Impeller Blade Design Research Articles

Hydraulic and axial force characteristics of large axial flow pumps under different flow conditions

Abstract Axial flow pumps often experience uneven distribution of axial force on the blades when deviating from design conditions, which can easily lead to local damage to the pump blades. In response to this issue, this article conducts a detailed study on the hydraulic and axial force characteristics of large vertical axial flow pumping stations in China based on constant and non-constant numerical simulation research methods. Research has found that under biased operating conditions, due to the angle between the water flow direction inside the impeller and the impeller blades, the water body collides with the blades, resulting in concentrated pressure distribution on both sides of the inlet side of the impeller blades. Under low flow conditions, the high axial force area of the impeller blade is concentrated in the middle and rear position of the suction surface, while under high flow conditions, the high axial force area is widely distributed. Under the conditions of 0.8 Q to 1.4 Q, the fluctuation of axial force on the impeller blades is mainly affected by the rotation of the impeller blades. However, under low flow conditions, due to the turbulence of the flow state, there is no obvious pattern of axial force variation on the impeller blades. In addition, under different flow conditions, there is no obvious pattern in the fluctuation of axial force on the guide vanes. This also proves that there are problems such as uneven axial force distribution and no periodic changes in the impeller blades under low flow conditions, which can easily lead to damage to the impeller blades. The above analysis can provide some reference for the design of impeller blades.

Study on the influence of the blade inlet area-to-impeller inlet area ratio on hydraulic performance under various specific speed conditions

Abstract To investigate the unknown effects of the relationship between the impeller inlet area and blade design on the hydraulic performance of centrifugal pumps at various specific speeds within typical rotating fluid equipment, this paper aims to conduct experiments on three types of pumps with different specific speeds (ns =155, ns =125, and ns =88). The study analyzes how the S1/S0 ratio, which represents the blade inlet area to impeller inlet area ratio, affects the hydraulic performance of different centrifugal impellers. Furthermore, it explores the changing patterns of how the S1/S0 ratio influences the pump’s head and efficiency. The results indicate a recommended range of S1/S0 ratios for centrifugal pumps optimized for efficiency at different speeds. When considering the impact on cavitation performance, it is suggested that the S1/S0 ratio should not exceed the upper limit of this recommended range.

Design and Optimization of Centrifugal Pump Impeller Blade

Centrifugal pumps exploit the transformation of rotating kinetic energy into hydrodynamic energy to move fluid. They are a subclass of dynamic axisymmetric work-absorbing turbo machines. In order to aid in pump design, this project uses computational fluid dynamics software to explore intricate internal flows in centrifugal pump impellers. Three distinct kinds of pump impellers were taken in this instance. Pump specs under consideration include speed and discharge. These parameters have been adjusted in order to conduct a comparison analysis of these pump impellers. The plane between blades is modeled in CFD software is used to perform the flow analysis in addition to CAD software. As a consequence, the pressure and velocity distributions were the basis for the valid results, and the computational results were used to compare the pumps' respective performances.

Analysis of Pump Performance by Optimizing Impeller Blade Design

Analysis of Pump Performance by Optimizing Impeller Blade Design

Study on mixing characteristics of viscoplastic fluid in a rigid-flexible impeller stirred tank

Abstract The rigid-flexible impeller (RF impeller) was used in the mixing process of viscoplastic fluid, and the mixing performance of RF impeller was explored by using numerical simulation and experimental analysis. Results indicated that RF impeller could reduce the power consumption (P) and demonstrate the advantage of energy-saving compared with Rushton turbine (RT). RF impeller demonstrated a more pronounced force coupling effect between the impeller and surrounding fluid, and exhibited superior adaptability in the flow field compared with RT. Meanwhile, the utilization of RF impeller can effectively enhance the expansion of high velocity region, expand the cavern zone, and decrease the mixing efficiency number while maintaining constant P compared with RT, and the size of high velocity region and cavern zone could be increased with an increase in impeller speed. Moreover, the cavern structure was obtained through the visualization experiment, and the results were similar to that in the simulation. The findings suggested that incorporating rigid-flexible combination structure design of impeller blades could effectively expand the cavern zone, reduce the stagnant zone, and enhance the mixing efficiency in the viscoplastic fluid mixing process.

