The effect of impeller type and shear rate on the evolution of floc size and structure during shear-induced flocculation of polystyrene particles with aluminum sulfate is investigated by image analysis. One radial flow (six-blade Rushton turbine) and two axial flow (three-blade fluid foil, four-blade 45° pitch) impeller configurations are examined. The steady state average floc size is show...

The paper presents experimental evidence for the potentials of CFD methodology in revealing external flow and inner flow shear deformation rates in stirred tanks. Two basic issues are considered: could CFD produce valid solutions for shear rates in mixing vessels, and could practical shear rate differences relevant to specific impeller designs be reproduced by CFD. In a first part, the shear ra...

Stirred tank reactors are one of the most commonly used equipments in industry for achieving mixing and reaction. Flow fields in a stirred reactor are obtained via computational fluid dynamics. In this work CFD is used for the simulation of a reactive flow process consisting of a second order reaction. The extent of reaction is found to depend on impeller speed and its position from the bottom ...

This study involves CFD simulation of blood flow through a non-pulsatile, axial pump consisting of a complex multisectioned impeller with rotating and stationary components, and a stationary housing. We use a particlebased method, Smoothed Particle Hydrodynamics (SPH), to investigate the effects of varying the impeller blade pitch angle and the gap size between the rotor and housing. Regions of...

Influence of diffuser vane position on dangerous blade vibration due to blade flow interactions at part load operating condition was investigated in a centrifugal compressor. By means of some measurement and analysis techniques a mechanism of interaction between blade vibration and circumferential flow condition in the impeller with vaned diffuser was determined, which is a cause of dangerous b...

Nowadays, compact and reliable electronic devices including up-to-date ceramic micro-electro-mechanical systems require thick-film resistors with significantly reduced dimensions and stable and precise resistance values. For that reason, instead of standard laser trimming method, high voltage pulse trimming of thick-film resistors is being introduced. This method allows controlled and reliable ...

Flow in baffled stirred vessels involve interactions between flow around rotating impeller blades and stationary baffles. When more than one impeller is used, which is quite common in practice, the flow complexity is greatly increased, especially when there is an interaction between the multiple impellers. The extent of interaction depends on relative distances between the impellers and clearan...

BACKGROUND When scaling up lignocellulose-based ethanol production, the desire to increase the final ethanol titer after fermentation can introduce problems. A high concentration of water-insoluble solids (WIS) is needed in the enzymatic hydrolysis step, resulting in increased viscosity, which can cause mass and heat transfer problems because of poor mixing of the material. In the present study...

In a gas-liquid stirred reactor, gas tends to accumulate in low-pressure regions behind the impeller blades. Such gas accumulation forming so-called gas cavities, significantly alters impeller performance characteristics. We have computationally investigated gas-liquid flow generated by a Rushton turbine. Rotating Rushton turbine generates trailing vortices behind the blades, which enhance the ...

The impeller blades are very important and precise parts in turbine, but they can be worn and deformed easily. In this paper, we present a novel approach to detect the shape of the impeller blades. The proposed approach is to compare the designed 3D model of the impeller blades with the virtual 3D model of the tested part which is reconstructed by non-contact coordinate measuring machine. The n...