Effects of Lean Mode of Blade Trailing Edge On Pressure Fluctuation Characteristics of a Vertical Centrifugal Pump with Vaned Diffuser

2021 ◽  
Author(s):  
Yongshun Zeng ◽  
Zhifeng Yao ◽  
Ran Tao ◽  
Weichao Liu ◽  
Ruofu Xiao
Keyword(s):  
Centrifugal Pump ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
Hydraulic Performance ◽  
Wake Flow ◽  
Long Distance ◽  
Trailing Edge ◽  
Excessive Pressure ◽  
Vaned Diffuser ◽  
Rotor Stator Interaction

Abstract A vertical centrifugal pump with a vaned diffuser is very attractive in the field of long-distance water supply. Excessive pressure fluctuations in the vaneless region due to rotor stator interaction (RSI) need careful evaluation. In the present investigation, the hydraulic performance and pressure fluctuation characteristics of a vertical centrifugal pump with three different lean modes of the blade trailing edge were quantitatively analyzed by comparison experiments, using the same test rig. Results showed that the pressure fluctuation level was the highest in the vaneless region, closest to the volute tongue, and increased as the flowrate deviated from the design flowrate. The lean mode of the blade trailing edge was found to have a slight influence on hydraulic performance, and the relative deviation of experimental specific speeds with three different lean modes was within 6%. The influence of the lean mode of the blade trailing edge on the pressure fluctuation level was experimentally verified for the first time. In particular, the flowrate-averaged peak-to-peak value of pressure fluctuation with the positive lean mode (PLM) was 62% of the corresponding value with the zero lean mode (ZLM), while no significant improvement was observed for the negative lean mode (NLM). The flow mechanism behind this may be explained as a weakening of the jet-wake flow pattern with PLM.

scholarly journals Numerical Investigation on Pressure Fluctuations for Different Configurations of Vaned Diffuser Pumps

2007 ◽  
Vol 2007 ◽  
pp. 1-10 ◽  
Author(s):  
Jianjun Feng ◽  
Friedrich-Karl Benra ◽  
Hans Josef Dohmen
Keyword(s):  
Unsteady Flow ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
Leading Edge ◽  
Wake Flow ◽  
Trailing Edge ◽  
Vaned Diffuser ◽  
Blade Number ◽  
Radial Gap

Numerical simulations on impeller-diffuser interactions in radial diffuser pumps are conducted to investigate the unsteady flow, and more attention is paid to pressure fluctuations on the blade and vane surfaces. Calculations are performed at different operating points, different blade number configurations, and different radial gaps between the impeller and diffuser to examine their effects on the unsteady flow. Computational results show that a jet-wake flow structure is observed at the impeller outlet. The biggest pressure fluctuation on the blade is found to occur at the impeller trailing edge, on the pressure side near the impeller trailing edge, and at the diffuser vane leading edge, independent of the flow rate, radial gap, and blade number configuration. All of the flow rate, blade number configuration, and radial gap influence significantly the pressure fluctuation and associated unsteady effects in the diffuser pumps.

scholarly journals Numerical Investigation of Pressure Fluctuation Characteristics in a Centrifugal Pump with Variable Axial Clearance

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Lei Cao ◽  
Zhengwei Wang ◽  
Yexiang Xiao ◽  
Yongyao Luo
Keyword(s):  
Centrifugal Pump ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
Maximum Pressure ◽  
Centrifugal Pumps ◽  
Pressure Surface ◽  
Clearance Flow ◽  
Rotor Stator Interaction ◽  
Entire Flow ◽  
Axial Clearance

Clearance flows in the sidewall gaps of centrifugal pumps are unsteady as well as main flows in the volute casing and impeller, which may cause vibration and noise, and the corresponding pressure fluctuations are related to the axial clearance size. In this paper, unsteady numerical simulations were conducted to predict the unsteady flows within the entire flow passage of a centrifugal pump operating in the design condition. Pressure fluctuation characteristics in the volute casing, impeller, and sidewall gaps were investigated with three axial clearance sizes. Results show that an axial clearance variation affects the pressure fluctuation characteristics in each flow domain by different degree. The greatest pressure fluctuation occurs at the blade pressure surface and is almost not influenced by the axial clearance variation which has a certainly effect on the pressure fluctuation characteristics around the tongue. The maximum pressure fluctuation amplitude in the sidewall gaps is larger than that in the volute casing, and different spectrum characteristics show up in the three models due to the interaction between the clearance flow and the main flow as well as the rotor-stator interaction. Therefore, clearance flow should be taken into consideration in the hydraulic design of centrifugal pumps.

