Impeller Diameter Research Articles

Investigation of flow pattern and hydraulic performance of a centrifugal pump impeller through the PIV method

The objective of this study is to analyse the quantitative relationship between the local Euler head distribution and the internal flow in a centrifugal impeller and provide guidance for the design specifications of inverse design methods. The local Euler head at the inlet is mainly affected by the clockwise vortex on the blade suction side. At the outlet, it is affected by the relative motion of clockwise and counterclockwise vortexes. The effect of the two types of vortexes on the local Euler head makes the pump head almost constant under deep part-load conditions, proving that the impeller has an effective diameter. The mean local Euler head distribution along the impeller passage is closely interrelated with the flow pattern. The position in which the mean local Euler head increases fastest coincides with the radial position of the clockwise vortex centre. The position of its maximum value is consistent with the radial position of the end of the clockwise vortex. The position of its maximum value moves towards the inlet as the flow rate decreases, confirming the impeller has an extreme impeller diameter. The inflection points of the mean local Euler head ratio curve correspond to the appearance of vortex structures. • The distribution rules of local Euler head are investigated by PIV experiments. • The local Euler head distribution is related to the internal flow patterns. • The local Euler head distribution determines the hydraulic performance of pump. • The mean local Euler head ratio curve can reflect the position of vortex.

Experimental study of agitator geometry and speed on heat transfer coefficients for both Newtonian and time dependent Power law fluids

Experimental studies on heat transfer coefficients were carried out of Newtonian and time dependent power law fluids in mechanically agitated vessel. Three different Non-Newtonian fluids containing 0.5%(n = 0.973), 1%(n = 0.851), 2%(n = 0.793) CMC (Carboxy Methylcellulose) and water were studied in the coil and 1, 2 and 4 percentages (n = 0.698) Non-Newtonian solutions of CMC in the test vessel. In this section of investigation we are focusing on heat transfer from wall to agitated vessel. In order to find results, the entire experimental data were discussed for jacketed vessel in three different impeller diameter and different speeds. It has been observed that a Modified Wilson plot is most appropriate for finding individual heat transfer coefficients. Data of 1, 2 and 4% CMC, for three impeller diameters, has been correlated and the overall heat transfer coefficient have been approximated with standard deviation $$\pm$$ 8.03%.

Effects of gap between impeller and volute tongue on a pressure fluctuation in double-suction pump

The pump is a machine that receives power through a rotating shaft and converts the mechanical energy into pressure and kinetic energy of fluid. Therefore, it is widely used in various industrial fields, and many studies have been conducted to improve the performance of pumps. In this paper, the effect of the gap between the impeller and the volute tongue on the performance and pressure fluctuation of the double suction pump was investigated. Numerical analysis was conducted using the commercial code ANSYS CFX ver. 18.1. Three different values of gap between the impeller and the volute tongue, 0.067%, 0.145% and 0.224% of the impeller diameter were considered.

Analysis of power consumption for gas dispersion in non-Newtonian fluids with a coaxial mixer: New correlations for Reynolds and power numbers

Coaxial mixers are efficient in mixing of highly viscous fluids. The main objective of this study was to assess the power consumption for the gas dispersion in carboxymethyl cellulose solution, a power-law non-Newtonian fluid, with a coaxial mixer consisting of an anchor impeller and two central impellers as a function of the speed ratio (central impeller speed/anchor speed), fluid rheology, pumping direction of the central impeller, and the rotation mode (co-rotating vs. counter-rotating). This goal was achieved using both experimental and numerical approaches. A computational fluid dynamic model (CFD) was developed and validated using the experimental data. Electrical resistance tomography (ERT) was employed to measure the gas holdup. New equivalent impeller speed and diameter were defined and two novel correlations for the Power number and Reynolds number were proposed and successfully validated at different operating conditions. Additionally, new dimensionless correlations for the ratio of the gassed to un-gassed power consumption and the aerated power number as a function of the flow number, Froude number, and Reynolds number were developed and successfully tested for different coaxial mixing configurations.

