Unsteady Pressure Pulsation Measurements and Analysis of a Low Specific Speed Centrifugal Pump

Intense pressure pulsation, resulted from the flow structure shedding from the blade trailing edge and its interaction with the volute tongue and the casing, is detrimental to the stable operation of centrifugal pumps. In the present study, unsteady pressure pulsation signals at different positions of the volute casing are extracted using high response pressure transducers at flow rate of 0-1.55 Phi(N). Emphasis is laid upon the influence of measuring position and operating condition on pressure pulsation characteristics, and components at the blade passing frequency f(BPF) and root-mean-square (RMS) values in 0-20.66f(n) frequency band are mainly analyzed. Results clearly show that the predominant components in pressure spectra always locate at f(BPF). The varying trends versus flow rate of components at f(BPF) differ significantly for different points, and it is considered to be associated with the corresponding flow structures at particular positions of the volute casing. At the near-tongue region, high pressure amplitudes occur at the position of theta = 36 deg, namely the point at the after tongue region. For different measuring points, angular distributions of amplitudes at f(BPF) and RMS values in 0-20.66f(n) frequency band are not consistent and affected significantly by the pump operating conditions.