Unsteady Flow Numerical Analysis of New-Type Deep Well Pump Under Multi-Conditions

2010 ◽  
Author(s):  
Wei-gang Lu ◽  
Ling Zhou ◽  
De-sheng Zhang ◽  
Ping-ping Zou ◽  
Chuan Wang
Keyword(s):  
Unsteady Flow ◽  
Pressure Fluctuation ◽  
Guide Vane ◽  
Maximum Amplitude ◽  
Impeller Blade ◽  
Blade Passage ◽  
Deep Well ◽  
Unsteady Simulation ◽  
New Type ◽  
Steady Simulation

The interaction between impeller and guide vane of the deep well pump is one of the most important factors which cause the pressure fluctuation in the channels. However, even nowadays some flow events in the deep well pump are still under study and far from fully understood. So the unsteady flow field of a two-stage deep well pump was simulated with FLUENT code based on sliding mesh and the RNG k-ε turbulence model, to investigate the pressure fluctuation by interactions between the impeller and guide vane. The computing domain extends from the inlet of the first stage deep well pump to the outlet of the second stage guide vane. With the Fast Fourier Transform (FFT) analysis, the pressure fluctuation and frequency fluctuation are analyzed under multi-conditions. In this paper, the pressure fluctuation differences between the first stage and secondary are also compared. The numerical results show that the pressure fluctuates at the blade passage frequency, and the maximum amplitude of blade passage frequency occurs in the region from the rotor to the stator when the impeller blade gets close to the guide vane trailing edge, but it decreases rapidly after fluid entering the guide vane. Compared with the steady simulation, the averaged calculated single-stage head of unsteady simulation is more accord with the reality, which is less than the tested head with a relative deviation of 5%.

Numerical Investigation of Pressure Fluctuation and Rotor-Stator Interaction in a Multistage Centrifugal Pump

2013 ◽  
Author(s):  
Ling Zhou ◽  
Weidong Shi ◽  
Ling Bai ◽  
Weigang Lu ◽  
Wei Li
Keyword(s):  
Centrifugal Pump ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
Maximum Amplitude ◽  
Leading Edge ◽  
Pulsation Period ◽  
Impeller Blade ◽  
Blade Passage ◽  
Multistage Centrifugal Pump ◽  
Sst Turbulence Model

The unsteady flow field in a multistage centrifugal pump was simulated with ANSYS-CFX code based on transient rotor-stator method, and Shear Stress Transport (SST) turbulence model to investigate the pressure fluctuations in the three stages passages. With the Fast Fourier Transform (FFT) analysis, the pressure fluctuations and frequency domains are analyzed and compared between stages. The numerical results show that the pressure fluctuates at the blade passage frequency, and the maximum amplitude of blade passage frequency occurs in the region from the rotor to the stator when the impeller blade gets close to the diffuser vane leading edge. The pressure pulsation period mainly associated with the number of impeller blades, but the influence gradually reduce when the fluids flow into the diffuser. The flow patterns and pressure fluctuation between stags are similar.

scholarly journals Numerical analysis of pressure fluctuation in a multiphase rotodynamic pump with air–water two-phase flow

2019 ◽  
Vol 74 ◽  
pp. 18 ◽  
Author(s):  
Wenwu Zhang ◽  
Zhiyi Yu ◽  
Yongjiang Li ◽  
Jianxin Yang ◽  
Qing Ye
Keyword(s):  
Pressure Fluctuation ◽  
Two Phase Flow ◽  
Guide Vane ◽  
Fluid Model ◽  
Pure Water ◽  
Maximum Amplitude ◽  
Phase Flow ◽  
Two Phase ◽  
Rotor Stator Interaction ◽  
Two Fluid Model

Pressure fluctuation in single-phase pumps has been studied widely, while less attention has been paid to research on multiphase pumps that are commonly used in the petroleum chemical industry. Therefore, this study investigates the pressure fluctuation for a multiphase rotodynamic pump handling air–water two-phase flow. Simulations based on the Euler two-fluid model were carried out using ANSYS_CFX16.0 at different Inlet Gas Void Fractions (IGVFs) and various flow rate values. Under conditions of IGVF = 0% (pure water) and IGVF = 15%, the accuracy of the numerical method was tested by comparing the experimental data. The results showed that the rotor–stator interaction was still the main generation driver of pressure fluctuation in gas–liquid two-phase pumps. However, the fluctuation near the impeller outlet ascribe to the rotor–stator interaction was weakened by the complex gas–liquid flow. For the different IGVF, the variation trend of fluctuation was similar along the streamwise direction. That is, the fluctuation in the impeller increased before decreasing, while in the guide vane it decreased gradually. Also, the fluctuation in the guide vane was generally greater than for the impeller and the maximum amplitude appeared in the vicinity of guide vane inlet.

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.

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.

