scholarly journals Energy Performance and Radial Force of a Mixed-Flow Pump with Symmetrical and Unsymmetrical Tip Clearances

Energies ◽  
2017 ◽  
Vol 10 (1) ◽  
pp. 57 ◽  
Author(s):  
Yue Hao ◽  
Lei Tan ◽  
Yabin Liu ◽  
Yun Xu ◽  
Jinsong Zhang ◽  
...  
Keyword(s):  
Energy Performance ◽  
Radial Force ◽  
Mixed Flow ◽  
Flow Pump

Influence of tip leakage flow and inlet distortion flow on a mixed-flow pump with different tip clearances within the stall condition

2019 ◽  
Vol 234 (4) ◽  
pp. 433-453 ◽  
Author(s):  
Leilei Ji ◽  
Wei Li ◽  
Weidong Shi
Keyword(s):  
Internal Flow ◽  
Energy Performance ◽  
Rotating Stall ◽  
Design Flow ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Mixed Flow ◽  
Tip Leakage ◽  
Flow Pump

In order to investigate the effect of impeller tip clearance on internal flow fields and the rotating stall inception impacted by tip leakage vortex and inlet unsteady flow in a mixed-flow pump, mixed-flow pump models with tip clearances of 0.5 mm, 0.8 mm, and 1.1 mm were numerically calculated, and then the energy performance curves and internal flow structures were obtained and compared. The results show that the pump efficiency and the internal flow fields of numerical calculation are in good agreement with experimental results at design flow rate and near-stall condition. A portion of the positive slope segment appears in the energy performance curves under different tip clearances. The lowest head of the mixed-flow pump in the positive slope region decreases with the increase of the tip clearance while the highest head shows an opposite situation indicating that mixed-flow pumps are easier to stall under small tip clearance. At the design flow rate condition, the tip leakage vortex is relatively stable under different tip clearances and appears as a “snail shell” shape, whereas in rotating stall conditions, the “snail shell” shape disappear and the tip leakage flow on blade front forms a “flat” vortex structure. The inlet swirl flow not only affects the tip leakage flow in rotating stall conditions under different tip clearances, but also blocks the fluid from the inlet pipe. Under the circumstance of the same tip clearance, the main frequency amplitude of pressure pulsation coefficient gradually shifts away from blade passing frequency (96.67 Hz) to the axial frequency (24.17 Hz) when the pump operates in the stall condition.

Effect of Tip Clearance on Rotating Stall in a Mixed-Flow Pump

2019 ◽  
Author(s):  
Wei Li ◽  
Ramesh K. Agarwal ◽  
Ling Zhou ◽  
Enda Li ◽  
Leilei Ji
Keyword(s):  
Flow Separation ◽  
Internal Flow ◽  
Energy Performance ◽  
Rotating Stall ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Pump Efficiency ◽  
Mixed Flow ◽  
Performance Curves ◽  
Flow Pump

Abstract The non-uniform disturbance in the circumferential direction is the main cause for the occurrence of rotating stall in turbomachinery. In order to study the effect of tip clearance leakage flow on rotating stall, the mixed-flow pump models with different tip clearances are numerically simulated, and then the energy performance curves and internal flow structures are obtained and compared. The results show that the computed pump efficiency and the internal flow field of the pump from numerical simulation are in good agreement with the experimental results. A saddle region appears in the energy performance curves of the three tip clearances, and with decrease in tip clearance, the head and efficiency of the mixed-flow pump increase and the critical stall point shifts, and the stable operating range of the mixed-flow pump decreases, which indicates that the mixed-flow pump stalls easily for smaller tip clearance. Under the deep stall condition, the influence of the leakage flow in the end wall area increases gradually with decrease in clearance. For small clearance, the leakage flow moves away from the suction surface to some distance to form a number of leakage vortex strips with the mainstream flow and flows over the leading edge of the next blade and then flows downstream into different flow passages, generating backflow and secondary flow separation at the blade inlet, which seriously damages the spatial structure of the inlet flow. This results in the earlier occurrence of stall. With increase in clearance, the leakage vortex develops along the radial direction towards the middle of the flow channel and large flow separation occurs in the downstream channel, which induces deep stall. For 0.8mm clearance, the whole impeller outlet passage is almost blocked by the backflow of the guide vane inlet, and a deep stall is induced.

