Influence of the Blade Trailing Edge Profile on the Performance and Unsteady Pressure Pulsations in a Low Specific Speed Centrifugal Pump

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Bo Gao ◽  
Ning Zhang ◽  
Zhong Li ◽  
Dan Ni ◽  
MinGuan Yang
Keyword(s):  
Centrifugal Pump ◽  
Pressure Pulsation ◽  
Pressure Pulsations ◽  
Trailing Edge ◽  
Unsteady Pressure ◽  
Pulsation Amplitude ◽  
Trailing Edges ◽  
Edge Profile ◽  
Low Specific Speed ◽  
Specific Speed

The blade trailing edge profile is of crucial importance for the performance and pressure pulsations of centrifugal pumps. In the present study, numerical investigation is conducted to analyze the effect of the blade trailing edge profile influencing the performance and unsteady pressure pulsations in a low specific speed centrifugal pump. Five typical blade trailing edges are analyzed including original trailing edge (OTE), circle edge (CE), ellipse on pressure side (EPS), ellipse on suction side (ESS), and ellipse on both sides (EBS). Results show that the well-designed blade trailing edges, especially for the EPS and EBS profiles, can significantly improve the pump efficiency. Pressure amplitudes at fBPF and 2fBPF are together calculated to evaluate the influence of the blade trailing edge profile on pressure pulsations. The EPS and EBS profiles contribute obviously to pressure pulsations reduction. In contrast, the CE and ESS profiles lead to increase of pressure pulsation amplitude compared with the OTE pump. Vorticity distribution at the blade trailing edge demonstrates that the EPS and EBS profiles have an effective impact on reducing vortex intensity at the blade trailing edge. Consequently, rotor–stator interaction could be attenuated leading to lower pressure pulsation amplitude. It is thought to be the main reason of pressure pulsations reduction obtained with the proper modified blade trailing edges. The results would pave the way for further optimization of the blade trailing edge profile.

scholarly journals The Role of Blade Sinusoidal Tubercle Trailing Edge in a Centrifugal Pump with Low Specific Speed

Processes ◽  
2019 ◽  
Vol 7 (9) ◽  
pp. 625 ◽  
Author(s):  
Bowen Li ◽  
Xiaojun Li ◽  
Xiaoqi Jia ◽  
Feng Chen ◽  
Hua Fang
Keyword(s):  
Centrifugal Pump ◽  
Pressure Pulsation ◽  
Suction Side ◽  
High Amplitude ◽  
Pressure Pulsations ◽  
Trailing Edge ◽  
Low Specific Speed ◽  
Specific Speed ◽  
And Performance ◽  
The Impact

Pressure pulsations may cause high-amplitude vibrations during the process of a centrifugal pump. The trailing edge shape of the blade has a critical influence on the pump’s pressure fluctuation and hydraulic characterization. In this paper, inspired by the humpback whale flipper, the authors research the impact of applying the sinusoidal tubercles to the blade suction side of the trailing edge. Numerical calculation and experiments are carried out to investigate the impact of the trailing edge shape on the pressure pulsations and performance of a centrifugal pump with low specific speed. Two designed impellers are tested, one is a sinusoidal tubercle trailing edge (STTE) impeller and the other is the original trailing edge (OTE) prototype. The detailed study indicates that the sinusoidal tubercle trailing edge (STTE) reduces pressure pulsation and enhances hydraulic performance. In the volute tongue region, the pressure pulsation amplitudes of STTE at fBPF decrease significantly. The STTE impeller also effectively changes the vortex structure and intensity in the blade trailing edge area. This investigation will be of great benefit to the optimal design of pumps.

Blade Thickness Redesign to Improve Efficiency and Decrease Unsteady Pressure Pulsation of a Low Specific Speed Centrifugal Pump

2021 ◽  
Author(s):  
Chengshuo Wu ◽  
Peng Wu ◽  
Dazhuan Wu
Keyword(s):  
Energy Loss ◽  
Secondary Flow ◽  
Centrifugal Pump ◽  
Pressure Pulsation ◽  
Dynamic Performance ◽  
Entropy Generation Rate ◽  
Pressure Pulsations ◽  
Blade Thickness ◽  
Low Specific Speed ◽  
Specific Speed

Abstract The existence of secondary flow in the impeller brings extra energy loss and aggravates the pressure pulsation which will worsen the hydraulic and dynamic performance of the pump. In this paper, based on the forces balance in the direction perpendicular to the streamline, an optimal design method for the blade thickness of a low specific speed centrifugal pump is proposed to suppress the secondary flow in the impeller. The origin impellers with 5 and 7 cylinder blades are redesigned and the hydraulic and dynamic performance of the model pump are investigated by numerical simulation and experimental. Results show that the blade modification proposed in this paper can effectively improve the efficiency of the model pump and reduce the internal pressure pulsations. The internal flow analysis shows that the performance improvement attributes to the suppression of secondary flow in the impeller. And the entropy generation rate is introduced to measure and locate the loss in the pump. Results show that on the one hand, the suppression of secondary flow can reduce the energy loss in the pump and improve the efficiency; on the other hand, it can repress the jet wake structure at impeller outlet and alleviate the intensity of pressure pulsations.