Turbulent blend times with off‐centre v‐mounted agitators

AbstractExperimental measurements in a flat‐bottom tank with narrow‐blade hydrofoil and pitched‐blade impellers are used to develop guidelines for off‐centre, or eccentric, placement of vertical agitators in unbaffled tanks. The guidelines are based on providing a turbulent blend time that is no more than 20% longer than that of the same impeller operating at the same rotational speed on the centreline of a baffled tank. In addition to investigating the effect of impeller type, impeller diameter and off‐bottom clearance are also considered. The results support the commonly noted rule of thumb that as off‐centre distance is increased, performance in an unbaffled vessel approaches that in a baffled tank. A notable exception to this axiom occurs when a large impeller is located close to the tank base (specifically, D/T = 0.40, C/T = 0.10, and O/T = 0.25). In this case, a stable impeller tip vortex forms with both impeller types, with slow exchange of material between the vortex and bulk liquid leading to long blend times. Besides blend time decreasing with increasing off‐centre distance, the uncertainty or run‐to‐run variation in blend time also decreases dramatically. In most cases, the pitched‐blade turbine requires a smaller off‐centre distance than the hydrofoil impeller to approximate the blending performance provided during baffled operation.

CFD Research on the Influence of 45° Disk Turbine Agitator Blade Diameter on the Solid–Liquid Mixing Characteristics of the Cone-Bottom Stirred Tank

A numerical simulation of a solid–liquid mixture concentration field in a cone-bottom stirred tank (diameter D = 150 mm) was conducted using computational fluid dynamics (CFD). The influence of the 45° disk turbine impeller diameter on the mixing time number of solid–liquid mixture, mixing energy per unit volume, concentration standard deviation, turbulence energy and turbulent dissipation rate as well as solid just-suspended impeller speed was analyzed. The Eulerian two-fluid model was employed along with the standard k–e turbulence model to simulate the turbulent solid–liquid flow in the cone-bottom stirred tank. A multiple reference frame approach was used to simulate the impeller rotation in a fully baffled reactor. The Fluent® 14.5 commercial CFD software was employed for the transient simulation. The radial and tangential velocities at the outer edge of the impeller along the blade width were compared with the experimental data of Wu and Patterson (Chem Eng Sci 44:2207–2221, 1989), Mahouast et al. (Entropy 133:7–17, 1987) and Kemoun et al. (IChemE Symp Ser 136:399–406, 1994). The further extended computational model could well predict the influence of impeller diameter on the solid–liquid mixing characteristics.

Analisa Pengaruh Diameter Impeller Terhadap Kapasitas Dan Penurunan Tekanan Blower Sentrifugal

Blower is a device used to increase or increase the pressure of air or gas that will be flowed in a particular room as well as suctioning certain air or gas where the Blower produces a relatively high pressure ratio with a greater volume of gas flow. At present the role of the Blower has begun to be widely used, especially in the engineering field, where the Blower role was created to facilitate the process of air exhaust. The blower itself is a producer of air movement which is generally used for ventilation. Blowers consist of several types, namely Axial Blowers and Centrifugal Blowers. Blowers have one component, namely Impeller. To determine the right diameter of the impeller, a performance test on centrifugal blowers with different variations in the size of the impeller diameter is needed, such as an anemometer, wattmeter and tachometer, and the impeller diameters are 180 mm, 190 mm and 200 mm with a rotational speed of 1500 rpm. The results obtained from testing on the diameter of the 200 mm impeller obtained the highest efficiency with a value of 0.0086%. The maximum air velocity is found in the diameter of the impeller with a size of 200 mm which is equal to 19.82 km / h. Then, the maximum pressure drop (∆p) is found at the diameter of the impeller with a size of 200 mm and 190 mm with the same result which is 136,206954 Pa. Then followed by the largest capacity value (Q) found in the variation of the diameter of the impeller with a size of 200 mm that is equal to 118.92 m3 / h. And the largest motor power is found in variations in the diameter of the impeller with a size of 200 mm that is equal to 62.85 W.

Investigation of Heat Transfer Efficiency of Improved Intermig Impellers in a Stirred Tank Equipped with Vertical Tubes

AbstractThe heat transfer of a reactor with improved Intermig impellers was numerically investigated by the finite element method (FEM) simulation software Fluent (V.19). A turbulence model utilized the standard k-ε model, and the turbulent flows in two large vortexes between vertical tubes were collided to form a strong convection. The influence of heat and mass transfer developing from the impeller diameters, the distance between the two impellers (C1), the rotational speed and the installation height of the bottom impeller (C2) were studied. The reactor was equipped with special structure vertical tubes to increase the heat exchange areas. The rate of heat transfer, including criteria such as the convective heat transfer coefficient, the Nusselt number of outside vertical tubes, and the temperature boundary layer thickness, assured the accurate control of the heat exchange mixing state. The experimental testing platform was designed to validate the simulated results, which revealed the influence order of related factors. The Nusselt number Nu was affected by various related factors, resulting in the rotation and diameter of impellers extending far beyond the distance between the two impellers (C1) and the installation height of the impeller (C2). The average temperature boundary layer thicknesses of the symmetrical and middle sections were 3.24 mm and 3.48 mm, respectively. Adjusting the appropriate parameters can accurately control the heat exchange process in such a reactor, and the conclusions provide a significant reference for engineering applications.

