Performance Of Impeller Research Articles

Mixing Performance of the Novel Kar Dynamic Mixer Impeller in Small Laboratory-Scale Systems

Small (<100 mL) lab-scale systems for rapid screening are widely employed in research and development in chemistry and biology, but commonly encounter significant mixing challenges. Researchers fro...

Numerical Simulation and Study on Three-Dimensional Flow Field of Wind Turbine Impeller

hree-dimensional aerodynamic performance of wind turbine impeller is one of the most important elements in the wind turbine design process; its accuracy directly impacts the efficiency and stability of wind turbine operation. As the current numerical simulation for three-dimensional aerodynamic performance of wind turbine impeller does not fully consider the impact of the rotation effect of the wind turbine and other factors, a relatively large calculation error can be resulted. In this paper, a 1.65MW Vestas wind turbine was taken as an model, and design process of wind turbine blade was made. Also, three-dimensional numerical simulation was made to get a comprehensive dynamic performance of the wind turbine, and the influence of wind turbine power and wind farm efficiency by the pitch angle and wind speed were made.

The Key Process Technology Research of Open Impeller Processing

The whole impeller machining technology has long been an important object of study, and has been widely used in aerospace applications. In this paper, CNC machining technology for the whole open impeller is the object of study. First, the geometric characteristics of such parts and processing difficulties are analyzed, and then the key technologies for the rough and the finishing are made. The key technologies described in the paper comprise the building of the leaf ruled envelope surface and the choice of tool axis vector in plunge mill rough process, and the whole leaf processing cutting tool path planning using the parameters method in the finishing process. Finally, completed the machining simulation verification base on VERICUT software, and finished the whole process of the open impeller machining.

Diagnosis of Centrifugal Pump Faults Using Vibration Methods

Pumps are the largest single consumer of power in industry. This means that faulty pumps cause a high rate of energy loss with associated performance degradation, high vibration levels and significant noise radiation. This paper investigates the correlations between pump performance parameters including head, flow rate and energy consumption and surface vibration for the purpose of both pump condition monitoring and performance assessment. Using an in-house pump system, a number of experiments have been carried out on a centrifugal pump system using five impellers: one in good condition and four others with different defects, and at different flow rates for the comparison purposes. The results have shown that each defective impeller performance curve (showing flow, head, efficiency and NPSH (Net Positive Suction Head) is different from the benchmark curve showing the performance of the impeller in good condition. The exterior vibration responses were investigated to extract several key features to represent the healthy pump condition, pump operating condition and pump energy consumption. In combination, these parameter allow an optimal decision for pump overhaul to be made [1].

Prediction method of impeller performance and analysis of loss mechanism for mixed-flow pump

A loss model for the mixed-flow pump impellers was developed by summarizing a variety of loss calculation formulas systematically. The internal flow field of the impeller was obtained by employing the iterative calculation for S1 and S2 stream surfaces to solve the continuity and motion equations of fluid. Based on the calculation method of the flow field and the loss model, it is achieved to predict the impeller performance of the mixed-flow pump and the performance curves of a mixed-flow pump model with adjustable blades. Compared with the test data, the loss model of the mixed-flow pump based on the iterative calculation can predict the impeller performance quickly and accurately, which has a high value on the engineering applications. Based on the test verification, curves of various kinds of losses varied for the flow rate were analyzed under different blade angles. In addition, the mechanisms of various kinds of losses inside the mixed-flow pump impeller were discussed in-depth.

전산유체역학을 이용한 워터펌프 축력 저감

Computational Fluid Dynamics (CFD) method has been used to investigate the axial force of automotive water pump. As the excessive axial force can make some unexpected problems like impeller interference and coolant leakage we have focused on finding the cause of axial force and its reduction in this paper. First, we have tested the closed type water pump with and without balance hole by the calculation methods. By examining the pressure contour around the impeller, we have found that the axial force arises not only from the pressure difference around shroud but also from the pressure difference around hub. So we have tested two impellers - one is normal open type impeller and the other is open type impeller with modified hub. The results show that the axial force reduction is about 150~200N for normal one and 700N@3000RPM for modified impeller. And the hydraulic efficiency which is important in aspect of engine fuel efficiency is reduced about 6.5% for normal one but increased 4%@3000RPM for modified impeller.

