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.

scholarly journals Efficiency improvement and evaluation of a centrifugal pump with vaned diffuser

2019 ◽  
Vol 11 (3) ◽  
pp. 168781401982590 ◽  
Author(s):  
Kai Wang ◽  
Yu-cheng Jing ◽  
Xiang-hui He ◽  
Hou-lin Liu
Keyword(s):  
Centrifugal Pump ◽  
Axial Force ◽  
Flow Rate ◽  
Pressure Pulsation ◽  
Energy Performance ◽  
Radial Force ◽  
Design Flow ◽  
Vaned Diffuser ◽  
Original Scheme ◽  
Design Flow Rate

In order to enhance the efficiency of centrifugal pump, the structure of a centrifugal pump with vaned diffuser, whose specific speed is 190, was numerically improved by trimming back-blades of impeller and smoothing sharp corner in annular chamber. The energy performance, the internal flow field, the axial force, the radial force, and the pressure pulsation of the pump were analyzed. Results show that efficiency of the improving scheme 1 under the design flow rate is 77.47%, which can balance 69.82% of the axial force, while efficiency of the improving scheme 2 under the design flow rate is the maximum, which could still balance 62.74% of the axial force. The pressure pulsations of the improving scheme 2 at the typical monitoring points are less than that of the improving scheme 1 and the original scheme. The difference of the radial force peak between the improving scheme 1 and the improving scheme 2 is very small. The vector distributions of the radial force of the improving scheme 1 and the improving scheme 2 are more uniform than that of the original scheme. Considering the efficiency, pressure pulsation, and axial force, experiment measurements on the improving scheme 2 were carried out to verify the effectiveness of the improvement result. Results of energy performance experiment show that efficiency of the improving scheme 2 under the design flow rate is 76.48%, which is 5.26 percentage points higher than that of the original scheme.

Numerical investigation of clocking effect on a centrifugal pump with inlet guide vanes

2016 ◽  
Vol 33 (2) ◽  
Author(s):  
WANSHI QU ◽  
lei tan ◽  
Shuliang CAO ◽  
YUCHUAN WANG ◽  
YUN XU
Keyword(s):  
Flow Field ◽  
Numerical Investigation ◽  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
Design Methodology ◽  
Design Flow ◽  
Guide Vanes ◽  
Inlet Guide Vanes ◽  
Design Flow Rate

Purpose The paper aims to investigate the clocking effect on a centrifugal pump with inlet guide vanes (IGVs). Design/methodology/approach The paper uses a computation fluid dynamics (CFD) framework to solve the unsteady flows in a centrifugal pump with inlet guide vanes. The relative position between the stationary vanes and the stationary volute tongue is defined as the clocking position when IGVs inside the suction pipe rotate along the circumferential direction. Findings The results show that clocking positions have little effect on the pump head and efficiency, however their influences are obvious for the pressure fluctuation and flow field in the centrifugal pump. The maximum difference of pressure amplitude at dominant frequency reach up to 28% on the monitoring point V8 at different clocking positions under design flow rate. For the large flow rate, the clocking effect on flow field and pressure fluctuation in centrifugal pump is similar to that of design flow rate. However, the clocking effect is nearly negligible at partial flow rate, because there are reverse flows around the tongue tip and obvious vortexes forming and developing in the impeller. Those complex phenomena interacting in the centrifugal pump make the clocking effect less evident. Originality/value The numerical investigation reveals the clocking effect on a centrifugal pump with inlet guide vanes, which also valuable for the stable operation and optimal design of centrifugal pumps.

scholarly journals Comprehensive Numerical Investigations of Unsteady Internal Flows and Cavitation Characteristics in Double-Suction Centrifugal Pump

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Xuelin Tang ◽  
Mingde Zou ◽  
Fujun Wang ◽  
Xiaoqin Li ◽  
Xiaoyan Shi
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuations ◽  
Dominant Frequency ◽  
Secondary Flows ◽  
Design Flow ◽  
Sharp Drop ◽  
Blade Loading ◽  
Blade Passing Frequency ◽  
Design Flow Rate

