Stirrer Blade Research Articles

ОПТИМИЗАЦИЯ КОНСТРУКТИВНЫХ И РЕЖИМНЫХ ПАРАМЕТРОВ ТУРБИННОЙ МЕШАЛКИ ДЛЯ ДИСПЕРГИРОВАНИЯ РАСТВОРОВ ПОЛИМЕРНЫХ КОМПОЗИТОВ

The use of polymer composites in the restoration of worn-out body parts of agricultural machinery significantly increases their post-repair life and leads to significant savings in material resources during repair. The composite should have high mechanical and thermophysical properties, which is possible provided that the filler particles are evenly distributed in the volume of the solution. Aggregation of particles, their non-uniform distribution in the polymer solution significantly impairs the performance of the material. Mechanical mixing and dispersion of polymer composite solutions using agitators is a promising treatment method that improves the consumer properties of the material. Theoretical studies were carried out and, taking into account the physical properties of the elastomeric nanocomposite solution, the design of the open turbine stirrer was chosen. It has been found that when developing a device with a stirrer, the effect of the design parameters of the stirrer on the power consumed by the device on the mixing of components, as well as the quality of mixing and dispersion of the polymer composite solution should be taken into account. The effect of the design parameters of the stirrer on the power consumption was analyzed and the design parameters of the stirrer were determined. An active experiment according to the plan was implemented V2 in which the response function took the estimated parameter of the mixing quality of the light transmission coefficient, and the factors of the inclination angle of the stirrer blade and its rotation frequency. A regression model in the form of a second-order polynomial was obtained and its optimization was carried out. The optimal design and operating parameters of the stirrer have been established, which ensure the highest quality of mixing solutions. Based on the results of the studies, the design of an open, turbine stirrer for mixing nanocomposite solutions was developed.

Effect of Stir Casting Process Parameters and Stirrer Blade Geometry on Mechanical Properties of Al MMCs – A Review

Effect of Stir Casting Process Parameters and Stirrer Blade Geometry on Mechanical Properties of Al MMCs – A Review

Evaluating the effects of vortex generation and the settling time of reinforcing particles on the mechanical characteristics of the PRMMC: A real-time simulation and experimental study

Particle Reinforced Metal Matrix Composite (PRMMC) has a significant impact on the various aerospace and automotive industries. This research aims to examine the reason behind the non-homogenous distribution of the reinforcement particles using numerical and real-time simulation approaches. A novel Real-Time Simulation (RTS) technique was adopted to evaluate the stirring performance of the reinforcement particles. The RTS experiments have been carried out using a transparent solution as the liquid medium and Silicon Carbide (SiC) particles as the reinforcement particles. In this research, three major parameters such as particle size (105, 63 and 44 μm), Volume fraction (5, 10 and 15 %) and stirrer blade (Flat Blade (FB), Turbine Blade (TB) and Propeller Blade (PB)) was used to analyze the vortex formation in the liquid medium and settling time of the reinforcement particles. The confirmation experiments were done using the Al-5Zn-2.3Mg-1.4Cu alloy with SiC as the reinforcement particles. Elemental mapping, Electron backscatter diffraction (EBSD) and the clustering analysis using the RTS technique support the attainment of the uniform distribution of the particles. Mechanical characterization such as tensile, hardness and wear tests were carried out. From the confirmation experiments, it was concluded that the optimal condition (particle size of 63 μm, 10 % volume fraction of SiC particles and PB stirrer) shows 18.2 % higher tensile strength and uniform hardness value of 83VHN and 32 % more wear resistance than the initial conditions (particle size of 44 μm, 15 % volume fraction of SiC particles and FB stirrer).