Analysis of the Pressure Pulsation and Vibration in a Low-Specific-Speed Centrifugal Pump

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Baoling Cui ◽  
Yingbin Zhang ◽  
Yakun Huang
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Vortex Core ◽  
Pressure Pulsation ◽  
Radial Force ◽  
Design Flow ◽  
Low Flow ◽  
Pressure Pulsations ◽  
Low Specific Speed ◽  
Specific Speed

Abstract Unsteady pressure pulsation and fluid force induced by flow instabilities in the centrifugal pump is an important cause of vibration, which is detrimental to the safe operation of the pump. In this study, we numerically investigated the pressure pulsation and radial force in a low-specific-speed centrifugal pump by using the detached-eddy simulation method. We also performed a vibration displacement experiment on the shaft of the centrifugal pump. The vortex identification method was introduced to clarify the internal correlation between unsteady flow structures with pressure pulsations. The results showed that the pressure pulsations at the impeller outlet were closely associated with the periodic vortex shedding from the blade pressure surface. The rotor–stator interaction between a relatively big trailing vortex core and volute tongue generated larger pressure pulsation and radial force in the pump at a low flow rate. Under a large flow rate, the trailing vortex core was easily broken and dispersed, and this resulted in smaller pressure pulsation and radial force compared with that at a low flow rate. Under the design flow rate, the pressure pulsation intensity and the radial force in the impeller were smaller than that under the off-design flow rate. Compared with the spectra between the radial force on the impeller and radial displacement on the shaft, they both presented higher amplitude at the shaft frequency. The vibration of the pump shaft was closely related to the radial force on the impeller.

Effects of the staggered blades on unsteady pressure pulsations and flow structures of a centrifugal pump

2021 ◽  
pp. 095765092098732
Author(s):  
Ning Zhang ◽  
Bo Gao ◽  
Chao Li ◽  
Dan Ni ◽  
Guoping Li
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Pulsation ◽  
Second Harmonic ◽  
Simulation Method ◽  
Pump Efficiency ◽  
Pressure Amplitude ◽  
Pressure Pulsations ◽  
Unsteady Pressure ◽  
Negative Effect

Effects of the staggered blades on unsteady pressure pulsations of a centrifugal pump with a specific speed ns=147 are investigated by the numerical simulation method. The obtained results are compared with the original blades. To clarify the resulting effects, eight monitoring points are used to extract pressure signals at three typical working conditions, and component at the blade passing frequency fBPF is emphasized. Results show that the pump efficiency and head will be reduced by the staggered blades, and at the nominal flow rate, the reduction is about 1.5% from comparison with the original blades. For all the eight points, the staggered blades contribute to the reduction of pressure amplitudes at fBPF when the pump works at three flow rates. The averaged reduction is 15.5% at the nominal flow rate. However, the negative effect on the second harmonic of fBPF will be caused by the staggered blades, and the corresponding pressure amplitude will increase at 2fBPF. It means that the pressure pulsation energy will be redistributed among the discrete components in pressure spectrum by the staggered blades. From the TKE distribution, it is found that the TKE values on the blade pressure side will be significantly affected by the staggered blades.

The effect of front streamline wrapping angle variation in a super-low specific speed centrifugal pump

2018 ◽  
Vol 232 (23) ◽  
pp. 4301-4311 ◽  
Author(s):  
Dong Liang ◽  
Zhao Yuqi ◽  
Liu Houlin ◽  
Dai Cui ◽  
Gradov D Vladimirovich ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Pressure Pulsation ◽  
Energy Performance ◽  
Sweep Angle ◽  
Angle Variation ◽  
Noise Characteristics ◽  
Ansys Cfx ◽  
Low Specific Speed ◽  
Specific Speed ◽  
Element Method

In this research, super-low specific speed centrifugal pump ( ns = 25, Chinese units: ns = 3.6 nQ1/2/ H3/4) is studied. The effect of the front streamline wrapping angles variation (135°, 139° and 145°) of the turbine on energy performance is considered. The pressure pulsation, interior and exterior noise characteristics and the performance of the impeller are thoroughly evaluated both experimentally and numerically. The pump has been modeled by means of computational fluid dynamics code of commercial software ANSYS CFX 11.0 to estimate energy performance and pressure pulsation. Boundary element method and finite element method are used to investigate the interior and exterior noise characteristics of the centrifugal pump by varying the front sweep angle. The front sweep angle variation was found to have insignificant influence on centrifugal pump performance characteristics. However, it influences fluid hydrodynamics around the volute tongue. In addition, the decreasing of the front streamline sweep angle slightly reduces the sound pressure level for the exterior acoustics, but the radiation distribution of the acoustic field does not change. In its turn, the modified trailing edge of the blades can reduce the peak value of the superposition decreasing the pressure pulsations at the blade passing frequency and its harmonic frequencies.

