Micro Cooling Fan air volume is how come?

And "Micro Cooling Fan" related to the amount of wind is how come? Air volume fan ventilation area refers to the area of the plane and plot speed. Ventilation area is exports minus scroll area at the projected area of the tongue. Plane speed velocity gas stream through the entire plane, the unit is m / s. Flat rate constant, blade impeller diameter, the greater the ventilation area, the greater the amount of wind. The larger the amount of wind, cold air heat absorption is greater, can take more heat transfer of air flow, cooling effect is more obvious. "Micro Cooling Fan" in practice, the nominal value of the maximum wind blowing amount is not obtained actual fins, air volume, it does not mean strong ventilation capacity. Due to air flow, air flow path will encounter in their fins obstruction, the impedance will limit the free flow of air. That is when the wind increases, air pressure decreases. Therefore, there must be an optimum operating point operations, namely intersection "Micro Cooling Fan" performance curve and drag the curve. At the operating point, the slope of the characteristic curve of the fan to a minimum, change the system characteristic curve was the lowest.