scholarly journals Influence of Axial Clearance on Water-Jet Axial Flow Pump

2021 ◽  
Author(s):  
Chen Li ◽  
Hongming Wang
Keyword(s):  
Flow Field ◽  
Axial Flow ◽  
Pressure Rise ◽  
Leading Edge ◽  
Hydraulic Performance ◽  
Suction Surface ◽  
Surface Separation ◽  
Axial Clearance ◽  
Axial Flow Pump ◽  
Flow Pump

Three dimensional Reynolds averaged N-S equation and S-A turbulent model were adopted to simulate the flow field and hydraulic performance of the waterjet axial flow pump with the different impeller axial clearance. The numerical research results show that with the increase of axial clearance size, total pressure and static pressure rise at first and then decreases, torque and shaft power remain basically unchanged, the efficiency decreases gradually, the suction surface separation zone of stator expanded under the design condition. When the axial clearance is 30mm, the pump hydraulic performance and flow field are the best, and stator load distribution is the most uniform. When the axial clearance is 40–50mm the load of the lower part of stator leading edge is reduced greatly, which is not conducive to maintain static blade strength and maintain the stator rectifying action.

Experimental Study on Cavitating Flow in Impeller of Axial-Flow Pump

2011 ◽  
Author(s):  
Zhong Li ◽  
Minguan Yang ◽  
Can Kang ◽  
Bo Gao ◽  
Kai Ji
Keyword(s):  
Rotation Axis ◽  
Axial Flow ◽  
Leading Edge ◽  
Cavitating Flow ◽  
Experimental Results ◽  
Suction Surface ◽  
Cavitation Bubbles ◽  
Cavitation Region ◽  
Axial Flow Pump ◽  
Flow Pump

Based on the external characteristic test, the performance of designed axial-flow model pump was determined. The cavitation performance of model pump at the best efficiency point was confirmed through the cavitation test. The cavitating flows in impeller at different NPSH values were shot by the high speed digital camera. MiVnt image analysis software was utilized to process the shooting images, track the cavitation region and outline of cavitation bubbles cluster. The experimental results show that the incipient cavitation regions are located in the inlet of blade suction surface near the tip and the leading edge of tip airfoil. With the decrease of NPSH values, the cavitation region at tip airfoil moves gradually from leading edge to trailing edge and the type of cavitation is vortex cavitation, its rotation axis direction is the same as circumferential direction. The cavitation region at blade suction surface indicates the same moving trend as at tip airfoil. The emerging of cloudy cavitation at the middle of blade suction surface indicates the beginning of pump cavitation. With the further increase of volume proportion of cavitation bubbles in impeller channel, the pump performance decreases severally. The experimental results reveal the preliminary laws of cavitating flow and provide an effective reference for the cavitation region and development process in impeller of axial-flow pump.

scholarly journals Effect of Tip Clearance on Helico-Axial Flow Pump Performance at Off-Design Case

Processes ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1653
Author(s):  
Nengqi Kan ◽  
Zongku Liu ◽  
Guangtai Shi ◽  
Xiaobing Liu
Keyword(s):  
Optimization Design ◽  
Flow Characteristics ◽  
Axial Flow ◽  
Leading Edge ◽  
Tip Clearance ◽  
Hydraulic Loss ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Axial Flow Pump ◽  
Flow Pump

To reveal the effect of tip clearance on the flow behaviors and pressurization performance of a helico-axial flow pump, the standard k-ε turbulence model is employed to simulate the flow characteristics in the self-developed helico-axial flow pump. The pressure, streamlines and turbulent kinetic energy in a helico-axial flow pump are analyzed. Results show that the tip leakage flow (TLF) forms a tip-separation vortex (TSV) when it enters the tip clearance and forms a tip-leakage vortex (TLV) when it leaves the tip clearance. As the blade tip clearance increases, the TLV moves along the blade from the leading edge (LE) to trailing edge (TE). At the same time, the entrainment between the TLV and the main flow deteriorates the flow pattern in the pump and causes great hydraulic loss. In addition, the existence of tip clearance also increases the possibility of TLV cavitation and has a great effect on the pressurization performance of the helico-axial flow pump. The research results provide the theoretical basis for the structural optimization design of the helico-axial flow pump.