Effect of Tip Clearance on Rotating Stall in A Mixed-Flow Pump

2021 ◽  
pp. 1-39
Author(s):  
Wei Li ◽  
Leilei Ji ◽  
Enda Li ◽  
Ling Zhou ◽  
Ramesh Agarwal
Keyword(s):  
Flow Separation ◽  
Internal Flow ◽  
Energy Performance ◽  
Rotating Stall ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Pump Efficiency ◽  
Mixed Flow ◽  
Performance Curves ◽  
Flow Pump

Abstract The non-uniform disturbance in circumferential direction is main cause for occurrence of rotating stall in turbomachinery. In order to study the effect of tip clearance leakage flow on rotating stall, mixed-flow pump models with different tip clearances are simulated and energy performance curves and internal flow structures are obtained and compared. The results show that the computed pump efficiency and the internal flow field of the pump are in good agreement with experimental results. A saddle region appears in energy performance curves of three tip clearances and with decrease in tip clearance, the head and efficiency of mixed-flow pump increase and critical stall point shifts and stable operating range of mixed-flow pump decreases, which indicates that mixed-flow pump stalls easily for smaller tip clearance. Under deep stall condition, influence of leakage flow in end wall area increases gradually with decrease in clearance. For small clearance, the leakage flow moves away from suction surface to some distance to form number of leakage vortex strips with mainstream flow and flows over the leading edge of next blade and then flows downstream into different flow passages generating back flow and secondary flow separation at the blade inlet, which seriously damages the spatial structure of inlet flow. This results in earlier occurrence of stall. With increase in clearance, the leakage vortex develops along radial direction towards middle of flow channel and large flow separation occurs in downstream channel which induces deep stall.

Performance and Radial Loading of a Mixed-Flow Pump Under Non-Uniform Suction Flow

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
B. P. M. van Esch
Keyword(s):  
Velocity Profile ◽  
Radial Force ◽  
Rotor System ◽  
Flow Profile ◽  
Centrifugal Pumps ◽  
Mixed Flow ◽  
Pipe Bend ◽  
Suction Velocity ◽  
Suction Flow ◽  
Flow Pump

Many centrifugal pumps have a suction velocity profile, which is nonuniform, either by design like in double-suction pumps, sump pumps, and in-line pumps, or as a result of an installation close to an upstream disturbance like a pipe bend. This paper presents an experimental study on the effect of a nonuniform suction velocity profile on performance of a mixed-flow pump and hydrodynamic forces on the impeller. In the experiments, a newly designed dynamometer is used, equipped with six full Wheatstone bridges of strain gauges to measure the six generalized force components. It is placed in between the shaft of the pump and the impeller and corotates with the rotor system. A high accuracy is obtained due to the orthogonality of bridge positioning and the signal conditioning electronics embedded within the dynamometer. The suction flow distribution to the pump is adapted using a pipe bundle situated in the suction pipe. Results of measurements show the influence of the suction flow profile and blade interaction on pump performance and forces. Among the most important observations are a backward whirling motion of the rotor system and a considerable steady radial force.

scholarly journals Energy Performance and Flow Patterns of a Mixed-Flow Pump with Different Tip Clearance Sizes

Energies ◽  
2017 ◽  
Vol 10 (2) ◽  
pp. 191 ◽  
Author(s):  
Yabin Liu ◽  
Lei Tan ◽  
Yue Hao ◽  
Yun Xu
Keyword(s):  
Energy Performance ◽  
Flow Patterns ◽  
Tip Clearance ◽  
Mixed Flow ◽  
Flow Pump

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

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Leilei Ji ◽  
Wei Li ◽  
Weidong Shi ◽  
Ling Zhou ◽  
Ramesh Agarwal
Keyword(s):  
Performance Test ◽  
Pressure Pulsation ◽  
Rotation Period ◽  
Low Frequency ◽  
Energy Performance ◽  
Tip Clearance ◽  
Wavelet Coherence ◽  
Energy Concentration ◽  
Mixed Flow ◽  
Flow Pump

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.

Role of blade rotational angle on energy performance and pressure fluctuation of a mixed-flow pump

2017 ◽  
Vol 231 (3) ◽  
pp. 227-238 ◽  
Author(s):  
Tan Lei ◽  
Yu Zhiyi ◽  
Xu Yun ◽  
Liu Yabin ◽  
Cao Shuliang
Keyword(s):  
Pressure Fluctuation ◽  
Guide Vane ◽  
Pressure Fluctuations ◽  
Maximum Amplitude ◽  
Energy Performance ◽  
Mixed Flow ◽  
Rotational Angle ◽  
Flow Pump ◽  
Dominant Frequencies

The role of blade rotational angle in the energy performance and pressure fluctuation of a mixed-flow pump is investigated through an experimental measurement and numerical simulation. The mixed-flow pump head increases at a blade rotational angle of 4° and decreases at a blade rotational angle of −4° compared with a blade rotational angle of 0°. Meanwhile, the highest efficiency decreases by 0.3% at a blade rotational angle of 4° and increases by 0.8% at a blade rotational angle of −4°. The pressure fluctuation characteristics in the mixed-flow pump at different blade rotational angles are also revealed. The dominant frequencies of pressure fluctuations in the impeller are the axis rotation frequency or six times this frequency corresponding to six guide vanes. The dominant frequencies of pressure fluctuations at the middle plane of impeller and guide vane are the blade-passing frequencies or twice this frequency. The maximum amplitude of pressure fluctuation in the impeller at a blade rotational angle of −4° is greater than that of blade rotational angle 0° and 4° because of strong vortex intensity. The maximum amplitude of pressure fluctuation at the middle span of the impeller and vane occurs at a blade rotational angle of 4° because of the largest pressure gradient.

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