有关风扇的各种定律和公式：
各种参数：
D = Fan size风扇直径mm
N = Rotational speed转速 RPM
P = Pressure风压
Q = Volume flow rate风量 CFM
W = Power功率
ρ = Gas density空气密度
Fan Law 1风量与转速，直径的关系
The first fan law relates the airflow rate to the fan rotational speed: Volume flow rate, Q, is directly proportional to the fan rotational speed, N.
同一个风扇，风量与转速成比例变化。
Fan Law 2风压与转速，直径的关系
The second fan law relates the fan total pressure or fan static pressure to the fan rotational speed: Total or static pressure, P, is proportional to the square of the fan rotational speed, N.
同一个风扇，风压与转速的平方成比例关系。
Fan Law 3功率与转速，直径的关系
The third fan law relates the total or static air power (and the impeller power), W, to the fan rotational speed: Power, W, is proportional to the cube of the fan rotational speed, N.
同一个风扇，功率与转速的立方成比例关系。
声功率与转速，直径的关系
常见轴流扇的风扇转速变化与声压差值的关系：
参考链接
http://www.hse.gov.uk/pubns/top10noise.pdf
http://www.formfactors.org/developer%5Cspecs%5Cacoustic_overview.pdf
