Why don’t screw compressors suffer from surge?

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Why don’t screw compressors suffer from surge? 1. Principle of surge: Surge is a fault specific to turbine compressors (centrifugal/axial flow). Essentially, it occurs when the compressor’s discharge volume falls below the minimum stable flow rate, causing rotational stall of the airflow within the impeller; this leads to severe fluctuations in inlet and outlet pressures as well as a vicious cycle of back-and-forth airflow impacts. This phenomenon relies on the working principle of using the centrifugal force/axial force generated by the high-speed rotation of the impeller to move the gas. 2. The working principle of screw compressors, which eliminates surge at its source. Screw compressors belong to the category of positive-displacement compressors; they function by means of a pair of intermeshing male and female rotors that rotate within a casing, thereby creating continuous and sealed compression chambers. In this process, the compressor \"forces compression within the chambers and delivers a fixed volume of gas\", which is different from how turbines convert gas flow energy into pressure energy. “The characteristics of \"sealed chamber, forced compression, and quantitative delivery\" ensure that the air flow in screw compressors is continuous and stable. There are no issues related to speed matching between the impeller and the air flow, nor any problems with air flow adhesion as in turbines; as a result, rotational stall does not occur. Rotational stall is a necessary prerequisite for surge, and without stall, surge cannot be triggered. 3. Summary: Surge occurs when there is a problem with the interaction between the impeller and the airflow; screw compressors, on the other hand, do not rely on airflow driven by an impeller, as they use their mechanical structure to force compression of the gas, so surge cannot occur in them at all.