scholarly journals Influence of Balance Hole Diameter on Leakage Flow of the Balance Chamber in a Centrifugal Pump

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Wei Dong ◽  
Diyi Chen ◽  
Jian Sun ◽  
Yan Dong ◽  
Zhenbiao Yang ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Axial Force ◽  
Flow Rate ◽  
Volume Flow Rate ◽  
Vortex Motion ◽  
Internal Flow ◽  
Hole Diameter ◽  
Leakage Flow ◽  
Centrifugal Pumps ◽  
Axial Thrust

The balancing holes in centrifugal pumps with seals mounted in both suction and discharge sides are one of the approaches used by pump manufacturers to reduce the axial thrust. The balance hole diameter directly affects the axial force of the centrifugal pump. The flow characteristics in the balance chamber are closely related to the balance hole diameter. However, research is not very clear on the internal flow of the balanced chamber, due to the small axial and radial sizes and the complicated flow conditions in the chamber. In this paper, we analyzed the influence of the balance hole diameter on the liquid leakage rate, flow velocity, and vortex motion in the balance chamber. The results indicated that when the balance hole diameter was lower than the design value, the volume flow rate of leakage flow was proportional to the diameter. The liquid flow rate and vortex distribution rules in the balance chamber were mainly associated with the coeffect of radial leakage flow in the rear sealing ring interval and the axial balance hole leakage flow. The research has revealed the mechanisms of leakage flow of the balance chamber in the centrifugal pump and that this is of great significance for accurate calculation and balancing of the axial force.

scholarly journals Effect of Blade Outlet Angle on Unsteady Hydrodynamic Force of Closed-Type Centrifugal Pump with Single Blade

2014 ◽  
Vol 2014 ◽  
pp. 1-16 ◽  
Author(s):  
Yasuyuki Nishi ◽  
Junichiro Fukutomi
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Static Pressure ◽  
Hydrodynamic Forces ◽  
Centrifugal Impeller ◽  
Leakage Flow ◽  
Axial Thrust ◽  
Outlet Angle ◽  
Closed Type ◽  
Radial Thrust

Geometrically, the single-blade centrifugal impeller, commonly used today as a sewage pump, is not axially symmetric. For this reason, the static pressure around the impeller fluctuates greatly when the impeller is rotating, and not only the radial thrust but also the axial thrust shows large fluctuations. Therefore, it is extremely important for the improvement of pump reliability to quantitatively grasp these fluctuating hydrodynamic forces. In this study, we investigated the unsteady hydrodynamic forces in a closed-type centrifugal pump with a single blade for different blade outlet angles using a numerical analysis that takes into account both experiment and the leakage flow. The results clearly showed the effect of the blade outlet angle on that act on the impeller. The root-mean-square value of the fluctuating component of the total radial thrust was roughly the same for whichever impeller at low flow rate, but at high flow rates, the value increased for impellers with larger blade outlet angles. Moreover, when the leakage flow rate increased with increasing static pressure around the impeller, such that the rear and front shroud parts were subject to high pressure, the absolute value of the axial thrust on both these parts increased.

Research of Unsteady Characteristics of Torque in Centrifugal Pumps

2019 ◽  
Author(s):  
Luo Yin ◽  
Han Yuejiang ◽  
Dong Jian
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Time Domain ◽  
Internal Flow ◽  
Operating Parameters ◽  
Centrifugal Pumps ◽  
Flow Rates ◽  
Operation Conditions ◽  
Unsteady Characteristics ◽  
Dominant Frequencies

Abstract Torque is one of the most important operating parameters of centrifugal pumps which reflects the internal flow rate of centrifugal pumps. In order to explore the unsteady characteristics of torque of centrifugal pumps based on sensorless monitoring technology, a series of accurate measurements of torque of experimental centrifugal pump were carried on based on the test data collected. The frequency characteristic spectrums of torque were established and analyzed under different operation conditions. The analysis results shows that the torque of the experimental centrifugal pump varies approximately linearly with the increase of flow rate in time domain. Besides, a gentle trend of the torque fluctuation is also founded. Through frequency domain, the analysis results show that the dominant frequencies under different flow rates and cavitation conditions are all axial frequencies. The magnitude of amplitude has nothing to do with the flow rates or the cavitation conditions, and the internal flow rates of centrifugal pumps have no obvious effects on the fundamental frequency of torque of centrifugal pumps.

