The most widely used form is the "24V DC Cooling Fan" downward blast, why so popular is because of the combined effect of good and inexpensive. If the direction of the axial flow fan, in turn, becomes upward ventilation, especially in certain models of the radiator will use this form. The difference is that the two forms of air flow in the form of different, "24V DC Cooling Fan" is generated when the blast of turbulence, wind pressure resistance but susceptible to loss; generated when ventilation is laminar, but little pressure airflow stable. In theory, the thermal efficiency is much greater turbulence than laminar flow, and therefore did not become mainstream design form. "24V DC Cooling Fan" axial fans, although widely used, but there are inherent flaws. Axial fan motor position by blocking the air flow is not flowing through the middle of the blast area, which is called "dead zone."