Performance Of Impeller Research Articles

Investigating the ‘techno-eco-efficiency’ performance of pump impellers: metal 3D printing vs. CNC machining

The economic, environmental, and social impacts caused by the extensive resource consumption and harmful emissions from the metal manufacturing industry should be lowered through innovative sustainable manufacturing strategies. This study aims to investigate the techno-eco-efficiency performance of metal 3D-printed parts in comparison with CNC-machined parts to determine the technical, economic, and environmental performance as a decision support tool for selecting the most techno-eco-efficient manufacturing method. In this study, a novel metal extrusion 3D printing technology has been used to create a centrifugal semi-open pump impeller in 316L stainless steel material. The technical feasibility of the impellers has been determined by evaluating the geometry, build material, mechanics, morphology, and functional performance of the impellers. The eco-efficiency performance of technically feasible impellers was evaluated through environmental life cycle assessment, life cycle costing, and portfolio analysis. This eco-efficiency analysis helped ascertain the cost-competitiveness and environmentally friendliness of the 3D-printed impellers by comparing it with the conventional impellers. The findings reveal that the AM impeller is eco-efficient mainly due to lower normalised environmental impacts (54.6%) compared to the SM impeller. The functional parts made by metal extrusion 3D printing are technically feasible, cost-effective, and environmentally friendly compared to the SM counterparts.

The Influence of Rotating Speed on the Sealing Characteristics of a Liquid-Sealing Impeller for a Liquid Oxygen Turbopump

In order to explore the influence of rotating speed on the internal flow and sealing characteristics of the liquid-sealing impeller for a liquid oxygen turbopump of a rocket engine, unsteady numerical simulations of the flow characteristics and sealing performance of the first-stage liquid-sealing impeller for a liquid oxygen turbopump under liquid phase conditions were performed. The results show that the pressurization value increases with the increase in the rotating speed. The first-stage liquid-sealing impeller, whose structure is symmetrically distributed along the center of the rotation axis, tends to be an isobaric seal at a rotating speed of 12,000 rpm, and when the rotating speed is decreased or increased, it enters the leakage state or negative pressure sealing state, respectively. The matching relationship between the rotating speed and inlet pressure has a significant effect on the pressurization value, pressurization coefficient and leakage flow rate. Under the working condition with a good match between the rotating speed and inlet pressure, the pressurization value increases significantly and the leakage flow rate decreases significantly, and the pressurization coefficient is stable between 0.88 and 0.89. The empirical formulas proposed by Wood and the Shanghai Research Institute of Chemical Industry (1979) have high reference values for the design of the liquid-sealing impeller with a flow channel (groove) and retainer.

Hydrodynamic performance of a mono-tangent backward-rotating impeller based on tidal current energy utilization

Owing to the continuous consumption of fossil fuel and increasing environmental problems, there is an urgent need to develop technologies for the efficient use of clean energy. In this study, a mono-tangent backward-rotating impeller based on tidal current energy utilization is proposed, and its hydrodynamic performance was studied using the computational fluid dynamics method by establishing a hydrodynamic model of the backward-rotating impeller. The influences of the number of blades, impeller aspect ratio (λ), and different flow speeds on the coefficient of power (cp) of the mono-tangent impeller were investigated. The results show that the value of cp of the mono-tangent impeller with four blades is higher than that of the impellers with two, three, five, and six blades. λ has a significant impact on the backward-rotating impeller, with cp of the impeller reaching an optimal value when λ = 0.5 and the flow speed is 1.25–1.5 m/s (with a tip speed ratio of 0.6–0.75).

