Aerodynamics and Acoustics of a 3D Annular Cascade - Comparison with a 2D Linear Cascade

Abstract

The fan interaction noise is modeled as an annular cascade in terms of the Euler equations linearized about a nonuniform rotational ∞ow. The model fully accounts for the in∞ow-fan-duct coupling and the high frequency of the interaction process. Comparisons between the 3D annular and 2D linear cascade models show signiflcant difierences in the aerodynamic and aeroacoustic response, particularly at high frequencies. It is also shown that the linear cascade results are more sensitive to the geometry of the cascade. The sound power predictions between the linear cascade and the annular cascade are found to difier by as much as 5.4 dB, with the linear cascade predicting lower levels than the annular cascade model. The difierence between the sound power predictions indicate that capturing 3D and loading efiects are important in the calculation of rotor wake/stator interaction noise.