Relationship Between Unsteady Flow, Pressure Fluctuations, and Noise in a Centrifugal Pump—Part B: Effects of Blade-Tongue Interactions

1995 ◽  
Vol 117 (1) ◽  
pp. 30-35 ◽  
Author(s):  
S. Chu ◽  
R. Dong ◽  
J. Katz
Keyword(s):  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Pressure Difference ◽  
Pressure Fluctuations ◽  
Primary Sources ◽  
Pressure Measurements ◽  
Local Pressure ◽  
Pressure Distributions ◽  
Flow Pressure ◽  
Tip Of The Tongue

Maps of pressure distributions computed using PDV data, combined with noise and local pressure measurements, are used for identifying primary sources of noise in a centrifugal pump. In the vicinity of the impeller pressure minima occur around the blade and near a vortex train generated as a result of non-uniform outflux from the impeller. The pressure everywhere also varies depending on the orientation of the impeller relative to the tongue. Noise peaks are generated when the pressure difference across the tongue is maximum, probably due to tongue oscillations, and when the wake impinges on the tip of the tongue.

scholarly journals Effect of Modification to Tongue and Impeller Geometry on Unsteady Flow, Pressure Fluctuations, and Noise in a Centrifugal Pump

1997 ◽  
Vol 119 (3) ◽  
pp. 506-515 ◽  
Author(s):  
R. Dong ◽  
S. Chu ◽  
J. Katz
Keyword(s):  
Centrifugal Pump ◽  
Pressure Fluctuations ◽  
Primary Sources ◽  
Local Pressure ◽  
Minimal Impact ◽  
Image Velocimetry ◽  
Noise Measurements ◽  
Flow Pressure ◽  
Tip Of The Tongue ◽  
Impeller Geometry

Particle Image Velocimetry (PIV), pressure, and noise measurements are used to study the effect of modifications to tongue and impeller geometries on the flow structure and resulting noise in a centrifugal pump. It is demonstrated that the primary sources of noise are associated with interactions of the nonuniform outflux from the impeller (jet/wake phenomenon) with the tongue. Consequently, significant reduction of noise is achieved by increasing the gap between the tongue and the impeller up to about 20 percent of the impeller radius. Further increase in the gap affects the performance adversely with minimal impact on the noise level. When the gap is narrow, the primary sources of noise are impingement of the wake on the tip of the tongue, and tongue oscillations when the pressure difference across it is high. At about 20 percent gap, the entire wake and its associated vorticity trains miss the tongue, and the only (quite weak) effect of nonuniform outflux is the impingement of the jet on the tongue. An attempt is also made to reduce the nonuniformity in outflux from the impeller by inserting short vanes between the blades. They cause reduction in the size of the original wakes, but generate an additional jet/wake phenomenon of their own. Both wakes are weak to a level that their impacts on local pressure fluctuations and noise are insignificant. The only remaining major contributor to noise is tongue oscillations. This effect is shown to be dependent on the stiffness of the tongue.

scholarly journals Effect of Modification to Tongue and Impeller Geometry on Unsteady Flow, Pressure Fluctuations and Noise in a Centrifugal Pump

1995 ◽  
Author(s):  
R. Dong ◽  
S. Chu ◽  
J. Katz
Keyword(s):  
Centrifugal Pump ◽  
Pressure Fluctuations ◽  
Primary Sources ◽  
Local Pressure ◽  
Minimal Impact ◽  
Image Velocimetry ◽  
Noise Measurements ◽  
Flow Pressure ◽  
Tip Of The Tongue ◽  
Impeller Geometry

Particle Image Velocimetry (PIV), pressure and noise measurements are used to study the effect of modifications to tongue and impeller geometries on the flow structure and resulting noise in a centrifugal pump. It is demonstrated that the primary sources of noise are associated with interactions of the non-uniform outflux from the impeller (jet/wake phenomenon) with the tongue. Consequently, significant reduction of noise is achieved by increasing the gap between the tongue and the impeller up to about 20% of the impeller radius. Further increase in the gap affects the performance adversely with minimal impact on the noise level. When the gap is narrow, the primary sources of noise are impingement of the wake on the tip of the tongue, and tongue oscillations when the pressure difference across it is high. At about 20% gap, the entire wake and its associated vorticity trains miss the tongue, and the only (quite weak) effect of nonuniform outflux is the impingement of the jet on the tongue. An attempt is also made to reduce the non-uniformity in outflux from the impeller by inserting short vanes between the blades. They cause reduction in the size of the original wakes, but generate an additional jet/wake phenomenon of their own. Both wakes are weak to a level that their impacts on local pressure fluctuations and noise are insignificant. The only remaining major contributor to noise is tongue oscillations. This effect is shown to be dependent on the stiffness of the tongue.

