Twin-screw compressor is widely used in most fields such as air conditioning, refrigeration chemical industry and water conservancy. It is one of the essential important devices in industrial production process. However, the consequence of blindly improving the compression ratio and flow rate is the vibration and noise of the twin screw-compressor, which has a great impact on the life of the compressor and causes economic losses instead. Ingersoll Rand want to figure out whether the time-varying gas force has a critical effect on the dynamic response of the system. They require a theoretically based mathematical and physical model for compressor design reference and part select-ion.

The twin-screw compressor compresses air from atmospheric into high pressure by screw rotor: male rotor and female rotor. During the compression, air pressure and temperature rise, the flow volume becomes small. The main motor power is 185kW and its operation speed is 1485r/min. Package inlet pressure is equal to atmospheric pressure. Package discharge pressure is 7barG, 8barG, 10barG. The outlet pressure can be changed with different gear ratio. Apply fluid mechanics, rotor dynamics and structure mechanics on compressor, to obtain

(1) gas pressure distribution characteristics on rotor profile by CFD; simulation value or mathematical formula of the gas force. Deviation                                                10% compared with calculation.

(2) critical speed curve under different gas pressure by Dyrobes, output pressure correction with critical speed curve or formula.

By verifying the results of the simulation calculation with the theoretical model, our team obtain

(1)    gas pressure distribution characteristics on the rotor profile line

(2)    simulation value or mathematical formula of the gas axial force

(3)    vibration mode of the rotor system

(4)    influence curve of different gas pressure on the critical speed.