Cavitation Analysis Near Blade Leading Edge of an Axial-Flow Pump

2009 ◽  
Author(s):  
Can Kang ◽  
Minguan Yang ◽  
Guangyan Wu ◽  
Haixia Liu
Keyword(s):  
Axial Flow ◽  
Leading Edge ◽  
Axial Flow Pump ◽  
Flow Pump ◽  
Blade Leading Edge

Computer-Aided Design and Numerical Flow Analysis of Axial-Flow Pump With Inducer

2006 ◽  
Author(s):  
Yaojun Li ◽  
Fujun Wang
Keyword(s):  
Flow Characteristics ◽  
Axial Flow ◽  
Leading Edge ◽  
Hydraulic Loss ◽  
Trailing Edge ◽  
Impeller Blade ◽  
Pump Design ◽  
Axial Flow Pump ◽  
Flow Pump ◽  
Blade Leading Edge

Axial-flow pump equipped with inducer are widely used in marine propulsion systems. The interaction of inducer and impeller has significant effect on the performance of pump. In this study, a special axial-flow pump is designed and analysed by CAD-CFD approaches to study the interaction of inducer and impeller. The pump includes two main elements, an inducer with 3 blades mounted on a conical hub and a 6-blade impeller. The blade angle of impeller is adjustable to generate different relative circumferential angles between the inducer blade trailing edge and the impeller blade leading edge. The 3D pump solid model is generated by taking the data file as interface between hydraulic-design and 3D modelling. A computational fluid dynamics code is used to investigate the flow characteristics and performance of the axial-flow pump. Numerical simulation is performed by adopting 3D RANS equations with RNG k-epsilon turbulence model. An unstructured grid system and the finite-volume method are used for the solution procedure of the discretized governing equations for this problem. The rotator-stator interaction is treated with a multiple reference frame (MRF) strategy. Computations are performed in different cases: 7 different relative circumferential angles (Δθ) between the inducer blade trailing edge and the impeller blade leading edge, 3 different axial gaps (G) between the inducer and the impeller. Variation of the hydraulic loss in the rotator is obtained with the change of delta theta. The numerical results show that the pressure generated is minimum in case of (G = 3%D). This indicates that the interference between inducer and impeller is strong if the axial gap is small. The pump performances are predicted and compared to the experimental measurements. The current investigation leads to a thorough enough understanding of the flow characteristics in axial-flow pumps with complex configurations. Recommendations for future modifications and improvements to the pump design are also given.

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.

Simulation Research on Cavitation Flow in Tip Clearance of Axial-Flow Pump

2012 ◽  
Vol 588-589 ◽  
pp. 1255-1258
Author(s):  
Zhong Li ◽  
Ning Zhang ◽  
Bo Hong ◽  
Qing Li
Keyword(s):  
Development Process ◽  
Axial Flow ◽  
Leading Edge ◽  
Tip Clearance ◽  
Cavitation Flow ◽  
Simulation Research ◽  
Cavitation Region ◽  
Axial Flow Pump ◽  
Rng Turbulence Model ◽  
Flow Pump

Based on external characteristic test, the performance of designed axial-flow model pump was determined. Combingmixture N-S equations with RNG turbulence model and full cavitation model, the cavitation flow in tip clearance of axial-flow pump at flow rate of best efficiency point is simulated. The results show that the incipient cavitation region is located in the leading edge of tip airfoil. With the decrease of cavitation number, the cavitation region at tip airfoil moves gradually from leading edge to trailing edge. The development process of cavitation can be divided into three different stages and the typical characteristics of each stage are given

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 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.

Suction Reverse Flow in an Axial-Flow Pump

1991 ◽  
Vol 113 (1) ◽  
pp. 90-97 ◽  
Author(s):  
K. Alpan ◽  
W. W. Peng
Keyword(s):  
Power Consumption ◽  
Reverse Flow ◽  
Experimental Studies ◽  
Axial Flow ◽  
Leading Edge ◽  
Power Coefficient ◽  
Recirculation Flow ◽  
Shaft Power ◽  
Axial Flow Pump ◽  
Flow Pump

Experiments are carried out to determine the effects of different inlet geometries on the onset of suction recirculation and its associated power consumption in an axial-flow pump. The critical flow rate is determined by both the “string” visual technique and “pressure” method. The results are correlated with the inlet area and flow velocity distribution upstream of the impeller. Four different conical covers matching the impeller leading edge are employed to cover the impeller inlet completely or partially. Covering the inlet area reduces the critical flowrate corresponding to the onset of suction recirculation and eliminates all recirculation at higher flowrates. The power consumption associated with the suction recirculation flow for the uncovered impeller is determined by comparing the shaft powers with and without inlet covers. At the shut-off condition, the power is estimated from a comparison with the shaft power measured with the impeller inlet completely covered. Experimental studies conclude that the power consumption due to suction recirculation is mainly controlled by the impeller inlet area and is insensitive to the inlet pipe configuration. At shut-off condition, the power coefficient correlates well with the parameter based on the hydraulic radius of inlet area. At a finite through flowrate the analytical model recommended by Tuzson (1983) is adequate, except for a proportionality coefficient determined from the test data.