Computational fluid-dynamic investigation of a centrifugal compressor with inlet guide vanes for supercritical carbon dioxide power systems

A centrifugal compressor for large-scale supercritical carbon dioxide applications (∼50 MW) is analyzed by means of RANS simulations. The purposely designed compressor includes adjustable inlet guide vanes, an open impeller, and a wedge-shaped vaned diffuser. The upstream total state is located at 78.70 bar and 305.15 K, close to the thermodynamic critical point, whereby non-ideal effects and two-phase flows are significant. To account for these effects, the computational model implements a homogeneous equilibrium model (using pressure and specific enthalpy as state variables) complemented with a state-of-the-art equation of state explicit in the Helmholtz free energy and specific correlations for transport properties. It is found that the compressor can provide the entire pressure ratio required by the cycle (∼3.25) with high efficiency (87.9%, excluding parasitic losses). Three inlet vane rotations are considered: −10deg, 20deg, and 40deg. The preswirl has a limited effect on efficiency, which is reduced by 0.3% points away from choked conditions with vane rotation of 40deg. Nonetheless, the preswirl affects the extent of the two-phase region at the impeller intake, which has a detrimental impact on the compressor flexibility by setting an early choking.

Numerical and Experimental Investigation of the Performance of Tandem Vanes for a Centrifugal Pump

Abstract Conventional vane designs come with the disadvantage of flow detachment for high deflection. For axial machines, often tandem vanes are prevalent which combines two vanes for redirection of the flow and thus effectively prevents detachment. However, their application for radial machines has hardly been investigated so far. This study investigates the influence of tandem vanes on the performance in terms of head and efficiency of a centrifugal pump. First, different tandem designs were numerically investigated based on computational fluid dynamics (CFD). For a selected tandem variant, the numerical results were validated by experimental investigations. The preceding numerical investigations were done stationary by using a single passage model to compare the performance of different tandem impellers with a conventional impeller (unsplit vane). Therefore, a method was developed to design tandem vanes from given undivided vanes. In this way, the influence of the offset in the circumferential direction and the angle of attack of the rear blade profile were systematically investigated. Transient CFD simulations have been done for a complete single-stage volute pump. In the experiments, the performance curves for both the conventional and tandem impeller were determined. The results of this study show that tandem blades can increase the pressure rise of a centrifugal pump while maintaining almost the same efficiency if a suitable combination of blade angle and offset in the circumferential direction of the rear blade has been selected. Furthermore, the CFD results show that the detachment can be prevented inside the impeller passage.

Research on machining error prediction of open blade under dynamic loading

The instantaneous cutting contact relationship between tool and workpiece is changing with the change of curvature profile of open blade impeller. This leads to a strong nonlinear characteristic of the dynamic cutting load change during the machining of this type of parts, which affects the machining accuracy of the blade. This paper proposes a method to predict the machining error of ball-end milling under dynamic load. This method considers the influence of the curvature change of blade profile. Based on the analysis of the instantaneous cutting contact of complex surface in ball-end milling, a prediction model of the instantaneous undeformed cutting thickness of ball-end milling under the influence of surface curvature changes is constructed. Based on this model, the correction of the prediction model of machining complex surface milling force is realized. The prediction of the machining error when the complex surface is thin-walled impeller is processed under dynamic load. Finally, the effectiveness and accuracy of the method are verified through ball-end milling experiments. The research can provide guidance for the control and compensation of milling machining errors of complex-shaped thin-walled open blade.

Mixing intensification through modifications of PBT impellers studied by DEM-VOF method

A coupled method of discrete element method (DEM) and volume of fluid (VOF) is applied to study the hydrodynamics and mixing characteristics in solid-liquid stirred tanks with a free surface. By making cutouts or adding fittings on pitched blade turbine (PBT) blades, five modified impellers are obtained, and named as Boundary-cut (BC), V-cut (VC), U-cut (UC), UC-F and UCC impellers. The power consumption, pumping capacity, pumping efficiency, solids suspension, local solids distribution, flow field structure, fluid velocity profiles, trailing vortex, and turbulent kinetic energy (TKE) are investigated carefully in this paper. Results show that the power number decreases by 18.62–29.91% and the pumping efficiency increases by 2.03–22.18% for the modified impellers when comparing to the classical blade. Moreover, adding fittings on the blades has both positive and negative effects on the impeller performance and the mixing of multiphase flows, which depends on the relative position of the fittings to the rotation direction. In addition, the local gradient of TKE have significant impact on the particle distribution. The smaller the local gradient of TKE is, the more even the solid distribution. The results obtained in this report are helpful to guide the improvement and design of impeller blades.

