Flow Field Of Centrifugal Pump Research Articles

Numerical Investigation of Vortex Generator on Controlling Flow Field of Centrifugal Pump Based on Response Surface Method

Numerical Investigation of Vortex Generator on Controlling Flow Field of Centrifugal Pump Based on Response Surface Method

The effect of the impeller eccentricity on the hydrodynamic characteristics of a centrifugal pump

To explore the effect of impeller eccentricity caused by shaft parallel misalignment on the hydrodynamic characteristics of a centrifugal pump, a numerical simulation model based on computational fluid dynamics (CFD) is established. The SST k-ω turbulence model is used to describe the flow field in centrifugal pump. The eccentric motion of the impeller is described by the sliding mesh method (SMM). The results indicates that the nonuniformity and instability of flow field will be aggravated with the increment of impeller eccentricity, which then reduce the pump head and efficiency to a certain extent. The radial force exerted on the impeller is directly proportional to the eccentricity of the impeller. In addition, the impeller eccentricity has a significant impact on the peak rotation frequency of shaft frequency. This study can provide a numerical reference for eccentricity fault diagnosis and vibration control of centrifugal pump impellers to carry out optimal design and vibration reduction.

RESEARCH ON THE FLUID-INDUCED EXCITATION CHARACTERISTICS OF THE CENTRIFUGAL PUMP CONSIDERING THE COMPOUND WHIRL EFFECT

In order to study the correlation mechanism between the flow characteristics and the fluid-induced force under the compound whirl motion in the centrifugal pump, the RNG k-ε model is selected in this paper to simulate a low specific speed centrifugal pump with impeller eccentricity based on the N-S equation. The changes of fluid-induced force with impeller eccentricity and the unsteady flow characteristics of the internal flow field of centrifugal pump under different flow conditions and rotation speeds are investigated, and the relationship between the fluid-induced force of the impeller and the internal flow field characteristics is discussed. The results show that the trend of fluid-induced force and the pressure coefficient is similar. When the rotation speed changes and when the flow is similar, the pressure coefficient under different rotation speeds almost coincides. With the increase of impeller speed and impeller eccentricity, the dynamic and static interferences between the impeller and the volute tongue are more significant, the uneven distribution of the pressure around the impeller makes the internal flow of centrifugal pump more disordered and increases the fluid-induced force near the volute tongue. The research results can provide important reference value for accurately grasping the internal flow excitation principle of the centrifugal pump.

Numerical investigation of clocking effect on irreversible energy loss in volute for centrifugal pump with vaned diffuser based on entropy generation method

In order to study temporal and spatial variation of energy loss and reveal influence rule of clocking effect on energy loss and flow field in centrifugal pump with vaned diffuser, numerical simulations were carried out. Numerical simulations were validated by experiments. Local equilibrium of turbulence generation and dissipation was verified to state feasibility of energy loss methods. Hydraulic loss in each component was assessed, which shows that variation of hydraulic loss in volute is more significant due to clocking effect than that in other components. Vortical structure in volute varies greater under different guide vane positions than it in other components. The results show that positive and negative flow angle appears interlaced in tongue region with high velocity gradient, especially when diffuser is mounted at θd1. Since a clearance presents between tongue and vane trailing edge at θd1, a small vortex forms. Which promotes the blocking effect of the large-scale vortex at volute outlet pipe. Therefore, high velocity gradient appears at small vortex region and volute outlet pipe region. The shear strain rate at the tongue and volute outlet pipe is more significant than that at other diffuser mounted positions. Energy loss at these regions increases. This situation can be improved by a more suitable diffuser mounted position θd4, where the clearance and small vortex vanishes, the shear strain rate, velocity gradient, and energy loss decrease.

Numerical simulation on cavitation pressure fluctuation in centrifugal pump at low flow rate

The RNG κ-ε turbulence model and the modified mass transport cavitation model are applied to simulate the unsteady cavitation flows in a centrifugal pump at low flow rate. Unsteady cavitation flows analyses in centrifugal pump are focused mainly in the volute. The accuracy and reliability of the numerical model and method are demonstrated by the good agreement between with experimental and numerical values of the pump performance. 13 monitor points are positioned in the volute. The time domain and frequency domain of pressure fluctuations on monitor points are analyzed and discussed. Under different conditions, the pressure fluctuation at each monitoring positions has obvious periodic property. The intensity of pressure fluctuation gets stronger with the development of pump cavitation. The dominant frequency of pressure fluctuations in volute is the blade pass frequency (fBPF) and its harmonic frequency. Under cavitation condition, the pressure fluctuations is the most intense in the volute diffusion tube, and the maximum amplitudes is about 2∼3 times of non-cavitation. It is indicate that cavitation has a great influence on the outlet flow field of centrifugal pump.

