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

Proceedings of the Institution of Mechanical Engineers, Part A:

Gao

et al. 2021

Self Cite

Effects of the staggered blades on unsteady pressure pulsations of a centrifugal pump with a specific speed ns=147 are investigated by the numerical simulation method. The obtained results are compared with the original blades. To clarify the resulting effects, eight monitoring points are used to extract pressure signals at three typical working conditions, and component at the blade passing frequency fBPF is emphasized. Results show that the pump efficiency and head will be reduced by the staggered blades, and at the nominal flow rate, the reduction is about 1.5% from comparison with the original blades. For all the eight points, the staggered blades contribute to the reduction of pressure amplitudes at fBPF when the pump works at three flow rates. The averaged reduction is 15.5% at the nominal flow rate. However, the negative effect on the second harmonic of fBPF will be caused by the staggered blades, and the corresponding pressure amplitude will increase at 2fBPF. It means that the pressure pulsation energy will be redistributed among the discrete components in pressure spectrum by the staggered blades. From the TKE distribution, it is found that the TKE values on the blade pressure side will be significantly affected by the staggered blades.

Section: Introductionmentioning

confidence: 99%

Effects of the staggered blades on unsteady pressure pulsations and flow structures of a centrifugal pump

Proceedings of the Institution of Mechanical Engineers, Part A:

Gao

et al. 2021

Self Cite

“…They showed that the outlet angle of the impeller blade has a significant effect on the jet wake structure and pressure pulsation in guide vanes. Gao et al [12] experimentally measured the dynamic pressure pulsation signal at the impeller outlet and found that the pressure pulsation amplitude near the wake vortex is large on the basis of numerical simulation results. Yan et al [13] modified the impeller and the volute to study the effects of different modification schemes on the energy loss and pressure pulsation intensity of centrifugal pumps.…”

Section: Introductionmentioning

confidence: 99%

Influence of Cutting Angle of Blade Trailing Edge on Unsteady Flow in a Centrifugal Pump Under Off-Design Conditions

Cui

et al. 2020

Applied Sciences

The parameters of blade trailing edge have an important influence on the performance of centrifugal pump and internal unstable flow. In this study, the influences of cutting angles of blade trailing edge on unstable pressure pulsation and unstable flow structure are investigated using a centrifugal pump under off-design conditions through large eddy simulation. Three typical blade trailing edges, namely, original trailing edge (OTE), 15° cutting angle of blade trailing edge (OBS15) and 30° cutting angle of blade trailing edge (OBS30), are analysed. Results show that the cutting angle of blade trailing edge has a certain effect on the performance of the centrifugal pump. Under part-load conditions, the OBS30 impeller evidently contributes to the reduction in pressure pulsation intensity. By contrast, the OBS15 impeller has opposite effect because of the increase in wake vortex intensity. The OBS30 impeller can effectively improve the unstable vortex structure caused by backflow at the centrifugal pump tongue using a new Ω method. Consequently, reduction in the unstable flow structure mainly contributes to the reduction in pressure pulsation used by the proper cutting angle of blade trailing edge.

“…Previous researches have revealed that significant deterioration of the pump performance can be resulted in by the presence of gas inside the rotating pump impeller. For instance, cavitation 3 or free-gas entrainment 4 flow in the centrifugal pumps can induce pump's unsteady flow characteristics potentially, including abnormal vibration and noise, [5][6][7] etc., which are detrimental to the pump's run-life.…”

Section: Introductionmentioning

confidence: 99%

Effect of cavitation and free-gas entrainment on the hydraulic performance of a centrifugal pump

Wang

Proceedings of the Institution of Mechanical Engineers, Part A:

Zhu

et al. 2020

An experimental study on gas–liquid two-phase flow characteristics in a low-specific-speed centrifugal pump is presented via employing multiple investigation techniques, such as visualization observation, measurements of acoustic emission and vibration, etc. Specially, three different flow conditions were inspected, namely gas locking initiation, critical cavitation with/without free-gas presence, etc. For gas locking, the drastic deterioration of the pump performance and the disrupted balance of shaft were observed. Especially, at low rotational speeds, the gas locking accompanied with intermittent or churn flow can be triggered by even lower inlet gas volumetric fractions. When it came to the cavitation flow, a small amount of gas entrainment could induce the rapid deterioration of cavitation and stimulate much higher amplitude in low-frequency band of shaft rotation. The relationship between the gas bubble trajectory and the vibration level under the backflow is discussed. The results reveal that the combined effect of the free-gas entrainment and cavitation on the pump instability is much stronger than that under natural cavitation or free-gas entrainment flow, whose fault diagnosis can be determined by the data manifested in different spectral segments.