A propulsion arrangement is seen in ducted fans

rnThe air is thrown upwards or in forward motion by the duct fans thereby affecting the pressure of air and its velocity. To remove fumes, dirt-laden air, steam, hot air and smoke, duct fans are generally used in many industries or places where these problems are encountered. Duct fans have great many advantages as it is also to supply air for cooling, drying and ventilation.

The use of duct fans are registered in following areas aircraft, airships, airboats, hovercraft, fan packs. When compared with conventional propeller, Duct fans are considered to be as they are far more efficient at higher rotational speed. They can operate efficiently at higher air speeds as the designing of duct fan can adjust the air velocity through the fan. For the same static thrust, as compared to a free propeller a ducted fan has a smaller diameter enhancing its advantages.

They are quiet as they shield the blade noise by reducing the tip speed and intensity of the tip vortices making it one more major advantage to the kitty of duct fans. They also offer more safety on the ground.

Based on different needs, though the fan manufactures design fans but some of the design parts are common. To prevent resonance in the duct, ducted fans usually have an odd number of blades. Temperature is another factor in the design of these fans where they have to be built and used. Aircraft fans have more and short blades and therefore operate at higher rotational speed.

Duct fans have several advantages, like, these fans operates more efficiently at higher air speeds. Its designer can adjust the air velocity through the fan. Ducted fans do not make much noise, allows a limited amount of thrust vectoring and offer enhanced safety on the ground.

Duct fans have some disadvantages also. They require very small clearances between the blade tips and the duct for good efficiency and effective operation. Due to the design of these kinds of fans being complex, they may be expensive. Another problem with them is that they require high RPM and minimal vibration Even if they are constructed with advanced methods and technique, the weight would still be more.

Better design at lesser cost can result as competition between fan manufacturers is increasing day by day. The focus is on the design but these fan manufacturers is also on issues like energy conservation, energy labeling, performance standards, technology development etc.

Thus, any business set up with correct methods and surveys can work out well. Same is the case seen with duct fans and it has now become a big industry.