The RNG k-ε turbulence model combined with cavitation model was used to simulate unsteady cavitating flows inside a double-suction centrifugal pump under different flow rate conditions based on hexahedral structured grid. The numerical external characteristic performances agree well with the experimental performances. The predicted results show that the turbulence kinetic energy and the turbulence dissipation rate inside the impeller at design flow rate are lower than those at other off-design flow rates, which are caused by various vortexes. Based on frequency-domain analyses in the volute casing, the blade passing frequency is the dominant one of the pressure fluctuations except the vicinity of volute tongue for all operating cases, and the dominant frequency near the volute tongue ranges from 0 to 0.5 times the blade passing frequency for other off-design points, while the blade passing one near the volute tongue is the dominant one of the pressure fluctuations at design point. The increase of flow rate reduces the pressure fluctuations amplitude. For cavitation cases, the blade loading of the middle streamline increases a bit during the initial stage, but, for serious cavitation, the blade loading near the blade inlet reduces to 0 and even negative values, and the serious cavitation bubbles block the blade channels, which results in a sharp drop in pump head. Under noncavitation condition, the predicted power related to the pressure in the impeller channels increases from the inlet to the exit, while, under different cavitation conditions at the design flow rate, these power-transformation distributions in the impeller channels show that these power conversions are affected by the available NPSHa and the corresponding work in leading regions of the blades increases increases gradually a bit, and then it increases sharply in the middle regions, but it decreases in the blade trailing regions and is greatly influenced by secondary flows.

Turbulence Measurements in a Centrifugal Pump With a Synchronously Orbiting Impeller

1991 ◽  
Author(s):  
Ronald D. Flack ◽  
Steven M. Miner ◽  
Ronald J. Beaudoin
Keyword(s):  
Centrifugal Pump ◽  
Reynolds Stress ◽  
Flow Rate ◽  
Cross Product ◽  
Design Flow ◽  
Low Flow ◽  
Rate Variation ◽  
Flow Rates ◽  
The Individual ◽  
Design Flow Rate

Turbulence profiles were measured in a centrifugal pump with an impeller with backswept blades using a two directional laser velocimeter. Data presented includes radial, tangential, and cross product Reynolds stresses. Blade to blade profiles were measured at four circumferential positions and four radii within and one radius outside the four bladed impeller. The pump was tested in two configurations; with the impeller running centered within the volute, and with the impeller orbiting with a synchronous motion (ε/r2 = 0.016). Flow rates ranged from 40% to 106% of the design flow rate. Variation in profiles among the individual passages in the orbiting impeller were found. For several regions the turbulence was isotropic so that the cross product Reynolds stress was low. At low flow rates the highest cross product Reynolds stress was near the exit. At near design conditions the lowest cross product stress was near the exit, where uniform flow was also observed. Also, near the exit of the impeller the highest turbulence levels were seen near the tongue. For the design flow rate, inlet turbulence intensities were typically 9% and exit turbulence intensities were 6%. For 40% flow capacity the values increased to 18% and 19%, respectively. Large local turbulence intensities correlated with separated regions. The synchronous orbit did not increase the random turbulence, but did affect the turbulence in the individual channels in a systematic pattern.

Turbulence Measurements in a Centrifugal Pump With a Synchronously Orbiting Impeller

1992 ◽  
Vol 114 (2) ◽  
pp. 350-358 ◽  
Author(s):  
R. D. Flack ◽  
S. M. Miner ◽  
R. J. Beaudoin
Keyword(s):  
Centrifugal Pump ◽  
Reynolds Stress ◽  
Flow Rate ◽  
Cross Product ◽  
Design Flow ◽  
Low Flow ◽  
Rate Variation ◽  
Flow Rates ◽  
The Individual ◽  
Design Flow Rate