Gas-Liquid Contactors' Aeration Capacities When Agitated by Rushton Turbines of Various Diameters.

Mass transfer processes are one of the most important operations in chemical, biochemical, and food industries worldwide. In the processes that are controlled by the gas–liquid mass transfer rate, the volumetric mass transfer coefficient kLa becomes a crucial quantity. The dataset was measured with the aim to create a correlation for kLa prediction in a non-coalescent batch under the wide range of experimental conditions. The dynamic pressure method, which was reported as physically correct in the past, was chosen to be the method for experimental determination of kLa. Our previous work targeted the kLa dependencies in viscous and coalescent batches resulting in correlations that are viable for the broad range of process conditions. We reported that the best-fit correlation is based on the hydrodynamic parameter circumferential velocity of impeller blades in the case of non-coalescent liquids in the vessel equipped by single or multiple impellers at a constant D/T ratio (diameter of the impeller to the inner diameter of the tank). Now, we focus on the influence of various impeller diameters on transport characteristics (mainly kLa) in a non-coalescent batch. The experiments are carried out in a multiple-impeller vessel equipped with Rushton turbines (of four diameters) and in both laboratory and pilot-plant scales. Various impeller frequencies and gas flow rates are used. We examine the suitability of the hydrodynamic description, which was reported in the past, to predict kLa also when the D/T ratio changes. We show that the correlation based on the energy dissipation rate better fits the experimental data and predicts kLa values more accurately in the case of varying D/T values. This correlation could be adopted in the design and scale-up of agitated devices operating with non-coalescent batches.

Numerical Study of Flow Field in New Design Dynamic Cyclone Separators

In this paper the numerical simulation of flow field in the new design dynamic cyclone separator is investigated. The effects of different geometrical parameters such as impeller diameter, number of vanes, length and the location of impeller is investigated. The Reynolds averaged Navier–Stokes equations with Reynolds stress turbulence model (RSM) were solved. The Eulerian-Lagrangian computational procedure is used to predict particles tracking in the cyclones. The velocity fluctuations are simulated using the Discrete Random Walk (DRW). Results show that in new design dynamic cyclone, the collection efficiency is higher and the pressure drop is lower in compare with other studied on cyclones. Installing impeller at the lower positions leads to a decrease in efficiency. With increase in impeller diameter, pressure drop in dynamic new design decreases. Finally, with increase in impeller length, efficiency increases and pressure drop decreases.

Artificial Neural Network (ANN) model development for predicting just suspension speed in solid-liquid mixing system

Just-suspension speed (Njs) is one of the important criteria for the design of agitators for solid-liquid mixing processes. In this manuscript a novel approach on using Artificial Neural Network (ANN) modeling for of just-suspension speed prediction is developed based previous published work that contains 950 datasets including various solid loading, solid density, solid diameter, tank diameter, solution density, impeller diameter, number of impeller blade, blade hub angle, blade tip angle, the width of blade and the ratio of clearance between an impeller and the bottom of the tank with the tank diameter whereas the corresponding to just-suspension speed as an output. Multilayer perceptron type of feed-forward back-propagation neural network was employed for building the ANN model. It found that the configuration of 8 neurons in 1 hidden layer using tangent sigmoid as transfer function presented as the optimum ANN model (11-8-1). Results show the proposed ANN model could provide the desired accuracy on predicting just-suspension speed by achieves 0.96 of correlation coefficient and 0.0059 of mean square error. In addition, the results showed that the integrated Genetic Algorithm-Artificial Neural Network (GA-ANN) model enhanced the accuracy for predicting the just-suspension speed compare ANN model. This novel approach showed the high potential to be applied in chemical process industrial design system.

PIV Measurement of Internal Flow in Mini Centrifugal Pump

The diameter of the ventricular assist pump and cooling pump for electrical devices like servers is about a dozen millimetres and these kinds of pumps belong to the mini pump. The internal flow condition of the mini centrifugal pump has to be clarified because there are so many types of mini pumps according to special specifications and shapes. Therefore, in this research, an open impeller was adopted as a mini centrifugal pump with 55mm impeller diameter in consideration of reduction in impeller manufacturing cost and its internal flow was investigated. Since the outlet angle of the test impeller is large, the maximum efficiency flow rate moves to a large flow rate and the relatively high head and efficiency were obtained in large flow rate region. In the present paper, the velocity and vorticity distribution near the volute tongue are shown and the internal flow in the mini centrifugal pump is clarified based on the PIV measurement results.

