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.

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.

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.

POD and Extended-POD Analysis of Pressure Fluctuations and Vortex Structures Inside a Steam Turbine Control Valve

2018 ◽  
Author(s):  
Peng Wang ◽  
Hongyu Ma ◽  
Yingzheng Liu
Keyword(s):  
Steam Turbine ◽  
Pressure Fluctuation ◽  
Pressure Field ◽  
Pressure Fluctuations ◽  
Turbulence Models ◽  
Control Valve ◽  
Vortex Structures ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Pod Analysis

In steam turbine control valves, pressure fluctuations coupled with vortex structures in highly unsteady three-dimensional flows make essential contributions to aerodynamic forcing on the valve components, and are major sources of flow-induced vibration and acoustic effects. Advanced turbulence models, such as scale adaptive simulation (SAS), detached eddy simulation (DES) and large eddy simulation (LES), can capture detailed flow information of the control valve, but it is challenging to identify the primary flow structures due to the massive flow database. The present study used state-of-the-art data-driven analysis, namely proper orthogonal decomposition (POD) and extended-POD, to extract the energetic pressure fluctuations and dominant vortex structures of the control valve. To this end, the typical annular attachment flow inside a steam turbine control valve was investigated by performing a DES study. Subsequently, the energetic pressure fluctuation modes were extracted by performing POD analysis on the valve’s pressure field. The vortex structures contributing to these energetic pressure fluctuation modes were extracted by performing extended-POD analysis on the pressure-velocity coupling field. Finally, the dominant vortex structures were revealed directly by POD analysis of the valve’s velocity field. The results demonstrated that the flow instabilities inside the control valve were mainly induced by oscillations of the annular wall-attached jet and the derivative flow separations and reattachments. In POD analysis of the pressure field, the axial, antisymmetric and asymmetric pressure modes occupied most of the pressure fluctuation intensity. By further conducting extended-POD analysis, the vortex structures’ incorporation with the energetic pressure modes was identified as mainly attributed to the synchronous, alternating and single-sided oscillation behaviors of the annular attachment flow. However, based on POD analysis of the unsteady velocity fields, the vortex structures, buried in the dominant modes at St = 0.017, were found to result from alternating oscillations of the annular wall-attached jet.

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.

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.

scholarly journals Investigation on Reduction of Pressure Fluctuation for a Double-Suction Centrifugal Pump

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Qianqian Li ◽  
Shiyang Li ◽  
Peng Wu ◽  
Bin Huang ◽  
Dazhuan Wu
Keyword(s):  
Centrifugal Pump ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
Fluctuation Analysis ◽  
Centrifugal Pumps ◽  
Large Power ◽  
Pressure Contour ◽  
Dimensionless Pressure ◽  
Fluctuation Amplitude ◽  
Radial Gap

AbstractDouble-suction centrifugal pumps have been applied extensively in many areas, and the significance of pressure fluctuations inside these pumps with large power is becoming increasingly important. In this study, a double-suction centrifugal pump with a high-demand for vibration and noise was redesigned by increasing the flow uniformity at the impeller discharge, implemented by combinations of more than two parameters. First, increasing the number of the impeller blades was intended to enhance the bounding effect that the blades imposed on the fluid. Subsequently, increasing the radial gap between the impeller and volute was applied to reduce the rotor-stator interaction. Finally, the staggered arrangement was optimized to weaken the efficacy of the interference superposition. Based on numerical simulation, the steady and unsteady characteristics of the pump models were calculated. From the fluctuation analysis in the frequency domain, the dimensionless pressure fluctuation amplitude at the blade passing frequency and its harmonics, located on the monitoring points in the redesigned pumps (both with larger radial gap), are reduced a lot. Further, in the volute of the model with new impellers staggered at 12°, the average value for the dimensionless pressure fluctuation amplitude decreases to 6% of that in prototype pump. The dimensionless root-mean-square pressure contour on the mid-span of the impeller tends to be more uniform in the redesigned models (both with larger radial gap); similarly, the pressure contour on the mid-section of the volute presents good uniformity in these models, which in turn demonstrating a reduction in the pressure fluctuation intensity. The results reveal the mechanism of pressure fluctuation reduction in a double-suction centrifugal pump, and the results of this study could provide a reference for pressure fluctuation reduction and vibration performance reinforcement of double-suction centrifugal pumps and other pumps.