Pressure Distribution on the Inner Wall of the Volute Casing of a Centrifugal Pump

In order to grasp the distribution characteristics of the pressure field on the inner wall of the volute casing of an atypical open impeller centrifugal pump, the instantaneous pressure at different operating conditions was experimentally measured under four operating rotational speeds to obtain the distribution characteristics of the average static pressure field in the volute casing of this pump model. The pressure pulsation amplitude and pressure pulsation intensity were also analyzed at different rotational speed cases, and the standard deviation analysis was performed. The results showed that the instantaneous pressure pulsation on the inner wall of the volute casing strongly fluctuates during the pump operating, and the closer to the volute casing outlet, the more intense the pressure pulsation was. After increasing the pump shaft speed, the fluctuation amplitude gradually decreased. The pressure pulsation on the wall of tip clearance is more intense than that on the inner wall of the volute shell. The intensity of the pressure pulsation on the wall of tip clearance decreases with the increase of the rotational speed, and the higher the speed, the less intense the pressure pulsation.

The effect of bell mouth height on the hydraulic characteristics of the two-way pumping station based on the parameter design

Pump intake is an important part of pumping station. To improve the inflow condition of the two-way pumping station, the optimal design of two-way intake of an in-operation pumping station was carried out based on the numerical and experimental study. A design scheme that incorporates the parametric design of the bell mouth height by introducing a parabola, and combined criteria for comprehensively evaluating the performance of the two-way intake, was developed to better estimate the outflow conditions. Moreover, the flow regime in intake and its’ influence on the impeller performance were comprehensively analyzed. With the verified results by the experimental test, they show that the uniformity of intake outflow affects both the hydraulic performance and forces of the impeller. As the bell mouth height decreases, the partial flow in intake has been greatly improved. Furthermore, it has been found that a more uniform outflow suppresses the adverse flow conditions on blade surfaces making the rotor more evenly stressed, while the excessively low height causes the serious hydraulic loss in intake. The present study is helpful in enhancing the operational performance of the two-way pumping station.

Impact of the inducer meridional length on the tandem impeller performance within a transonic centrifugal compressor

Tandem impeller configuration has the potential to improve the performance of highly loaded transonic centrifugal compressors, while the related research is still in the early stages and general design guidelines, such as the selection of inducer meridional length, are limited so far. In this paper, a highly loaded transonic centrifugal compressor with various tandem impeller configurations is numerically investigated. The objective is to evaluate the impact of inducer meridional length [Formula: see text] on the tandem impeller flow structure and performance, and further to look into the underlying flow mechanisms and design principles of the tandem impeller. The results indicate that the inducer meridional length [Formula: see text] has significant effect on the tandem impeller and compressor stage performance. There exits an optimized tandem impeller [Formula: see text] value of Appr. 38% that achieves a compressor stage pressure ratio and efficiency gain (at the P.E. points) of 2.6% and 1.8%, respectively, and deviating from the optimized [Formula: see text] value will lead to deteriorated compressor performance. In terms of the impeller performance, the inducer trailing edge determined by the inducer meridional length [Formula: see text] should be located downstream of the passage shock to reduce the shock and inducer wake losses. However, the inducer blade should also be placed in the impeller axial part to avoid the exudcer incidence angle deviation. In terms of the diffuser performance which is partly determined by the impeller discharge flow uniformity, the inducer meridional length [Formula: see text] directly affects the tandem impeller discharge flow uniformity by rearranging and controlling the secondary flow patterns, and the flow uniformity is prone to be insensitive to the [Formula: see text] variation when the [Formula: see text] value is large enough (i.e. ≥30%). Additionally, the [Formula: see text] value should be large enough (i.e. ≥20%) to generate intense inducer shedding vortexes, which can suppress the development of Coriolis vortex and finally improve the impeller flow uniformity.