INVESTIGATION OF IMPELLER BLADES DESIGN FOR AXIAL FLOW PUMP USING COMPUTATIONAL FLUID DYNAMICS

The investigation of the impeller blade design for axial flow pumps used in power transformers is discussed in this paper. Due to the symmetry of the blade type, axial pumps typically have efficiency levels that are significantly lower than those of classical pumps. In this study, the geometry of the blades is modified to achieve a high efficiency in an axial pump by concentrating on a pump impeller. CF Turbo is the proprietary program used in this simulation. The computational Fluid Dynamics results for hydraulic efficiency, head torque, and pump torque were compared. To identify the key effects and their ideal design factors, Orthogonal Array, Analysis of variance and optimization techniques are used. The best ideal solution for satisfying the pump torque and head limitations is discovered when an effective design variable in impeller blades is taken into account.

On the Effect of Side Clearance in the Vaned Diffuser of a Centrifugal Compressor

AbstractEnvironmental and regulatory pressures have prompted original equipment manufacturers (OEMs) to explore highly boosted internal combustion (IC) engines as a means to minimize toxic air pollutants and meet strict legislative targets. The exhaust gas turbocharger is a key technology used to achieve the boost pressures necessary for advanced engines of the future. Centrifugal compressors with vaneless diffusers have been widely implemented in turbochargers for IC engines, particularly passenger vehicles, primarily due to their compact size and ability to deliver high-pressure ratios over a wide range of flowrates. Methods to improve compressor efficiency near surge without reducing the surge margin have received considerable interest in the past. In many situations, changes to the impeller blade design and/or diffuser are limited by the need to meet the strict engine-rated power target. Such competing demands have encouraged designers to develop variable geometry compressors with the aim of improving near surge performance without sacrificing rated power performance. The on/off-type vaned diffuser is a variable geometry compressor capable of delivering a pressure ratio benefit near surge by utilizing a vaned diffuser rather than a vaneless diffuser. The vanes are retracted prior to the diffuser choking to form a vaneless diffuser in order to reach the engine-rated power condition. Diffuser vane-shaped clearances in the hub or the shroud end wall, termed side clearances, enable axial sliding variability of the vanes into and out of the diffuser passage. Unfortunately, the clearances manifest themselves as a discontinuity in the flow field which gives rise to an efficiency penalty. It is not yet clear how the side clearance geometry and position affect the compressor performance i.e., efficiency and stability. Hence, a numerical and experimental investigation was carried out to determine the impact of side clearance geometry and end wall position on compressor performance. It was found that a side clearance positioned at the shroud end wall reduced the surge margin of the investigated compressor for both types of clearance geometry considered. In contrast to this, a clearance positioned at the hub end wall improved the compressor surge margin but had the lowest efficiency benefit near surge. An experimentally validated Computational Fluid Dynamics (CFD) model was used to inspect the flow field and to elucidate the reasons behind the changes in compressor performance.

Design of impeller blades for intensification on fluid mixing process in a stirred tank

