An average rotary screw air flow compressor has two interlocking helical rotors within a housing. Air will come in through a valve, typically called the inlet valve and is certainly taken into the space between your rotors. As the screws turn, they reduce the level of the air, thus increasing the pressure.
The heart of an air compressor is the screw element which is also called air-end. The air-end is definitely the most important component of any screw-type compressor. It’s that section of the machine where in fact the actual compression occurs. It is the center of the rotary screw atmosphere compressor.
A Rotary Screw Air Compressor is a compressor that uses a rotary-type positive displacement system, called a rotary screw, air-end. … Rotary Screw Compressors also make use of two inter-twined helical 
designed screws, known as rotors, to compress the air.