Numerical study on flow and wear characteristics of dense fine particle solid–liquid two-phase flow in centrifugal pump

The solid–liquid two-phase centrifugal pump is one of the core power equipment of solid phase material hydraulic transportation, widely used in hydraulic engineering, petrochemical industry, marine metal mineral exploitation, urban sewage treatment, and other sectors of the national economy. There is a significant increase in the need to transport dense fine particle slurry in industrial production. Under this condition, the influence of particle parameters on the performance of the centrifugal pump is still not clear. In order to study the flow and wear characteristics of dense fine particle solid–liquid two-phase transported by an open impeller centrifugal pump, the Re-Normalization Group k − ε and dense discrete phase models in Fluent were used to describe the characteristics of the solid–liquid two-phase flow. The numerical model is validated with the experimental data of the pump’s performance. The study indicates that the particle size and concentration have great influence on the wear of the impeller. The wear of the blade pressure surface is the most serious. With the increase of particle concentration and size, the wear area expands to the leading edge and the upper surface of the blade. These results can provide supporting theories for the design of a dense fine particle solid–liquid two-phase medium conveying pump.

Experimental study on fiber suspension in a centrifugal pump by PIV

Abstract To study the influence of fiber particles on the flow field within the passages of an open impeller centrifugal pump, an experiment was performed. The hair fiber was used as solid particle phase in this experiment. After measuring the performance characteristic and PIV data, the flow field in impeller was measured and analyzed. It was shown that at the concentration of 0.1%, a varied distribution of relative velocity from different flow channels was observed. The outlet velocity of the impeller in the second flow channel was obviously higher than that in the first flow channel. The variation of the relative velocity near the hub tended to be consistent at the position of the front plane and the middle plane of the impeller. At 0.2% concentration, the relative velocity at the suction surface of the two channels changes more sharply than the other positions. Within the second channel, it was found that the relative velocity under low flow condition was obviously higher than that under rated and large flow rates. Under different concentrations, the increase of the relative velocity at low flow rate changed intensely compared with the other two conditions. The low velocity zone will be formed near the middle part of the suction surface of the flow channel which gradually decreases with the increase of the flow rate. The external characteristic test shows that the efficiency of the pump and the drag reducing feature increase with the increase of concentration.

Numerical simulation for a punched impeller in a solid-liquid stirred tank based on the EE-KTGF model

The improvement of mixing efficiency in a solid-liquid stirred vessel is one of the important challenges in industrial processes. The present study aims at evaluating the performance of the punched impeller. The mixing process in a stirred tank with the down-pumping pitched blade turbine (PBTD) and down-pumping pitched blade punched turbine (PPBTD) was predicted adopting the Eulerian–Eulerian method combined with kinetic theory of granular flow (EE-KTGF). The flow field and solid particles distribution of two impellers were compared in detail through various parameters. It was found that that the PPBTD impeller has positive significance in improving suspension quality and reducing power consumption. Moreover, the effects of aperture diameter, aperture ratio, and liquid viscosity on mixing characteristics were discussed. It can be observed that the PPBTD impeller can effectively enhance the mixing degree of liquid with different viscosity. The aperture diameter and aperture ratio have great influence on turbulence parameters, solid particles distribution, and power consumption. The better suspension quality can be obtained, and power consumption was dramatically decreased by 7.1% when the aperture diameter and aperture ratio are 8 mm and 13%, respectively. These results can be the significant guidance to the design of the punched impeller in chemical and biochemical engineering applications.

