Effect of incidence angle on cavity blockage and flow stability in the net positive suction head drop of mixed-flow pumps

2020 ◽  
pp. 095440622097305
Author(s):  
Yong-In Kim ◽  
Sung Kim ◽  
Kyoung-Yong Lee ◽  
Young-Seok Choi
Keyword(s):  
Flow Pattern ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
Incidence Angle ◽  
Experimental Tests ◽  
Design Flow ◽  
Inlet Pressure ◽  
Stable Flow ◽  
Fft Analysis ◽  
Design Flow Rate

The cavitation is an inevitable factor in pumps used in the whole industry, which is a major cause of energy loss and mechanical breakdown. In this study, the cavitation phenomena at the design flow rate were numerically analyzed for two pumps with different incidence angles. The design flow rate for both models was located near the best efficiency point (BEP). The incidence angle was determined with the impeller inlet diameter and the blade angle. A pump with a smaller incidence angle consistently showed a stable flow pattern as the inlet pressure decreased, whereas a pump with a larger incidence angle contained non-uniform flow streamlines despite a very small amount of the generated cavities. The flow pattern at the impeller inlet was handled by the shape and thickness of the generated cavities which could act as an additional blockage in the pumps. The inception and growth of the cavity with a decrease of inlet pressure were also inferred, which was specifically quantified as the blockage ratio. A pump with a larger incidence angle performed poor cavitation characteristics and obtained the pressure fluctuation and cavity oscillation. The magnitude of pressure fluctuation was indicated using the fast Fourier transform (FFT) analysis. The experimental tests were performed on both pumps to validate the numerical results.

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.

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.

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.

Pressure fluctuation and flow pattern of a mixed-flow pump under design and off-design conditions

2017 ◽  
Vol 232 (13) ◽  
pp. 2430-2440 ◽  
Author(s):  
Yun Xu ◽  
Lei Tan ◽  
Yabin Liu ◽  
Yue Hao ◽  
Baoshan Zhu ◽  
...  
Keyword(s):  
Flow Pattern ◽  
Flow Rate ◽  
Pressure Fluctuations ◽  
Rotation Frequency ◽  
Design Flow ◽  
Mixed Flow ◽  
Partial Load ◽  
Flow Pump ◽  
Dominant Frequencies ◽  
Design Flow Rate

The pressure fluctuations and flow pattern in a mixed-flow pump are numerically investigated under design and off-design conditions. The accuracy and reliability are validated by good agreement of numerical results and experimental data of pump energy performance. At design flow rate, the dominant frequencies of pressure fluctuations are impeller rotation frequency or integer multiples of it, which are mainly induced by the rotor–stator interaction. At overload condition, the dominant frequencies of pressure fluctuations are similar as those of design flow rate, but the maximum amplitudes increase to about 2.5 times of those of design flow rate. At partial load condition, the pressure fluctuations and flow pattern are complicated. The low dominant frequencies below the impeller rotation frequency are related to the process of vortex emergency, movement and disappearance.

scholarly journals Numerical study on the cavitation phenomenon for the head drop and unsteady bubble patterns with a difference in the incidence angle of a mixed-flow pump

2020 ◽  
Vol 12 (4) ◽  
pp. 168781402091479 ◽  
Author(s):  
Yong-In Kim ◽  
Hyeon-Mo Yang ◽  
Jun-Won Suh ◽  
Sung Kim ◽  
Kyoung-Yong Lee ◽  
...  
Keyword(s):  
Numerical Study ◽  
Incidence Angle ◽  
Experimental Tests ◽  
Design Flow ◽  
Inlet Pressure ◽  
Mixed Flow ◽  
Bubble Generation ◽  
Cavitation Phenomenon ◽  
Suction Performance ◽  
Flow Pump

In this study, two types of mixed-flow pump models exhibiting different suction performances were investigated to understand the cavitation characteristics of head drop gradients due to the decrease in inlet pressure. Both models were designed with the same specifications except for the shroud inlet blade angle and inlet radius which directly affect the incidence angle. The steady- and unsteady-state analyses were performed using ANSYS CFX, and the results of both models were compared. Bubble generation and patterns were systemically represented at the design flow rate to observe their influence on suction performance. Furthermore, experimental tests were performed to validate the numerical results. From the results, the head drop gradient can determine the suction performance of mixed-flow pumps. The amount and shape of the bubbles concerning the suction performance of a mixed-flow pump exhibit significant differences with the changes in time and inlet pressure. The patterns of generated bubble are not stable even for each blade.

scholarly journals Modeling Study of Design Flow Rates for Cascade Water Supply Systems in Residential Skyscrapers

