What is typically true about the design of rotary compressors?

The design of rotary compressors is typically associated with the principle of positive displacement. This means that these compressors work by trapping a specific volume of air or gas and then mechanically reducing that volume to increase the pressure. In rotary compressors, this is achieved through the rotation of mechanisms such as rotors or vanes which compress the gas within a chamber as it moves through the system.

Using positive displacement is essential as it defines the operational characteristics of rotary compressors and distinguishes them from dynamic compressors, which achieve compression through kinetic energy. Rotary compressors are known for their efficiency in handling a continuous flow of gas and maintaining consistent output pressure, which makes them widely utilized in various applications.

The other aspects mentioned, like the configuration of rotors, cooling systems, and stage designs, can vary across different types of rotary compressors. While it's true that some rotary compressors may use multiple rotors or need an external cooling system, these features aren't universally applicable to all rotary compressor designs. Therefore, the defining characteristic that truly encapsulates their operational function is the use of positive displacement principles.