Relationship Between Unsteady Flow, Pressure Fluctuations, and Noise in a Centrifugal Pump—Part A: Use of PDV Data to Compute the Pressure Field

1995 ◽  
Vol 117 (1) ◽  
pp. 24-29 ◽  
Author(s):  
S. Chu ◽  
R. Dong ◽  
J. Katz
Keyword(s):  
Centrifugal Pump ◽  
Flow Structure ◽  
Pressure Field ◽  
Pressure Fluctuations ◽  
Local Pressure ◽  
Large Vortex ◽  
Realistic Description ◽  
Flow Pressure ◽  
Field Noise ◽  
The Impact

Velocity distributions determined by using Particle Displacement Velocimetry are used for computing the pressure field within the volute of a centrifugal pump. It is shown that blade-tongue interactions and nonuniform outflux from the impeller are primary contributors to local pressure fluctuations and far field noise. Consequently, a slight increase in the space between the impeller and the tongue causes significant changes in flow structure and reductions in the resulting noise. The impact is significant as long as the tongue-impeller gap is less than 20 percent of the impeller radius. It is also shown that the vorticity distributions, particularly the large vortex trains associated with the jet/wake phenomenon, dominate variations in the total pressure. Thus, it is unlikely that a potential flow model can provide any realistic description of the flow structure.

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.

3D Quasi-Unsteady Flow Simulation in a Centrifugal Pump: Comparison With the Experimental Results

2004 ◽  
Author(s):  
Miguel Asuaje ◽  
Farid Bakir ◽  
Andres Tremante ◽  
Ricardo Noguera ◽  
Robert Rey
Keyword(s):  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Cfd Simulation ◽  
Pressure Fluctuations ◽  
Pressure Sensors ◽  
Flow Simulation ◽  
Turbulence Models ◽  
Numerical Predictions ◽  
Radial Thrust ◽  
Unsteady Flow Simulation

A 3D-CFD simulation of the impeller and volute casing of a centrifugal pump has been performed using commercial codes CFX 5.5 and CFX-TASCflow 2.12. The pump has an specific speed of 32 (metric units) and an outside impeller diameter of 400 mm. First, a 3D-flow simulation for the isolated impeller with a structured grid is presented. A sensitivity analysis regarding grid quality and turbulence models were also performed. A 3D quasi-unsteady flow simulation of the impeller-volute assembly is presented, as well. This flow simulation was carried out for several impeller blades and volute tongue relative positions. As a result, the radial thrust on the pump shaft were calculated for different flow rates. Experimental test were carried out in order to compare theoretical pressure fluctuations with the experimental ones measured by various unsteady pressure sensors placed on the impeller shroud and volute. The qualitative and quantitative results ratify numerical predictions.

Numerical and Experimental Study of Unsteady Flow in a Large Centrifugal Pump With Stay Vanes

2014 ◽  
Vol 136 (7) ◽  
Author(s):  
Zhongxin Gao ◽  
Wenruo Zhu ◽  
Li Lu ◽  
Jie Deng ◽  
Jianguang Zhang ◽  
...  
Keyword(s):  
Experimental Data ◽  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Pressure Fluctuations ◽  
Rate Variation ◽  
Operation Condition ◽  
Calculation Results ◽  
Static Performance ◽  
Steady Simulation ◽  
Comparison Of The Results

The unsteady flow inside a large centrifugal pump with stay vanes was analyzed in this study. The static performance and pressure fluctuations in the pump were numerically predicted and were compared with experimental data. Considering the relative positions of the impeller to the volute tongue and stay vanes, the static performance which was obtained using a full unsteady calculation was compared with traditional steady calculation results. A comparison of the results with the experimental data showed that the operation condition farther from the design condition resulted in larger differences between the steady simulation and experimental results, with errors beyond reasonable limits, while the performance curves obtained by the unsteady calculations were closer to the experimental data. A comparison of the pressure fluctuations at four monitoring points with the experimental data showed that the amplitudes at HVS1 and HVS2 are much larger than at HD1 and HD2. The main frequency for these four monitoring points, which agreed well with the experimental data, was the blade passing frequency. The relative obvious errors in pressure fluctuations for HD1and HD2 were due to the inlet flow rate variation of the simulation. Thus, unsteady numerical simulations can be used to predict the pressure fluctuations when designing a pump.

Numerical investigation of influence of inlet guide vanes on unsteady flow in a centrifugal pump

2015 ◽  
Vol 229 (18) ◽  
pp. 3405-3416 ◽  
Author(s):  
Wang Yuchuan ◽  
Tan Lei ◽  
Zhu Baoshan ◽  
Cao ShuLiang ◽  
Wang Binbin
Keyword(s):  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Pressure Fluctuations ◽  
Turbulence Models ◽  
Rotational Frequency ◽  
Pump Impeller ◽  
Guide Vanes ◽  
Pump Performance ◽  
Inlet Guide Vanes ◽  
Dominant Frequencies

The influence of inlet guide vanes on unsteady flow in a centrifugal pump is numerically investigated. The independences of mesh elements, time steps and turbulence models are studied, and the satisfactory agreement between experimental and numerical results of the centrifugal pump performance validates the reliability and accuracy of the numerical model. The frequency characteristics of pressure fluctuations in impeller and volute are nearly the same for the pump without and with inlet guide vanes in the angle range from −36° to +36°. In the pump impeller, the dominant frequencies are mainly the rotational frequency fi (24.17 Hz) or 2 fi, and in volute they are the blade passing frequency fBPF (145 Hz). For the large inlet guide vanes angles of −60°and +60°, the maximum amplitudes of pressure fluctuations in pump impeller and volute are stronger than that in pump without inlet guide vanes. Therefore, the influence of inlet guide vanes on unsteady flow in the centrifugal pump is slight when the inlet guide vanes angles are regulated in a suitable region.