Hydraulic Axial Thrust in Multistage Centrifugal Pumps

1980 ◽  
Vol 102 (1) ◽  
pp. 64-69 ◽  
Author(s):  
T. Iino ◽  
H. Sato ◽  
H. Miyashiro
Keyword(s):  
Boundary Layer ◽  
Computer Program ◽  
Flow Rate ◽  
Theoretical Study ◽  
Experimental Results ◽  
Leakage Flow ◽  
Centrifugal Pumps ◽  
Axial Thrust ◽  
Pressure Distributions ◽  
Annular Seal

An experimental and theoretical study is performed with a single stage pump. The influence of the flow rate, the axial displacement of the impeller, and annular seal clearances on the hydraulic axial thrust is investigated. Pressure distributions measured in the space between the impeller and the casing agree with those calculated by the Kurokawa-Toyokura method when the leakage flow is inward in the space. It is clarified that the method is sometimes not available for the outward leakage flow because of the large thickness of the boundary layer in the space. A computer program for calculating the axial thrust in multistage centrifugal pumps is developed based on the method and experimental results. Axial thrusts measured in prototype multistage pumps agree with the calculation.

scholarly journals Effect of Rotation Speed and Flow Rate on Slip Factor in a Centrifugal Pump

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Bo Chen ◽  
Baolin Song ◽  
Bicheng Tu ◽  
Yiming Zhang ◽  
Xiaojun Li ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Rotation Speed ◽  
Internal Flow ◽  
Load Flow ◽  
Optical Measurements ◽  
Centrifugal Pumps ◽  
Pump Impeller ◽  
Slip Factor ◽  
Deviation Coefficient

This work analyzes the causes of the slip phenomenon in the impeller on the basis of the internal flow mechanism. Detailed optical measurements of the flow inside the rotation passages of a five-bladed centrifugal pump impeller are obtained through particle image velocimetry (PIV). On the basis of experimental data, the deviation coefficient of slip velocity is proposed and then revised according to the slip factor calculation formula of Stechkin. Results show that, at the same rotation speed, the slip factor increases with the flow rate and reaches the maximum value at 1.0 QBEP flow rate. At different rotation speeds, the slip factor increases with the rotation speed and shows a relatively large variation range. Moreover, a revised slip factor formula is proposed. The modified model is suitable for the correction of slip factor at part-load flow rates and serves as a guide for the hydraulic performance design and prediction of centrifugal pumps.

Numerical Optimal Design of Impeller Back Pump-Out Vanes on Axial Thrust in Centrifugal Pumps

2013 ◽  
Author(s):  
Feng Hong ◽  
Jianping Yuan ◽  
Yanguang Heng ◽  
Yanxia Fu ◽  
Banglun Zhou ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Axial Force ◽  
Navier Stokes ◽  
Geometrical Parameters ◽  
Centrifugal Pumps ◽  
Navier Stokes Equation ◽  
Axial Thrust ◽  
Pump Failure ◽  
Ansys Cfx ◽  
Structured Meshes

