There are a number of large industrial fans used in manufacturing applications which require moving large quantities of air. Although there are architectural considerations which can enhance airflow through a building or facility, most often the answer to high airflow needs will be large industrial fans.
As airflow requirements increase, there are two basic engineering options that Custom Fans can assist you with. The first is to increase the efficiency of normal sized fans; the other is to simply design larger fans. There is some performance gain by using air foil shapes for fan blades. Placing an axial flow fan in a duct or tube will markedly increase performance and efficiency by negating blade tip vortex efficiency loses. Blade tip vortex occurs when air falls off the tip of the blade. This phenomenon occurs in many aerodynamic applications, and is the reason that small winglets are mounted on the wings of jet liners.
A fan is an essentially simple machine, so simple that it is a difficult concept to improve upon. There comes a point where the only way to increase output is to increase the size of the machine. Increasing motor power will increase airflow and velocity, but power increases alone soon reach a point of diminishing returns. Increased motor power is a way to increase blade speed, but there is a limit to the effectiveness of increased blade speed, a fan blade moving at Mach 1 will make a lot of noise, but may not be moving a significant amount of air.
Once the aerodynamic efficiency has reached its maximum, the only remaining way to increase airflow capacity is to increase the size or number of fans. Very large industrial fans are often custom made for each application. This is partly due to the low demand for fans of such a large physical size, but there is also transportation to be considered. It may be simpler to carry the component parts to the industrial site and assemble the fan locally than it would be to transport an over-sized, fully assembled fan.
In normal sized industrial fans, the blade assembly is usually directly coupled to the motor shaft. This may not be a practical solution for very large industrial fans. Because of the torque and physical size of the fan motor, mount the motor to the frame of the fan and driving the blades with a belt or chain may be a better option. Motors of this size often have a significantly increased service life if “soft start” circuitry is incorporated into their controls.
Very Large Industrial Fans
The HVAC systems of the huge Internet server farms often require very large industrial fans. These server warehouses are often built in areas of abundant low cost energy, such as hydro-power, because a very significant portion of their operating budget goes toward air conditioning and cooling costs. The main circulating fan for these large HVAC systems may look just like the squirrel cage fan in your central AC system at home, but the casing shroud will be the size of small house.
Another large industrial fan application is HVLS technology. High Volume, Low Velocity fans were developed for the dairy industry. A fan which is six to twenty four feet in diameter is more efficient, but aerodynamically and in energy consumption, than a number of smaller fans that it replaces. The airflow will be smoother and steadier, which contributes to greater evaporative cooling and comfort in the space.