Effect of the volute tongue cut on pressure pulsations of a low specific speed centrifugal pump

2020 ◽  
Vol 32 (4) ◽  
pp. 758-770 ◽  
Author(s):  
Ning Zhang ◽  
Bo Gao ◽  
Bin Xia ◽  
Qi-feng Jiang
Keyword(s):  
Centrifugal Pump ◽  
Pressure Pulsations ◽  
Low Specific Speed ◽  
Specific Speed

scholarly journals Pressure fluctuation–vortex interaction in an ultra-low specific-speed centrifugal pump

2018 ◽  
Vol 38 (2) ◽  
pp. 527-543 ◽  
Author(s):  
Cong Wang ◽  
Yongxue Zhang ◽  
Zhiwei Li ◽  
Ao Xu ◽  
Chang Xu ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Pressure Fluctuation ◽  
Leading Edge ◽  
Experimental Results ◽  
Vortex Interaction ◽  
Trailing Edge ◽  
Pressure Surface ◽  
Baroclinic Torque ◽  
Low Specific Speed ◽  
Specific Speed

To provide a comprehensive understanding of the pressure fluctuation–vortex interaction in non-cavitation and cavitation flow, in this article, the unsteady flow in an ultra-low specific-speed centrifugal pump was investigated by numerical simulation. The uncertainty of the numerical framework with three sets of successively refined mesh was verified and validated by a level of 1% of the experimental results. Then, the unsteady results indicate that the features of the internal flow and the pressure fluctuation were accurately captured in accordance with the closed-loop experimental results. The detailed pressure fluctuation at 16 monitoring points and the monitoring of the vorticity suggest that some inconsistent transient phenomena in frequency spectrums show strong correlation with the evolution of vortex, such as abnormal increasing amplitudes at the monitoring points near to the leading edge on the suction surface and the trailing edge on the pressure surface in the case of lower pressurization capacity of impeller after cavitation. Further analysis applies the relative vortex transport equation to intuitionally illustrate the pressure fluctuation–vortex interaction by the contribution of baroclinic torque, viscous diffusion and vortex convection terms. It reveals that the effect of viscous diffusion is weak when the Reynolds number is much greater than 1. Pressure fluctuation amplitude enlarges on the suction side of blade near to the leading edge due to the baroclinic torque in cavitation regions, whereas the abnormal increase of pressure fluctuation after cavitation on the pressure surface of blade approaching the trailing edge results from the vortex convection during vortices moving downstream with the decrease of available net positive suction head at the same instance.

Numerical investigation of the effects of splitter blade deflection on the pressure pulsation in a low specific speed centrifugal pump

2019 ◽  
Vol 234 (4) ◽  
pp. 420-432 ◽  
Author(s):  
Jinfeng Zhang ◽  
Guidong Li ◽  
Jieyun Mao ◽  
Shouqi Yuan ◽  
Yefei Qu ◽  
...  
Keyword(s):  
Velocity Distribution ◽  
Turbulence Intensity ◽  
Pressure Fluctuation ◽  
Relative Velocity ◽  
Pressure Pulsation ◽  
Maximum Pressure ◽  
Flow Rates ◽  
Pulsation Amplitude ◽  
Low Specific Speed ◽  
Specific Speed

A combination of experimental and numerical simulation was carried out to analyze the influences of the splitter blade deflection on the performance and pressure fluctuation in low specific speed pumps with and without splitter blades under different flow rates. Performance experiments and particle image velocimetry (PIV) tests were performed to verify the results of the numerical calculation. Several monitoring points were placed in the calculation model pump to collect the pressure fluctuation signals, which were processed by Fast Fourier Transform to obtain the frequency results for further analysis. In addition, turbulence intensity and relative velocity distribution were also analyzed in the regions of the impeller and volute. The results showed that compared with a prototype without a splitter blade and the splitter blade schemes, the maximum pressure pulsation amplitudes are the lowest at different monitoring points of the model pump when the splitter blade deflects to the suction side of the main blade. The variation of pressure pulsation amplitude in this scheme is relatively stable with the change of flow rates compared with other schemes. Furthermore, the impeller scheme with an appropriate deflection of the splitter blade has the lowest turbulence intensity and optimal relative velocity distribution in the main flow passage. Therefore, this paper proposes a reference scheme of the impeller with the splitter blade to effectively decrease the predominate pressure pulsation amplitude.

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