Axial thrust in centrifugal pumps attracts extensive attention in order to improve the operating reliability of pumps. High axial thrust can cause rapid thrust bearing wear and subsequent pump failure or frequent overhauls. A centrifugal pump (XA65/20) was selected in this study, based on L16 (43) orthogonal array and CFD methods. The time-averaged Navier-Stokes equation was calculated for a 3D steady flow in the model pump in ANSYS CFX with the standard k-ω turbulence model and standard wall function applied. The structured meshes with different numbers were used for comparison in order to confirm that the computational results were not influenced by the mesh. Meanwhile, the effects of impeller back pump-out vane geometrical parameters, including its thickness Sk, its outlet diameter De and axial clearance δ, on the axial thrust and performances of the model centrifugal pump were analyzed. The different orthogonal schemes were obtained on the different values of Sk, De, and δ. Finally, when the parameters of the impeller Sk, De, and δ are 5mm, 100mm, 1.5mm, respectively. The Best Efficiency Point (BEF) of 69.9% was achieved with 60.12m for the designed head and −952.133N for the minimum total axial force. The corresponding impeller with minimum total axial force was considered as the optimal scheme and manufactured for experimental test. The external characteristics by CFD have a good agreement with their experimental data, which also better verified the accuracy of the numerical method of axial thrust applied in this research.

scholarly journals Influence of wall roughness on cavitation performance of centrifugal pump

2021 ◽  
Vol 43 (6) ◽  
Author(s):  
Weihui Xu ◽  
Xiaoke He ◽  
Xiao Hou ◽  
Zhihao Huang ◽  
Weishu Wang
Keyword(s):  
Flow Field ◽  
Centrifugal Pump ◽  
Internal Flow ◽  
Wall Roughness ◽  
Blade Surface ◽  
Centrifugal Pumps ◽  
Three Dimensional Model ◽  
Cavitation Inception ◽  
Cavitation Performance ◽  
Critical Cavitation

AbstractCavitation is a phenomenon that occurs easily during rotation of fluid machinery and can decrease the performance of a pump, thereby resulting in damage to flow passage components. To study the influence of wall roughness on the cavitation performance of a centrifugal pump, a three-dimensional model of internal flow field of a centrifugal pump was constructed and a numerical simulation of cavitation in the flow field was conducted with ANSYS CFX software based on the Reynolds normalization group k-epsilon turbulence model and Zwart cavitation model. The cavitation can be further divided into four stages: cavitation inception, cavitation development, critical cavitation, and fracture cavitation. Influencing laws of wall roughness of the blade surface on the cavitation performance of a centrifugal pump were analyzed. Research results demonstrate that in the design process of centrifugal pumps, decreasing the wall roughness appropriately during the cavitation development and critical cavitation is important to effectively improve the cavitation performance of pumps. Moreover, a number of nucleation sites on the blade surface increase with the increase in wall roughness, thereby expanding the low-pressure area of the blade. Research conclusions can provide theoretical references to improve cavitation performance and optimize the structural design of the pump.

scholarly journals Analysis of the Influence of Different Bionic Structures on the Noise Reduction Performance of the Centrifugal Pump

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 886
Author(s):  
Cui Dai ◽  
Chao Guo ◽  
Yiping Chen ◽  
Liang Dong ◽  
Houlin Liu
Keyword(s):  
Flow Field ◽  
Noise Reduction ◽  
Centrifugal Pump ◽  
Great Influence ◽  
Frequency Doubling ◽  
Sound Field ◽  
Internal Flow ◽  
Test System ◽  
Centrifugal Pumps ◽  
External Characteristics

The strong noise generated during the operation of the centrifugal pump harms the pump group and people. In order to decrease the noise of the centrifugal pump, a specific speed of 117.3 of the centrifugal pump is chosen as a research object. The bionic modification of centrifugal pump blades is carried out to explore the influence of different bionic structures on the noise reduction performance of centrifugal pumps. The internal flow field and internal sound field of bionic blades are studied by numerical calculation and test methods. The test is carried out on a closed pump test platform which includes external characteristics and a flow noise test system. The effects of two different bionic structures on the external characteristics, acoustic amplitude–frequency characteristics and flow field structure of a centrifugal pump, are analyzed. The results show that the pit structure has little influence on the external characteristic parameters, while the sawtooth structure has a relatively great influence. The noise reduction effect of the pit structure is aimed at the wide-band noise, while the sawtooth structure is aimed at the discrete noise of the blade-passing frequency (BPF) and its frequency doubling. The noise reduction ability of the sawtooth structure is not suitable for high-frequency bands.

