Weidong Shi

Numerical Prediction and Performance Experiment in a Deep-well Centrifugal Pump with Different Impeller Outlet Width

The existing research of the deep-well centrifugal pump mainly focuses on reduce the manufacturing cost and improve the pump performance, and how to combine above two aspects together is the most difficult and important topic. In this study, the performances of the deep-well centrifugal pump with four different impeller outlet widths are studied by the numerical, theoretical and experimental methods in this paper. Two stages deep-well centrifugal pump equipped with different impellers are simulated employing the commercial CFD software to solve the Navier-Stokes equations for three-dimensional incompressible steady flow. The sensitivity analyses of the grid size and turbulence model have been performed to improve numerical accuracy. The flow field distributions are acquired and compared under the design operating conditions, including the static pressure, turbulence kinetic energy and velocity. The prototype is manufactured and tested to certify the numerical predicted performance. The numerical results of pump performance are higher than the test results, but their change trends have an acceptable agreement with each other. The performance results indicted that the oversize impeller outlet width leads to poor pump performances and increasing shaft power. Changing the performance of deep-well centrifugal pump by alter impeller outlet width is practicable and convenient, which is worth popularizing in the engineering application. The proposed research enhances the theoretical basis of pump design to improve the performance and reduce the manufacturing cost of deep-well centrifugal pump.

3D FEM analyses on flow field characteristics of the valveless piezoelectric pump

Due to the special transportation and heat transfer characteristics, the fractal-like Y-shape branching tube is used in valveless piezoelectric pumps as a no-moving-part valve. However, there have been little analyses on the flow resistance of the valveless piezoelectric pump, which is critical to the performance of the valveless piezoelectric pump with fractal-like Y-shape branching tubes. Flow field of the piezoelectric pump is analyzed by the finite element method, and the pattern of the velocity streamlines is revealed, which can well explain the difference of total flow resistances of the piezoelectric pump. Besides, simplified numerical method is employed to calculate the export flow rate of piezoelectric pump, and the flow field of the piezoelectric pump is presented. The FEM computation shows that the maximum flow rate is 16.4 mL/min. Compared with experimental result, the difference between them is just 55.5%, which verifies the FEM method. The reasons of the difference between dividing and merging flow resistance of the valveless piezoelectric pump with fractal-like Y-shape branching tubes are also investigated in this method. The proposed research provides the instruction to design of novel piezoelectric pump and a rapid method to analyse the pump flow rate.

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

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.Copyright

Research and Development on the Hydraulic Design System of the Guide Vanes of Multistage Centrifugal Pumps

To improve accuracy and efficiency of the hydraulic design of the guide vanes of the multistage centrifugal pumps, four different-structured guide vanes are investigated, and the design processes of those systems are established. The secondary development platforms of the ObjectArx2000 and the UG/NX OPEN are utilized to develop the hydraulic design systems of the guide vanes. The error triangle method is adopted to calculate the coordinates of the vanes, the profiles of the vanes are constructed by Bezier curves, and then the curves of the flow areas along the flow-path are calculated. Two-dimensional and three-dimensional hydraulic models can be developed by this system.

Non-Overload Design of Low Specific Speed Submersible Pump

Based on the design of low specific speed submersible pump, the influence of impeller geometrical parameter on shaft power of pump is analyzed in this paper. Under the condition of the maximum value of shaft power being no more than the input power of matching electromotor, the method of reducing the maximum value of pump power is researched further in order to reduce the power of the matching electromotor. Then the design correlation formula of the geometrical parameters of impeller is presented. The value of shaft power was predicted by the software FLUENT. The results show that the ratio of maximum power of pump to the power at designing condition is less than 1.2 when the correlation formula presented is used. The experimentation of prototype shows that the maximum value of shaft power of pump reduces greatly whilst every parameter meets the rated requirements. The results demonstrated the guiding role of the discriminated formula in practice, so the desired aim was achieved.Copyright

Relationship between Planes of Cu2O Microcrystal and Photo-Catalytic Degradation of Methylene Blue