Turbulence profiles were measured in a centrifugal pump with an impeller with backswept blades using a two-directional laser velocimeter. Data presented include radial, tangential, and cross product Reynolds stresses. Blade-to-blade profiles were measured at four circumferential positions and four radii within and one radius outside the four-bladed impeller. The pump was tested in two configurations: with the impeller running centered within the volute, and with the impeller orbiting with a synchronous motion (ε/r2 = 0.016). Flow rates ranged from 40 to 106 percent of the design flow rate. Variation in profiles among the individual passages in the oribiting impeller were found. For several regions the turbulence was isotropic so that the cross product Reynolds stress was low. At low flow rates the highest cross product Reynolds stress was near the exit. At near-design conditions the lowest cross product stress was near the exit, where uniform flow was also observed. Also, near the exit of the impeller the highest turbulence levels were seen near the tongue. For the design flow rate, inlet turbulence intensities were typically 9 percent and exit turbulence intensities were 6 percent. For 40 percent flow capacity the values increased to 18 and 19 percent, respectively. Large local turbulence intensities correlated with separated regions. The synchronous orbit did not increase the random turbulence, but did affect the turbulence in the individual channels in a systematic pattern.

Pressure Fluctuation of the Low Specific Speed Centrifugal Pump

2012 ◽  
Vol 152-154 ◽  
pp. 935-939 ◽  
Author(s):  
Qiang Fu ◽  
Shou Qi Yuan ◽  
Rong Sheng Zhu
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
High Frequency ◽  
Pressure Fluctuations ◽  
Radial Force ◽  
Design Flow ◽  
Rate Condition ◽  
Low Specific Speed ◽  
Specific Speed

In order to study the rules of pressure fluctuation and the radial force under different positions in a centrifugal pump with low specific speed, and to find the relationship between each other, the three-dimensional ,unsteady Reynolds-averaged Navier-stokes equations with shear stress transport turbulent models were solved. The pressure fluctuation was obtained. The results showed that the pressure fluctuations were visible. The pressure fluctuations in the volute were relatively low at the design flow rate condition. The blade passing frequency dominates the pressure fluctuations, high frequency contents were found on the outlet of impeller but no high frequency information occured in casing. The radial force on the impeller was unsteady especially at the small flow rate.

Experimental Investigation of Time-Frequency Characteristics of Pressure Fluctuations in a Double-Suction Centrifugal Pump

2011 ◽  
Vol 133 (10) ◽  
Author(s):  
Zhifeng Yao ◽  
Fujun Wang ◽  
Lixia Qu ◽  
Ruofu Xiao ◽  
Chenglian He ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
Operating Conditions ◽  
Design Flow ◽  
Flow Rates ◽  
Time Frequency ◽  
Blade Passing Frequency ◽  
Design Flow Rate

Pressure fluctuation is the primary reason for unstable operations of double-suction centrifugal pumps. By using flush mounted pressure transducers in the semispiral suction chamber and the volute casing of a double-suction pump, the pressure fluctuation signals were obtained and recorded at various operating conditions. Spectral analyses were performed on the pressure fluctuation signals in both frequency domain and time-frequency domain based on fast Fourier transform (FFT) and an adaptive optimal-kernel time-frequency representation (AOK TFR). The results show that pressure fluctuations at the impeller rotating frequency and some lower frequencies dominated in the semispiral suction chamber. Pressure fluctuations at the blade passing frequency, the impeller rotating frequency, and their harmonic frequencies were identified in the volute casing. The amplitude of pressure fluctuation at the blade passing frequency significantly increased when the flow rate deviated from the design flow rate. At 107% of the design flow rate, the amplitude increased more than 254% than that at the design flow rate. The time-frequency characteristics of these pressure fluctuations were affected greatly by both operating conditions and measurement locations. At partial flow rates the pulsation had a great irregularity and the amplitudes at the investigated frequencies were much larger than ones at the design flow rate. An asymmetrical pressure fluctuation structure in the volute casing was observed at all flow rates. The pulsation behavior at the blade passing frequency was the most prominent near the volute tongue zone, and the pressure waves propagated in both the radial and circumferential directions.

scholarly journals Effects of impeller trim on performance of two-stage self-priming centrifugal pump

2017 ◽  
Vol 9 (2) ◽  
pp. 168781401769249 ◽  
Author(s):  
Kai Wang ◽  
Zixu Zhang ◽  
Linglin Jiang ◽  
Houlin Liu ◽  
Yu Li
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
Guide Vane ◽  
Radial Force ◽  
Design Flow ◽  
Two Stage ◽  
Rate Condition ◽  
Application Range ◽  
Save Energy