scholarly journals Numerical Study of Pressure Fluctuation and Unsteady Flow in a Centrifugal Pump

Processes ◽  
2019 ◽  
Vol 7 (6) ◽  
pp. 354 ◽  
Author(s):  
Ling Bai ◽  
Ling Zhou ◽  
Chen Han ◽  
Yong Zhu ◽  
Weidong Shi
Keyword(s):  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Pressure Fluctuation ◽  
Static Pressure ◽  
Numerical Study ◽  
Pressure Fluctuations ◽  
Flow Patterns ◽  
Lower Number ◽  
Centrifugal Pumps ◽  
Impeller Blade

A pump is one of the most important machines in the processes and flow systems. The operation of multistage centrifugal pumps could generate pressure fluctuations and instabilities that may be detrimental to the performance and integrity of the pump. In this paper, a numerical study of the influence of pressure fluctuations and unsteady flow patterns was undertaken in the pump flow channel of three configurations with different diffuser vane numbers. It was found that the amplitude of pressure fluctuation in the diffuser was increased gradually with the increase in number of diffuser vanes. The lower number of diffuser vanes was beneficial to obtain a weaker pressure fluctuation intensity. With the static pressure gradually increasing, the effects of impeller blade passing frequency attenuated gradually, and the effect of diffuser vanes was increased gradually.

Pressure Distributions in a Single and Two Versions of a Double Volute of a Centrifugal Pump

1992 ◽  
Author(s):  
W. de Ojeda ◽  
R. D. Flack ◽  
S. M. Miner
Keyword(s):  
Centrifugal Pump ◽  
Leading Edge ◽  
Pressure Measurements ◽  
Flow Rates ◽  
Pressure Drops ◽  
Pressure Distributions ◽  
Single Discharge ◽  
Repeated Pattern ◽  
Specific Speed

Pressure measurements were recorded around the impeller and along the casing wall of a centrifugal pump, 0.60 (1583 US units) specific speed, assembled with a single volute/single discharge, and two versions of a double volute/single discharge. The latter comprised a splitter positioned in the second half of the discharge (i) midway between the impeller and casing, and (ii) along a spiral symmetric to the first–half casing section. The objective of such double volute casings is to reduce forces on the impeller and thus provide longer lives. Flow rates tested ranged from 20% to 105% of design. A repeated pattern consisted of pressure increasing from the first cutwater to the splitter leading edge at which the pressure drops and thereafter increases to the discharge. This pattern was noted at all flow rates with the symmetric volute geometry and only at flow rates higher than 60% for the centered splitter. By integration of the pressures static forces were found. Time averaged static forces ranged from 6.2 N at design to 33.0 N at 20% flow for the single volute. Both double volute configurations showed considerable thrust reduction throughout but for a few exceptions. Reductions ranged from 26% at 30% flow to 62% at 90% flow for the center splitter, and from 52% reduction at 20% flow to 72% at 80% flow for the symmetric splitter. For comparison of performance of the different configurations, at flow rates above 85% of design the head was 8% and 9% less for the double volutes than for the single volutes. At flows below 40% of design the head was 3% and 4% higher for the double volutes than for the single volute.

Effects of Splitter Blades on the Unsteady Flow of a Centrifugal Pump

2012 ◽  
Author(s):  
Liting Ye ◽  
Shouqi Yuan ◽  
Jinfeng Zhang ◽  
Ye Yuan
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Numerical Simulations ◽  
Centrifugal Pump ◽  
Pressure Fluctuations ◽  
Internal Flow ◽  
Suction Side ◽  
Boundary Function ◽  
Wake Flow ◽  
Design Parameters

Numerical simulations and performance tests were conducted to analyze the effects of splitter blades on the performance and whole unsteady flow field of a centrifugal pump. The studied pump is a single stage pump with a shrouded impeller (diameter = 160mm, 4 blades, specific speed = 47). Based on the original impeller, we designed 5 impellers with different splitter blades parameters. All the numerical simulations were carried out by using the commercial software ANSYS CFX 12.1 based on standard k-ε turbulence model and standard boundary function. The results showed that, the head of the impellers with splitter blades was approximately 2%∼12% higher than that without splitter blades. When adding splitter blades, the pressure fluctuations at the impeller inlet, volute outlet and the interface of impeller and volute are reduced, this can improve the “jet-wake” flow structure. Different design parameters of splitter blades have a certain effect on the pressure fluctuations at the interface of impeller and volute. When the splitter blades deviated 5° to the suction side of the long blade and the splitter blade inlet diameter is 106 mm, the head is highest and the pressure fluctuations are lowest. The work will provide a basis for the further study on the internal flow field, reducing vibration and noise of a centrifugal pump.

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