Analysis of flow field and aerodynamic noise of marine gas turbine air intake system

The aerodynamic noise of air intake system is one of the main noise sources of a gas turbine power plant. In this study, large eddy simulation in conjunction with acoustic finite element method were used to simulate the flow field and acoustic field of the air intake system of marine gas turbine. Based on the acoustic analogy methods, the internal sound source distributions and inlet radiated noise characteristics of the air intake system under different working conditions and wind speeds were analyzed. The simulated flow fields show that the highest vorticity magnitude occurs around the output shaft as the flow largely separates when passing through. The total pressure loss across the intake system increases with the increasing of the air mass flow rate and the ambient wind speed. The acoustical results show that the low frequency noise of the intake system is more prominent than the high frequency noise. The far field sound pressure level increases quadratically with the intake mass flow rates. The introduction of the ambient wind speed at the inlet boundaries reduces the high frequency aerodynamic noise of the intake system, but the overall sound pressure level of the aerodynamic noise increases with the wind speeds.