Influence Due to the Blade Number on the Stator Tonal and Broadband Noise

The cascade’s response function can be used to effectively deal with the unsteady response of the interaction between the harmonic turbulence and the cascades. Based on this function, this paper presents the formulas for the stator broadband and tonal noises, whose inflow models are different from each other. The broadband noise comes from the impact of the random turbulence wave in the rotor wake on the stator, while the tonal noise comes from the interaction between the periodic rotor wake and the stator. According to the formulas for predicating the two kinds of noise, their inflow models are different from each other. Comparing with the test models of subsonic fan, the prediction models of the broadband and tonal noise prove to be correct. Meanwhile, the influence of the blade number on stator tonal and broadband noise is carried out through the prediction models, and the results are summarized that (1) the greater the number of blades, the higher the broadband sound power level of the stator in the high frequency. (2) An increase in the number of blades can “cut off” the tonal noise of the stator at BPF. So, reasonable arrangement of the number of stator and rotor blades is significant to the passive suppression of stator noise.