BackgroundMany studies reported that the nonlinear geometry could create a longer turbulence production region and higher turbulence intensities compared with conventional geometry. The self-similarity impeller based on Hibert curves was introduced to intensify the fluid mixing process in this work. MethodsThe mixing performance of Rushton turbine (RT) impeller and self-similarity impeller were evaluated using experimental analyzes and computational fluid dynamics (CFD) with detached eddy simulation (DES) approach. The chaotic mixing characteristics, mixing time, power consumption, trailing vortices structures, turbulence intensity, turbulent kinetic energy dissipation rate and velocity magnitude distribution were investigated. Significant findingsResults showed that self-similarity impeller can effectively increase the largest Lyapunov exponent (LLE) and multiscale entropy (MSE) of mixing system, shorten the fluid mixing time and decrease the mixing number (η) compared with RT impeller under the constant power consumption, and an improvement was achieved in mixing efficiency with the increase of self-similar iteration number of self-similarity impeller. Meanwhile, the reductions in the power number (Np) of 34.6% with self-similarity 1 impeller and 51.9% with self-similarity 2 impeller were achieved in a wide Re range compared with RT impeller. Two large recirculation zones and trailing vortices were easy to form at the suction side of rectangular impeller blade, which can be destroyed and decomposed into smaller ones through the jet flows produced by the concave-convex structure of self-similarity impeller. In addition, self-similarity impeller can improve the uniformity of fluid turbulence intensity, enhance the turbulent kinetic energy dissipation rate and increase the axial circulation capacity in the stirred tank, and increasingly so with the self-similar iteration number.

Anti-cavitation leading-edge profile design of centrifugal pump impeller blade based on genetic algorithm and decision tree

Anti-cavitation leading-edge profile design of centrifugal pump impeller blade based on genetic algorithm and decision tree

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.

Design of impeller blades in the intermediate stage of centrifugal pump to a preset shape of meridional flow pattern

While designing the stages of a centrifugal pump, there is an important and difficult task of impeller blade design. This article deals with an approach to impeller blade design that is based on analytical choice of dependency of flow change along the streamline. The given approach is implemented at JSC “VNIIAEN” in form of custom software which lets the user build a line drawing based on given parameters in normal duty of intermediate stage by designing the blade and calculating the geometrical dimensions of the impeller. The given method has been tested and proven with a physics experiment.

Retro Design of Impeller Blade of the Induced Draft Fan (Fn-280) Using a Coordinate Measuring Machine (Cmm)

Retro Design of Impeller Blade of the Induced Draft Fan (Fn-280) Using a Coordinate Measuring Machine (Cmm)

High Dimensional Matching Optimization of Impeller–Vaned Diffuser Interaction for a Centrifugal Compressor Stage

Abstract The matching and interaction between the impeller and vaned diffuser is the most important aerodynamic-coupling between the components of a high-speed centrifugal compressor. Many research studies have been carried out during the last decade, both experimentally and numerically, on the flow mechanisms underlying impeller–vaned diffuser matching and interaction, with the aim of achieving a high-performance stage. However, the published work lacks any study that optimizes the matching of the impeller–vaned diffuser components in the environment of a full compressor stage due to two unresolved issues, i.e., identifying an effective matching optimization strategy and the high dimensional nature of the problem. To tackle these difficulties, four different optimization strategies (i.e., (1) integrated, (2) single component, (3) parallel, and (4) sequential optimization strategies) have been proposed and validated through a high dimensional matching optimization of the Radiver compressor test case published by the Institute of Jet Propulsion and Turbomachinery at Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University. Particular attention has been paid to the slope of the diffuser total pressure ratio characteristic near the surge point to further extend the stage surge margin. The results showed that the integrated optimization strategy was the most effective one for achieving good matching of the impeller–vaned diffuser interaction due to its inherently strong coupling optimization. Compared with the baseline compressor, the optimized stage achieved a gain of 1.2% in total-to-total isentropic efficiency at the peak efficiency point as well as a predicted 26.17% increase in stable operating range. For the stage examined in this study, a fore-loaded design of impeller blade as well as an increased vane angle for the diffuser vane was beneficial to the impeller–vaned diffuser matching. The more uniform spanwise distributions of the impeller discharge flow angle and the diffuser vane incidence presented the opportunity for a more optimized matching of the flow field between the 3D impeller and the 2D vaned diffuser. The outcomes of this work are particularly relevant for the advanced design of high-speed centrifugal compressors.