Fish-friendly design of an axial flow pump impeller based on a blade strike model

2019 ◽  
Vol 234 (2) ◽  
pp. 173-186 ◽  
Author(s):  
Qiang Pan ◽  
Weidong Shi ◽  
Desheng Zhang ◽  
BPM van Esch ◽  
Ruijie Zhao
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Behavior ◽  
Integrated Design ◽  
Axial Flow ◽  
Hydraulic Performance ◽  
Fish Mortality ◽  
Computational Fluid Dynamics Analysis ◽  
Axial Flow Pump ◽  
Flow Pump

With environmental awareness growing in many countries, governments are taking measures to reduce mortality of migrating fish in pumping stations. Manufacturers seek to develop pumps that are less damaging to fish and still provide good hydraulic performance, but little is known about the implications design modifications may have on internal flow characteristics and overall hydraulic performance. In this paper, an integrated design method is proposed that combines a validated blade strike model for fish damage and a computational fluid dynamics method to assess the pump performance. A redesign of an existing, conventional, axial flow pump is presented as an example in this paper. It shows how the design of the impeller blades was modified stepwise in order to reduce fish mortality while its hydraulic performance was monitored. Computational fluid dynamics analysis of the flow near the hub of the highly skewed blades indicated that unconventional design modifications were required to ensure optimum flow behavior. In the final fish-friendly design, the risk of fish mortality has reduced considerably while the hydraulic performance of the pump is still acceptable for practical application.

scholarly journals Improvement of the Efficiency of the Axial-Flow Pump at Part Loads due to Installing Outlet Guide Vanes Mechanism

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Fan Yang ◽  
Hao-ru Zhao ◽  
Chao Liu
Keyword(s):  
Prediction Model ◽  
Flow Rate ◽  
High Efficiency ◽  
Guide Vane ◽  
Axial Flow ◽  
Hydraulic Performance ◽  
Operating Conditions ◽  
Ann Model ◽  
Axial Flow Pump ◽  
Flow Pump

In order to investigate the influence of adjustable outlet guide vane on the hydraulic performance of axial-flow pump at part loads, the axial-flow pump with 7 different outlet guide vane adjustable angles was simulated based on the RNG k-ε turbulent model and Reynolds time-averaged equations. The Vector graphs of airfoil flow were analyzed in the different operating conditions for different adjustable angles of guide vane. BP-ANN prediction model was established about the effect of adjustable outlet guide vane on the hydraulic performance of axial-flow pump based on the numerical results. The effectiveness of prediction model was verified by theoretical analysis and numerical simulation. The results show that, with the adjustable angle of guide vane increasing along clockwise, the high efficiency area moves to the large flow rate direction; otherwise, that moves to the small flow rate direction. The internal flow field of guide vane is improved by adjusting angle, and the flow separation of tail and guide vane inlet ledge are decreased or eliminated, so that the hydraulic efficiency of pumping system will be improved. The prediction accuracy of BP-ANN model is 1%, which can meet the requirement of practical engineering.

scholarly journals Unsteady Flow Field due to Nozzle Wake Interaction With the Rotor in an Axial Flow Turbine: Part I — Rotor Passage Flow Field

1995 ◽  
Author(s):  
Michael A. Zaccaria ◽  
Budugur Lakshminarayana
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Axial Flow ◽  
Leading Edge ◽  
Turbine Rotor ◽  
Suction Surface ◽  
Pressure Surface ◽  
Aerodynamic Interaction ◽  
Flow Gradients ◽  
Rotor Flow

The flow field in turbine rotor passages is complex with unsteadiness caused by the aerodynamic interaction of the nozzle and rotor flow fields. The two-dimensional steady and unsteady flow field at midspan in an axial flow turbine rotor has been investigated experimentally using an LDV with emphasis on the interaction of the nozzle wake with the rotor flow field. The flow field in the rotor passage is presented in Part I, while the flow field downstream of the rotor is presented in Part II. Measurements were acquired at 37 axial locations from just upstream of the rotor to one chord downstream of the rotor. The time average flow field and the unsteadiness caused by the wake has been captured. As the nozzle wake travels through the rotor flow field, the nozzle wake becomes distorted with the region of the nozzle wake near the rotor suction surface moving faster than the region near the rotor pressure surface, resulting in a highly distorted wake. The wake is found to be spread out along the rotor pressure surface, as it convects downstream of midchord. The magnitude of the nozzle wake velocity defect grows until close to midchord, after which it decreases. High values of unresolved unsteadiness were observed at the rotor leading edge. This is due to the large flow gradients near the leading edge and the interaction of the nozzle wake with the rotor leading edge. High values of unresolved unsteadiness were also observed near the rotor pressure surface. This increase in unresolved unsteadiness is caused by the interaction of the nozzle wake with the flow near the rotor pressure surface.