Numerical assessment on improving multistage centrifugal impeller performance by changing inlet skew angle at impeller inlet

Multistage centrifugal impellers with four different skew angles were investigated by using computational fluid dynamics. The purpose of this work is to investigate the influences of lean angle at the blade tip of the impeller inlet. Four variations of lean angles, that is, 8°, 10°, 15° and 20°, were made at first stage impeller. Reynolds Average Navier Stokes equation was used in simulation together with a shear-stress transport (SST) k-w turbulence model and mixing-plane approach, respectively. Three dimensional fluid flows were simplified using periodic model to reduce the computational cost and time required. A good performance was expected that the secondary flow can be effectively reduced in the flow passage of the impeller without excessive increase in manufacturing cost caused by the secondary flow. The results show that secondary flow affects the main flow intricately to form vortices or having non-uniform velocity in the flow passage, which in turn results in substantial fluid energy loss not only in the impeller but also in the guide vane downstream of impeller. The numerical solutions were performed and allowed the optimum design and operating conditions to be obtained.

On the hydrodynamics characterization of the straight Maxblend® impeller with Newtonian fluids

The hydrodynamics generated by the straight version of the Maxblend® impeller with Newtonian fluids in a baffled stirred vessel under the transitional and turbulent regime has been experimentally characterized by means of the particle image velocimetry technique. The flow fields obtained with the Maxblend were compared with those obtained with a double stage classical pitched blade turbine (PBT) and a double Ekato Intermig® impellers under the same specific power draw. It is shown that these open impellers induce complex local flows in the radial and axial direction, with an intensity decreasing away from the blades. By contrast, the Maxblend impeller generates a more regular circulation pattern, with efficient top-to-bottom pumping.

Study of the Impact of Quenching Process Parameters in High Dimension Rings of Steel AISI 4140

ABSTRACTManufacturing of high dimension steel rings impose several technological challenges. The lack of understanding of the principles and practices of quenching can result in inadequate hardness, excessive distortion or scrapping of costly machined components. This paper presents the results of an analytical study of the parameters of the quenching operation, among them the fluid dynamics of the agitation in the quenching media. Velocity components of the fluid were measured using an anemometer inside the quenching tank. Uniformity of agitation is compared with a Computational Fluid Dynamics (CFD) simulation. The CFD results revealed the impact of quench tank design, configuration and operation of impellers.

Transient Hydraulic Performance and Numerical Simulation of a Centrifugal Pump with an Open Impeller during Shutting Down

In this paper, the transient behavior of a low specific speed centrifugal pump with straight blades during shutting down is studied through the experimental test, theoretical calculation, and numerical simulation. The variations of the rota- tional speed, flow rate, and head with time are obtained in experiment. Based on the experimental results of the rota- tional speed and flow rate, the additional theoretical heads are quantitatively calculated and analyzed. The experimental results of the rotational speed and flow rate are worked as the boundary conditions to accurately accomplish the nu- merical simulation of the transient flow during shutting down. The experimental results show that the decrease history of the flow rate evidently lags behind that of the rotational speed, while the rotational speed slightly lags behind the head. Theoretical analysis shows that there exists a clear negative head impact phenomenon in the process of stopping. The transient behavior of the centrifugal pump with straight blades mainly comes from the rotation deceleration of im- peller, and has nothing to do with the fluid deceleration. The numerical simulations show that a large area backflow can be seen when the rotational speed decreases to zero due to the flowing inertia. In conclusion, the numerical simulation of the flow field is in good agreement with the internal flow theory of centrifugal pumps.

