水深 m = 1，重力加速度 m/s² = 9.80665，结果区显示：弗劳德数：0.958；流态：缓流（亚临界）；临界流速：3.1316 m/sFor example, entering Velocity m/s = 3, Characteristic length / depth m = 1, Gravity m/s² = 9.80665 in the Froude Number Calculator gives: Froude number: 0.958; Regime: subcritical; Critical velocity: 3.1316 m/s

哪些输入会被检查？Which inputs are validated?

「弗劳德数」会检查这些输入——「流速 m/s」：必须填写，不能为负数；「特征长度 / 水深 m」、「重力加速度 m/s²」：必须填写，须大于 0；绝对值超过 10¹⁵ 的数也会被拒绝。不符合时结果区显示具体提示，不会给出数字。The Froude Number Calculator checks its inputs — "Velocity m/s": required, cannot be negative; "Characteristic length / depth m", "Gravity m/s²": required, must be greater than 0; numbers above 10¹⁵ in absolute value are rejected too. When a value fails, the result area names the problem instead of showing a number.

有哪些选项可以调整？What options can I adjust?

「弗劳德数」的设置：「流速 m/s」默认 3；「特征长度 / 水深 m」默认 1；「重力加速度 m/s²」默认 9.80665。每次生成结果都按当前设置处理。Settings in the Froude Number Calculator — "Velocity m/s" default 3; "Characteristic length / depth m" default 1; "Gravity m/s²" default 9.80665. The result always uses the current settings.

计算结果可以用于作业或工程吗？Can I use the results for homework or engineering?

「弗劳德数」使用教科书标准公式（公式写在说明和常见问题中），适合学习和估算核对；涉及安全的工程设计请以规范和实测为准。The Froude Number Calculator uses standard textbook formulas (given in the description and FAQ), which is good for learning and checking estimates; for safety-critical engineering follow codes and measured values.

「弗劳德数」免费吗？需要注册吗？Is the Froude Number Calculator free? Do I need an account?

「弗劳德数」完全免费，无需注册或安装，打开网页即可使用，手机和电脑都能用；输入的内容只在你的浏览器本地处理。The Froude Number Calculator is completely free with no sign-up or install and works on phones and desktops; what you enter is processed only in your browser.