In order to save energy by broadening its application range, the influence of impeller trim on the performance of a two-stage self-priming centrifugal pump was numerically studied. The hydraulic performance experiments and self-priming experiments were carried out. And the unsteady performance of pressure fluctuation and radial force in the pump was analyzed. The results show that with the increase in impeller trim quantity, the best efficiency point of the pump would move to the small flow rate condition. Under the design flow rate, when both the two stages of the impeller were trimmed by 6%, head of the pump was reduced by 13%, efficiency of the pump was as well decreased by 1.69 percentage points, and self-priming time was increased by 1.7%. Thus, impeller trim can be used to meet the operating requirements in the head range of 94–107 m. With the increase in impellers trim quantity, the pressure fluctuation in the positive channel of the radial guide vane and the volute was smaller, while the radial force on the wall of radial guide vane and volute was also smaller.

Three-Objective Optimization of a Centrifugal Pump to Reduce Flow Recirculation and Cavitation

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Hyeon-Seok Shim ◽  
Kwang-Yong Kim ◽  
Young-Seok Choi
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Stokes Equations ◽  
Cavitation Number ◽  
Design Flow ◽  
Pareto Optimal ◽  
Objective Functions ◽  
Flow Recirculation ◽  
Critical Cavitation ◽  
Design Flow Rate

This work presents a three-objective design optimization of a centrifugal pump impeller to reduce flow recirculation and cavitation using three-dimensional (3D) Reynolds-averaged Navier–Stokes equations. A cavitation model was used to simulate the multiphase cavitating flow inside the centrifugal pump. The numerical results were validated by comparing them with experimental data for the total head coefficient and critical cavitation number. To achieve the optimization goals, blockage at 50% of the design flow rate, hydraulic efficiency at the design flow rate, and critical cavitation number for a head-drop of 3% at 125% of the design flow rate were selected as the objective functions. Based on the results of the elementary effect (EE) method, the design variables selected were the axial length of the blade, the control point for the meridional profile of the shroud, the inlet radius of the blade hub, and the incidence angle of tip of the blade. Kriging models were constructed to approximate the objective functions in the design space using the objective function values calculated at the design points selected by Latin hypercube sampling (LHS). Pareto-optimal solutions were obtained using a multi-objective genetic algorithm (MOGA). Six representative Pareto-optimal designs (POD) were analyzed to evaluate the optimization results. The PODs showed large improvements in the objective functions compared to the baseline design. Thus, both the hydraulic performance and the reliability of the centrifugal pump were improved by the optimization.

scholarly journals Experimental Investigation of Pressure Fluctuation, Vibration, and Noise in a Multistage Pump

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Kai Wang ◽  
Zixu Zhang ◽  
Chen Xia ◽  
Zhongchun Liu
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
Noise Level ◽  
Pressure Pulsation ◽  
Design Flow ◽  
Monitoring Point ◽  
Characteristic Frequencies ◽  
Noise Characteristics ◽  
The Difference

In order to measure the pressure pulsation, vibration, and noise characteristics of multistage centrifugal pump in different flow rates, a five-stage centrifugal pump was chosen as research object. The results show that the main frequency of pressure pulsation was BPF1, 9APF, BPF2, BPF2, and 9APF. According to the order of monitoring points, the intensity of the pressure fluctuation increased and then decreased, with the strongest fluctuation at monitoring point P2. The peak value of pressure fluctuation in monitoring point P2 was obviously higher than the other monitoring points. The main characteristic frequency of vibration is 4APF, BPF2, 9APF, 2BPF2, 3BPF1, 4BPF1, and 4BPF2. The number of characteristic frequencies at the outlet flange was significantly more than the number of characteristic frequencies at the inlet flange. As the flow rate increased, the vibration of motor gradually increased and the vibration of pump increased at first and then decreased. It reached the minimum vibration level in the design flow rate. Motor contributed the largest amount of noise caused by the pump unit. The noise level of measure point which is close to motor is higher than that of other measure points. As the flow rate increased, the noise incrementally increased, and the difference in noise level between measure points decreased gradationally. When the flow rate was 120 m3/h, the maximum difference value of different noise monitoring points was only 1.7 dB.

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