401 集水装置を有する軸流水車に関する研究(OS3-5 オーガナイズドセッション《熱・流体・エネルギー変換工学の進展》)

A hydraulic turbine for an open channel can generate power at low head and doesn't affect the environment because it doesn't have incidental equipment. However, because the rotational speed is low, the hydraulic turbine outer diameter becomes large. Therefore, an axial flow hydraulic turbine with collection device, using kinetic energy of open channel flow, is proposed. The performance and flow field of impeller only, collection device only and combination of impeller and collection device were clarified. It was checked the speed increasing of collection flow in collection device by analysis result of collection device only and analysis result of output of combination of impeller and collection device is larger than analysis result of impeller only.

J051032 小型遠心ブロワ用ディフューザの内部流れに関する研究

Compact centrifugal blowers with vaned diffusers are often used in home electric vacuum cleaners. To achieve high efficiency and low noise, it is important to improve the performance of impellers and diffusers. In this study, we used a large solidity diffuser whose flow duct is low in height. We studied the influence of internal flow on the diffuser performance by using PIV and pressure measurement and visualizing the flow field in detail. From our measurement results, low velocity was observed in the middle span section and the pressure side in the middle of the overlapped region. Area of the low velocity region became larger with the decrease of flow rate. Pressure recovery increased gradually at the downstream of the low velocity region. From our simulation results, we found that in the low velocity area, low-energy fluid from shroud and hub regions accumulated to the middle span region, which led to low velocity in the middle of the overlapped region.

Effect of impeller type on continuous‐flow mixing of non‐Newtonian fluids in stirred vessels through dynamic tests

AbstractMixing of non‐Newtonian fluids with axial and radial flow impellers is prone to a significant extent of nonideal flows (e.g., dead zones and channelling) within the stirred reactors. To enhance the performance of the continuous‐flow mixing of pseudoplastic fluids with yield stress, close‐clearance impellers were utilised in this study. We explored the effects of various parameters such as the type of close‐clearance impeller (i.e., the double helical ribbon (DHR) and anchor impellers), impeller speed (25–500 rpm), impeller pumping direction, fluid rheology (0.5–1.5% xanthan gum solution), fluid flow rate (3.20–14.17 L min−1) and the locations of outlet (configurations: top inlet–top outlet, top inlet–bottom outlet) on the dynamic performance of the mixing vessel. The performance of the DHR impeller was then compared to the performance of various types of impellers such as axial‐flow (Lightnin A320) and radial‐flow (Scaba 6SRGT) impellers. The dynamic tests showed that the DHR impeller was the most efficient impeller for reducing the extent of nonideal flows in the continuous‐flow mixer among the impellers employed in this study. In addition, the mixing quality was further improved by optimising the power input, increasing the mean residence time, decreasing the fluid yield stress, using the up‐pumping impeller mode and using the top inlet–bottom outlet configuration. © 2011 Canadian Society for Chemical Engineering

A numerical study of the effects of blade angle distribution on the performance and loss generation of centrifugal compressor impellers

The blade angle distribution from the inlet to outlet of an impeller in a centrifugal compressor is known to have significant influence on its flow characteristics. With the aim of understanding the effect of the blade angle distribution, particularly on performance, loss generation, and operating range, four different blade angle distributions were defined with fixed inlet and outlet blade angles, and numerical calculations were conducted over their whole operating ranges, as defined by their stall points and choke conditions. The impeller blade Blade80, which has the smallest variation of blade angle and is relatively radial, was found to exhibit the smallest wall skin friction loss due to its small surface area but the highest blade loading loss. Further, the flow separation near the hub at the suction side and the tip and resulting energy loss give rise to the smallest stall margin of the blades. In contrast, Blade110, which has the largest variation of blade angle, exhibits the largest wall skin friction and hub-to-shroud loading losses but the lowest blade loading loss because the flow from the inlet to the outlet is well guided. As the flow coefficient increases, the performance of Blade110 steeply decreases. The poor performance of Blade110 at high mass flowrates can be explained in terms of flow blockage at the narrow throat. An attempt is made to explain the relationships between the blade angle distributions and the flow characteristics, loss generation, and performance of these impellers.