An Evaluation of Impeller Blade Torque During an Impeller–Diffuser Interaction

2004 ◽  
Vol 126 (6) ◽  
pp. 960-965
Author(s):  
Kevin A. Kaupert
Keyword(s):  
Shear Stress ◽  
Flow Field ◽  
Unsteady Flow ◽  
Control Volume ◽  
Impeller Blade ◽  
Blade Passage ◽  
Fluid Forces ◽  
Numerical Predictions ◽  
Axial Moment ◽  
Control Surfaces

An evaluation of the torque on an impeller blade interacting with a diffuser blade is presented. Comparisons of time averaged quantities are made between computed and measured results. The calculation of the impeller blade torque was based on the axial moment from fluid forces acting on a control volume surrounding an impeller blade passage. Unsteady flow field contributions were incorporated in the computational model. Results are compared to numerical predictions of the impeller blade torque based on pressure and shear stress terms integrated over the blade and wall surfaces. From the fluid forces perspective the major contribution to the time averaged impeller torque originated on the impeller inlet and outlet control surfaces. Contrarily the major contribution to the unsteady impeller torque originated in the unsteady flow field within the impeller control volume.

Large Eddy Simulation of Unsteady Flow in a Mixed Flow Pump Guide Vane

2013 ◽  
Vol 444-445 ◽  
pp. 555-560 ◽  
Author(s):  
Yi Bin Li ◽  
Ren Nian Li ◽  
Xiu Yong Wang
Keyword(s):  
Large Eddy Simulation ◽  
Unsteady Flow ◽  
Pressure Fluctuation ◽  
Guide Vane ◽  
Suction Surface ◽  
Mixed Flow ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Small Flow ◽  
Flow Pump

In order to investigate the characteristics of unsteady flow in a mixed flow pump guide vane under the small flow conditions, several indicator points in a mixed flow pump guide vane was set, the three-dimensional unsteady turbulence numerical value of the mixed flow pump which is in the whole flow field will be calculated by means of the large eddy simulation (LES), sub-grid scale model and sliding mesh technology. The experimental results suggest that the large eddy simulation can estimate the positive slope characteristic of head & capacity curve. And the calculation results show that the pressure fluctuation coefficients of the middle section in guide vane inlet will decrease firstly and then increase. In guide vane outlet, the pressure fluctuation coefficients of section will be approximately axially symmetrical distribution. The pressure fluctuation minimum of section in guide vane inlet is above the middle location of the guide vane suction surface, and the pressure fluctuation minimum of section in which located the middle and outlet of guide vane. When it is under the small flow operating condition, the eddy scale of guide vane is larger, and the pressure fluctuation of the channel in guide vane being cyclical fluctuations obviously which leads to the area of eddy expanding to the whole channel from the suction side. The middle of the guide vane suction surface of the minimum amplitude pressure fluctuation to which the vortex core of eddy scale whose direction of fluids rotation is the same to impeller in the guide vane adhere.

Research on the Theory and Design Methods of the New Type Submersible Pump for Deep Well

2009 ◽  
Author(s):  
Wei-dong Shi ◽  
Wei-gang Lu ◽  
Hong-liang Wang ◽  
Qi-feng Li
Keyword(s):  
Design Method ◽  
Guide Vane ◽  
Single Stage ◽  
Maximum Diameter ◽  
Hydraulic Loss ◽  
Pump Efficiency ◽  
Submersible Pump ◽  
Axial Thrust ◽  
Deep Well ◽  
New Type

Submersible pump for deep well, widely used in the countryside, mines, geothermal utilization and so on, are the main equipment for pumping underground water. Due to the working conditions, the pump diameter is limited by the well diameter, and the single-stage head designed by traditional methods is low. In order to increase the single-stage head, the maximum diameter design method of impeller was created for the first time. The impeller front shroud diameter is almost equal to the inner casing diameter, and the back shroud diameter is almost the average of the impeller front shroud diameter and the guide vane shroud diameter. The blade extends to the impeller inlet to lengthen the back shroud streamline, which could prevent the back flow at the impeller outlet, and the front shroud is designed in a cone shape to make the outlet streamline upward, by which the pump efficiency increases. A new return guide vane with twisted inlet and 3D curved surface was designed to reduce the cost, and the hydraulic loss. The self-balancing design method of impeller axial thrust was accomplished by using the end-face seal at the impeller inlet and adopting the sliding fit between the pump shaft and impeller; the impeller axial thrust is self-balanced because the areas of the impeller front shroud and back shroud are almost equal. The interior flow was simulated based on Fluent RANS CFD, both numerical simulation and test results showed that the performance of the new type well pump was better than the traditional products. A series of submersible pumps for deep well were designed, manufactured and tested, compared to the similar products at market home and abroad, the single-stage head increases 20% to 50%, the efficiency increases 3% to 9%, and the whole axial length and weight decreases around 1/3.