Numerical Study of the Unsteady Flow Inside a Centrifugal Fan and its Downstream Pipe Using Detached Eddy Simulation

2020 ◽  
Author(s):  
Jian-Cheng Cai ◽  
Jia-Qi Zhang ◽  
Can Yang
Keyword(s):  
Unsteady Flow ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
Computational Domain ◽  
Centrifugal Fan ◽  
Detached Eddy Simulation ◽  
Impeller Blade ◽  
Eddy Simulation ◽  
Maximum Value ◽  
Outlet Pipe

Abstract The 3-D unsteady turbulent flow inside a centrifugal fan and its downstream pipe is investigated at the best efficiency point (BEP) flow rate using the computational fluid dynamics (CFD) package ANSYS FLUENT. The impeller with an outlet diameter of 400 mm has 12 forward curved blades. The computational domain comprises four parts: the inlet part, the impeller, the volute, and the downstream pipe. The flow domain was meshed in ANSYS ICEM-CFD with structured hexahedron cells, and nearly 9 million cells were used. The Detached Eddy Simulation (DES) turbulence modelling approach was employed with this fine enough mesh scheme. The impeller was set as the rotating domain at a speed of 2900 rpm. A sliding mesh technique was applied to the interfaces in order to allow unsteady interactions between the rotating impeller and the stationary parts; the unsteady interactions generate pressure fluctuations inside the centrifugal fan. One impeller revolution is divided into 2048 time steps, in order to capture the transient flow phenomena with high resolution. Monitoring points were set along the volute casing profile, and along the downstream pipe centerline. When the numerical simulation became stable after several impeller revolutions, the statistics of the unsteady flow was initiated with a total of 16384 time steps (8 impeller revolutions) data. The time history data of the pressure and velocity magnitude at the monitoring points were saved and with Fourier transform applied to obtain the frequency spectra. The time-averaged flow fields show clearly the static pressure rises gradually through the impeller, and further recovers from the velocity in the volute, and decreases gradually along the downstream pipe due to the friction. The mean pressure at the pressure side of the impeller blade is larger than it at the suction side, forming the circumferential nonuniform flow pattern. Owing to the forward-curved blades, large velocity region exists around the impellor exit, and the maximum velocity near the trailing edge can reach 1.5u2, where u2 is the circumferential velocity at the impeller outlet. The root mean square (rms) value distribution of pressure fluctuations show that most parts inside the centrifugal fan undergo large pressure fluctuation with the magnitude about 10% of the reference dynamic pressure pref = 0.5ρu22; the maximum value locating at the tongue tip can reach 30% of pref. The pressure fluctuation magnitude decreases quickly along the outlet pipe: after 5D (D is the outlet pipe diameter) the magnitude is 0.5% of pref. The pressure and velocity fluctuation spectra at the monitoring points in the volute show striking discrete components at the blade-passing frequency (BPF) and its 2nd, 3rd harmonics. The BPF component has the maximum value of 15% of pref in the tongue region, and it decreases dramatically along the downstream pipe with the amplitude less than 0.2% of pref after 5D distance.

Wind noise source characterization and transmission study through a side glass of DrivAer model based on a hybrid DES/APE method

2020 ◽  
pp. 095440702096955
Author(s):  
Yinzhi He ◽  
Siyi Wen ◽  
Yongming Liu ◽  
Zhigang Yang
Keyword(s):  
Pressure Fluctuation ◽  
Acoustic Pressure ◽  
Pressure Fluctuations ◽  
Transmission Efficiency ◽  
Interior Noise ◽  
Perturbation Equation ◽  
Detached Eddy Simulation ◽  
Source Characterization ◽  
Side Window ◽  
Eddy Simulation

