scholarly journals Pressure fluctuation analysis of axial-flow pump based on local mean decomposition

2018 ◽  
Vol 163 ◽  
pp. 012124
Author(s):  
H Pan ◽  
F Zhang ◽  
Y Zheng
Keyword(s):  
Pressure Fluctuation ◽  
Axial Flow ◽  
Fluctuation Analysis ◽  
Local Mean Decomposition ◽  
Local Mean ◽  
Axial Flow Pump ◽  
Flow Pump

Experimental and Numerical Investigation on Pressure Fluctuation of the Impeller in an Axial Flow Pump

2019 ◽  
Author(s):  
Xi Shen ◽  
Desheng Zhang ◽  
Bin Xu ◽  
Yongxin Jin ◽  
Xiongfa Gao
Keyword(s):  
Pressure Fluctuation ◽  
High Speed ◽  
Axial Flow ◽  
Suction Side ◽  
High Speed Photography ◽  
Detached Eddy Simulation ◽  
Transient Pressure ◽  
Unstable Flow ◽  
Axial Flow Pump ◽  
Flow Pump

Abstract The Detached Eddy Simulation (DES) has been used to simulate the pressure fluctuation of the impeller in an axial flow pump. The results were combined with experiments including high-speed photography and transient pressure measurements to investigate the unstable flow induced by tip leakage vortex (TLV). Numerical results show that maximum predictive error values of head is 2.9%, compared with experimental results. The pressure fluctuation at different monitoring points present a certain regularity, with 3 peaks and 3 troughs in a period, corresponding to the number of blades. The amplitude of pressure fluctuation at P1 (impeller inlet) is the highest among those monitoring points, where the amplitude decreases with the flow rates. The dominant frequency of pressure fluctuation at impeller under cavitation condition is the blade passing frequency (BPF). Besides, there are also N* = 6, 9, 12 and other more harmonic frequencies. The cavitation flow was analyzed with the pressure fluctuation of the blade tip. For the existence of the pressure difference between pressure side and suction side, the pressure at monitoring points change alternately. The amplitude of the fluctuation near tip is affected seriously by the cavitation bubbles, as the cavitation could is a low pressure region with unstable fluctuation.

Experimental Investigation of Blade Rows Interactions in Contra-Rotating Axial Flow Pump

2014 ◽  
Author(s):  
Linlin Cao ◽  
Hironori Honda ◽  
Hiroaki Yoshimura ◽  
Satoshi Watanabe ◽  
Akinori Furukawa
Keyword(s):  
Pressure Fluctuation ◽  
Axial Flow ◽  
Potential Interaction ◽  
Experimental Investigations ◽  
Cavitation Performance ◽  
Rotor Stator Interaction ◽  
Frequency Components ◽  
Axial Flow Pump ◽  
Theoretical Analyses ◽  
Flow Pump

As a high specific speed pump, the contra-rotating axial flow pump with two rotors rotating reversely has been proved with higher hydraulic and cavitation performance, while in our previous researches, our prototype rotors designed with equal rotational speeds for both the front and the rear rotors was also confirmed with the strong potential interaction between two blade rows. In the present study, the experimental investigations were focused on the rotor-rotor interactions in the contra-rotating rotors under two rotational speed combinations, an equal speed and a different speed ones with the lower speed of rear rotor; the latter is determined aiming at relieved rotor-rotor interaction. As the major experimental approach, casing wall static pressure measurements were conducted at pressure taps covering from upstream to downstream of the both rotors, and the pressure fluctuation modes were investigated by the FFT analyses. By series of pressure taps with different peripheral locations prepared at several axial locations, the pressure fluctuation modes with frequencies non-synchronous to the BPF (blade passing frequency) components were recognized, and confirmed to be related to the rotor-rotor interaction on the basis of theoretical analyses on the rotor-stator interaction in conventional rotor-stator types.

On the Vortical Characteristics of Horn-Like Vortices in Stator Corner Separation Flow in an Axial Flow Pump

2021 ◽  
Vol 143 (6) ◽  
Author(s):  
Chaoyue Wang ◽  
Fujun Wang ◽  
Lihua Xie ◽  
Benhong Wang ◽  
Zhifeng Yao ◽  
...  
Keyword(s):  
Deformation Mechanism ◽  
Pressure Fluctuation ◽  
Vortex Tube ◽  
Axial Flow ◽  
Separation Flow ◽  
Decomposition Approach ◽  
Corner Separation ◽  
Swirling Strength ◽  
Axial Flow Pump ◽  
Flow Pump