A method for classifying mixing devices using deep neural networks with an expanded receptive field

The paper presents the results of research aimed at developing a method and software tools for identifying the class of a mixing device by its resistance coefficient through experimental data processing. Currently, the main methods for studying mixing devices are finite element methods, as well as procedures of estimating turbulent transfer parameters using laser dopplerometry and chemical methods of sample analysis. These methods require expensive equipment and provide results only for certain types of equipment. This makes it difficult to extend the inferences to a wider class of devices with different designs of mixing impellers. The proposed method involves processing the results of an experiment in which a point light source forming a beam directed vertically upwards is located at the bottom of a container filled with a transparent liquid. A mixing device with variable rotation frequency is placed in the container. When performing experiments in real conditions, small deviations in the size and location of the mixing device lead to difficult-to-predict fluctuations of the funnel surface. Therefore, the image of one marker describes a trajectory that is difficult to predict. It, under certain conditions, can intersect with the trajectories of other markers or be interrupted at the moment when the marker is closed by a stirrer blade passing over it. The resulting image of the markers is associated with a change in the rotational speed of the blade by a rather complex relationship. To identify this dependence, it is proposed to use deep neural networks operating in parallel in two channels. Each channel analyzes the video signal from the surface of the stirred liquid and the time sequence characterizing the change in the speed of rotation of the blades of the device. It is proposed to use neural networks of various architectures in the channels - a convolutional neural network in one channel and a recurrent one in another. The results of the operation of each data processing channel are aggregated according to the majority rule. The computational novelty of the proposed algorithm lies in the expansion of the receptive field for each of the networks due to the mutual conversion of images and time sequences. As a result, each of the networks is trained on a larger amount of data in order to identify hidden regularities. The effectiveness of the method is confirmed by testing it with the use of a software application developed in the MatLab environment.

An overview of the effect of stirrer design on the mechanical properties of Aluminium Alloy Matrix Composites fabricated by stir casting

An overview of the effect of stirrer design on the mechanical properties of Aluminium Alloy Matrix Composites fabricated by stir casting

Fabrication and mechanical characterization of red mud based Al2025-T6 MMC using Lichtenberg optimization algorithm and Whale optimization algorithm

This Investigation provides an insight of fabrication Aluminium alloy 2025 T6 metal matrix composite reinforced with Red Mud using stir casting methodology. % of reinforcement along with grain size and stirrer blade angle are considered as control factor which are used for the fabrication of orthogonal trail design of Taguchi philosophy. Mechanical characterization like tensile strength and micro hardness were considered as output responses. Recently formulated Lichtenberg Optimization Algorithm and Whale optimization Algorithm were utilized for obtaining optimized control factor. According to ANOVA outcome, blade angle and grain size are the most significant factor for maximization of tensile strength and micro-hardness respectively. Also, confirmatory results shown that Lichtenberg optimization algorithm has provided more precise prediction which can be helpful for casting of Aluminium alloy 2025 T6 metal matrix composite reinforced with Red Mud.

Mixing Performance of Anchor and Helical Stirrer Blades for Viscous Fluid Applications

Mixing performance is critical as it may influence the quality of the mixture and operation cost. In a viscous fluid application, the torque required to sustain the high viscosity is very important as it will affect the selection of motor power and cost. The final product of the mixing process is critically influenced by the blade design. The objective of this work is to study the mixing behaviour and the performance of different stirrer blade designs. Two different types of blades were designed and studied to determine how their distinct design features affected flow characteristics in a stirred tank. The liquid viscosity during the formation of grease is taken into account in the determination of viscous force. Fluid flow vector shows that the helical blade efficiently creates a more homogenous uniform mixing. It was found that the helical blade produced 0.25 Nm of torque, whilst the anchor blade produced 0.28 Nm of torque. These values are comparable with the calculation with 8 % error. Therefore, the helical blade can be used as an alternative for the anchor blade due to an efficient mixing process at a faster time and lower power consumption.