Experimental Investigation of Pressure Fluctuations on Inner Wall of a Centrifugal Pump

2019 ◽  
Vol 36 (4) ◽  
pp. 401-410 ◽  
Author(s):  
Xiao-Qi Jia ◽  
Bao-Ling Cui ◽  
Zu-Chao Zhu ◽  
Yu-Liang Zhang
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
High Flow ◽  
Low Flow ◽  
Centrifugal Pumps ◽  
Flow Rates ◽  
Pressure Distributions ◽  
Blade Passing Frequency

Abstract Affected by rotor–stator interaction and unstable inner flow, asymmetric pressure distributions and pressure fluctuations cannot be avoided in centrifugal pumps. To study the pressure distributions on volute and front casing walls, dynamic pressure tests are carried out on a centrifugal pump. Frequency spectrum analysis of pressure fluctuation is presented based on Fast Fourier transform and steady pressure distribution is obtained based on time-average method. The results show that amplitudes of pressure fluctuation and blade-passing frequency are sensitive to the flow rate. At low flow rates, high-pressure region and large pressure gradients near the volute tongue are observed, and the main factors contributing to the pressure fluctuation are fluctuations in blade-passing frequency and high-frequency fluctuations. By contrast, at high flow rates, fluctuations of rotating-frequency and low frequencies are the main contributors to pressure fluctuation. Moreover, at low flow rates, pressure near volute tongue increases rapidly at first and thereafter increases slowly, whereas at high flow rates, pressure decreases sharply. Asymmetries are observed in the pressure distributions on both volute and front casing walls. With increasing of flow rate, both asymmetries in the pressure distributions and magnitude of the pressure decrease.

scholarly journals Pressure Fluctuation Reduction of a Centrifugal Pump by Blade Trailing Edge Modification

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1408 ◽  
Author(s):  
Bin Huang ◽  
Guitao Zeng ◽  
Bo Qian ◽  
Peng Wu ◽  
Peili Shi ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Pressure Fluctuation ◽  
Pressure Side ◽  
Centrifugal Pumps ◽  
Trailing Edge ◽  
Impeller Blade ◽  
Blade Passing Frequency ◽  
Impeller Outlet ◽  
Edge Profile ◽  
Edge Trimming

The pressure fluctuation inside centrifugal pumps is one of the main causes of hydro-induced vibration, especially at the blade-passing frequency and its harmonics. This paper investigates the feature of blade-passing frequency excitation in a low-specific-speed centrifugal pump in the perspective of local Euler head distribution based on CFD analysis. Meanwhile, the relation between local Euler head distribution and pressure fluctuation amplitude is observed and used to explain the mechanism of intensive pressure fluctuation. The impeller blade with ordinary trailing edge profile, which is the prototype impeller in this study, usually induces wake shedding near the impeller outlet, making the energy distribution less uniform. Because of this, the method of reducing pressure fluctuation by means of improving Euler head distribution uniformity by modifying the impeller blade trailing edge profile is proposed. The impeller blade trailing edges are trimmed in different scales, which are marked as model A, B, and C. As a result of trailing edge trimming, the impeller outlet angles at the pressure side of the prototype of model A, B, and C are 21, 18, 15, and 12 degrees, respectively. The differences in Euler head distribution and pressure fluctuation between the model impellers at nominal flow rate are investigated and analyzed. Experimental verification is also conducted to validate the CFD results. The results show that the blade trailing edge profiling on the pressure side can help reduce pressure fluctuation. The uniformity of Euler head circumferential distribution, which is directly related to the intensity of pressure fluctuation, is improved because the impeller blade outlet angle on the pressure side decreases and thus the velocity components are adjusted when the blade trailing edge profile is modified. The results of the investigation demonstrate that blade trailing edge profiling can be used in the vibration reduction of low specific impellers and in the engineering design of centrifugal pumps.

scholarly journals Experimental Analysis on Pressure Fluctuation Characteristics of a Centrifugal Pump with Vaned-Diffuser

Water ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 126
Author(s):  
Houlin Liu ◽  
Ruichao Xia ◽  
Kai Wang ◽  
Yucheng Jing ◽  
Xianghui He
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
Dominant Frequency ◽  
Design Flow ◽  
Signal Source ◽  
Vaned Diffuser ◽  
Impeller Outlet ◽  
Variation Tendency ◽  
Design Flow Rate

Experimental measurements to analyze the pressure fluctuation performance of a centrifugal pump with a vaned-diffuser, which its specific speed is 190. Results indicate that the main cause of pressure fluctuation is the rotor-stator interference at the impeller outlet. The head of the pump with vaned-diffuser at the design flow rate is 15.03 m, and the efficiency of the pump with a vaned-diffuser at the design flow rate reaches 71.47%. Pressure fluctuation decreases gradually with increasing distance from the impeller outlet. Along with the increase of the flow rate, amplitude of pressure fluctuation decreases. The amplitude of pressure fluctuation at the measuring points near the diffusion section of the pump body is larger than other measuring points. The variation tendency of pressure fluctuation at P1–P10 is the same, while there are wide frequency bands with different frequencies. The dominant frequency of pressure fluctuation is the blade passing frequency. The rotor-stator interference between the impeller and the vaned-diffuser gives rise to the main signal source of pressure fluctuation.