Effect of the Radial Measurement Position on the Determination of Just-Suspended Speed Using Pressure Gauge Technology

Pressure gauge technology (PGT) is one of the promising methods to determine the just-suspended speed (Njs) because of its objectivity and adaptability. To identify the flexibility of PGT, the effect of radial measurement position on the determination of Njs was investigated for the first time. The results indicated that the difference between hydrostatic pressure changes measured at different positions was not significant and decreased with increasing impeller diameter and speed, and relative ranges of Njs with an impeller diameter of 0.35T (T represents tank diameter) and 0.53T were within 10.1 and 3.4%, respectively. Meanwhile, the Grubbs method showed no outlier at a confidence interval of 0.95 in measurements. Finally, the consistency was found between measurements from PGT and visual method with a maximum deviation of 18%. Therefore, the radial measurement position had a negligible effect on the determination of Njs, showing the good flexibility of PGT.

Periodic Behaviour of Mean Velocity Fields in Rushton Turbine (RT) Driven Stirred Tank

The present study predicts the periodic behavior of mean velocity fields from the properly verified and validated CFD model to determine the extent of vortex and turbulent activity in a baffled tank stirred by standard six bladed Rushton Turbine. This region includes most of the vortex and turbulent action that controls the mixing and mass transfer processes in the stirred tank. The complexity of periodicity of mean radial and tangential velocities in the radial direction and mean axial velocity in the axial direction is used to fix the proper radial as well as axial extents of the vortex generated by RT. The extent of flow periodicity in the present stirred tank configuration is confined within a cylindrical region around the impeller of radius 0.753 times the impeller diameter and a height of 0.323 times the impeller diameter above and below the impeller center plane.

Numerical Investigation of Hydrodynamics Induced by a Pitched Blade Turbine: Effect of the Shape of Vessel Base

This paper presents an numerical analysis influence of bottom shape on the hydrodynamic structure for cylindrical stirred vessel with bump. The turbulent flow generated in stirred tanks is numerically predicted by the resolution of the Navier-Stokes equation using standard k-ε turbulent model. Several parameters on the mixture efficiency has been investigated. Particularly, we have studied the bottom shape of the tank, which is the distance between the bump-turbine with down pumping direction and impeller diameter. The numerical obtained results of the CFD (computational fluid dynamics) code CFX V13.0 with the MRF (Multi Reference Frame) are presented in order to understand the flow structure. The three components velocity profiles and the turbulent kinetic energy dimensionless distributions obtained at bottom tanks with three different heights are analyzed and discussed. From these results, we can confirm that including a bump at the bottom center of the tank closer to the turbine improves significantly the operating conditions of stirring and mixing. Predictions have been compared with literature data and a satisfactory agreement has been found.

Influence of Impeller Diameter on the Performance of Centrifugal pumps.

The impeller is the most important part of the centrifugal pump because it determines the flow or efficiency of the pump. The design of the impeller and its diameter are very essential when considering pump efficiency. The capacity of the pump is determined from the impeller vanes and channels. The three types of impellers include open impeller, enclosed impeller and semi-open impeller are each designed for a specific application. Impellers are made of cast iron or carbon steel and special alloys depending on their application. The research involves the study of the application of impellers in the centrifugal pumps used by Rand Water Company in Johannesburg. The paper considers how variations in the impeller diameter affect the performance of the centrifugal pump. Simulations were conducted at different diameters of the impeller. The impeller was modelled using AutoCAD and simulated using ANSYS software to determine the performance of the centrifugal pump on different diameters. Calculations were done to compare the results of simulation of the different diameters of 2000mm, 2200mm, and 2400mm. The results show that changing the diameter of a pump impeller affects the flow, head and input brake horsepower of the pump in different proportions. The centrifugal pump gives a high flow rate as the diameter of the impeller increases.