Effects of Shroud Curvature on the Performance of Centrifugal Compressor Blade

The purpose of the study described in this paper was to investigate the impact of shroud curvature on the performance of a centrifugal impeller or stage. The paper discusses a computational fluid dynamics (CFD) study done to assess the influence of shroud curvature on impeller performance. The computational fluid dynamics (CFD) and finite element analyses (FEA) methods were used to describe the various designs of the impeller. Aerodynamic and mechanical analysis results are presented for four impellers of varying cover curvature and axial length. The aerodynamic results showed there were clear aerodynamic benefits to decreasing the curvature along the impeller shroud. The mechanical analytical results showed that the impeller with the lowest curvature or longest axial length provided the highest performance; it also yielded the lowest Von Mises stress level. In closing, there are clear aerodynamic benefits to decreasing the curvature along the impeller shroud but these benefits must be weighed against the impact on the rotordynamic considerations Comments are offered regarding the rotordynamic issues that must be considered when increasing the length of impellers.

CFD simulation of the laminar flow in stirred tanks generated by double helical ribbons and double helical screw ribbons impellers

Abstract In this paper, the mixing performance of double helical ribbons and double helical screw ribbons impellers mounted on stirred tanks is numerical investigated. The computer simulations are conducted within a specific computational fluid dynamic (CFD) code, based on resolution of the Naviers-Stokes equations in the laminar flow with a finite volume discretization. The field velocity and the viscous dissipation rate are presented in different vessel planes. The global characteristics and the power consumption of these impellers are also studied. The numerical results showed that the velocity field is more active with the double helical screw ribbons impeller. In this case, the effectiveness of the viscous dissipation and the pumping flow has been obviously noted. Also, the pumping and the energy efficiency reach the highest values at the same Reynolds number. The good agreement between the numerical results and the experimental data quietly confirmed the analysed method.

CFD Study of the Mixing of Pseudoplastic Fluids with Yield Stress in a Two-Staged Stirred Tank

The 3D flow field generated by two-stage impellers in the agitation of xanthan gum, a pseudoplastic fluid with yield stress, was simulated using the commerical CFD package. The effect of impeller speed and impeller spacing on power number, cavern size and viscosity distribution was investigated in this work. The results showed that the power number was slightly influenced by impeller spacing. Higher impeller speed and larger impeller spacing contributed to creation of a bigger cavern. The range of high viscosity zone between the impellers increased with an increase in impeller spacing. Impeller speed and impeller spacing could be used as important parameters to improve the mixing performance of multi-stage impellers in the mixing of pseudoplastic fluids with yield stress.

Design Optimization and Performance Studies of an Adult Scale Viscous Impeller Pump for Powered Fontan in an Idealized Total Cavopulmonary Connection

Numerical and experimental studies are carried out to assess the hydraulic and hemodynamic performance and the biocompatibility of a viscous impeller pump (VIP) for cavopulmonary assist in patients with a univentricular Fontan circulation. Computational fluid dynamics (CFD) predictions of impeller performance are shown to be in very good agreement with measured pressure-flow data obtained in a Fontan mock-circulation system. Additional CFD and experimental design studies intending to balance pump performance and biocompatibility with the manufacturability limitations of a percutaneous expandable impeller are also reported. The numerical models and experimental studies confirm excellent performance of the VIP with augmentation of Fontan pressure up to 35 mmHg for flow rates up to 4.5 L/min and operational speeds no higher than 5000 RPM. Scalar stress predictions on the VIP surface and laboratory hemolysis measurements both demonstrate very low hemolysis potential. The impeller designs reported offer ideal performance and can meet manufacturing tolerances of a flexible, catheter-based percutaneous expandable rotary pump.

