The three-dimensional turbulent flow in the last stage of a propylene compressor in a megaton ethylene equipment was simulated with the Helmholtz real gas equation and the Realizable k-ε turbulence model.To accelerate convergence

full multigrid technology was used to obtain the initial solution

and a polynomial with variables to the power six was adopted to fit the Helmholtz real gas equation.The variation rate of time with the static pressure

p/t

was applied to identify dipole source.The analysis on space distribution and frequency characteristics of dipole source was performed.The results show that the maximum dipole source is located at the junction of the impeller and the diffuser. The high-frequency noise components attenuate faster than the blade passing frequency with the working fluid flowing downstream from the diffuser. In addition

the noise in the last stage of the compressor is mainly at blade passing frequency.