Research of transient rotor–stator interaction effect in a mixed-flow pump under part-load conditions

Through numerical simulations, this work analyzes the unsteady pressure pulsation characteristics in new type of dishwasher pump with double tongue volute and single tongue volute, under volute static and rotation conditions. Likewise, the performance tests were also carried out to verify the numerical results. Multiple monitoring points were set at the various positions of new type dishwasher pump to collect the pressure pulsation signals, and the relevant frequency signals were obtained via Fast Fourier Transform, to analyze the influence of volute tongue and its passive speed on the pump performance. The results reveal that when the double tongue volute is stationary, the pressure pulsation amplitudes increase from the impeller inlet to the impeller outlet. Under the influence of shedding vortex, the pressure pulsation in the lateral region of tongue becomes disorganized, and the main frequency of pressure pulsation changes from blade frequency to shaft frequency. In addition, compared with the static volute, double tongue volute can effectively guide the water flow out of the tongue during the rotation process, thus ensuring good periodicity for pressure pulsation in the tongue region. Accordingly, a volute reference scheme with passive rotation speed is proposed in this study, which can effectively improve the pressure pulsation at tongue position, and provides a new idea for rotor-stator interference to guide the innovation of dishwasher.

Section: Introductionmentioning

confidence: 77%

Investigation of Unsteady Pressure Pulsation in New Type Dishwasher Pump with Special Double Tongue Volute

Zhang

Zhu

et al. 2022

“…At present, numerical simulation and experiments are dominant research approaches of RSI, mainly revealing the flow field structure and the pressure pulsation characteristics by time-frequency domain analysis. Cao et al and Rodriguez et al [12,13] proceed research to capture the unstable flow properties and the pressure pulsation features induced by RSI between the guide vanes and impeller of centrifugal pump, obtaining the conclusion that the dominant frequency of pressure pulsation is roughly consistent with the blade passing frequency and the number of peaks and valleys of pressure pulsation curve is coincident with blades. Also, Issa et al [14] explored the influence of the RSI on the steady and unsteady radial force in a centrifugation between impeller blade and volute tongue.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Unsteady Flow Characteristics of Centrifugal Pump under Part Load Based on DDES Turbulence Model

Tang

Liu

Zhao

et al. 2021

To better reveal the mechanism of the rotor-stator interference between the impeller and the guide vane and the evolution process of the stall vortex under the part-load conditions, numerical simulation is carried out based on the DDES turbulence model, which can better capture vortex structure. And the pressure pulsation and the radial velocity distribution of the centrifugal pump are studied. The vortex structure and pressure fluctuation of pump internal flow field under part-load condition of Q = 0.4 Qdes are mainly analyzed. The analysis results show that the stall vortex is formed at the inlet of the impeller and evolves to the outlet of the impeller, the front cover to the rear cover according to the fluid flow direction, and then disappears. Besides, under the part-load condition, the vorticity of the impeller outlet is always obviously less than that of the impeller inlet as the flow rate increases. Due to the asymmetric action of the volute, the radial velocity distribution law of flow channel C1 is different from other flow channels at different blade heights. By analyzing the radial velocity, the phenomenon that the jet-wake flow impacts the guide vane with the rotation of the impeller is the main reason for the rotor-stator interference. And large radial velocity gradients appear at the front and rear cover plates, which will cause high energy loss and reduce pump efficiency. Besides, the conclusion can be drawn that the region with the strongest rotor-stator interference is the inlet region of the guide vane suction surface. It also occurs near the volute tongue but is lower due to the effect of the guide vane. This research may serve as a reference for the safe operation of centrifugal pumps under part-load conditions.

“…e mixed-flow pump is a common hydrodynamic rotating mechanical device widely used in engineering [1][2][3][4][5] due to its moderate head and the capacity of transporting a larger flow rate. As the semiopen impeller is usually used in the mixed-flow pump, the internal flow fields of a mixedflow pump are extremely complex and totally turbulent, including tip leakage flow (TLF) [6,7], back flow [8], and vortex shedding from the blade tip region [9], as well as the RSI between the impeller and guide vane [10]. Among the all complex flows, the TLF, driven by the high-pressure gradient between the blade pressure surface and suction surface, will affect most of the flow fields of impeller flow channels and make the pump efficiency drop a lot [11].…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of Pressure Pulsation in a Mixed-Flow Pump with Different Tip Clearances Based on Wavelet Analysis

Shi

et al. 2020

Self Cite

In order to investigate the effect of various impeller tip clearances on the pressure pulsation in a mixed-flow pump, the energy performance test and pressure pulsation experiment of a mixed-flow pump with different tip clearances are studied simultaneously. The pressure pulsation signals at impeller inlet, middle, and oulet are processed and analyzed by the wavelet transform. The results show that the change of tip clearance can affect the head and efficiency of mixed-flow pump. Under designed flow rate, when the tip clearance increases from 0.2 mm to 1.1 mm, the head and efficiency decrease by 18.1% and 11.6%, respectively. Due to the strong influence of blade passing frequency (BPF) at impeller middle, the period of pressure pulsation curve is about 1/4 of impeller rotation period. At impeller inlet, the low-frequency pulsation with energy concentration is the main disturbance frequency, and, with the increase of tip clearance, not only does the high-value region of wavelet spectrum expand to low-frequency direction but also it is easy to form second-order peaks in the time-averaged wavelet curve. At impeller outlet, affected by BPF and rotor-stator interaction (RSI), the high-frequency disturbance in RSI area decreases first and then increases. The wavelet coherence demonstrates the stable low-frequency disturbances in comparison to others and it will affect the flow field at impeller middle.