Want to make your own air knife to cut things with? Unfortunately that’s not what these devices are intended for, but [This Old Tony] will show you how to make your own, while explaining what they are generally intended for. His version deviates from the commercial version which he got his hands on in that he makes a round version instead of the straight one, but the concept is the same.
In short, an air knife is a laminar pressurized airflow device that provides a very strong and narrow air pattern, using either compressed air or that from a blower. Generally air knives will use the Coandă effect to keep the laminar flow attached to the device for as long as possible to multiply the air pressure above that from the laminar flow from the air knife itself. These are commonly used for cleaning debris and dust off surfaces in e.g. production lines.
As [Tony] shows in the disassembly of a commercial device, they are quite basic, with just two aluminium plates and a thin shim that creates the narrow opening through which the air can escape. The keyword here is ‘thin shim’, as [Tony] discovers that even a paper shim is too thick already. Amusingly, although he makes a working round air knife this way, it turns out that these are generally called an air amplifier, such as those from Exair and are often used for cooling and ventilation, with some having an adjustable opening to adjust the resulting airflow.
Some may recognize this principle for those fancy ‘bladeless’ fans that companies like Dyson sell, as they use essentially the same principle, just with a fan providing the pressure rather than a compressor.
Continue reading “Make Your Own Air Knife And Air Amplifier”