Abstract The phenomenon of horn-like vortex in stator corner separation flow in an axial flow pump was first reported by Wang et al. (2020, “Investigation on the Horn-Like Vortices in Stator Corner Separation Flow in an Axial Flow Pump,” ASME J. Fluids Eng., 142(7), p. 071208), and the associated external features were preliminarily presented. However, internal vortical characteristics of horn-like vortices, including the distributions of swirling strength, the deformation mechanism of vortex tube and the correlation with pressure fluctuation surge, are not revealed. In this paper, the newly developed vorticity decomposition approach is introduced, and thus more novel quantitative results are provided for the physics of horn-like vortex evolution in an axial flow pump. First, the distributions of absolute swirling strength, relative swirling strength and Liutex spectrum are presented to outline the vortical features of the horn-like vortex fields. Second, the deformation mechanism of the horn-like vortex tube is revealed. It is found that the horn-like vortex spatial evolution can be described by the deformation terms (Liutex stretching term, Liutex dilatation term, and curl term of the pseudo-Lamb vector) controlling the Liutex transport process. These terms constantly act on the horn-like vortex tube in an almost independent way, causing its continuous deformations in the transit process. Third, the quantitative correlation between horn-like vortex transit and pressure fluctuation surge is given. It is proved that periodic vortex transit can cause severe pressure fluctuation that is much larger than that induced by rotor–stator interaction. From multiple perspectives, a clearer evolution process of the horn-like vortex is outlined, which is conducive to controlling the corner separation flows and improving the stability of large-capacity and low-head pumping stations.

scholarly journals Effects of an Inlet Vortex on the Performance of an Axial-Flow Pump

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2854
Author(s):  
Wenpeng Zhang ◽  
Fangping Tang ◽  
Lijian Shi ◽  
Qiujin Hu ◽  
Ying Zhou
Keyword(s):  
Pressure Fluctuation ◽  
Axial Velocity ◽  
Guide Vane ◽  
Shape Change ◽  
Axial Flow ◽  
Weighted Average ◽  
Stable Operation ◽  
Hydraulic Loss ◽  
Axial Flow Pump ◽  
Flow Pump

The formation of an inlet vortex seriously restricts axial-flow pump device performance and poses a great threat to the safe and stable operation of the entire system. In this study, the change trends of an inlet vortex and its influence on an axial-flow pump are investigated numerically and experimentally in a vertical axial-flow pump device. Four groups of fixed vortex generators (VGs) are installed in front of the impeller to create stable vortices at the impeller inlet. The vortex influence on the performance of pump device is qualitatively and quantitatively analyzed. The vortex patterns at different positions and moments in the pump device are explored to reveal the vortex shape change trend in the impeller and the pressure fluctuation induced by the vortex. The reliability and accuracy of steady and unsteady numerical results are verified by external characteristics and pressure fluctuation experimental results. Results show that it is feasible to install VGs before the impeller inlet to generate stable vortices. The vortex disturbs the inlet flow fields of the impeller, resulting in significant reductions of the axial velocity weighted average angle and the axial velocity uniformity. The vortex increases the inlet passage hydraulic loss and reduces the impeller efficiency, while it only slightly affects the guide vane and outlet passage performance. The vortex causes a low-frequency pressure pulsation and interacts with the impeller. The closer the vortex is to the impeller inlet, the more significant the impeller influence on the vortex. The blade cuts off the vortex in the impeller; afterwards, the vortex follows the blade rotation, and its strength weakens.

Analysis of Common Axial-Flow Pump Under Reverse Operation

2014 ◽  
Author(s):  
Pengfei Ma ◽  
Jun Wang
Keyword(s):  
Numerical Method ◽  
Pressure Fluctuation ◽  
Static Pressure ◽  
Operation Mode ◽  
Axial Flow ◽  
Rotation Direction ◽  
Axial Pump ◽  
Pump Station ◽  
Axial Flow Pump ◽  
Flow Pump

A direct reverse changing of the rotation direction can be a reverse operation mode for bi-directional pump station. However, research in this area was rarely conducted due to several reasons. In this paper, an axial-pump was designed by lifting method, of which approximate specific speed was 1250. The external performances, inner flow properties and pressure fluctuation characteristics of the pump were analyzed by numerical method, in both positive and reverse operation. The effectiveness of numerical method was verified by the existing experiment data of bi-directional axial-pump. The results show that the static pressure variation of the inner channel, during positive and reverse operation, is similar. However, the static pressure in the blade surface is obviously different in that the low pressure area in the back moves to the central part of the blade under reverse operation. The maximum value of amplitude occurs near to the inlet edge. Besides, the main frequencies of the pressure fluctuation in each monitoring points are multiple or equal to the blade passing frequency in both positive and reverse operation. This investigation would provide some references to the practical application of the directly reversed axial flow pump station.

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