Experimental Investigation of In-homogeneity in Particle Distribution During the Processing of Metal Matrix Composites

Particle reinforced metal matrix composites are skilled to fulfill the late needs of cutting edge designing applications, because of its tunable mechanical properties. Stir casting is one of the unmistakable and affordable strategies for preparing of particle reinforced metal matrix composites. However, complete investigation and evaluation of the vortex pressure and the homogenous distribution of particles are still an obstacle for the research community. In this method, vortex pressure and flow pattern are the important factors for the dispersion of particles in the liquid metal. Effectual flow pattern and vortex pressure can be attained by optimizing stir casting parameters such as volume concentration (5%, 10%), stirrer blade angle (45º, 90º), impeller position (20%, 40%) from the base, viscosity of Al melt (1.04 mPa-s, 1.24 mPa-s) and holding time (10 minutes, 15 minutes). In this research, computational fluid dynamics has been used to find the vortex pressure, which influences the particle distribution. A new photographic technique was implemented to find out the flow pattern of the reinforcement particles and the stir casting parameters are optimized using Taguchi method. Optimized parameters have been utilized for the production of PRMMCs. In addition, micro structural image and hardness test confirm the uniform particle distribution of the reinforcement particles. From the outcome of various experimentations, 10 minutes holding time of the stirrer blade with 45º angle which was kept 40% from the base and the viscosity of the Al melt (1.04 mPa-s) with 10% volume fraction of SiC particles shows effective flow pattern and optimum vortex pressure with homogenous distribution of SiC particles.

Influence of stirrer blade design on stir casting of Al Mg Cu/12% SiC composite

Aluminium metal matrix composites are generally produced employing stir casting technique. The effect of stirrer blade on stir casting of aluminium composite with 12 wt% SiC, 4 wt% magnesium and 2 wt% copper was observed. The composites were prepared with 6061 base metal using three different design of stirrer blade which created different vortex fluid flow while stirring. Due to high density of SiC particles, it tries to settle in lower part of the molten metal matrix. Hence change in vortex technique by stirrer design modification can have influence on the mechanical and microstructure behaviour of the composites. The aluminium SiC composite are evaluated by mechanical properties and microstructure analysis based on stirrer blade design used while stir casting. The change in blade stirrer shows variation in testing tensile strength and hardness. The optical microstructure and SEM images were observed to analyze the cast structure and reinforcement distribution in the composites. The SiC particles were appeared to distribute along the grain boundaries of the composite and also cast defects were observed. Composite prepared with alternate peddle blade produced best mechanical properties.

Studies on the Influence of Stirrer Blade Design on the Microstructure and Mechanical Properties of a Novel Aluminum Metal Matrix Composite

AbstractIn the present work, the influence of stirrer blade design on the dispersion of reinforcement particles in the aluminum metal matrix was studied extensively through experiments and also simulated them using the computational fluid dynamics (CFD) method. The microstructure and mechanical properties of the produced metal matrix composites (MMCs) were studied. The analysis of the microstructure was performed using an optical microscope to visualize the reinforcement distribution and binding within the matrix. Further, field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD) were used to characterize the MMCs. The experimental density was assessed using the Archimedes method, and the theoretical density was determined using the mixture law to determine the percentage of porosity in the MMCs. Hardness, compression, and tensile testing were performed on the produced samples. A three-dimensional computational method was used to predict the flow field of aluminum melt and study the influence of the blade design on the distribution of the reinforcement. Experimental results validated the CFD recommendation on the blade design. The CFD recommendation was based on the structure, power number, and the number of blades, and accordingly, the four-blade flat stirrer (B4) design was the best. The experimental results also corroborated the CFD recommendation with the four-blade flat stirrer design achieving the highest compressive strength (642 MPa), highest hardness (45 HRB), and highest tensile strength (206 MPa) among the five different blade designs investigated.