원심압축기 최적화를 위한 연구(I): 형상변수 및 설계변수에 관한 연구

원심압축기 임펠러의 최적화연구를 수행하기 위하여 임펠러의 형상변수와 설계변수에 관한 연구를 수행하였다. 최적화된 결과로부터 성능향상이 달성되었는지를 평가하기 위하여 기존에 실험되어진 임펠러를 선택하였으며, 이 임펠러에서 최적화를 위한 설계변수를 선정하였다. 임펠러 유로에서 허브와 쉬라우드에서의 형상은 베지어곡선으로 재설계되었다. 또한 임펠러 허브와 팁에서의 블레이드 캠버선도 베지어곡선으로 표현하였다. 각각의 형상곡선은 6-8개의 조정점으로 충분히 일치하는 곡선을 얻게 되었으며, 이 중 형상의 변화에 큰 영향을 미치는 조정점을 선택하여 8개의 설계변수로 최적화가 가능함을 보여주었다. 따라서 기존에 사용되고 있는 원심압축기 임펠러의 점 데이터를 활용하여 최적화 형상을 위한 연구가 진행될 수 있음을 보여주었다. Shape parameters and design variables for a centrifugal compressor impeller were investigated for optimizing a centrifugal compressor. In order to compare the performance of an optimized impeller with the performance of the original impeller, an already tested impeller was chosen and design variables for optimization were selected. The meridional shapes at the shroud and at the hub were re-designed using the Bezier curve. The camber-lines of the impeller blade at the hub and at the tip were also expressed by the Bezier curve. The shape curves for impeller could be expressed using 6-8 control points. Among them, eight control points which have strong effect to the shape can be selected as design variables for optimization. Therefore, any impeller which is expressed by data points for its shape can be optimized using few design variables.

Numerical Design and Performance Prediction of Low Specific Speed Centrifugal Pump Impeller

Abstract In this paper, Based on Two-dimensional Flow Theory, adopting quasi-orthogonal method and point-by-point integration method to design the impeller of the low specific speed centrifugal pump by code, and using RANS (Reynolds Averaged N-S) Equation with a standard k-e two-equation turbulence model and log-law wall function to solve 3D turbulent flow field in the impeller of the low specific speed pump. An analysis of the influences of the blade profile on velocity distributions, pressure distributions and pump performance and the investigation of the flow regulation pattern in the impeller of the centrifugal pump are presented. And the result shows that this method can be used as a new way in low speed centrifugal pump impeller design. Key words : Low Specific Speed, Centrifugal Pump impeller, Two-dimensional Flow Theory, Numerical Design ， Performance Prediction 1. Introduction Centrifugal pump is the most widely used vane pump, and a wide variety of centrifugal pump types are used in many different applications in industry and other technical sectors. After long-term research and practice in centrifugal pump, a wealth of experience of slope of head-capacity characteristic curve which bring about low flow rate instability and high flow rate power overload [1]. Traditional impeller design methods, which are mainly based on the similarity theory, empirical correlation, combination of model testing, and engineering experience, their design process are difficult task, mainly due to the great number of free geometric parameters. [2, 3, 4] So well hydraulic design of low specific pump impeller becomes more difficult and more necessary. Regardless of the design process used, the final decision of a new pump impeller design is usually made following physical testing. These tests are often time and resources consuming. In addition, the flow field in impeller channels is very complicated, so that no simple mathematic model can be established to well predict the performance of impellers. For these reasons CFD (computational fluid dynamics) analysis is currently being carried out on centrifugal impeller. [5, 6, 7, 8] By using it can provide quite accurate information on the fluid behaviour, and thus helps the engineers to obtain a thorough performance evaluation of the design. In this paper, based on Two-dimensional flow theory low specific speed pump impeller design method, which adopting quasi-orthogonal method and point-by-point integration, is put forward. 3D turbulent flow field in the designed impeller is calculated numerically by using RANS (Reynolds Averaged N-S) Equation with standard k-e turbulence model and log-law wall function. And predicting result of impeller according to the flow is presented.