Role of blade rotational angle on energy performance and pressure fluctuation of a mixed-flow pump

2017 ◽  
Vol 231 (3) ◽  
pp. 227-238 ◽  
Author(s):  
Tan Lei ◽  
Yu Zhiyi ◽  
Xu Yun ◽  
Liu Yabin ◽  
Cao Shuliang
Keyword(s):  
Pressure Fluctuation ◽  
Guide Vane ◽  
Pressure Fluctuations ◽  
Maximum Amplitude ◽  
Energy Performance ◽  
Mixed Flow ◽  
Rotational Angle ◽  
Flow Pump ◽  
Dominant Frequencies

The role of blade rotational angle in the energy performance and pressure fluctuation of a mixed-flow pump is investigated through an experimental measurement and numerical simulation. The mixed-flow pump head increases at a blade rotational angle of 4° and decreases at a blade rotational angle of −4° compared with a blade rotational angle of 0°. Meanwhile, the highest efficiency decreases by 0.3% at a blade rotational angle of 4° and increases by 0.8% at a blade rotational angle of −4°. The pressure fluctuation characteristics in the mixed-flow pump at different blade rotational angles are also revealed. The dominant frequencies of pressure fluctuations in the impeller are the axis rotation frequency or six times this frequency corresponding to six guide vanes. The dominant frequencies of pressure fluctuations at the middle plane of impeller and guide vane are the blade-passing frequencies or twice this frequency. The maximum amplitude of pressure fluctuation in the impeller at a blade rotational angle of −4° is greater than that of blade rotational angle 0° and 4° because of strong vortex intensity. The maximum amplitude of pressure fluctuation at the middle span of the impeller and vane occurs at a blade rotational angle of 4° because of the largest pressure gradient.

scholarly journals Effect of the Reynolds Number and Clearance Flow on the Aerodynamic Characteristics of a New Variable Inlet Guide Vane

Aerospace ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 172
Author(s):  
Hengtao Shi
Keyword(s):  
Reynolds Number ◽  
Guide Vane ◽  
Three Dimensional ◽  
High Growth ◽  
Aerodynamic Characteristics ◽  
Inlet Guide Vane ◽  
Separation Region ◽  
Clearance Flow ◽  
New Type ◽  
Variable Inlet Guide Vane

Recently, a new type of low-loss variable inlet guide vane (VIGV) was proposed for improving a compressor’s performance under off-design conditions. To provide more information for applications, this work investigated the effect of the Reynolds number and clearance flow on the aerodynamic characteristics of this new type of VIGV. The performance and flow field of two representative airfoils with different chord Reynolds numbers were studied with the widely used commercial software ANSYS CFX after validation was completed. Calculations indicate that, with the decrease in the Reynolds number Rec, the airfoil loss coefficient ω and deviation δ first increase slightly and then entered a high growth rate in a low range of Rec. Afterwards, a detailed boundary-layer analysis was conducted to reveal the flow mechanism for the airfoil performance degradation with a low Reynolds number. For the design point, it is the appearance and extension of the separation region on the rear portion; for the maximum incidence point, it is the increase in the length and height of the separation region on the former portion. The three-dimensional VIGV research confirms the Reynolds number effect on airfoils. Furthermore, the clearance leakage flow forms a strong stream-wise vortex by injection into the mainflow, resulting in a high total-pressure loss and under-turning in the endwall region, which shows the potential benefits of seal treatment.

scholarly journals Numerical study of unsteady flow and exciting force for swept turbomachinery blades

2016 ◽  
Vol 20 (suppl. 3) ◽  
pp. 669-676
Author(s):  
Di Zhang ◽  
Ma Jiao-Bin ◽  
Qi Jing
Keyword(s):  
Boundary Layer ◽  
Unsteady Flow ◽  
Pressure Fluctuation ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Aerodynamic Performance ◽  
Rotor Blades ◽  
Stable Operation ◽  
Straight Blade ◽  
Excitation Force

The aerodynamic performance of blade affects the vibration characteristics and stable operation of turbomachinery closely. The aerodynamic performance of turbine stage can be improved by using swept blade. In this paper, the RANS method and the RNG k-? turbulence mode were adopted to investigate the unsteady flow characteristics and excitation force of swept blade stage. According to the results, for the swept blade, the fluid of boundary layer shifts in radial direction due to the influence of geometric construction. It is observed that there is similar wake development for several kinds of stators, and the wake has a notable effect on the boundary layer of the rotor blades. When compared with straight blade, pressure fluctuation of forward-swept blade is decreased while the pressure fluctuation of backward-swept blade is increased. The axial and tangential fundamental frequency excitation force factors of 15?forward-swept blade are 0.139 and 0.052 respectively, which are the least, and all excitation force factors are in the normal range. The excitation factor of the forward-swept blade is decreased compared with straight blade, and the decreasing percentage is closely related to the swept angle. As for backward-swept blades, the situation is the other way around. Additionally, the change of axial excitation factor is more obvious. So the vibration reduction performance of forward-swept blade is better.

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