Applying visualization techniques to study the fluid flow pattern and the particle distribution in the casting of metal matrix composites

Abstract For a past few decades, metal matrix composite has a significant role in the various industrial and automobile applications. Production of metal matrix composite using stir casting technique is one of the most effective and economical technique. Achieving the uniform distribution of the reinforced particles was the major problem facing during the production of particle reinforced metal matrix composites and also achieving the effective fluid flow pattern was the greatest challenge to the research community. In this research, some of the major stir casting process parameters such as blade geometry, stirring speed and impeller position were optimized based on the vortex height of the fluid and settling time of the reinforced particles using visualization experiments and Grey relation analysis. Flow pattern of the fluid and the trace of the particles was analysed using a new technique called streak photography. Streak photography was one of the visualization experiments using glycerol water based model. Al8011/SiC metal matrix composites were manufactured based on the optimized stir casting process parameters. Finally, the fabricated composites were carried out for OM, SEM analysis and Brinell hardness testing for confirming the uniform distribution of the reinforced particles. Based on the confirmation results, 45ᴼ stirrer blade angle, impeller position 40 % from the base and 250 rpm stirring help to produce uniform distribution of the particles.

Investigation on the Effect of Stirring Process Parameters on the Dispersion of SiC Particles Inside Melting Crucible

Stirring based liquid metal processing is the widely explored process by researchers for the production of metal matrix composites (MMCs). The dispersion of reinforcement particles is the major challenge in the process. The stirring process parameters govern the dispersion of reinforcement particles in MMCs. The important stirring process parameters are stirring speed, stirrer geometry, stirrer position, and stirring time. In the literature, research works are reported, where the effect of such parameters on the dispersion of particles was investigated either by analyzing flow field using computational methods (assuming constant fluid properties) or by sectioning the casted samples. In cast condition, the dispersion of particles is also influenced by the solidification phenomena. The aim of the present work is to investigate the significance and the effect of stirrer geometry, stirrer position and stirring speed on the dispersion of reinforcement particles inside melting crucible, during the stirring. Aluminium alloy LM25 was used as the matrix material and silicon carbide (SiC) particles having mean size 37.58 microns (d50 value) were used as the reinforcement phases. Samples of the composite slurry during the stirring process were dragged using a quartz tube at three levels inside crucible and microstructure analysis was carried out. Number density (ND) and inter particle distance were evaluated for parameter combinations. The uniform dispersion of SiC particles was observed at 45° stirrer blade angle, 400 rpm stirring speed and 40 mm stirrer position. And, significance order of individual parameter was observed as stirring speed < stirrer position < stirrer blade angle.

Effect of Ceramic Reinforcement Amount on the Hardness of the Aluminum Matrix Composite

Composite are one of the necessity of the current industrial infrastructure because of change in day to day requirements of the consumers. One of the most useful composite in aeronautical and automobile industries are aluminum ceramic composites because of their improved mechanical and thermal properties. However, amount of reinforcement has significant effect the properties of the composites material. Therefore, it is necessary to find out optimum amount of reinforcement that has the significant effect on the particular property of the composite material. Therefore, in the current study, Al-SiC (Aluminum-Silicon Carbide) metal matrix composite was fabricated using stir casting method. Parameters like stirring speed and temperature were kept constant during the process. Sic particle of 200 mesh size was used in different proportions. The reinforcement amount was varied from 0 to 12.5%. The influence of the percentage variation of the composite was studied based on the hardness test, microstructure analysis, optical Emission Spectroscopy (OES) and SEM-EDX. The OES, microstructure analysis and SEM-EDX analysis show retention of SiC in pure aluminium. The SEM-EDX of composite with 7.5% SiC addition shows 5.94% SiC retention that suggests the 79 % efficiency of the process. Moreover, it was observed from the hardness analysis that increases in the percentage of SiC increases hardness. Optical Emission Spectroscopy (OES) and EDS show the inclusion of iron [Fe] from stirrer blade material in results.

Three‐Dimensional Observation of Single Air Bubble Breakup in a Stirred Tank

AbstractA fully automated three‐dimensional observation of single bubble breakup trajectories in a stirred tank is demonstrated to gain unbiased and statistically relevant information about the breakup process. The mother bubble size is kept constant, independently of the stirring rate. The investigated parameter in this work is the power input. Three‐dimensional bubble breakup trajectories and heat maps for the initial breakup location probability for the bottom and side views are provided. The influence of the stirrer blade angle position, at the moment of bubble detachment from the capillary, on the breakup probability is analyzed. The breakup positions are linked to the current flow field, related to the stirrer blade angle, within the tank.