Experimental Study on Operational Stability of Centrifugal Pumps of Varying Impeller Types Based on External Characteristic, Pressure Pulsation and Vibration Characteristic Tests

This study performed external characteristics, dynamic pressure, and vibration tests on the closed impeller model, semi-open type impeller model, and open impeller model in order to study the influence of the impeller structure on the operational stability of the pump. According to the research findings, the external characteristics of the three impellers enjoyed favorable stability with flat curves under low flow rates. As the flow increases, the stability of the external characteristics weakens, and the poorest stability can be observed in the open impeller, while the enclosed impeller has the best stability under a large flow rate. In addition, intense pressure fluctuations arise near the casing tongue due to the dynamic and static interference between the blade and the casing tongue, causing a large amplitude of pressure pulsation near the casing tongue and the pump outlet. It can be seen that the stability of pressure pulsation of the closed impeller in the casing tongue area was the best, whereas the stability of pressure pulsation of the open impeller was the poorest. The minimum casing vibration can be found in the closed impeller, followed by the semi-open impeller, and the open impeller, with the maximum vibration. In addition, the optimum stability of rotor vibration can be observed in the closed impeller, semi-open impeller, and open impeller with similar stability of rotor vibration.

Large eddy simulation of the flow energy dissipation in the blade channels of a stalled pump impeller

Pump impellers usually work with the rotating stall phenomenon. The performance will be strongly affected by the undesirable flow. Understanding the features of flow energy dissipation is very important. In this study, large eddy simulation is conducted for the turbulent flow field based on a typical 6-blade pump impeller with “alternating stall” phenomenon. The stalled channels and well-behaved channels alternatively and stably distribute. Compared with the experimental data, the numerical simulation is proved accurate. In the well-behaved channel, flow pattern is relatively smooth. In the stalled channel, flow is completely blocked by several stall cells. Vortex shedding is well predicted mainly in three regions including the leading-edge region of stalled channel, the outlet region of stalled channel, and the blade suction side region of well-behaved channel. Turbulence kinetic energy is high in these regions. High flow energy dissipation is found among shedding vortexes due to flow-flow interaction and in the near-wall region because of flow-wall interaction. In the core region of vortexes, flow energy dissipation is not that high. The flow-flow interaction and the flow-wall interaction are two main sources of flow energy dissipation. In the well-behaved impeller blade channel with smooth flow pattern, the flow energy dissipation is mainly caused by flow-wall interaction. On the contrary, in the stalled impeller blade channel with vortical flow pattern, the flow energy dissipation is mainly caused by flow–flow interaction. The large eddy simulation-based study will be very helpful in enhancing the performance of pump impellers especially with the rotating stall phenomenon.

Investigation on Broadening Compressor Surge Margin by Using Active Magnetic Bearing

The impeller design usually expects to achieve high efficiency and a wide working range while they are influenced by tip clearance in different ways. In this study, a blower with a controllable magnetic suspension bearing was studied. The magnetic bearing enables the impeller to adjust the tip clearance during operation to optimize the efficiency of the blower at the design point and significantly expand the surge margin when it deviates from the design point. The clearance ratio (CR) is defined as the ratio of tip clearance over impeller outlet width. The computational fluid dynamics (CFD) method is used to study the performance of a centrifugal impeller under CR = 2.61%∼7.83% and verified by experiments. The results show that the pressure ratio and efficiency of the impeller at the design point decreased linearly with the increase of the gap. For each 1% increment in CR, the pressure ratio reduces by 0.02 and the polytropic compression efficiency declines by 0.5%. Conversely, the surge margin increases with the expansion of CR. For every 1% rise in CR, the surge margin would improve by 7.8%. A control method of changing the reference suspension position according to the optimal efficiency fitting model is proposed. It realizes the real-time control of the axial suspension position of the impeller according to the changes of pressure and flow rate signals to obtain the optimal work efficiency with a broad surge margin. Experimental results show that using an impeller equipped with a controllable magnetic suspension bearing could minimize the gap stably in the nonsurge area to obtain high efficiency, and when necessary, it could enlarge the gap to meet the low flow rate condition.