Based on a DrivAer model with notchback, the characteristics of convective and acoustic pressure fluctuations on the side window, as well as their contributions to interior noise were studied. Firstly, a full-size DrivAer clay model was produced with a real glass set on the front left window, and the rest parts with thick clay. In this way, the side glass becomes the exclusive transmission path for the exterior convective and acoustic pressures into acoustic cabin inside. In this study, the acoustic pressure fluctuation on the side window surface was calculated by solving the acoustic perturbation equation (APE) based on the calculation results of convective pressure fluctuation with the incompressible Detached Eddy Simulation (DES). Furthermore, with the convective and acoustic pressure fluctuations as power inputs, the interior noise was calculated with Statistical Energy Analysis (SEA). The calculated interior noise level shows good agreement with the tested results in the wind tunnel, which indirectly validates the reliability of the calculated acoustic pressures with APE method. The contributions of the convective and acoustic pressure fluctuations to the interior noise show that the acoustic pressure fluctuation takes much higher transmission efficiency than the convective one, especially at the high frequency range above the coincidence frequency of the glass, the contribution of acoustic pressure fluctuation is absolutely dominant.

scholarly journals Experimental Investigation of Flow Instabilities and Rotating Stall in a High-Energy Centrifugal Pump Stage

2009 ◽  
Author(s):  
Stefan Berten ◽  
Philippe Dupont ◽  
Laurent Fabre ◽  
Maher Kayal ◽  
Francois Avellan ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Pressure Fluctuation ◽  
Rotational Speed ◽  
Pressure Fluctuations ◽  
Pressure Sensors ◽  
High Energy ◽  
Operating Conditions ◽  
Centrifugal Pumps ◽  
Impeller Blade ◽  
Pump Stage

In centrifugal pumps, the interaction between the rotating impeller and the stationary diffuser generates specific pressure fluctuation patterns. When the pump is operated at off design conditions, these pressure fluctuations increase. The resulting rise of mechanical vibration levels may negatively affect the operational performance and the life span of mechanical components. This paper presents detailed pressure fluctuation measurements performed in a high speed centrifugal pump stage at full scale at various operating conditions. The impeller and stationary part (diffuser, exit chamber) of the pump stage have been equipped with piezoresistive miniature pressure sensors. The measured data in the impeller have been acquired using a newly developed onboard data acquisition system, designed for rotational speeds up to 6000 rpm. The measurements have been performed synchronously in the rotating and stationary domains. The analysis of pressure fluctuations at the impeller blade trailing edge, which had significantly larger amplitudes as the pressure fluctuations in the stationary domain, allowed the detection and exploration of stalled channels in the vaned diffuser. This stall may be stationary or rotating with different rotational speeds and number of stalled channels, depending on the relative flow rate and the rotational speed of the pump. The stall yields pressure fluctuations at frequencies which are multiples of the rotational speed of the impeller and generates additional sources of mechanical excitation.

scholarly journals Effect of Stall Cells on Pressure Fluctuations Characteristics in a Centrifugal Pump

Symmetry ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1116 ◽  
Author(s):  
Peijian Zhou ◽  
Jiacheng Dai ◽  
Chaoshou Yan ◽  
Shuihua Zheng ◽  
Changliang Ye ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuations ◽  
Low Frequency ◽  
Rotating Stall ◽  
Design Flow ◽  
Eddy Simulation ◽  
Leading Role ◽  
Stall Cells ◽  
Design Flow Rate

Rotating stall is an unsteady flow phenomenon, which always leads to instability and efficiency degradation. In order to reveal pressure fluctuations in the impeller of centrifugal pump induced by stall cells, the flow structures in a volute-type centrifugal pump were calculated using Large Eddy Simulation (LES) method. The predicted results of the numerical model were compared with experimental flow-head curve. The simulation results were in good agreement with the experimental results. The stall phenomenon occurred when the flow rate dropped to 70% of design flow rate. Three stall cells located at the entrance of passages could be observed, which remained stationary relative to the rotating impeller. With the decrease of flow rate, the area occupied by stall cells gradually increased. The peak value of pressure fluctuation at 25% of design flow rate is obviously larger than that at 50% of design flow rate. For the unstalled or stalled passage, the impeller-volute interaction played a leading role in the pressure fluctuations of the impeller. For the stalled passage, the amplitude of the low frequency induced by stall cell is relatively insignificant.

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