scholarly journals Optimal Design of Slit Impeller for Low Specific Speed Centrifugal Pump Based on Orthogonal Test

2021 ◽  
Vol 9 (2) ◽  
pp. 121
Author(s):  
Yang Yang ◽  
Ling Zhou ◽  
Hongtao Zhou ◽  
Wanning Lv ◽  
Jian Wang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Centrifugal Pump ◽  
Large Scale ◽  
Internal Flow ◽  
Orthogonal Test ◽  
Centrifugal Pumps ◽  
Initial Model ◽  
Low Specific Speed ◽  
Specific Speed ◽  
Four Levels

Marine centrifugal pumps are mostly used on board ship, for transferring liquid from one point to another. Based on the combination of orthogonal testing and numerical simulation, this paper optimizes the structure of a drainage trough for a typical low-specific speed centrifugal pump, determines the priority of the various geometric factors of the drainage trough on the pump performance, and obtains the optimal impeller drainage trough scheme. The influence of drainage tank structure on the internal flow of a low-specific speed centrifugal pump is also analyzed. First, based on the experimental validation of the initial model, it is determined that the numerical simulation method used in this paper is highly accurate in predicting the performance of low-specific speed centrifugal pumps. Secondly, based on the three factors and four levels of the impeller drainage trough in the orthogonal test, the orthogonal test plan is determined and the orthogonal test results are analyzed. This work found that slit diameter and slit width have a large impact on the performance of low-specific speed centrifugal pumps, while long and short vane lap lengths have less impact. Finally, we compared the internal flow distribution between the initial model and the optimized model, and found that the slit structure could effectively reduce the pressure difference between the suction side and the pressure side of the blade. By weakening the large-scale vortex in the flow path and reducing the hydraulic losses, the drainage trough impellers obtained based on orthogonal tests can significantly improve the hydraulic efficiency of low-specific speed 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.

Partial Admission, Axial Impulse Type Turbine Design and Partial Admission Radial Turbine Test for SCO2 Cycle

2017 ◽  
Author(s):  
Hyungki Shin ◽  
Junhyun Cho ◽  
Young-Jin Baik ◽  
Jongjae Cho ◽  
Chulwoo Roh ◽  
...  
Keyword(s):  
Axial Force ◽  
Flow Rate ◽  
Volume Flow Rate ◽  
Small Diameter ◽  
Volume Flow ◽  
Working Fluid ◽  
Rotating Speed ◽  
Turbo Generator ◽  
Partial Admission ◽  
Reduce Development Time

Power generation cycle — typically Brayton cycle — to use CO2 at supercritical state as working fluid have been researched many years because this cycle increase thermal efficiency of cycle and decrease turbomachinery size. But small turbomachinery make it difficult to develop proto type Supercritical Carbon dioxide (S-CO2) cycle equipment of lab scale size. KIER (Korea Institute of Energy Research) have been researched S-CO2 cycle since 2013. This paper is about 60kWe scale and sub-kWe class turbo generator development for applying to this S-CO2 cycle at the lab scale. A design concept of this turbo-generator is to use commercially available components so as to reduce development time and increase reliability. Major problem of SCO2 turbine is small volume flow rate and huge axial force. High density S-CO2 was referred as advantage of S-CO2 cycle because it make small turbomachinery possible. But this advantage was not valid in lab-scale cycles under 100kW because small amount volume flow rate means high rotating speed and too small diameter of turbine to manufacture it. Also, high inlet and outlet pressure make huge axial force. To solve these problem, KIER have attempt various turbines. In this paper, these attempts and results are presented and discussed.

Sign in / Sign up

Export Citation Format

Share Document