Four kinds of Cu2O microcrystals with different morphologies are synthesized via low temperature hydrothermal synthetic method. The photocatalytic degradation of methylene blue (MB) of the above different Cu2O is preliminary explored based on this observation. 6-facet, 8-facet, 14-facet are prepared by PVP system and 26-facet is prepared by NaOH system. They are characterized by means of Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Diffuse Reflectance Spectra (DRS). Under 150 W xenon lamp irradiation, 0.5 gL1 catalyst and 0.1% (v/v) 30% H2O2 as co-catalyst are used to degrade 5% 100 mL MB solution. The reaction time is 80 min. 26-facet Cu2O polyhedral discolor about 89.48% of MB while 6-facet Cu2O microcrystal about discolor about 20.18% which is the lowest decolourization rate among all the samples. The photocatalytic performance of 8-facet Cu2O microcrystal is slight better than that of 14-facet. The decolourization rate of 8-facet and 14-facet are 56.00% and 41.08%, respectively. The main reason is that the planes of Cu2O microcrystal have a main influence on photocatalytic degradation of MB.

Numerical Simulation of Solid Particles Movement in the Axial Flow Impeller and Wear Experiment

The performance curves of a submersible axial flow pump were predicted based on mixture multiphase flow model, RNG k-ε turbulence model and SIMPLEC algorithm, and the solid-liquid two-phase flow in the impeller was simulated. The numerical results show that the performance prediction of the head and efficiency curves show good agreement with the experimental data in the whole flow rate range, and the solid particles in the impeller are mainly distributed on pressure side of blades, while less on the suction side.The solid particles are mainly concentrated in the blade inlet and region near the hub of the pressure side. The experimental results also show that the blade pressure sides have serious erosion, particularly near the hub, but less wear and tear on the suction side.The accuracy of the numerical simulation results are verified by the experiments.

Study on Operation Optimal Control of Double Impeller Underwater Aeration Machine

Under water aerator is one of the most important biological wastewater treatment equipments, and it is one of the main power of the sewage treatment plant equipments as well, therefore, effects of aeration is good or bad just as oxygenation capacity is good or bad that is the main basis for the under water aerator . In this paper fuzzy control theory and frequency control principle are used to research running method of the double-impeller underwater aerator and by the demand for dissolved oxygen in water through the aerator variable frequency control, the aerator is controlled to adjust the operating speed, so that to achieve energy savings.

Analysis on Effects of the Blade Wrap Angle and Outlet Angle on the Performance of the Low-Specific Speed Centrifugal Pump

In order to research the effect of the blade wrap angle and outlet angle on the hydraulic performance of the low-specific speed sewage pump, the Reynolds time-averaged Navier-Stokes equations was discretized based on the finite volume method, and the modified k-ε turbulence model were chosen in FLUENT. Numerical simulation of the internal flow within the centrifugal pump with the specific speed of 60 at different blade wrap angle and outlet angle is carried out. The analysis of the velocity and the turbulent kinetic energy distribution in different cases, and predicts the external characteristics of the several cases based on the loss analysis method. The study results show that the efficiency of pumps increase with decreasing the outlet angle and increasing the wrapping angle at the design of sewage pumps. According to the analysis, changing the blade outlet Angle has much more influence on the performance of the pump than changing the wrap angle.

Regression Test of Stainless Steel Stamping Well-Pump Based on Numerical Simulation

In order to develop stamping well pump with high efficiency, 4SP14 stainless steel stamping well pump was set as an example. Combined with the features of stamping technology, this research was taken on raising the efficiency of stamping well pump, using hydraulic design of impeller and CFD and regression test method. The experiment was designed with four factors including impeller inlet angle Δβ1, impeller outlet angle β2, and impeller outlet width b2 and inlet width of guide vane B3. 30 groups of programs were designed according to CCD central composite test method. The whole flow field of well pump at the operating point was simulated by FLUENT using the standard k-ε model, SIMPLE algorithm, first-order upwind scheme. 30 group of efficiency were obtained. Use regression equation to fit the function relationship between the efficiency value and each factor. Through the analysis of the regression equation, the optimal combination of geometric parameters can be found as inlet angle 4º, outlet angle 27.5º, outlet width 9.5mm and inlet width of guide vane 11.5mm. After manufactured and tested according to the above geometric parameters, the efficiency of the optimal model pump reaches 60.28%, which reaches the international advanced level.