Investigation of axial spacing effect on noise radiation generated by rotor-stator interaction

The effect of axial spacing on tonal noise generated by rotor-stator interaction is numerically investigated. In the present hybrid method, acoustic sources related to wake and stator interaction are calculated using the nonlinear harmonic method, and sound radiation in the free field is solved via an acoustic analogy. The scattering effect of the duct is considered by implementing the boundary integral element method. The proposed method is first validated by predicting the tonal noise of the advanced noise control fan developed by NASA John H. Glenn Research Center. The effect of interface locations on the predicted sound radiation is studied. Results of the interface location in the middle of the rotor and stator are closest to the experimental data of tonal noise. The numerical results indicate that harmonic loading on the stator vanes and sound radiation in the far field exhibit a decreasing trend with an increase in axial spacing.