Granular dynamics in a vertical bladed mixer: Secondary flow patterns

This article deals with numerical simulations and experimental measurements of the granular mixing process in a vertical cylindrical mixer with two opposed flat blades with a 45° rake angle. The computer simulations were conducted via discrete element method. The experimental measurements were recorded by a color high-speed camera. Both approaches describe the mixing process in the same way with significant agreement in observations. Even though the geometry and operating conditions are simple, the dynamics of the system is often very complex and a variety of flow structures can be created. For that reason, the behavior of individual flows patterns was analyzed and discussed. The effect of the centrifugal force on deformation of the free level of the granular material and the formation of empty spaces behind the stirrer blades was described. In addition, the behavior of individual particles in specific regions was characterized. At low rotational speed of the blades, particles tend to move close to the bottom of the vessel behind the stirrer blade towards the shaft. At high values, particles are moving in the exact opposite direction. Described movements near the base of the vessel create secondary flow in the form of recirculation zones. Presence of the secondary flow during the mixing process was also confirmed by the experimental measurements. Based on the acquired knowledge, two competing mechanisms of secondary flow formation were presented: (i) the different contact time of the particles with the blade; (ii) the different magnitude of inertial forces acting on the particles around the stirrer blade.

Optimization of Stir Casting Parameters for Manufacturing Aluminium Based Nanocomposites Through Numerical Investigation

Due to technological advancements, nanocomposites are being considered as one of the candidate materials for manufacturing wide variety of automobile components such as brake rotors, pistons, cylinder liners and transmission housings etc. Due to lower manufacturing cost and simplicity, stir casting is the most common method to produce the nanocomposites. The final properties of nanocomposites produced through stir casting primarily depend upon the uniform distribution of nanoparticles, but then influenced by stir cast processing parameters. The influence of stir casting parameters such as stirrer blade angle (90°, 70° and 50°), rotating speed (400 rpm, 600 rpm and 800 rpm) on the better distribution of nanoparticles (2% by wt.) in the molten aluminium alloy matrix was investigated using finite element analysis. These casting parameters were also optimized to provide a fluid flow behavior that results in the effective distribution of nanoparticles. The validation of numerical results was done by manufacturing a nanocomposite at these optimized processing conditions. The microstructural evaluation of the developed nanocomposite revealed the uniform distribution of nanoparticles in the base matrix.

Investigation on the Tensile Strength and Microhardness of AA6061/TiC Composites by Stir Casting

AA6061 is widely used in aircraft, marine and automobile industries for its high strength to weight ratio, good ductility and corrosion resistance. The stir casting process parameters play a vital role in deciding the particle dispersion and the mechanical strength of the composites. In this paper, an attempt has been made to develop the empirical relationship to predict tensile strength and microhardness of the AA6061 reinforced with TiC by incorporating the process parameters such as stirrer blade angle (α), stirring speed (N) and stirring time (T) whose values were optimized. Three factors, five level central composite design has been used to minimize the number of experimental conditions. Response surface method has been used for developing the mathematical model, which can be used to predict the tensile strength and the microhardness of the cast composites at 95 % confidence level. The result indicates that the stirrer blade angle α has the greatest influence on the tensile strength and microhardness followed by N and T.