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2580
Author(s):  
Yang Zhou ◽  
Eric Lee ◽  
Ling-Tim Wong ◽  
Kwok-Wai Mui
Keyword(s):  
Water Supply ◽  
Mathematical Models ◽  
Flow Rate ◽  
Supply System ◽  
Water Supply System ◽  
Design Flow ◽  
Water Volume ◽  
Water Supply Systems ◽  
Supply Systems ◽  
Design Flow Rate

Skyscrapers are common nowadays around the world, especially in cities with limited development area. In order to pump water up to the higher level of a skyscraper, a cascade water supply system has to be installed. Currently, cascade water supply systems are mainly designed based on practical experiences or requirements of existing standards/guidelines that, in fact, are not specifically for skyscrapers. However, thorough studies on cascade water supply system designs are still limited in the literature. This study proposes mathematical models and uses Monte Carlo simulations to evaluate the design flow rate of a typical cascade water supply system that feeds various appliances in a residential skyscraper in Hong Kong. Graphs that showed the correlations between the inflow rate in the supply pipe and water volume in the tank are obtained. While tank storage volume is confirmed, the design flow rate of the cascade water supply system can be determined from these graphs. The proposed mathematical models can also be applied to evaluate the design flow rate of cascade water supply systems in other types of skyscrapers (e.g., office, commercial building) as well as with the changes in water demand patterns in the models.

scholarly journals Multicondition Optimization and Experimental Measurements of a Double-Blade Centrifugal Pump Impeller

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Houlin Liu ◽  
Kai Wang ◽  
Shouqi Yuan ◽  
Minggao Tan ◽  
Yong Wang ◽  
...  
Keyword(s):  
Objective Function ◽  
Flow Rate ◽  
Performance Characteristic ◽  
Weighted Average ◽  
Design Flow ◽  
Meridional Plane ◽  
Original Design ◽  
Piv Measurements ◽  
Average Efficiency ◽  
Design Flow Rate

In order to improve internal unsteady flow in a double-blade centrifugal pump (DBCP), this study used major geometric parameters of the original design as the initial values, heads at three conditions (i.e., 80% design flow rate, 100% design flow rate, and 120% design flow rate) as the constraints conditions, and the maximum of weighted average efficiency at the three conditions as the objective function. An adaptive simulated annealing algorithm was selected to solve the energy performance calculation model and the supertransitive approximation method was applied to fix optimal weight factors of individual objectives. On the basis of hydraulic performance optimization, three-condition automatic computational fluid dynamics (CFD) optimization of impeller meridional plane for the DBCP was realized by means of Isight software integrated Pro/E, Gambit, and Fluent software. The shroud arc radii R0 and R1, shroud angle T1, hub arc radius R2, and hub angle T2 on the meridional plane were selected as the design variables and the maximum of weighted average hydraulic efficiency at the three conditions was chosen as the objective function. Performance characteristic test and particle image velocimetry (PIV) measurements of internal flow in the DBCP were conducted. Performance characteristic test results show that the weighted average efficiency of the impeller after the three-condition optimization has increased by 1.46% than that of original design. PIV measurements results show that vortex or recirculation phenomena in the impeller are distinctly improved under the three conditions.

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.

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.

scholarly journals The effect of increasing CO2concentration and flow rate on amine still performance in meeting gas sale specifications

2018 ◽  
Vol 67 ◽  
pp. 03006
Author(s):  
Yuswan Muharam ◽  
Hendra Kristianto
Keyword(s):  
Flow Rate ◽  
Design Flow ◽  
Equilibrium Curve ◽  
Total Flow ◽  
Total Flow Rate ◽  
Gas Well ◽  
Desorption Equilibrium ◽  
Packing Column ◽  
Design Flow Rate

The main purpose of this study is to examine the effect of increasing CO2removal and flow rate on performance of an amine still. The amine still is located in Field X in South East Sumatra at a new gas well producing gases with a rich CO2content. The still uses activated MDEA as the amine and has an IMTP 40-type packing column. Two film and desorption equilibrium curve theories were employed to analyse the amine still design conditions. Design equations were utilized to find the slope of the equilibrium curve. A slope of the equilibrium curve of 45° in the amine still is obtained in this study. The maximum liquid CO2composition of the amine still feedstock (xo) which can be separated to produce lean amine according to the specification design flow rate is 0.0307. The total flow rate of CO2-rich amine at xo= 0.029 is 761,157.6 kg/hour; the total flow rate of CO2-rich amine atxo= 0.0295 is 628,861.1 kg/hour; the total flow rate of CO2- rich amine at xo= 0.03 is 513,962.6 kg/hour; and the total flow rate of CO2-rich amine at xo= 0.0305 is 409,575.3 kg/hour.

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