Investigation on the Horn-Like Vortices in Stator Corner Separation Flow in an Axial Flow Pump

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Chaoyue Wang ◽  
Fujun Wang ◽  
Yuan Tang ◽  
Benhong Wang ◽  
Zhifeng Yao ◽  
...  
Keyword(s):  
Guide Vane ◽  
Pressure Fluctuations ◽  
Axial Flow ◽  
Maximum Amplitude ◽  
Separation Flow ◽  
Suction Surface ◽  
Corner Separation ◽  
Axial Flow Pump ◽  
Velocity Moment ◽  
Flow Pump

Abstract Stator corner separation flow existing in the guide-vane domain has significant effects on the characteristics of an axial-flow pump. The objective of this paper is to investigate the vortical structures in stator corner separation flow. Transient numerical simulation with a proof experiment was conducted for an axial-flow pump. Structural features of the vortices and their effects on velocity moment attenuation and pressure fluctuations in the guide-vane domain were analyzed. Horn-like vortices are found in the stator corner separation flow. A full cycle of the horn-like vortex evolution, “inception-growth-development-decay,” is presented. During this transit process, the vortex tube is gradually elongated and deformed, which forms an oblique separation line on the vane suction surface. High velocity moment always exists in the flow passages of the guide-vane domain, and the uniformity of main flows is gradually reduced. Meanwhile, periodic pressure fluctuations arise. The maximum amplitude of pressure fluctuations in the flow passages occurs in the region where the horn-like vortex cores at the “growth” stage lie in, which is approximately 3.39 times higher than that in the vaneless region between the impeller and guide-vane. The dominant frequency of pressure fluctuations in the flow passages is approximately 0.75 times the rotating frequency, which is close to the frequency of the full cycle of the horn-like vortex evolution. Horn-like vortices have remarkable effects on the flow fields, and more attention should be paid to them.

Numerical simulation on hydraulic performance and tip leakage vortex of a slanted axial-flow pump with different blade angles

2021 ◽  
pp. 095440622110329
Author(s):  
Zhaodan Fei ◽  
Hui Xu ◽  
Rui Zhang ◽  
Yuan Zheng ◽  
Tong Mu ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Strain Tensor ◽  
Axial Flow ◽  
Hydraulic Performance ◽  
Tip Leakage Flow ◽  
Blade Angle ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Axial Flow Pump ◽  
Flow Pump

The blade angle has a great effect on hydraulic performance and internal flow field for axial-flow pumps. This research investigated the effect of the blade angle on hydraulic performance and tip leakage vortex (TLV) of a slanted axial-flow pump. The hydraulic performance and the TLV are compared with different setting angles. The dimensionless turbulence kinetic energy (TKE) is used to investigate the TLV. A novel variable fv is utilized to analyze the relation among the TLV, strain tensor and vorticity tensor. The proper orthogonal decomposition (POD) method is used to analyze TLV structure. The results show that with the increase of the blade angle, the pump head is getting larger, the flow rate of the best efficiency moves to be larger, and both the primary TLV (P-TLV) and the secondary TLV (S-TLV) are getting stronger. The P-TLV often exists in the outer edge of TKE distribution and S-TLVs often exist in the largest value area of TKE. This phenomenon is more evident with blade angle increasing. Through POD method, it shows that the first six modes contain more than 90% of TKE. The reason why the TKE value near the region of S-TLV is high is that the tip leakage flow is a kind of jet-like flow with high kinetic energy. The main structure of the P-TLV is shown in modes 4−6, resulting in a reflux zone but not with the highest TKE.

1613 Influence of rotor specific speeds on hydraulic performance of contra-rotating axial flow pump

2015 ◽  
Vol 2015 (0) ◽  
pp. _1613-1_-_1613-2_
Author(s):  
Tomoki TSUNEDA ◽  
Satoshi WATANABE ◽  
Shinichi TSUDA ◽  
Akinori FURUKAWA
Keyword(s):  
Axial Flow ◽  
Hydraulic Performance ◽  
Axial Flow Pump ◽  
Flow Pump
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