Analysis of drop deformation dynamics in turbulent flow

Drop breakage and coalescence influence the particle formation in liquid–liquid dispersions. In order to reduce the influencing factors of the whole dispersion process, single drops where coalescence processes can be neglected were analyzed in this work. Drops passing the turbulent vicinity of a single stirrer blade were investigated by high-speed imaging. In order to gain a statistically relevant amount of drops passing the area of interest and corresponding breakage events, at least 1600 droplets were considered for each parameter set of this work. A specially developed fully automatic image analysis based on Matlab® was used for the evaluation of the resulting high amount of image data. This allowed the elimination of the time-consuming manual analysis and furthermore, allowed the objective evaluation of the drops' behavior. Different deformation parameters were considered in order to describe the drop deformation dynamics properly. Regarding the ratio of both main particle axes (θaxes), which was therefore approximated through an ellipse, allowed the determination of very small deviations from the spherical shape. The perimeter of the particle (θperi) was used for the description of highly deformed shapes. In this work the results of a higher viscosity paraffin oil (ηd=127mPa·s) and a low viscosity solvent (petroleum, ηd=1.7mPa·s) are presented with and without the addition of SDS to the continuous water phase. All results show that the experimentally determined oscillation but also deformation times underlie a wide spreading. Drop deformations significantly increased not only with increasing droplet viscosity, but also with decreasing interfacial tension. Highly deformed particles of one droplet species were more likely to break than more or less spherical particles. As droplet fragmentation results from a variety of different macro-scale deformed particles, it is not assumed that a critical deformation value must be reached for the fragmentation process to occur. Especially for highly deformed particles thin particle filaments are assumed to induce the breakage process and, therefore, be responsible for the separation of drops.

PERANCANGAN PROTOTIPE BIOREAKTOR UNTUK PENGOLAHAN LANJUT LIMBAH CAIR PABRIK KELAPA SAWIT (LCPKS) SECARA AEROBIK

LCPKS further processing is usually done by using activated sludge system is implemented in an open pond.This system requires a large enough dissolved oxygen so that if the system would lead to poor aeration then the HRT will be great. In addition to the spread of foul smell due to the system being used is open. This study aims to produce a prototype bioreactor that can be used to replace the above processing system. Bioreactor tank made ​​of transparent plastic tube that comes by baffles and stirrer are made ​​of stainless steel. In addition, the bioreactor is also equipped with a motor stirrer, aeration systems, and deodorizing unit. The resulting prototype has 11.078 cm high and 21.4 cm diameter, 9.2-liter operating volume, and fluid and baffle height is 24.5 cm. Bioreactor equipped with two stirrer blade that is horizontal turbine disc type at 7.13 cm of the tank bottom and paddle 4-rowing at 12.84 cm above the first blade. Bioreactor prototype has passed the leakage testand if the air flowing in at a constant velocity 0.5 m/s then the value of gasholdup (ε) is 0.02. Used this prototype for further processing LCPKS cause COD value of waste fell from 4,482 mg/l to 3,096 mg/l for 30 days long processed.

Single use bioreactors for the clinical production of monoclonal antibodies – a study to analyze the performance of a CHO cell line and the quality of the produced monoclonal antibody

Background In recent years, the use of disposables in the pharmaceutical industry has increased extensively. Disposables can be used in many areas of biopharmaceutical production. The use of disposables not only reduces investment costs, but also requires less manpower to operate, since time consuming change-over procedures are significantly reduced. In addition, disposables enable a high flexibility by reducing unit operation times such as cleaning and sterilization as well as the validation of these procedures [1]. Disposable bioreactors can be subdivided into two main groups, static and dynamic systems. The dynamic systems differ with regard to the power input in stirred, vibromixed or wave-induced systems [2]. Since the power input, the mixing time, the tip speed and the oxygen transfer coefficient may influence the cell culture process and the product quality itself, a thorough characterization of the system used is necessary [3]. SSB (stainless steel bioreactors) and SUB (single use bioreactors) differ in terms of their physical design. Usually, an SSB is equipped with two or three stirrer blades. In contrast, stirred SUBs usually have just one stirrer blade. In addition, the design and the position of the stirrer differ significantly. These distinctions lead to different physical characteristics regarding the power input, mixing time, and tip speed. The SUBs are characterized by a significantly lower power input and tip speed and a significantly higher mixing time. In order to maintain a sufficient oxygen transfer coefficient, the single use bioreactor is equipped with a micro sparger with a pore size of 25 μm. Furthermore, pure oxygen can be used to achieve higher dissolved oxygen concentrations in the cell cultivation medium. This study describes the influence of these technical differences on the performance of a CHO cell line and the product quality of a monoclonal antibody.