scholarly journals Numerical Analysis of Mechanical Energy Dissipation for an Axial-Flow Pump Based on Entropy Generation Theory

Energies ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 4162 ◽  
Author(s):  
Simin Shen ◽  
Zhongdong Qian ◽  
Bin Ji
Keyword(s):  
Energy Dissipation ◽  
Mechanical Energy ◽  
Axial Flow ◽  
Leading Edge ◽  
Tip Clearance ◽  
Turbulent Dissipation ◽  
Generation Theory ◽  
Mechanical Energy Dissipation ◽  
Axial Flow Pump ◽  
Flow Pump

Mechanical energy dissipation is a major problem affecting hydraulic machinery especially under partial-load conditions. Owing to limitations of traditional methods in evaluating mechanical energy dissipation, entropy generation theory is introduced to study mechanical energy dissipation with varying discharge and tip clearance intuitively through numerical simulations in an axial-flow pump. Results show that the impeller and diffuser are the main domains of mechanical energy dissipation, respectively accounting for 35.32%–55.51% and 32.61%–20.42% of mechanical energy dissipation throughout the flow passage. The mechanical energy dissipation of the impeller has a strong relation with the hump characteristic and becomes increasingly important with decreasing discharge. Areas of high turbulent dissipation in the impeller are mainly concentrated near the blades’ suction sides, and these regions, especially areas near the shroud, extend with decreasing discharge. When the pump enters the hump region, the distributions of turbulent dissipation near the shroud become disordered and expand towards the impeller’s inlet side. Unstable flows, like flow separation and vortices, near the blades’ suction sides lead to the high turbulent dissipation in the impeller and hump characteristic. Turbulent dissipation at the tip decreases from the blade leading edge to trailing edge, and regions of high dissipation distribute near the leading edge of the blade tip side. An increase in tip clearance for the same discharge mainly increases areas of high turbulent dissipation near the shroud and at the tip of the impeller, finally reducing pump performance.

scholarly journals Study on tip leakage vortex in an axial flow pump based on modified shear stress transport k-ω turbulence model

2013 ◽  
Vol 17 (5) ◽  
pp. 1551-1555 ◽  
Author(s):  
Desheng Zhang ◽  
Dazhi Pan ◽  
Weidong Shi ◽  
Suqing Wu ◽  
Peipei Shao
Keyword(s):  
Shear Stress ◽  
Turbulence Model ◽  
Flow Rate ◽  
Axial Flow ◽  
Leading Edge ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Starting Point ◽  
Axial Flow Pump ◽  
Flow Pump

The tip leakage vortex structure and trajectory in an axial flow pump were investigated numerically and experimentally based on the modified shear stress transport k-? turbulence model. Numerical results were compared with the experimental leakage vortex trajectories, and a good agreement was presented. The detailed trajectories of tip leakage vortex show that the starting point of tip leakage vortex occurs near the leading edge at small flow rate, and it moves from leading edge to about 30% chord length at design flow rate. At larger flow rate condition, the starting point of tip leakage vortex shifts to the middle of chord.

Strength Analysis of Axial-Flow Pump Impeller Based on FSI

2015 ◽  
Vol 799-800 ◽  
pp. 581-584
Author(s):  
Xin Zhang ◽  
Yuan Zheng ◽  
Zheng Yang Zhang ◽  
Jun Qian ◽  
Jie Fu ◽  
...  
Keyword(s):  
Water Pressure ◽  
Axial Flow ◽  
Leading Edge ◽  
Static Stress ◽  
Strength Analysis ◽  
Pump Impeller ◽  
Finite Element Software ◽  
Pump Station ◽  
Axial Flow Pump ◽  
Flow Pump

It’s necessary to calculate and analyze the strength of the pump impeller for the safe operation of the pump. In this paper, the impeller strength of a two-way full-adjust horizontal axial-flow pump in a domestic pump station under forward pumping conditions was calculated by using the unidirectional fluid-structure interaction method; it means loading the blade surface water pressure calculating from CFD software CFX as structure surface loads to the blade, and then calculating the strength of the impeller using finite element software ANSYS ; the strength of the impeller was calculated under different blade rotating angle conditions. Through the calculation, we has got static stress and deformation distribution in the impeller. The results show that under each blade rotating angle, the maximum static stress always increases with lift increasing; the maximum static stress occurs at the junction of the blade and hub; the stress concentration also occurs in there prone to cause fatigue failure; maximum deformation of the blade occurs in the leading edge close to the rim; the maximum static stress is far less than yield strength of the material that the static stress can not cause cracks.

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