Numerical simulation and experimental study on the comparison of the hydraulic characteristics of an axial-flow pump and a full tubular pump

An axial-flow pump impeller is designed on the basis of plane cascade theory, which is based on surface element method, to study the influence of impeller rotor on the hydraulic performance of the a full tubular pump. Then, the performance of the full tubular and axial-flow pumps has been compared and analyzed through CFD and model test, respectively. First, two-dimensional plane cascade theory is used for the hydraulic design of pump impeller blades according to the design condition of an axial-flow pump. Second, the CFD calculations of full tubular pump and axial-flow pumps are performed using numerical simulation software. Finally, the reliability of the numerical simulation is verified by using a model test. Results show that under the design condition of the axial-flow pump, the head, efficiency, and maximum efficiency correspond to 3.30 m, 86.3%, and 86.69%, respectively. In the design condition, the head of the full tubular pump is 3.12 m and decreases by 5.5%, and the hydraulic efficiency is 78.54% and declines by 7.76%. The hydraulic loss caused by clearance backflow and the disc friction loss caused by rotor housing mainly caused the reduction in the hydraulic performance of the full tubular pump. Meanwhile, the decrease in the maximum operating head of the full tubular pump is greater than that of the axial-flow pump. Moreover, the safe and stable operation area of the full tubular pump is only 82.43% of that of the axial-flow pump. This work has important theoretical and guiding significance in the design and practical engineering application of the full tubular pump.

CFD simulation of single-phase flow in flotation cells: Effect of impeller blade shape, clearance, and Reynolds number

A series of numerical simulations of turbulent single-phase flows are performed to understand the flow and mixing characteristics in a laboratory scale flotation tank. Four impeller blade shapes covering a wide range of surface areas and lip lengths are considered to highlight and contrast the flow behavior predicted in the impeller stream. The mean flow close to the impeller is fully characterized by considering velocity components along the axial direction at different radial locations. Normalized results suggest the development of a comparatively stronger axial velocity component for a blade design with the smallest lip length, called big-tip impeller here. Normalized turbulent kinetic energy profiles close to the impeller reveal the existence of an asymmetric trailing vortex pair. The highest turbulence kinetic energy dissipation rates are observed close to the impeller blades and stator walls where the radial jet strikes the stator walls periodically. Furthermore, liquid phase mixing in the flotation cell is studied using transient scalar tracing simulations providing mixing time data. Finally, pumping capacity and efficiency of different impeller designs are calculated based on which the impeller blade design with a rectangular blade design is found to perform most efficiently.

Discrete element method and experiments applied to a new impeller blade design for enhanced coverage and uniformity of shot blasting

Shot blasting is the process of exfoliating the surface of a substance to remove scales or impurities. Shot blasting can be classified into two categories based on the type of material used: air-blowing and impeller-impact types use air and shot balls, respectively. For impeller-type shot blasters, coverage and uniform distribution are more critical than residual stress for the purpose of scale removal. In this study, the discrete element method is used to analyze the coverage and uniformity of the impeller-type shot blasting process with a very large number of shot balls. To enhance coverage and uniformity, filleted and bulged blade designs are proposed and evaluated by discrete element method (DEM) simulations and the amount of fillets and bulges is optimized, realizing an efficiency increase of up to 20%. Shot blasting experiments using bulged blades also show good agreement with results obtained using the discrete element method.

Design of Impeller Blades for Intensification of Gas-Liquid Dispersion Process in a Stirred Tank

Abstract Gas-liquid dispersion characteristics were experimentally investigated by measuring largest Lyapunov exponent (LLE), relative power demand (RPD), and local gas holdup in a stirred tank with rigid impellers, rigid-flexible impellers, and punched rigid-flexible impellers. Results showed that punched rigid-flexible impeller could enhance the value of LLE, namely, the chaotic mixing degree of gas-liquid system compared with rigid impeller and rigid-flexible impeller. RPD for punched rigid-flexible impeller was higher than that for rigid impeller and rigid-flexible impeller. The local gas holdup of punched rigid-flexible impeller system was higher than those of rigid impeller system and rigid-flexible impeller system at the same Pg,m. In addition, a long flexible connection piece length could improve the chaotic mixing degree, RPD, and local gas holdup. The aperture diameter of 8 mm and free area ratio of 12 % of punched rigid-flexible impeller were particularly suitable for the gas-liquid dispersion process in this work.

