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.

Hydraulic Optimization and Loss Analyses of a Low Specific-Speed Centrifugal Pump With Variable-Thickness Blades

2016 ◽  
Author(s):  
Shiyang Li ◽  
Peng Wu ◽  
Dazhuan Wu
Keyword(s):  
Energy Loss ◽  
Centrifugal Pump ◽  
Cfd Simulation ◽  
Transient Flow ◽  
Thickness Distribution ◽  
Dynamic Performance ◽  
Thermodynamic Efficiency ◽  
Constant Flow Rate ◽  
Low Specific Speed ◽  
Specific Speed

This paper investigates the hydraulic and dynamic performance of a low specific-speed centrifugal pump with CFD simulation. Three different impellers are designed with different thickness distributions along the same mean line of the blades. The entropy production is introduced to study the energy losses in the three models and the energy loss distributions of the whole flow passages are fully revealed. The simplified energy loss equation is carefully validated by comparing the thermodynamic efficiency to the traditional hydraulic efficiency, and the errors between them can be considered acceptable. The circumferential Euler head distribution out of the impeller is used to predict the uniformity of the flow into the volute. To obtain the transient flow characteristics, the sliding mesh technique and the unsteady CFD simulation are applied and the pressure pulsations in the volute are well captured. The head fluctuation intensities of the three models are quantitatively compared under constant flow rate. The results show that the thickness distribution can affect the hydraulic performance to a large extent, and it can strongly affect the pressure pulsation in the volute.

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.

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.

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

Improve of Unsteady Pressure Pulsation Based On Jet-Wake Suppression for a Low Specific Centrifugal Pump

2021 ◽  
Author(s):  
Chengshuo Wu ◽  
Qianqian Li ◽  
Feng Zheng ◽  
Peng Wu ◽  
Shuai Yang ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Pressure Pulsation ◽  
Dynamic Performance ◽  
Internal Flow ◽  
Work Capacity ◽  
Wake Flow ◽  
Entropy Generation Rate ◽  
Wake Structure ◽  
Unsteady Pressure ◽  
Impeller Outlet

Abstract In this study, three impellers with different blade pressure side (PS) profiles were designed and the influence on the hydraulic and dynamic performance of a low specific speed centrifugal pump was investigated by numerical simulation and experimental research. The result shows that blade PS modification introduced in this study can efficiently alleviate the unsteady pressure pulsation of pump. In order to study the effects of blade modification on the internal flow filed, the volute domain was replaced by an even outlet region for CFD analysis. Relative velocity distribution was extracted to visualize the three-dimensional (3-D) flow characteristics at the impeller outlet. The result shows that the flow at impeller outlet presents a typical jet-wake structure which is significantly suppressed after the blade modification. The suppression of jet-wake structure, which is attributed to the redistribution of pressure and velocity in the impeller caused by the change of blade work capacity can directly reduce the intensity of pressure pulsation in the volute by increasing the velocity uniformity at impeller outlet. Given that the existence of jet-wake flow results in large mixing loss and velocity deviation at the impeller outlet, entropy generation rate and slip velocity calculation were introduced here to measure the extent of jet-wake configuration. Result shows that both indicators introduced here can be used to quantify the extent of the wake-jet structure at impeller outlet, and thus, indirectly predict the strength of unsteady pressure pulsation in pump volute.

scholarly journals Effects of the impeller–volute tongue interaction on the internal flow in a low-specific-speed centrifugal pump with splitter blades

2017 ◽  
Vol 232 (2) ◽  
pp. 170-180 ◽  
Author(s):  
Yandong Gu ◽  
Shouqi Yuan ◽  
Ji Pei ◽  
Jinfeng Zhang ◽  
Fan Zhang ◽  
...  
Keyword(s):  
Energy Loss ◽  
Centrifugal Pump ◽  
Time History ◽  
Internal Flow ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Impeller Outlet ◽  
Pressure Peak ◽  
Low Specific Speed ◽  
Specific Speed

To investigate the effects of the main blades and splitter blades interacting with the volute tongue on the internal flow in a low-specific-speed centrifugal pump, the Reynolds-averaged Navier–Stokes equation, coupled with SST k-ω turbulence model, is employed to simulate the transient turbulent flow in the whole flow passage. The numerical simulation results have been verified with the experimental measurements by comparing the head and efficiency. The pressure fluctuation caused by impeller–volute tongue interaction, including time–history and frequency characteristics, is calculated and analyzed at five monitoring points adjoining the impeller outlet and tongue, as well as the torque of a single main blade and a single splitter blade. After that, both the energy loss and vorticity distributions on the middle section are discussed when the impeller rotates to four circumferential positions relative to the cutwater. The results show that the maximum pressures at the monitoring points occur before the blades reach the closest circumferential position with respect to the cutwater, and the peak pressure near the trailing edge of splitter blades is larger than main blades. There is only one torque peak of a single blade in one revolution when the angle between the monitoring blade and tongue is about 15°. Additionally, the torque peak arises before the torque valley, but the pressure valley at monitoring points in the impeller comes earlier than the pressure peak. Both the energy loss and vorticity are enlarged around the volute tongue evidently after the blades pass by the cutwater, and the splitter blades produce more unsteadiness and energy dissipation than main blades.

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