Influence of wall roughness on the static performance and pressure fluctuation characteristics of a double-suction centrifugal pump

2018 ◽  
Vol 232 (7) ◽  
pp. 826-840 ◽  
Author(s):  
Zhifeng Yao ◽  
Min Yang ◽  
Ruofu Xiao ◽  
Fujun Wang
Keyword(s):  
Centrifugal Pump ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
Design Flow ◽  
Experimental Investigations ◽  
Wall Roughness ◽  
Detached Eddy Simulation ◽  
Centrifugal Pumps ◽  
Eddy Simulation ◽  
Static Performance

The unsteady flow field and pressure fluctuations in double-suction centrifugal pumps are greatly affected by the wall roughness of internal surfaces. To determine the wall roughness effect, numerical and experimental investigations were carried out. Three impeller schemes for different wall roughness were solved using detached eddy simulation, and the performance and pressure fluctuations resolved by detached eddy simulation were compared with the experimental data. The results show that the effects of wall roughness on the static performance of a pump are remarkable. The head and efficiency of the tested double-suction centrifugal pump are raised by 2.53% and 6.60% respectively as the wall roughness is reduced by means of sand blasting and coating treatments. The detached eddy simulation method has been proven to be accurate for the prediction of the head and efficiency of the double-suction centrifugal pump with roughness effects. The influence of the roughness on pressure fluctuation is greatly dependent on the location relative to the volute tongue region. For locations close to the volute tongue, the peak-to-peak value of the pressure fluctuations of a wall roughness of Ra = 0.10 mm may be 23.27% larger than the case where Ra = 0.02 mm at design flow rate.

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.

Unsteady Hydrodynamic Forces due to Rotor-Stator Interaction on a Diffuser Pump With Identical Number of Vanes on the Impeller and Diffuser

2005 ◽  
Vol 127 (4) ◽  
pp. 743-751 ◽  
Author(s):  
M. Zhang ◽  
H. Tsukamoto
Keyword(s):  
Computational Study ◽  
Pressure Fluctuations ◽  
Vortex Method ◽  
Hydrodynamic Forces ◽  
Pump Impeller ◽  
Vaned Diffuser ◽  
Fluid Forces ◽  
Rotor Stator Interaction ◽  
Identical Number ◽  
Good Agreement

Experimental and computational study was developed for unsteady hydrodynamic forces on a diffuser pump impeller excited by the interaction between the impeller and the vaned diffuser with the same number of vanes as impeller. Unsteady flow calculations are made using commercially available CFD software, CFX-TASCflow, as well as the two-dimensional vortex method. Calculated pressure and fluid forces on the impeller show good agreement with measured ones. It has been demonstrated that the fluid forces on the impeller with the same number of vanes as the vaned diffuser are smaller compared with other combinations of vane numbers. However, the pressure fluctuations are found to be greater than other cases.

Comparative Study on Hydraulic Performance of Single-Suction Centrifugal Pump and Double-Suction Centrifugal Pump

2017 ◽  
Author(s):  
Chaoyue Wang ◽  
Fujun Wang ◽  
Zhichao Zou
Keyword(s):  
Centrifugal Pump ◽  
Pressure Fluctuation ◽  
Hydraulic Performance ◽  
Wake Structure ◽  
Suction Pump ◽  
Cavitation Performance ◽  
Impeller Outlet ◽  
Quantitative Results ◽  
Design And Manufacture ◽  
External Characteristics

In engineering applications, design and manufacture of double-suction impeller are on the basis of single-suction impeller. However, there is a lack of clear view on the differences of hydraulic performance between single-suction centrifugal pump and double-suction centrifugal pump which has the same blades. In this paper, a single-suction centrifugal pump and double-suction centrifugal pump with the same blades are investigated respectively, and their hydraulic performances have been compared in terms of external characteristics, flow pattern, pressure fluctuation and cavitation characteristics. In operating range of 0.6Q0∼1.1Q0, results show that the efficiency of double-suction pump is 4.14% higher than that of single-suction pump stably, and the head of single suction pump is 3.5% higher than that of double-suction pump stably. Single-suction impeller and double-suction impeller have similar jet-wake structure in impeller outlet, but the amplitude of velocity of single suction impeller changes more sharply. In the vicinity of rated condition, the amplitude of pressure fluctuation of double suction pump is about half that of the single suction pump, and the cavitation performance of double suction pump and single suction pump are basically the same. These quantitative results show that pressure fluctuation characteristics and cavitation performance of single-suction pump and double-suction pump with the same blades have little difference in the vicinity of rated condition. Compared with single-suction pump, the head of double-suction pump has declined, while the efficiency has improved remarkably. The research results have significant guidance on excavating the potential of excellent hydraulic models and guiding the design of double-inlet multistage double-suction centrifugal pump.

Sign in / Sign up

Export Citation Format

Share Document