CFD Study on the Flow Field and Power Characteristics in a Rushton Turbine Stirred Tank in Laminar Regime

Abstract A computational fluid dynamics (CFD) simulation was performed to study the hydrodynamics characteristics in a Rushton turbine stirred tank in laminar regime. The effects of operating condition, working medium and geometrical parameter on the flow field and power number characteristics were investigated. It is found that the two-loop flow pattern is formed in laminar regime when the impeller is not very close to tank bottom, while its shape and size vary with Reynolds number and impeller diameter. For a given geometrical configuration, the flow pattern, power number and dimensionless velocity profile are mainly depended on Reynolds number, and do not change with working medium and scale-up for a constant Reynolds number. When impeller off-bottom clearance is too low and Reynolds number is relatively high, the fluid flow would transit from two-loop flow pattern to sing-loop flow pattern as that occurs in turbulent regime. Power number falls for larger impeller in laminar regime. Surprisingly, in laminar regime, power number in the baffled tank with small impeller is almost identical to that in the unbaffled tank.

Effect of impeller diameter on Nusselt number in mechanically agitated vessel

PurposeThe purpose of the study is to developed the effect of Nusselt number on impeller diameter in agitated vessel, which is beneficial to find out the heat transfer coefficient in the process industry. A comparison has been done between the experimental and calculated Nusselt numbers with standard deviation found to be 8.03 per cent.Design/methodology/approachFor studying the effect of impeller diameter on Nusselt Number, the heat transfer measurements were made with three different impellers of diameter. Although the diameter of impeller, Da shows its effect in Reynolds number, an attempt has been made to find the relationship between the impeller diameter and Nusselt number. A correlation between (NNuj/N″Pra1/3 N″Rea2/3) vs Da/DT and (NNuoc/N″Pra1/3 N″Rea2/3) vs Da/Dc in which data of three fluids [1, 2 and 4 per cent carboxy methyl cellulose solution of A type (CMC-A) solutions] have been plotted.FindingsThe heat transfer data for agitated Newtonian and non-Newtonian fluids have been successfully correlated by using the viscosity of the fluid evaluated at the impeller tip assuming a cylinder of diameter equal to that of impeller rotating in an infinite fluid. Data of 1, 2 and 4 per cent CMC-A, for three impeller diameters, have been correlated by equations. Using the above concepts of Reynolds and Prandtl numbers, Nusselt Numbers and Da/DT, it is also possible to correlate the available published data for other non-Newtonian fluids obtained with different impeller geometries.Originality/valueA set up was made for studying the effect of impeller diameter, the heat transfer measurements were made with three impellers of diameter 7.5, 12.7 and 18.35 cm respectively. Although the diameter of impeller, Da shows its effect is Reynolds number, an attempt has been made to find the effect of Da/DT ratio on Nusselt number.

Investigation on the Flow Field and Mixing Efficiency of a Stirred Tank Equipped with Improved Intermig Impellers

Abstract The flow field in a transparent stirred tank with a diameter of D = 0.42 m equipped with dual-layer improved Intermig impellers was numerically investigated using a multi-reference frame method based on the computational fluid dynamics (CFD) simulation code: Fluent. The simulation results were validated by experiments based on a stirred tank testing platform and a Particle Image Velocimetry (PIV) testing instrument. The effects on the flow field arising from the diameter of impellers, the installation height of impellers (C 1), the rotational speed as well as the distance between two impellers (C 2) were investigated. It was revealed that the distance between two impellers and the installation height has obvious influences on the local flow field around impellers. Appropriately increasing the two parameters can enhance the axial flow and achieve a better mass transfer effect. For the tank model rescaled for experiments, the optimized geometrical parameters are C 1 = 0.36D and C 2 = 0.49D that can result in full occupation of large eddies in the entire volume. The mixing process simulation indicates that the mixing efficiency is the best in the region near the impellers while it is the worst in the bottom of the tank. An appropriate increase in the diameter of the lower impellers and a reduction in the distance from the lower impellers to the tank bottom can improve the mixing efficiency in the central region near the tank bottom.

Experimental Investigation on Drawdown of Floating Particles in Viscous Systems Driven by Coaxial Mixers

In view of the current situation of single form and low efficiency, a coaxial mixer with wide adaptability was combined with the drawdown of floating particles in viscous systems, and the effects of operation mode, impeller type, impeller diameter, impeller submergence, system viscosity, solid concentration and particle size were investigated experimentally. It is found that the coaxial mixer under corotation mode can achieve the critical drawdown of floating particles with lower speed and power than the corresponding single-shaft mixer, and the advantage becomes more obvious with increasing system viscosity and solid volume fraction. Under the same conditions, compared with the axial and radial flow impellers, the mixed flow impeller with down-pumping mode can effectively draw the floating particles down with the lowest critical speed and power. Moreover, a larger impeller diameter and smaller impeller submergence are recommended for the drawdown of floating particles, but the impeller diameter should not exceed half of the vessel diameter.