Numerical investigation of pressure distribution in a low specific speed centrifugal pump

To study the pressure distribution of the volute casing, front casing and back casing in a prototype centrifugal pump, the pressure experiments and numerical simulations are carried out at six working conditions in this paper. The experimental results shows that the asymmetry of static pressure distribution on volute casing and front cavity is caused by the tongue of the volute and it may result in high radial and axial resultant force which can cause vibration and noise in the centrifugal pump. With the increasing of flow rate, the asymmetry of static pressure distribution and the magnitude of static pressure values reduce. The numerical results indicate that the pressure fluctuation near the tongue is strongest and it becomes slighter at point away from the tongue. With the increasing of flow rate, the local high-pressure region in impeller passage reduces and the flow becomes smoother accordingly, whereas the fluid speed becomes much higher which may cause further flow losses. The results predicted by numerical simulation are in coincident with the experimental ones. It shows that the turbulence model for simulating the flow field in centrifugal pumps is feasible.

Multiobjective Optimization Design and Experimental Study of Desulfurization Dust Removal Centrifugal Pump Based on Immune Particle Swarm Algorithm

In view of the problems of low efficiency, poor anticavitation performance, and curve hump for current centrifugal pump in the process of desulfurization and dust removal, the desulfurization dust removal centrifugal pump was designed. The velocity coefficient method was used for hydraulic design of centrifugal pump, and the three‐dimensional modeling and numerical simulation of flow field of centrifugal pump were carried out by using computational fluid dynamics technology (CFD). The optimal mathematical model with the highest efficiency and the lowest pump net positive suction head (NPSHr) as the objective function was established under the condition of no curve hump. The immune particle swarm optimization algorithm was used to optimize the multiobjective function, and the optimal combination of the main parameters was obtained. The simulation results showed that, compared with the traditional centrifugal pump, the performance of the optimized centrifugal pump had been greatly improved, which eliminated the phenomenon of curve hump. Based on IH model chemical pump to build a prototype test platform, the experimental results of the external characteristics of the prototype pump and the optimization pump under different working conditions were obtained. At the rated flow rate, the optimization pump efficiency was increased by 13.30%, the head was increased by 11.52%, and NPSHr was decreased by 10.14%. The experimental results showed that the optimized indexes met the design requirements and improved the performance of centrifugal pump. At the same time, the accuracy of the immune particle swarm control method was verified, which provided some reference for the design of desulfurization dust removal centrifugal pump.

Sensitivity analysis of the effective centrifugal pump parameters using the EFAST method

In the present study, the effective parameters of centrifugal pumps are investigated using the EFAST Sensitivity Analysis (SA) method. The SA is performed using GMDH type artificial neural networks (ANN) which are based on validated numerical data of flow field in centrifugal pumps. There are four design variables namely: leading edge angle of blades on hub section (β1 Hub), leading edge angle of blades on shroud section (β1 Shroud), trailing edge angle of blades (β2), and the stagger angle of blades on mid span (γ mid) and there are two objective functions namely: efficiency (h) and the required NPSH of impeller. The results show that among design variables, β2 has the highest effect on variations of h (46%) and NPSH (45%). Except β2, β1 Hub and γ mid has the highest effect on NPSH (33%) and h (28%) respectively. The effects of all of the design variables on objective functions are shown in the results.

Differential amplification method for flow structures analysis of centrifugal pump between design and off-design points

The three-dimensional internal flow field of centrifugal pump is complex and variable with design parameters and operation conditions. The post-processing technique named differential amplification method was proposed for the comparison study of different flow structures. The full steady flow fields of an industrial centrifugal pump working on-design and off-design points were numerically investigated by solving Reynolds average Navier-Stokes equations together with a shear−stress transport (SST) k−ω turbulence model. And the numerically predicted performance curves of the studied pump agree well with test measurement results. Compared with the flow flied on design point under the help of differential amplification method, the disturbance caused by interaction between blade and volute tongue is very obvious and it extends to the diffuser pipe on the working point with 0.8 times rated flux. While on the point with 1.2 times rated flux, the flow distribution in impeller region is roughly even and it flows more to the bottom section of the diffuser pipe. The above method was proved to be good at displaying the subtle secondary flow structure changes with a higher resolution effect relative to single isolated case observation, which helps the optimization decision-making from multiple design cases.

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

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.

Effects of Impeller Trimming Methods on Performances of Centrifugal Pump

AbstractImpeller trimming can improve the hydrodynamic performances of the centrifugal pump and expand the application range of the pumps. However, most researches focus on single-impeller cutting method; the literature slightly lacks a comparison of the different impeller trimming methods, which is very important in deciding on an impeller trimming method. In this paper, by taking the centrifugal pump as the research object, the accuracy of computational fluid dynamics (CFD) was verified by comparing experimental results and those of the numerical simulation. On the basis of impeller straight trimming, miscut, and triangle trimming methods, a new unconventional parabolic impeller trimming method was put forward. In different trimming sizes and operating conditions, performance curves of four impeller trimming methods were compared to get several different trimming models. By researching the flow field of centrifugal pump, the change reasons of centrifugal pump’s performance curves were further revealed. ...