Numerical investigation of the turbulent flow generated with a radial Turbine using a converging hollow blade

Abstract The aim of this study is to investigate the effect of the blade shape on the characteristic of the flow patterns in a stirred tank. A new impeller blade design has been proposed. It is characterized by a converging hollow. The investigations of the flow structure generated in the vessel are made by using the computer code ANSYS CFX (version 16.0). The analysis has shown that the converging hollow blade yields highly radial flows which gave an increase in the radial velocity by 35% with less power consumption than the flat blade. Also, the effectiveness of the energy dissipation and the quality of mixing has been obviously noted. A validation test of our predicted results with other literature data was done, and a satisfactory agreement has been found.

Design and optimization of mixed flow pump impeller blades by varying semi-cone angle

The mixed flow pump is a cross between the axial and radial flow pump. These pumps are used in a large number of applications in modern fields. For the designing of these mixed flow pump impeller blades, a lot number of design parameters are needed to be considered which makes this a tedious task for which fundamentals of turbo-machinery and fluid mechanics are always prerequisites. The semi-cone angle of mixed flow pump impeller blade has a specified range of variations generally between 45o to 60o. From the literature review done related to this topic researchers have considered only a particular semi-cone angle and all the calculations are based on this very same semi-cone angle. By varying this semi-cone angle in the specified range, it can be verified if that affects the designing of the impeller blades for a mixed flow pump. Although a lot of methods are available for designing of mixed flow pump impeller blades like inverse time marching method, the pseudo-stream function method, Fourier expansion singularity method, free vortex method, mean stream line theory method etc. still the optimized design of the mixed flow pump impeller blade has been a cumbersome work. As stated above since all the available research works suggest or propose the blade designs with constant semi-cone angle, here the authors have designed the impeller blades by varying the semi-cone angle in a particular range with regular intervals for a Mixed-Flow pump. Henceforth several relevant impeller blade designs are obtained and optimization is carried out to obtain the optimized design (blade with optimal geometry) of impeller blade.

Design and Optimization of Mixed Flow Pump Impeller Blades with Hydrostatic Loading and Varying Semi-Cone Angle

Mixed Flow pumps are a combination of both axial and radial flow pumps. In present days they are having a wide range of applications. The impeller blade designing of mixed flow pump has always been a difficult task, the reason being it requires a lot of designing parameter to be considered for successful designing. When compared with radial and axial flow turbo-machines the mixed flow type of turbo-machines always get less importance for these complexities in their designing process. This complexity arises because of the complicated blade and geometry of fluid flow passage. Impeller is considered as one of the most important components in a mixed flow pump for the flow passage. The main motive behind the study of impeller blade design is to cite the reasons for the low hydraulic performance of the pump originally taken into consideration. When the pump is in functioning or operating condition, the rotation of the impeller provides with a geometric shape and the passage of flow gets distorted. It has been observed that all the available designs of the mixed flow pump, impeller blades are designed with a constant semi-cone angle, where as various data books for pump model test signify the fact that the semi-cone angle for these impeller blades can vary a specified range. So it is always an option to verify the fact that if variation of semi-cone angle in this specified range affects the designing parameters or not. From the literature survey it is found that various design methods such as Fourier expansion singularity method, free vortex method, mean stream line theory method, inverse time marching method, the pseudo-stream function method etc., adapted by various researchers, but the design methodology is always a tedious task.Here the authors have proposed the blade designs with a variation of semi-cone at hub.The concepts of Fluid Mechanics and Hydraulic Machines play a vital role in this designing process. Further taking the Hydraulic loading into consideration analysis is done to obtain the possible designs for the impeller blades. Finally optimization is carried out and the optimized design (blade with optimal geometry) is obtained with a varying semi-cone angle taking Hydraulic Loading into consideration.