Main engine speed and tooth tip speed of screw air compressor
When it comes to the speed of screw air compressor, generally non professional people only think about the speed of motor. More professional people may know the actual speed of male rotor through gear increase and decrease. So, how to determine the speed of the main engine?
The determination of rotational speed points to an index, that is, the tooth top speed of the main engine. What is tip speed? That is, the circumferential speed value of the tooth top of the male rotor. This value is related to the rotor profile, pressure difference, pressure ratio, volume flow, gas properties, clearance, operation mode and other factors. The compression efficiency of the main engine is the highest under a certain optimal tooth top speed. If it deviates from this optimal tooth top speed, in many cases, although there will be no immediate mechanical damage or failure, it will lead to reduced efficiency and increased noise and vibration.
During the design of the complete machine, according to the performance specifications provided by the main machine factory, the complete machine factory selects motors with different pole numbers and matches with the transmission device to ensure that the tooth top speed is within the optimal tooth top speed range, so as to achieve the model configuration of a certain flow and pressure. Of course, now the complete machine factory does not need to calculate the tooth top speed. The male rotor speed and tooth top speed are one-to-one corresponding. It only needs to select the appropriate male rotor speed according to the performance curve table provided by the main engine factory.
The top gear speed of oil injection screw is usually 10 ~ 50M / s, and the range of oil-free screw is about 50 ~ 100M / s. The speed of male rotor oil injection screw is usually 700 ~ 10000 rpm, and that of oil-free screw is usually 3000 ~ 20000 rpm.
