Experimental Study on Radiation Noise Frequency Characteristics of a Centrifugal Pump with Various Rotational Speeds

To investigate the radiation noise frequency characteristics of a centrifugal pump under various rotational speeds, a noise measurement system was established in a soundproof room. Sixteen monitoring points were evenly arranged in a circumferential direction around the pump and the sound pressure levels (SPLs) at different monitoring points were measured by a microphone, then the changing patterns of radiation noise in a wide frequency range and at certain frequencies were studied. The results reveal that the SPLs reach a maximum between 1000 and 2000 Hz, while SPLs are lower in other frequency ranges. Additionally, the acoustic energy was introduced to determine the proportion of radiation noise in different frequency ranges to overall noise. When rotational speed increases from 1700 to 2900 rpm, the proportion of acoustic energy between 1000 and 2000 Hz is higher than 0.50 and shows an increasing trend. Meanwhile, the proportion between 0 and 1000 Hz is about 0.30 and decreases gradually, while that between 2000 and 8000 Hz is about 0.12 and shows little change. Also, the increase in radiation noise at high frequency is higher than that at low frequency. This study could provide theoretical guidance for research regarding radiation noise prediction and control technology at different frequencies of centrifugal pumps.