The flow field in a centrifugal pump with a large tongue gap and back blades

In this paper, the unsteady 3-D turbulent flow fields in an end-suction centrifugal pump with a vaneless volute are studied numerically at three different rotation speeds. The unshrouded impeller of the pump, as a reduced diameter version of the original full-size impeller, has five backswept blades and five pump-out blades. The results show that the flow rate and pressure vary with the rotational speed according to the similarity law, and the normalized internal flow fields at all speeds are very similar. Due to the reduced impeller diameter, the pump efficiency is relatively low. Flows discharged from the front and back blade passages interfere with each other and swirling motion exists in the volute. The pressure fluctuations on the casing wall near the impeller outlet are extracted, and their spectra show that the component at the blade passing frequency was prominent. This study sheds some light on the characteristics of the internal unsteady flow of a centrifugal pump at different rotational speeds, and forms a basis for future study of flow induced pump vibration and noise.

Analysis of Numerical Simulation and Performance Prediction in Centrifugal Pump for Warship

Through the ship flow field of centrifugal pump that can be numerical simulation of three-dimensional turbulent, the paper reveals the pump flow pressure and velocity distribution. It also introduces the function of hardware and module testing system, according to the centrifugal pump performance test data, to achieve the minimum two multiplication curve fitting module using VC programming, curve fitting for the transformed data, the results show that the system is running stable, and convenient operation in the test process, simple maintenance and high reliability.

Analysis and Numerical Simulation of Flow Field in Centrifugal Pump

The inner flow field of centrifugal pump is complex and presents a characteristic of three-dimensional turbulence. Used Solidworks software to establish a three-dimensional model of the pump and impeller, completed the numerical simulation of centrifugal impeller flow field based on the turbulence model and Fluent software, obtained the static pressure and velocity distribution of flow field, provided basis for the design and optimization of the subsequent product.

English

The three-dimensional unsteady flow field in centrifugal pump under different flows was numerically simulated based on the commercial fluent software, using standard k-ε turbulence model, SIMPLE algorithm and sliding mesh technique. The characteristics of the time domain and frequency domain of the pressure pulsations, as well as fluctuation strength were analyzed. The varying locus of transient radial force vector of the centrifugal pump with time and the varying pattern of transient radial force with time were investigated. The results show that the frequencies of the pressure pulsations are mainly the blade passing frequency at the monitoring points, and the most intense pulsation appears at the volute tongue under the same frequency; the variation cycle of the transient radial force is the same with the passing cycle of the blades, and the direction of the radial force deflects anticlockwise as flow rate increases. At the designed flow rate, the distribution region of the radial force vector is the closest to the origin point and the area of the region is the smallest, with the gentlest fluctuation.   Key words: Centrifugal pump, transient radial force, pressure pulsation, numerical simulation.

Simulation on the Flow Field of Centrifugal Pump Based on Fluent

In this paper, the software Fluent was employed and the two-dimensional flow fields, such as flow distribution, velocity distribution, pressure distribution, turbulent kinetic energy distribution are obtained. The results show that the flow, velocity, pressure and turbulent kinetic energy distribution are significantly different and asymmetric. The results have referenced significance for design and analysis of the Centrifugal Pump.

Numerical Simulation of Cavity Flow within the Flow Field

Analysis of numerical simulation was used on flow field and temperature field in mechanical seal cavity. It borrowed a new calculation method, which was more visual and simpler than before. And this method analysed the change in temperature field of mechanical seal ring and the distribution of temperature and pressure in the flow field when mechanical seal was working. The result showed that the numerical simulation method was effect to the flow field in centrifugal pump.

Numerical simulation of flow in centrifugal pump with complex impeller

Based on the Navier-Stokes equations and the Spalart-Allmaras turbulence model, three dimensional turbulent flow fields in centrifugal pump with long-mid-short blade complex impeller are calculated and analyzed numerically. The relative velocity and pressure distributions in the flowpart are obtained. It is found that the flow in the passage of the complex impeller is unsymmetrical due to the joint action between volute and impeller. The back-flow region is at inlet of long-blade suction side, near middle part of long-blade pressure side and outlet of short-blade suction side. The flow near volute throat is affected greatly by volute. The relative velocity is large and it is easy to bring back flow at outlet of the complex impeller near volute throat. The static and total pressure rise uniformly from inlet to outlet in the impeller. At impeller outlet, the pressure periodically decreases from pressure side to suction side, and then the static pressure sharply rise near the throat. The experimental results show that the back flow in the impeller has an important influence on the performance of pump.

NUMERICAL STUDY OF UNSTEADY FLOW IN CENTRIFUGAL PUMP WITH DIFFERENT TYPE OF IMPELLERS

For impellers without splitter blades, with long splitter blades and short splitter blades, the unsteady CFD method is applied to study the whole 3D flow field in centrifugal pumps. The effects of blades arrangement and the shape of splitter blades on the lift, pressure fluctuation at the inlet and outlet are discussed. The pressure distribution on the blade surfaces and in the contral rotative plane is also analyzed. In comparison with the impeller without splitter blades, the impact of splitter blades on flow field is analyzed in detail, and the variation of pressure depending on the orientation of impeller relative to the tongue is also illustrated. The results give some instructive directions to reduce the vibration and noise of centrifugal pump from dynamics.