Efficiency of PBT Impellers with Different Blade Cross-Sections

In this study, the mixing power and the axial and radial velocity distributions were determined for the standard PBT45-6 impeller with inclined blades and for three NACA impellers with airfoil blades. On the basis of the velocity distributions obtained by means of PIV techniques, the pumping efficiency and the size of the secondary circulation for the tested impellers were determined. The next stage was to calculate the efficiency of the impeller operation, in which the comparative criteria were the values of the mixing energy in the form of a dimensional and dimensionless criterion. The lowest mixing energy was obtained for impellers with symmetrical profiled NACA0021 blades, which was 20% lower than the similar mixing energy obtained for the standard PBT45-6 impeller.

Study on the Influence of Blade Outlet Backsweep Angle on Performance of Impeller

As an important parameter of compressor impeller, the design value of blade outlet backsweep angle has a great influence on the performance of impeller. In this paper, six impellers with blade outlet backsweep angle β2B equal to 0°, 10°, 20°, 30°, 40°, and 50° were designed to evaluate the influences of impeller backsweep angle β2B on the performance, characteristics of gas flow and equivalent stress using computational fluid dynamics (CFD) and finite element analysis (FEA). Results indicated that the performance curve for the outlet backsweep blade angle β2B of 50° has the largest stable operating range. The isentropic efficiency of the impeller with backsweep angle β2B equal to 40° is 16.8% - 25.9% higher than that of the impeller with backsweep angle β2B equal to 0°. When the blade outlet backsweep angle is 30°, the equivalent stress distribution of the impeller is more uniform, the maximum equivalent stress is the smallest.

PIV Measurement of Flow Conditions near Casing Tongue of Mini Centrifugal Pump

Flow conditions near the casing tongue have a significant impact on the performance and stable operation of the centrifugal pump, so the internal flow conditions have been measured by the experiment and PIV measurement. The internal flow conditions of mini centrifugal pumps especially smaller than 100mm are less measured by PIV measurement and its flow conditions near the casing tongue are not clarified yet. Therefore, PIV measurement was conducted near the casing tongue for the mini centrifugal pump having 55mm impeller diameter. The two-dimensional open impeller with the large blade outlet angle β2=60° was selected as the test impeller. FlowMaster Stereo-PIV by LaVision was used for the PIV measurement and the whole test section was made of the acrylic resin including the test impeller. Two CCD cameras with its resolution 2048×2048 pixels were used and velocity vector and contour were calculated by the PIV measurement software DaVis(Lavision). The internal flow conditions near the casing tongue were focused in this research. The PIV measurement results at different flow rates were shown and the tongue flow angle was defined to clarify the flow condition near the casing tongue with the impeller rotation. With the increase of the flow rate, the tongue flow angle increases which means the flow near the casing tongue is discharged to the casing throat. In the present paper, the internal flow near the casing tongue is clarified by PIV measurement results and the flow conditions with the impeller rotation are discussed.

Analysis and performance of centrifugal pump impeller

It is important to increase the production rate of oil and gas as the usage of them is increasing day by day. To increase the production rate of oil and gas, design of an efficient centrifugal pump impeller plays very important role. Due to the usual submergible pump, there might be the chances for failure and it is so complex when the pump is failed. So an alternative method such as artificial lift is necessary on behalf of submergible pumps for different flow rates. In the present study, 3D simulation of impeller and its stationary flow of centrifugal pump casing are analyzed using CFD. Pressure head and efficiency of the pump for different flow rates are analyzed as well as the data from pump manufacturers are taken and have good satisfactory agreement. Finally, the structural analysis of single impeller blade is carried out by changing different materials. These data are very useful to design the pumps in manufacturing industries.