general aspects on fan selection and layout

Introduction and Description of Fan Types
Small ventilators are generally called fans. Depending on the geometrical design of the impeller, various constructional types are distinguished to indicate the main direction of the airflow. Here are the descriptions of the most important types of fans:
• Axial Fans
Axial fans are characterized by their typical impeller form, which resembles a propeller (Figure 1). The air flows through the impeller essentially in parallel to the axis, giving rise to the nomenclature employed. The blade geometry required for different versions is generally calculated with a computer; e.g., using a CAD system. Axial fans for electronic cooling are usually equipped complete with an outer housing and an electric motor integrated into the impeller hub. This compact construction enables equipment installation in a minimum of space.