Experimental Determination of Special Frequencies With Constant SL (Sound’s Level) in Noise of a Centrifugal Pump That Lead or Lag Due to the Speed Fluctuation

In this work, an experimental study about the hydrodynamic tonal noise in an industrial centrifugal pump with seven blades has been carried out. Noise measurements on the casing surface have been made for different flow rates with constant shaft speed. The experiment explains that in the frequency domain, the noise of centrifugal pump can be categorized in to two parts. First, as was expected, those frequencies which sound level of them is related to the flow rate and second, those ones that the sound level of them is constant and related to the pump structure. The experiment determines that the frequencies at the second type are so few, and they have correlation with BPF fluctuations. Also with deep notification, it can be considered that these special frequencies, lead or lag due to the speed fluctuations which produced by flow rate changes in nearly constant shaft speed.